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_= NASA/CRy97-206591. /,,_" -/9". Rain Fade Compensation for Ka-Band. Communications. Satellites ......
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NASA/CRy97-206591
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Rain Fade Compensation for Ka-Band Communications Satellites W. Carl Mitchell Space Lan
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Systems/LORAL, Nguyen,
COMSAT
Asoka Laboratories,
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December
1997
Palo Alto, Dissanayake, Clarksburg,
California Brian
Markey,
Maryland
and Anh
Le
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NASA/CRm97-206591
Rain Fade Compensation for Ka-Band Communications Satellites W. Carl Mitchell Space
r_
Systems/LORAL,
Palo Alto, California
Lan Nguyen, Asoka Dissanayake, Brian Markey, COMSAT Laboratories, Clarksburg, Maryland
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Available from NASA Center for Aerospace Information 800 Elkridge Landing Road Linthicum Heights, MD 21090-2934 Price Code: A08
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CONTENTS Section
Page
SECTION
1 --
INTRODUCTION
SECTION
2-
SPACECRAFT
2.1
BENT-PIPE
2.2
ON-BOARD
SECTION
3-
RAIN
ARCHITECTURES
ARCHITECTURE
FADE
GASEOUS
3.2
CLOUD
3.3
RAIN
3.4
MELTING
3.5
TROPOSPHERIC
3.6
RAIN
3.7
COMBINED
3.8
FADE
ATTENUATION
AND
LAYER
.......................................................................................... ATTENUATION"
..... :..............
ICE DEPOLARIZATION EFFECT
DYNAMICS
FALL
3.10
ANTENNA
OF PROPAGATION
Inter'Event
of Change
FACTORS
FADE
Response
Beacon Time-
4.2.1
Accuracy-
4.2.2
Response
4.2.3
Implementation-
Response
4.3.3
Implementation-
ESTIMATING
FROM
Response
4.4.3
implementation-
3-20 4-1
..........................................
4-1 4-3 4-5
Voltage
AGC
Voltage
PSEUDO-BIT Bit Error
Pseudo
FROM BER from
Time
...........................................................
AGC
Rate
Bit Error
BER ON Channel
- BER from
4-6 4-8
...............................................
4-8
RATE
..............................
........................................................... Rate
Channel
4-8 4-9
...............................................
4-11
Rate ..............................................
4-11
CHANNEL Coded
4-5 4-6
.................................................
ERROR
Bit Error
Pseudo
FADE
4.4.2
3-18
...........................................................
Voltage
Modem
Time-
Accuracy-
....................................
...............................................
RECEIVER
Receiver
AGC
Pseudo
4.4.1
AREAS
.....................................................................
Modem
FADE
4.3.2
LARGE
3-15
Beacon Receiver ......................................................... FROM MODEM AGC VOLTAGE ..................................
Time-
Accuracy-
..............................................................
Receiver
Modem
4.3.1
3-11
3-13
BEACON
Beacon
3-8
Intervals .....................................................
TECHNIQUES
FROM
4.1.3 ImplementationESTIMATING FADE
ESTIMATING
.....................................
.........................................................................................
MEASUREMENT
4.1.2
3-8
3-12
OVER
WETTING
Accuracy-
3-6
......................................................
of Attenuation
CO_ATION
4.1.1
..............................................
................................................................................................
and
ESTIMATING
3-6
.................................................................
Durafion.i,_,.22,.Z,.L..L'...'..L..,
FADE
3-4
.................................................................
SCI_ILLATIONS
RAIN
4.4
3-1
3-3
3.9
4.3
...............................................................
......................................................................................
Rate
4.2
2-2
ATTENUATION
3.8.3
4.1
................................................
3-1
Inter-Fade
_2
ARCHITECTURES
2-1
......................................................................................
3.8.2
RAIN
2-1
ABSORPTION
Fade
4 --
....................................................................
CHARACTERIZATION
3.8.1
SECTION
1-1
..............................................................................
PROCESSING
3.1
m
.................................................................................................
CODED
Data Coded
DATA
................................ Data
.............
4-11
" .... 4-12
..............................
4-12
.............................
4-12
w
BER from
Channel
Coded
Data
SS/L-TR01363 Draft Final Version
iii
45M/TR01363/Part Use or disclosure
of the data
contained
on this
sheet
is subject
to the
restriction
on the
title
page.
1/-_-'_9"/
CONTENTS
= =
(Continued)
Section
Page 4.5
4.6
4.7 SECTION
ESTIMATING
FADE
4.5.1
Accuracy-
4.5.2
Response
4.5.3
Implementation-
4.6.1
Accuracy-
4.6.2
Response
4.6.3
Implementation-
FROM
5.1
BUILT-IN
5.2
OVERDRIVEN
5.3
UPLINK
5.4
DIVERSITY
Known
Time
Noise
- Signal
.........................................
to Noise
4-13
Pattern
.............................
4-14
RATIO
.............................
4-14 4-15 4-15
Ratio ...............................................
4-16
TECHNIQUES
4-17
..............................
........................................................................
...............................................................................
I
m g
l
5-1 5-1
...................................................
m
4-13
................................................
TRANSPONDER
CONTROL
4-13
...............................
.....................................................................................
SATELLITE
POWER
Ratio
MEASUREMENT
MARGIN
.............
Ratio ...........................................................
COMPENSATION
LINK
Data
TO NOISE
to Noise
Signal
PATTERN
DataPattern
Known
SIGNAL
Signalto
DATA
Data Pattern
BER from
OF FADE
FADE
Known
BER from
FADE
SUMMARY
BER ON KNOWN
BER from Time-
ESTIMATING
5 m RAIN
FROM
lira
5-3 5-4
m
I
TECHNIQUES
5.4.1
Frequency
5.4.2
Site
5.4.3 Back-up INFORMATION
5.6
DOWNLINK
SECTION 6.1
5-5
..................................................................................
5-5
Diversity
Diversity
5.5
...................................................................................
..............................................................................................
Terrestrial Network ................................................................... RATE AND FEC CODE RATE CHANGES .......................... POWER
SHARING System
.........................................................................
5.6.1
Preamble
and
5.6.2
Mulfiport
(or Matrix)
5.6.2.1
Muifiport
Amplifier
5.6.2.2
Non-Ideal
Considerations
5.6.2.3
Implementation
5.6.2.3
Insertion
5.6.2.4
Phase
5.6.2.5
Providing
5.6.2.6
Effects
Assumptions Amplifiers
Loss and
of I-IPA
Active
Transmit
Phased
5.6.5
Comparison
of total
5.6.6
Multimode
Amplifiers
5.6.7
Conclusions
ATM
Output
Matrix
HPAs
5.6.4
6.1.1
..........................................................
Redundant
Lens
OVERVIEW
of the
Nonlinearity
Array
.......................................
....................................................
Deviations
Transmit
ATM
Introduction
Amplitude
Active
....................................
........................................
5-10 5-10 5-12 5-12 5-16 5-16
................................................
5-22
...................................................................
5-23
..............................................................
5-24
DC Power
..............................................................
5-25
............................................................................ Power
FOR ATM'S
Sharing. ABR
5-27
..........................................
TRAFFIC
Categories
..................................
6-1
6-3
SS/L-TRO 1363 Draft Final Version 45M/rR01363/Part
of the data contained on this sheet is subject to the restriction on the title page.
5-30
6-1
...........................................................................
iv
use or disclosure
5-9
5-18
m_
LD_L
5-9
................................................
...................................................................................................
Service
5-8 5-8
Array
for Downlink
COMPENSATION
........................................................ ...........................................................
Issues
5.6.3
6 m FADE
5-6
1/-_J37
m
CONTENTS
=
(Continued)
Section
Page 6.1.1.1
Constant
Bit Rate ......................................................................
64
6.1.1.2
Variable
Bit Rate .......................................................................
6-4
6.1.1.3
Available
6.1.1.4
Unspecified
Bit Rate .....................................................................
64
=
6.1.2
ATM
Adaptation
6.1.3
ATM
Layer
6.1.4
Physical
6.1.5
ATM
Bit Rate ................................................................
64
Layer .............................................................................
6-5
..................................................................................................
Layer
Traffic
6-5
............................................................................................
Management
6.1.5.1
Traffic
6.1.5.2
Quality
6.1.5.3
Connection
6.1.5.4
Conformance
6.1.5.5
Congestion
6-5
........................................................................
Parameter
6-6
Descriptors
................................................
6-7
Parameters
................................................
6-7
.............................................
6-8
of Service
Admission
Control
Monitoring
and Enforcement
........................
6-8
=
6.2
!
ABR FEEDBACK
Control
FLOW
COMPENSATION 7"-C
6.2.1
Flow
Control
6.2.1.1
End-to-End
6.2.1.2
Explicit
Rate
6.2.1.3
Virtual
Source
Assessments
IN RAIN
6-9
FADE
...................................................................................
ABR Feedback
6.2.2
..................................................................
CONTROLS Mechanisms
Binary
...........................................
Feedback
Feedback and
6-10 6-11
...............................................
6-11
..........................................................
Destination
(VS/VD)
Feedback
6-13 ......... 6-13
..............................................................................................
6-15
E, m
6.3
6.2.2.1
Response
Delay
6.2.2.2
Rate
6.2.2.3
Reliability
6.2.2.4
Recommendation
......................................................................
Adjustment
Method
6-17
......................................................
6-17
................................................................................
6-17
...................................................................
6-18
SYSTEM CONFIGURATION FOR IMPLEMENTING FADE COMPENSATION ................................................................................................
6-18
W
SECTION
m
SYSTEM
REQUIREMENTS
7.1
SYSTEM
7.2
RESPONSE
7.3
COMPENSATION
SECTION 8.1
1!row
7-
MARGIN
7-1
..................................................................................................
7-1
TIME ....................................................................................................
7-4
RANGE
8 m EXPERIMENTS FADE
.................................................................................
AND
...................................................................................
ESTIMATED
MEASUREMENT
7-5
COSTS .....................................................
EXPERIMENT
- OVERVIEW
8-1
...................................
8-1
8.1.1
Fade
Measurement
Experiment
- Low
8.1.2
Fade
Measurement
Experiment
- Modem
8.1.3
Fade
Measurement
Experiment
- Link
Budgets
...................................
8-6
8.1.4
Fade
Measurement
Experiment
- Cost
Estimate
..................................
8-6
Cost
Beacon
Receiver
Modifications
............
...................
8-3 8-6
m
W
SS/L-TR01363 Draft Final Version
waf_d_E
'--D_L
V
m 45M/TFt01363/Part USe
or
disclosure
of
the
data
contained
on
this
sheet
is
su_ect
to
the
restriction
on
the
title
page.
II-_97
CONTENTS
(Continued)
Section
Page 8.1.5 8.2
FADE
Measurement
Experiment-Schedule EXPERIMENT
.............................................
- OVERVIEW
..................................
Multiplexing
Compensation
Experiment-
8.2.2
Fade
Compensation
Experiment
8.2.3
Fade
Compensation
Experiment-
Link
Budgets
................................
8-14
8.2.4
Fade
Compensation
Experiment-
Cost
Estimate
...............................
8-16
Fade
Compensation
Experiment-Schedule
Compensation
..........
Signaling..
..........................................
8-10 8-13 m
I
8-16
ATM
EXPERIMENT
8.3.1
Description
8.3.2
Development
............................................................................................
8-18
8.3.3
Cost
............................................................................................
8-19
8.3.4
Experiment
Estimate
I
8-8
Fade
- Fade
and Coding
8-8
8.2.1
8.2.5 8.3
Fade
COMPENSATION
.............................................................................................
8-16
................................................................................................
8-17
m
SECTION
9 --
SUMMARY
SECTION
10 m REFERENCES
Schedule
AND
...............................................................................
CONCLUSIONS
8-19
...................................................................
9-1 i
...................................................................................................
10-I b
m
w
w
LDr_aC_L
SS/L.-TR01363 Draft Final Version
vi
45M/l"R01363/Part1/-_J,97 Use or disclosure of the data contained on this sheet is su_'t
to the restriction on the title page.
m
ILLUSTRATIONS k..,
Page
Figure 2
:
2-1
Simplified
Block
Diagram
of A Bent-Pipe
2-2
Simplified
Block
Diagram
of An OBP Satellite
3-1
Gaseous angle
3-2
absorption
at 20 and 30 GHz;
Satellite
..................................................
.........................................................
temperature:
angle
absorption
at 20 and 30 GHz;
temperature:
25°C,
3-2
elevation
40 ° .........................................................................................................................
Specific Attenuation Temperature ..............
of Clouds as a Function .............. . ..........................
2-2
5°C, elevation
40 ° .........................................................................................................................
Gaseous
2-1
3-2
of Frequency and "... .... ...................................................
3-3
L
3-4
Attenuation
and
Maryland
--=
3-5
Rain
Rain Rate
Elevation
angle
Attenuation
Elevation
Cumulative
for Clarksburg,
39 ° .....................................................................................
Distribution
Angle
Distributions
at 20 GHz
for Different
Rain
3-5
Climates;
40 ° .......................................................................................................
3-5
3-6
Cumulative
Distribution
of Scintillation
Fading
at 20 GHz
...................................
3-7
3-7
Cumulative
Distribution
of Scintillation
Fading
at 30 GHz
...................................
3-7
3-8
Distribution
of XPD
3-9
Rain
w
event
observed
27.5 GHz
=
ACTS
30 GHz
at Clarksburg
beacon
signals
are
.......................................................................
Signal
attenuation
shown;
elevation
3-9
on 20.2 and angle
39 ° ............................
3-9
3-10
Power
Spectra
3-11
Ratio
of Spectral
3-12
Features
Commonly
3-13
Average
Fade
3-14
Fade
Duration
Distribution
at 20.2 GHz
..................................................................
3-14
3-15
Fade
Duration
Distribution
at 27.5 GHz
..................................................................
3-14
3-16
Inter
Fade
Interval
Distribution
at 20.2 GHz
..........................................................
3-15
3-17
Inter
Fade
Interval
Distribution
at 27.5 GHz
.................
3-16
3-18
Cumulative
Distribution
of Fade
Slopes
at 20.2
GHz
............................................
3-16
3-19
Cumulative
Distribution
of Fade
Slopes
at 27.5
GHz
............................................
3-17
3-20
Fade
Slope
3-21
Joint
Probability
w
i
at 20 and
Function 3-22
Joint
of the
Joint
Used
Histograms
Probability
of Site Separation
Depicted
at 27.5 and
in Figure 20.2
in Characterizing
at 20.2 GHz
Exceeding
for Los Angeles,
OH Specified
Events
.....................
i........................................
Threshold
Specified
3-10 3-10 3-11 3-13
3-17
as a
...................................................... Threshold
3-18
as a Function
CA ....................................................................
Exceeding
for Washington,
Precipitation
Specified
for Cleveland,
of Rainfall
.............................................
.........................................................................
of RainfaiiExceeding
of Rainfall
GHz
3-9 ..................................
........................................................................
at 20.2 GHz
of Site Separation
Probability
Event
Components
Duration
of Site Separation 3-23
Fading
Threshold
3-19
as a Function
DC ....................................................................
3-19
w
LD_L.
SS/L-TR01363 Draft Final Version
vii
45M/TR01363/Part Ids¢ or disclosure
of the
data
contained
on this
sheet
is subject
to the
r_stricffon
on the title
_g¢.
II- 9_,97
ILLUSTRATIONS
(Continued) w
Figure
Page
3-24
Antenna
Reflector
3-25
Antenna
Feed
3-26
Antenna
Reflector
3-27
Antenna
Feed
4-1
Beacon
Receiver
4-2
Effect
4-3
Shifted-Phase
4-4
Theoretical
4-5
Pseudo
4-6
C/N
4-7
Signal
5-1
Transponder
5-2
Cumulative
Wetting
Wetting
Loss
Wetting
Wetting
plus
....................................................................
at 30 GHz
Diagram
Decision
3-20
Loss at 30 GHz .............................................................
Noise
....................................................................
Uncertainty
on Estimated
for
BER Fade
Thresholds
Pseudo
of QPSK
Actual
Signal
BER on Ideal
on Ideal
m
3-21
11w
3-22
Linear
Channel
4-2
Fade .....................
Measurement
Linear
I
3-21
.................................................................................
Power
BER Performance
BER Versus
at 20 GHz .............................................................
at 20 GHz
Loss
Block
of Carrier
Loss
4-7
............
Channel
...........
....................................
4-9 4-10 4-10 m
Fading
Caused
to Noise
by Rain
Ratio
Measurement
TWTA
..............................................................
Hardware
Operation
Distribution
for a Mid-Atlantic
Attenuation
......................................................
in Overdrive
of Rain
Location;
Region
Attenuation
Elevation
4-15
Angle
4-16
.............................................
at Different
5-4
40 ° ....................................................
5-6
Diversity
Gain
at 20 GHz
as Function
of Site Separation
........................................
5-7
5-4
Diversity
Gain
at 30 GHz
as Function
of Site Separation
........ : ...............................
5-7
5-5
Top-Level
Input
Allowable HPAs
of Multiport
of Worst-Case Allowable
Matrix,
Contours
5-8
HPAs
of Worst-Case Phase
Matrix
Matrix, 20,000)
5-10
............................................................
Degradation A0 and Gain
Matrix
Port-Port
Deviation
or Output
Amplifier
Carrier Power Phase Deviation or Output
Contours of Average Degradation AC Due
5-9
=
7-Z
Diagram
Contours Maximum
5-7
J
Frequencies
5-3
5-6
l
5-10
AC Versus Deviation AG of
....................................................................
Isolation
Iso
Versus
A0 and Gain Deviation
5-17
Maximum
AG of Input
Matrix,
.............................................................................................
5-18
and (Average +2 x Sigma) of Carrier Power to Random Deviations in Characteristics of Input
HPAs or Output Matrix (K = 8 and # Monte Carlo Cycles ...........................................................................................................................
= 5-19
Contours of Average and Due to Random Deviations
(Average +2 x Sigma) of Port-Port Isolation Iso in Characteristics of Input Matrix or HPAs
(K = 8 and # Monte
Cycles
Contours Due
Carlo
of Average
to Random
and
(Average
Deviations
(K = 8 and # Monte 5-11
Active
Transmit
6-1
ATM
Cell Format
Carlo
Lens
= 20,000)
.............................................................
+2 x Sigma)
in Characteristics Cycles
Array
= 20,000)
Antenna
of Port-Port of Output
5-20
Isolation
Matrix
Iso
or HPAs
.............................................................
Concept
5-21
......................................................
5-23
..........................................................................................................
6-2
SS/L-TR01363
LD_L
viii
Draft
Final
45M/TR01363/Pa Use or disclosure
of the
data
contained
on this
sheet
is subject
to the
restriction
on the
title
page.
Version rt 11-9F_97
=
ILLUSTRATIONS
(Continued) Page
Figure
-
i;¸
w
w
-=-.
6-2
End-to-End
6-3
Simplified
6-4
Explicit
6-5
Simplified
6-6
VS/VD
6-7
Simplified
6-8
System
7-1
Distribution
of the Fade
7-2
Attenuation
Distributions
Binary Flow
Rate
Feedback
Diagram
Feedback
Flow
Flow
Flow
Flow
of Explicit
Diagram
Feedback
Control
....................
6-12 6-12
.......................................................................
6-14
Rate
6-14
Feedback
Control
...............................
................................................................................
of VS/VD
Feedback
for Implementing RatJ6
............................................................ Binary
Control
Control
Configuration
Control
of End-to-End
Diagram
Feedback
Flow
Control
Fade
Between
........................................
Compensation
27.5 and
6-15
20.2 GHz
6-16
............................
6-18
....................................
7-2
w
Angle 7-3
at 30 GHz
Rain
Zones;
Elevation
20 ° ........................................................................................................................
Down-Link Zones;
Degradation
Elevation
Distributions
Angle
Fade
Measurement
8-2
Low
Cost
8-3
Schedule
8-4
Fade
8-5
Signaling
and
8-6
Channel
Coding
8-7
Code
Rate
Transition
Sequence
8-8
Code
Rate
Transition
State
8-9
Schedule
8-10
ATM
Experiment
Configuration
8-11
ATM
Experiment
Schedule
Experiment
Beacon
Receiver
for Fade
Block
Block
Information Process
for Fade
Block
Channel
Rain 7-3
Diagram
8-2
.......................................................
...............................................................
Experiment
Experiment
for Different
7-3
:.... .................................................................
Diagram
Measurement
Compensation
at 20 GHz
20 ° ....................
8-1 w
for Different
...........................................................
Compensation
8-8
Diagram
...................................................
8-10
Multiplexing
.................................................
8-11
............................................................................................
8-12
.................................................................................
Diagram
8-5
8-13
........ i..i.. .......................................................... Experiment
.......................................................
...............................................................................
8-14 8-17 8-17
........................................................................................
8-20
E r i====
B i w
w
m
m
i,.D_L
ix
SS/L-TR01363 Draft Final Version 45MJTR01363/Part
=_
Use or disclosure of the data contained on this sheet is subject to the rest_ction on the title page.
1/- Sle,97
TABLES w
Table
Page
3-1
Average
4-1
Beacon
4-2
Low
4-3
Summary
5-1
Link
Properties Power
Cost
Measurement
Beacon
Budget
Cloud Fade
Receiver
of Fade
Parts
60 Mb/s
Types
Estimate
.......................................................... Accuracy
3-4
............................................
Techniques.:....:....
..... ..... ...........
Demod-Decode/Recode-Remod
per 0.6-deg
Beam
into
4-6
... .......................
4-17
Payload
70 cm receive
I
terminal
................
5-14
No. of Amplifiers, K, to Support 10-dB Power Increase for X of Y (=N) Carriers .........................................................................................................................
5-15
5-3
Effects
5-22
5-4
Representative
5-5
Total
5-6
of HPA
Failure
on Carrier
Power
and
Port-to-Port
I
4-4
Cost ........................................................................
Measurement
for Ka-band
Transmitting 5-2
of Different
Isolation
mJm
..................
g
[]
DC
Ka-band
Power
Systems
for Three
with
Transmit
Number
of Beams
Power-Sharing
per
required EIRP of 50.65 dBW, 128 0._deg Spot beams gain) ............. _i."...., .......... .......... .. .........................................
Number
of Active
Modules
.............
5-25
M
Approaches
(assumes dBi peak
Transmit
Satellite
(or Elements)
for
Three
with 48.7 ". .....................
m
5-25
I
Sharing m
Technique Power
.....................................................................................................................
Dissipated
Representative (OBO) Levels
and Radiator
Size for the
Three
Sharing
5-25
Techniques
Single-mode TWT Efficiencies at Several Output ................................................................................................................
6-1
Attributes
6-2
Feedback
6-3
Assessments
7-1
Link
Margins
8-1
Low
Cost
8-2
Beacon
8-3
Fade
Measurement
8-4
Cost
Estimate
8-5
LET to VSAT
8-6
VSAT
8-7
Cost
8-8
Preliminary
of ATM Controls
Traffic
Categories
for ATM
Beacon
Receiver
Tim_
Performance
Budget
Experiment
for Fade
Controls
for Availability
Receiver Link
Flow
5-28
, ........... ............................................
6-3
Requirements
at Threshold
and
6-16
99.7%
..........
7-4
.........................................
8-3
...............................................................
Communications
Measurement
6-10
....................................................... of 99%, 99.5%,
Experiment
Channel
Link
8-4
Budget
............
8-7
...................................................
8-7
Link
Budget
.........................................................................................
8-15
to LET Link
Budget
.........................................................................................
8-15
Compensation
8-16
Estimate
for the Fade Cost
Estimate
for ATM
Experiment
Experiment
.........................................
...................................................
8-20
SS/L-TR01363
LD ¢.
Draft
X
Final
Version
45M/TR01363/Part Use or disclosure of the data contained on this shett is subject to tht restriction
on tht title page.
g
5-26
Backoff
Traffic ..........................................................................
of ABR Feedback Required
................
............
I/-9_,_
L
EXECUTIVE
This
report
provides
alternatives
for Ka-band
estimates The
rain
depolarization,
L
_
three
fade
scaling
events
techniques
areas,
satellite
ratio
from
channel
coded
ratio.
The
evaluated
fade
and
beacon data,
practical
report
and
rain
fade
within wetting.
power,
compensation
pseudo
techniques
include
bit
error and
link
and
ice
fade
fade
pattern,
built-in
cost
rate,
simultaneity
evaluated
data
rain
interval,
bandwidth,
The
known
of and
depth,
inter-fade
AGC,
from
compensation
experiments.
or fade
a 1-GHz
modem
ratio
compensation
duration,
antenna
fade
a description
attenuation
of fades
bit error
rain
includes
measurement include
correlation
of
This
scintillation,
extended
include
fade
characteristics
of fade,
over
evaluation
systems. rain
tropospheric
frequency
and
satellite
for performing
evaluated
rain
a review
SUMMARY
of
measurement ratio,
bit error
signal-to-noise
margin,
overdriven
F_
satellite site
transponder,
diversity
code
rate
uplink
through
power
routing,
changes,
control,
and
downlink
back-up
power
diversity
techniques
terrestrial
network),
sharing
(i.e.,
active
(i.e.,
frequency
diversity,
information
phased
array,
rate active
and
lens
FEC array,
w
matrix
or
control w
have
multi-port
technique also
The
first
covers
been
the
ABR
service
Based
on
two
proposed
rain
with
the
the
ratio.
experiment
the rain
compensation
evaluation
are
The
two
are
uplink
fade
rate
techniques
power
control,
issues
related
to these
techniques
and
and
time,
rate
techniques. second
technique
and
further
one for
the
and
implementation
evaluation
coded
for further
information
experiments
the
control
flow
experiment.
channel
selected
while
flow third
for
from
feedback
Three
in the
ratio
ABR
source.
selected
bit error
an
the
accuracy
techniques
compensation
and
A feedback
is addressed
of measurement
power,
from
measurement
techniques.
measurement beacon
amplifier),
implementation
traffic)
criteria
three
multi-mode
information
to assess
deals
fade
the
(i.e., for ATM-based
experiments
noise
and
for varying
experiment
complexity, m
amplifier,
data,
in the and
signal-to-
evaluation
in the
FEC
rate
code
first
second
changes.
m
Implementation
of the
ABR
feedback
flow
control
technique
is carried
out
in the
third
experiment. From (1)
this
study,
Due
the following
to severe
margins system, m z
fading
should for
generally dynamically implemented.
conclusions in Ka-bands
be allocated
the
link
consists
earth
of a fixed
fixed
in a number
for
from
allocated The
can be made:
all carriers station
clear-sky the
A to earth
rain
clear-sky
margin
zones,
in a network.
margin
through
of rain
station
and
sufficient
system
In a Ka-band
satellite
B, the
margin
an additional
system margin,
which
is
fade
compensation
technique
being
is typically
in the
of 4-5 dB.
It is not
range
m
m
I..D_l..
SS/L-TR01363 Draft Final Version
xi
45M/TR01363/Part Use
or
disclosure
of
the
data
contained
on
this
sheet
is subject
to
the
restriction
an
the
title
page.
11-9F_
uncommon power (2)
to provide
control
In order power
system
and
a high
technique
FEC
code
up
to about
contribute
than
15 dB in the
in moderate
to provide control
rate
more
system
with rate
and
the
heavy
rain
margin,
4.5 dB toward
range
that
The
use
the
dynamic
of a typical
uplink
zones.
it is desirable
technique
changes.
dynamic
to combine
implements
of the
the
second
part
the
source
system
B
information
technique
of the
uplink
alone
will
margin. I
(3)
The
three
fade
proposed
experiments
measurement
and
are
intended
compensation
to assess
techniques,
the
and
feasibility
ABR
of the
selected
flow
control
feedback
m
technique.
The
beacon
first
power,
bit
experiment, error
planned
ratio
from
for
channel
a ten-month
period,
coded
and
data,
will
compare
the
signal-to-noise
ratio m
techniques
in terms
reliability,
stability
experiment, issues
also
related
of implementation of
planned
to the
implements
the
combination
of both
period,
will
address
control
technique.
measured
power
The
such
and
rate third
implementation
as measurement
ease
period,
control
information
techniques. the
data,
for a ten-month
uplink
source
issues
will
of
and
FEC
experiment, issues
operation.
address
technique
and code
rate
to the
The
the the
planned
related
accuracy
and second
implementation technique
changes,
which and
feedback
m
the
for a twelve-month ABR
i W
mid
flow J
m D
_
SS/L-TR01363 Draft Final Version
I_YtrTIIMB
LOlL
xii
45M/TR01363/Part1/Use
or disclosure
of the data
contained
on this
sheet
is subject
to the restrictian
on the
title
_g¢.
9=&/_7
SECTION
In the
last
two
Ka-band
satellite
to the
Federal
and
launch
time
frame
systems.
have
been
[5].
corporate
technologies
successful
known
affected
between
etc.)
the
earth
suitable
alleviate
spacecraft
(AGC),
pseudo
known
data
these
on
evaluation
overdriven
satellite
terrestrial
in
the
services
weather
establish
such
of
as voice,
technologies
Satellite
(ACTS)
distance
learning,
(DTH)
information,
satellite
realization
1998-2001 on-board
of these
include
and
firmly
increases GHz),
the
video, etc.
The
communications national
as
and
global
for performing
ratio,
bit
fade
characterization fade
information
An
or terminal
assessment is also
compensation
techniques
power
control,
and
forward
rate
such
frequency
gain
control
ratio
from
5 provides
as built-in site
and
of implementing
Section
and
OBP
evaluation
bit error cost
included.
systems,
events,
automatic
of the
and
attenuation,
a detailed
ratio.
uplink
rain
data,
to
advanced
4 provides
coded
fade
more
Section
from
stations
compensation
3.
channel
station
and
of fade
ratio
path
a review
simultaneity
error
earth
earth
dynamics,
modem
more
it is imperative
satellite
including
power,
Ku-
temperature,
provides
and
as beacon
the
at
measurement
bent-pipe
and
transmission
for Ka-band
of conventional fade
noise
system,
report
such
signal-to-noise
transponder,
This
experiments.
in Section
and
rain
satellite
these
scintillation, is described
system
implemented
to rain.
rain
rain
be
GHz) becomes
or downlink
alternatives
proposed
The
uplink Ka-band
means
(6/4
performance
in receive
in the
due
the C-band
carrier
increase
In a viable
overview
from
the
compensation
estimates
of the
network,
would
in the
direct-to-home
financial,
of rain
techniques
pattern,
data,
to construct
Technology
typically
filings
advanced
of some
tele-medicine,
(30/20
of
bit error
techniques
detailed
up
number
effects
measurement
feasibility
applications
effects
tropospheric
of fade
scale,
Communications
compensation
a general
wetting
on a global
on-orbit
frequency
fade
architectures.
depolarization,
The
satellite.
fade
cost
to use
periods
rain
and
proposed
attenuation,
and
of practical
2 presents
antenna
during
impairment
experiments,
systems
means
to rain
station
a
its authorization
emerging
systems
carrier
severe
includes
submitted
operation
scientific
Ka-band
adaptive
the
evaluation
to (due
depolarization,
to request
commercial
(NII/GII).
as the
GHz)
14 U.S. companies
to begin
training,
economical
that
(14/12
severely
w
music,
to implement
in Order
services, and
infrastructures
It is well
(FCC)
Advanced
of these
and
information
Section
these
deployment
alone,
plans
satellites
etc.
the
distribution
important
and
by
of software,
in 1995
begun
[2], [3] & [4] to offer,
Internet,
Through
data
distribution
GHz) of these
multimedia,
have
Commission
(30/20
demonstrated
program
that
For example,
A majority
(OBP)
video,
of companies
Communications
[1].
data,
band
a number
Ka-band
processing
an
years,
1 m INTRODUCTION
link
a
margin,
diversity,
back-
error
correction
(FEC)
code
rate
of these
techniques
is also
provided.
W
changes,
and
downlink
power
sharing.
A comparison
=_ w
SS/L-TR01363 Draft Final Version
m_ m
1-1
45MfTR01363]Part
w Use
or disclosllre
of the
data contained
ca
this
sheet
is sub_ect
to the
restriction
on
the title
page.
1/- 9/5,97
The
fade
rate
compensation
(ABR)
service
requirements
technique
for the
is presented
is derived
to
asynchronous
in Section serve
6.
as the
transfer
From
the
baseline
mode
above
system
(ATM)
relevant
design
available
results,
bit
a set
requirements.
of
W
These ==
requirements
are
compensation gives
the
contains
experiment summary an
satellite
presented
error
operating
and analysis with
in Section and
the
ATM
conclusions. for each back-off,
7. The
rain
fade
experiment
The
references
fade
measurement
a bent-pipe
measurement are
described
are given
satellite
experiments, in Section
in Section
technique
10.
applied
operating
in saturation
rain 8.
The
fade
Section
m
9
Appendix u
to a bent-pipe and
an
on=
board
processing
satellite.
m
J
m
I
p_ W
LD_L
SS/L-TRO 1363 Draft Final Version
1-2
45M/"r'RO Use or disclosure
of th_ data contained
on this
sheet
is subject
to the
restriction
on
the
title
page.
1363_art
II-9_97
w
i
SECTION 2 -- SPACECRAFT
-
In
general,
there
are
communications and
2.1
Ka-band
carriers down
channels
that,
for
received
by the
state
An
noise
frequency
and
terrestrial
performance
earth
combination
steps:
processing.
of the
bent-pipe
in
commercial
Most
current
type
while
noise
are
due
intersystem relay
a link
of various
can
and
Cmost
transmission
B, the (e.g.,
intermodulation
systems
interference.
(adjacent
sharing
limited
[9] and
interference
interference
or
[6],
the
[7],
& [8])
controlled
by
one
any
to
systems
is ratio
as uplink
transfer
and/or
and
particular,
due
to
interference the
component
[10];
downlink
interference
interference), In
amplifiers
downlink
such
modulation
bands.
into
carrier-to-noise
(co-channel
same
the
(LNAs),
satellite
Uplink
satellite
satellite,
tube in the
total
in
separation
or bent-pipe
components
to intra-system
be
and
stations
amplifiers
by traveling-wave
station
downlink
earth the
frequencies,
of transparent
major
low-noise
downlink
(SSPAs),
from
2-1, on-board
by
amplification
A to earth
interference;
in Figure
to
amplifiers
station
transmitted
amplification
final
on several
radio of
are
As shown
characteristic
uplink
entries reuse),
on-board
or signals
frequencies
power
thermal
interference
satellite.
of major
inherent
from
downlink
employed
type.
carriers
or transponders,
solid
a link
and
systems
of the OBP
uplink
at B depends
thermal
=_,
received
from
stations.
bent-pipe
satellite,
conversion
or
architectures
ARCHITECTURE
a number
earth
from
are
undergo
(TWTAs)
spacecraft
satellite
bent-pipe
are
individual
and
namely,
systems
BENT-PIPE
uplink
of
communications
in a conventional the
types
satellites,
Ku-band
proposed
two
ARCHITECTURES
carrier or
by
a
components. Input
Output
multiplexer filters
TWTAs/ SSPAs
multiplexer filters
Receive
Transmit
antenna
antenna
-<
HOownk__ cony.
LNA
/
•
=
M
Figure
2-1.
Simplified
Block
Diagram
of A Bent-Pipe
Satellite
Ul=l_a=m
LDI' L
SS/L-TR01363 Draft Final Version
2-1
45 M/T'R01363/Pa Use or disclosure
of the data
contained
an this
sheet
is su_ect
to the
restriction
on the
title
page.
rt 1/- _tr-a97
2.2
ON-BOARD
OBP
satellites
are more
complexities a specific can
be
OBP
design.
designed
switching
ARCHITECTURES
complex
are numerous
multiplexing,
three
PROCESSING
than
[2]-[4],
and
Depending
to
include
bent-pipe vary
types
slots
of
capabilities
OBP communications
from
satellite
added in
(Figure
such
as
beam
switching,
payloads
the
is implemented
an OBP
decoding/encoding, etc.
arising
of complexity
requirements,
a combination
or packets),
Benefits
as the degree
on network
demodulation/modulation, (time
satellites.
2-2)
J
demultiplexing/ baseband
can be grouped
into
I
as follows. m
(1)
In
the
first
type,
the
main
(demultiplex/multiplex) (i.e.,
downlink
function
of
from
upbeams
traffic
beams)
according
the
to certain
payload (i.e.,
is to
uplink
operational
route
beams)
or into
network
m
channelize downbeams
requirements.
For I
example,
in
(SS-TDMA) routed
by
INTELSAT
system
[11],
the
downbeams this
the
situation,
[12],
microwave
according the
VI
satellite-switched
TDMA
switch
matrix
to specific
TDMA
bursts
switch
carrier
arriving
(MSM) state
link
time-division on various
on board
time
the
plans.
performance
multiple
also
access
upbeams satellite
can
be !
to various
It should
be noted
depends
on
that,
U
in
a number
of
m m i
components
as described
transponders (2)
The
behave
second
type
demodulated
dynamic switch complete thereby
signals
are
improving
The
between
all beams principal
substantially
the
These
satellite,
and
degradations
the
carrier
can then
(users) with
using
this
be further Since
M
a baseband
architecture
(BER)
i uw
to implement
downlink
ratio
are first
downlinks.
it is possible
the
duration.
carriers
onto
and
bit error
state
uplink signals
channels realized
is established,
that switch
transmission
benefit
uplink
state
in which
signals. before
on board
among
a processor. isolation
baseband
a switch
during
payloads
and modulated available
connectivity and
into
once
transponders
to regenerative
decoded
and encoded
baseband
2.1 since,
like bent-pipe
refers
and
processed,
in Section
is the
degradations, performance
[2],
Transmit
Receive TWTA/SSPA
antenna
antenna
H°U°nv
Hc o°v F-I
OBP
Demultiplex/Multiplex Demodulation/Modulation Decode/Encode Beam switching Basebana switching Figure
2-2.
Simplified
Block
Diagram
of An OBP
Satellite
w
SS/L-TR01363 Draft Final Version
2-2
45 M/TRO Use or disclosure
of the data
contained
on this
sheet
is subject
to the
restriction
on the
title page.
1363/Part
1/-_,,97
J
[13].
Proposed
switching
Ka-band
systems
[3] include,
for
which
examples,
utilize
the
regeneration
CyberStar
[14]
and
and
baseband
circuit
Galaxy/Spaceway
[15]
systems.
(3)
In the
third
called
fast
Transfer the
this
access
system
respect E--.
provided
the
circuit the
that
(ATM)
utilizing two
to rain
in [14] and
this
are
carrier
architecture
is the
compensation
Here,
latter,
be transmitted
will
be performed very
benefit
and
in the these
little
respect
A proposed
to Ka-
[16]. regenerative TDMA
(FDMA)
for
with
realized.
uplinks,
access
switching,
of an Asynchronous
system
in the
will
since
same
bent-pipe
multiple
techniques
the is also
are
of baseband
to those
Astrolink
evaluated
carriers
evaluation
[3].
for the
form
similar
performance
frequency-division
(TDM)
advanced
capabilities
BER
In particular,
in the
a more
utilized
architectures
a high-level fade
with
swich
of the
multiplex only
and
switching,
switching.
satellite
time-division noted
packet Mode
study,
baseband
regeneration
improvement
band In
type,
mode;
downlinks. two
technical
with
carriers
will
and,
large
It should
architectures information
be with was
[15].
L:
t_
-::z
B m E m
m
LDr4._6
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2-3
m
45M/TR01363/Part Use or dL_losurr of the data contained on tE@ sheet is sub_ect to the restriction
on the title page.
I 1-9,_,97
il
z g
r
m
J
g
J
m m
II
zm li
_m w
z
I mini
L
SECTION
=
Propagation
factors
elevation
angles
• gaseous • cloud
layer
attenuation
• rain
and
absorptive
received
designing
frequency
scaling
of the
constant temperature relative
the
relative
the
water
to water
humidity
[17].
is shown
in Figures
angle
humidity vapor
that
the
can
must
to high
be
given
in this
attenuation
produce
respect, are
rain
signal
rates,
of special
to
and
ice
attenuation
different
fade
in the
polarization by
to the
are
increase
orthogonal
and
are presented
rain
produced
mechanisms
line
at
the
impairment fade
durations,
importance.
A brief
below.
be considered
small.
with
than
3-2 for
two
and
amounts
frequencies
and
are
temperature
0.8 under
equal
makes
high
than
of
and
the
the
It is seen
that
in the
figures.
and
varies
approximately
conditions.
with
frequency
when
shown
down-link
increases
at
also
humidity
as a function
down-link
1.5 dB under
is nearly in
up-
absorption
absorption. to less
25°C
water
to variations
absorption
occurs
and
to oxygen
Ka-band
of the
the This
oxygen
and
gaseous
Closeness
oxygen
in response
typical
the
GHz
from due
at 5°C
frequency. the
time
absorption
temperature. at 22.2
arising
Absorption
slowly
3-1 and
absorption
humidity
conditions
absorption
varies
up-link
larger
the
gaseous
Gaseous
as the
gaseous
between
of both dry
and
employing
is 40 ° . As evidenced,
absorption
is significantly
ratio
vapor
as well
absorption
the ratio
moderate
a proportionate
is non-absorptive
is relatively
and
The
and
interference
schemes,
effects
due
angles
from
factors
that
elevation
attenuation,
Systems
of fading
atmosphere
exceed
complete
mitigation
absorptive
elevation
a function
port.
consideration
behavior
frequency
fade
at
ABSORPTION
humidity
frequencies;
Due
ia_er
attenuation
scintillation
fade
in the
and
signal
suffer
impairment
to other
present
melting
antenna
reuse
various
GASEOUS
Compared
E
at the
enhancements.
when
vapor
both
Tropospheric
as
3.1
attenuation,
producing
frequency
review
r_==
cloud
effects
implement
and
operating
scintillation
depolarization.
z
links
ice depolarization
noise
factors
satellite
attenuation
absorption,
as well
Ka-band
CHARACTERIZATION
attenuation
• rain
thermal
affect
FADE
include:
• tropospheric
m
that
RAIN
absorption
• melting
Gaseous
3 --
to
down-link
water
vapor
for moderate
most The
conditions. fade
between
For practical
ratio
is
1.5 for purposes
to unity.
i
SS/L-TR01363 Draft Final Version
3-1
45fWTR01363/Part
w Use or disclosure
of the data
contained
on this
sheet
is subject
to the
restriction
on the title
page.
II- 96,97
g
Gaseous Absorption at 25°C 1.6 1.4 :;
k
i
i =="''30
1.2
20 GHz
---_ade
i
Ratio ] I
-= 0.8 _i
._0.6 <
M
0.4 0.2 I 20
40
60
Relative
Figure
3-1.
Gaseous
Humidity
absorption
80
I00
(%)
at 20 and 30 GHz; temperature:
5°C, elevation
angle 40 ° IB
Gaseous Absorption at 25°C
m
16 _20
,4\ 1.2 Absorption
GHz _30
mmmm_ade _.
z
GHz
El m I
Ratio
J
(dB) 0.8 0.6 0.4
0.2
-f
0 0
20
40 Relative
Figure 3-2.
Gaseous
absorption
60 Humidity
80
I00
(%)
at 20 and 30 GHz; temperature:
25°C, elevation
angle 40 °
SS/L-TR01363 Draft Final Version
I_e_a_=m =Pf_l'rt_Ul6
LE3_L
3-2
45 M,rFR01363,'Pa
r t 1/- 9,'5,97 m
Use
or disclosure
of the data
contained
on
this sheet
is subject
to the restriction
on the title
page.
3.2
CLOUD
At Ka-band and
frequencies
amplitude
small a
size
function
and
cloud
of
cloud
relative
Figure
for
of several
and
3-3 show The
(dB/km)
liquid
to the
temperature
temperature.
properties
containing [18]; ice clouds,
particles
path.
attenuation
angle
clouds
scintillations
of cloud
propagation
L
ATTENUATION
the
specific
of 40 °. Attenuation
levels
wavelength the
and
makes
are calculated
assuming
water
shown 3.
of expected
these
effects.
along
attenuation, is defined Table
shows for
distribution
the
frequency, as the
3-1
The
essentially
content
attenuation
a uniform
attenuation
attenuation
cloud
of 1 gm/m
signal
produce
liquid
coefficient
levels
both
cloud
between
content the
produce
do not
integrated
relationship
water
types
can
in general,
attenuation
a liquid
cloud
water
specific average
an elevation of the liquid
z
water
within
expected
the
at the
approximated
cloud. up-link
It is seen frequency
_at
significant
of 30 GHz.
amounts
The
fade
of cloud
ratio
attenuation
between
two
can
frequencies
be is
by [19]:
r
m
.....
A.__.L=(f_2
i
A2
where
A 1 are A 2 are
Although
reliable
fade
are
rates
attenuation
information
thought
[,f2)
(3-1)
(dB) at frequencies
on fading
to be relatively
small
rates
fl and
f2, respectively.
associated
(in the
range
with
clouds
is generally
lacking,
0.1 to I dB/min).
-._ _C"
0 °C IO°C
0.4 Specific
/
A Itenuation
Coefficient (dB/km)/(grn/m
"_)
0.2
I0
15 Frequency
Figure
m
3-3.
Specific
Attenuation
Frequency
ls_n_m
LE3_L
?0 (GHz)
of Clouds
_0
5
as a Function
of
and Temperature
I_'YB'I"EMa
3-3
SS/L-TR01363 Draft Final Version
m
45M/TR01363/Part11-_/97 Use or disclosureof the data contained on this sheetis subject to the restriction on the titlt page.
Table 3-1.
Average
Properties
of Different
Cloud Types
Density (g/m3)
Vertical Extent
(km)
20 GHz Attenuation (dB)
1.0
1.0 - 3.5
0.8
1.8
Stratus
0.15
0.5 - 2.0
0.4
0.9
Stratocumulus
0.55
0.5 - 1.0
0.6
1.3
0.4
2.5 - 3.0
0.4
0.9
Cloud Type
30 GHz Attenuation (dB)
=_
m
Cumulus
R
J
Altostratus
w I M
3.3 Rain
RAIN ATTENUATION attenuation
I
is the dominant
attenuation
is a ftmction
rain drop
size distribution
propagation
of frequency,
impairment
elevation
angle,
at Ka-band polarization
and rain drop temperature.
frequencies.
angle,
Fade durations
rain
and rates
Rain
intensity,
m
g
are closely
correlated with the rain type; e.g. stratiform rain are conducive to longer fade durations and slower fade rates. Frequency scaling of rain attenuation is largely determined by the raindrop same
size distribution
frequency
more rigorous Figure
scaling scaling
3-4 shows
Clarksburg,
The data
5%.
Annual
path
is somewhat
cloud figure,
time
Figure
higher
given
year.
3-5 shows
3-1 may be used
for rain as well.
A
at 20.2 and 27.5 GHz
at
in equation
the g
in [17]. attenuation
observed
using
the beacon
path
attenuation
that
in the distributions. the annual
for which
raining rain
signals
include
gaseous
absorption
in the figure
time for the measurement is present
attenuation
g
on the ACTS satellite
Also shown
attenuation
due to the fact that rain
raining
and
is the rain
site is around
along
the observation
is produced
by the presence
time along the path can not be easily discerned.
at 27.5 GHz Fading
under
becomes
the fade distributions
elevation
angle
elevation
Both
attenuation
are found
to be distributed
angles
for low-elevations at 20 GHz
is 40 o. The distributions
model.
in subsection
moderate
worse
prediction
!i1_¢k¢21
approximation,
collected
attenuation detail
As a first order
the satellite path and the rain rate distribution pertains only to a point near the earth station antenna. Due to the presence of other factors such as
fade depths
the ITU-R;
are included
percentage
attenuation,
an average
were
It is seen that
temperature.
of signal
is 39 °. Total
effects
rate distribution.
of rain along measurement
relationship
law can be found
angle
clear-air
the rain
the distribution
MD.
[20]; elevation other
and
m
M
fade
durations
and/or
for different have
fade
rainfall
rain climates using
rates
fashion;
climates.
as defined
by
the ITU-R rain
associated these
in the
20 dB for 0.1% of
severe
been derived
and
in a log-normal
exceed
As shown
with
are discussed
rain in
3.8 on fade dynamics.
m'Y1B'¢_6
I.I¢I_L
3-4
SS/L-TR01363 Draft Final Version 45MJTR01363/Part
Use or disclosure
of the data contained
on this sheet is subject to the restriction on the title page.
1/-_u97
I
Cumumative Distribution of 20.2 and 27.5 GHz Attenuation; Clarksburg, MD; March, 199_ - February, 1995
50
Attenuation (dB)/ Rain Rate (mm/hr)
45 40
I IIIII "_ IJlll
35 30 25 20
.. "Nlll ,,, a,i,w,_ L
I IIII-I- 20 GHz IIIII 111.,_27 G_
Jllll
I II II-'IIIIIII I IIIIII
_111 i]'l,ifi_"_
15 10
II1_ ,k_'_d
IIII111 I IIIII
• IIIII1 ' _ /i_i'._,_ !!1111
5 0 0.01
Rai_e.at_ lliii I III1[
0.1
IIIII IIIIII
I
_11111
I
Percent
Time
I0
Ordinate
IIIII IIIII IIIII IIIII II111 IIIIII 11111_ IIII1{
1,,i I00
Exceeded
w
Figure 3-4. Attenuation and Rain Rate Cumulative Distributions for Clarksburg, Maryland. Elevation angle 39°
50E =,
45
Rain Zone
40
m
---,I--B 35
--l--D
30
--I_--F --X--H
25 Attenuation (dB)
-,¢---K
20
-@--M -.4.-p
15
,oJ 5 0 P.0I
0.1
I00
10 Percent
Time Ordinate
m
Figure 3-5. Rain Attenuation Distribution at 20 GHz for Different Rain Climates; Elevation Angle 40 °
_
u'v'l_r'rlml_lg
SS/L-TR01363 Draft Final Version
3-5
4 SM/TR01 Use
or disclosure
of the
data
contained
on this
sheet
is subject
to the
restriction
on
the
title
page.
_163/Par
t 1/- 9,eB7
3,4
MELTING
The melting aloft
melt
mainly
layer to form
of the
however,
rain.
layer
are
3.5
similar
layer
from
order
than
fade
levels
up
produced
where
defined
stratiform
of 500
attenuation
TROPOSPHERIC
m.
in the
may
become
to about
by rain
melting
layer
clouds
and
Specific
that
snow
and
or radar for low
attenuation
rain
below.
fade
rain
from band
rates.
melting
Therefore,
under
factor
in the
a significant
low
bright
in the
3 dB can be expected
under
ice particles
present
are in the
layer, rain
total
path
[21].
Fade
U
L--
i
conditions. m g
amplitude
lower
i
The
light
at 30 GHz
is
SCINTILLATIONS
scintillations
inhomogenieties
of a well
precipitation
to those
Tropospheric
the 0°C isotherm
presence
to be higher
typically,
w
around
is of the
melting
attenuation;
The
with
is expected
conditions,
ATTENUATION
is the region
associated
width
rates
LAYER
part
fluctuations
produced
of the troposphere.
by
Scintillation
refractive
can occur
with
u
I
or without wet
fading
scintillations
scintillation
since
increases
decrease
of the
scintillation 80%
on the
relative
scintillation
the
former
increase
diameter.
at 20 GHz and
distributions
statistics
the
albeit
as dry
by
on
Figure
for
several
3-6
Signal
smaller
follows
the
_-
A1
and
respectively. around
are
Frequency 2 Hz.
magnitude several
A2
spectrum
Associated
and dB/s
attenuation
the
fade
frequency
distribution
enhancements
due
magnitude.
Figure
frequency
of and
n
m
of amplitude antenna,
3-7 shows
to scintillations
The
as
angle,
[17]; a 1.2 m diameter assumed.
latter
magnitude
of elevation
statistical angles
The
the
m
the
i
follow scaling
of
[17]: w
= _,f-_z)
(3-2)
enhancement
of scintillations
content.
path.
and
7
or
rates
the
are
in
relationship
scintillations
decrease
temperature
A, where
shows
elevation
20 ° C surface
somewhat
rain
of frequency,
at 30 GHz.
approximately
is known
is accompanied
with
humidity,
corresponding similar
it
antenna
fading
path;
are
are
(dB) limited
a function
Under
severe
at
of
frequencies
to a maximum the
peak-to-peak
scintillation
conditions
fl
and
frequency
= =
f2, of
scintillation fade
rates
of
can be expected.
SS/L-TR01363 Draft Final Version
3-6
45M/TR01363/Part Use or disclosure
o_ th¢ data contained
on this
sheet
is subject
to tht
restriction
on the
title
pag¢_
1t- 9,597
m
30 GHz Scintillation Fading Distribution
4-
if
÷
-;
I]- -___ I IIii
i
',
Ii
t
f
/
_
.--_--!o_L +20 ° i-_r_o
_
'!
o
=
0.1
l
I0
Percent Time Ordinate Exceeded
Figure 3-6. =
=
Cumulative Distribution Fading at20 GHz
of Scintillation
w
30 GHz Scintillation Fading Distribution 5
II]
¸
,,vaf, otH,,
Ill
_ •--6--20 X
10 o o 40 o
_I1(--- 50o Fade Depth (dB)
._ _ ,_
I
--
w
l0
0.1 PercentTime
)rdinate Exceeded
E
Figure 3-7. Cumulative
Distribution
of Scintillation
Fading at 30 GHz = m_
r===
ll_/=tJ_E
SS/L-TR01363 Draft Final Version
_
LIE3RM_L
3-7
M 45M/TR01363/Part
Use
or
disclosure
of
the
data
contained
on
this
sheet
is
subject
to
tht
restriction
on
the
title
page,
1/-gr-J37
3.6
RAIN
Satellite suffer
AND
systems from
ICE DEPOLARIZATION employing
frequency
interference
through
re-use
coupling
by
means
between
of orthogonal
wanted
and
polarization
unwanted
may
polarization m
states.
Such
caused
by
and
coupling precipitation
needle
states.
arises
or plate
In the
tilt angle
with
like
case
ice particles
having
significant
of linear
respect
only
depolarization
of the
at
may
fade
and
polarized
angle.
At
levels
signal
excess
of
without
about
10
significant
along
the
the
polarization
the
m
ii
tilt angle
for a linearly
On
g
and
is
polarized
depolarization
dB.
fading
the
when
as that rain
angle,
with
a maximum
drops
polarization
elevation
increases
frequencies
rain
orthogonal
state,
is same
depolarization
as spheroidal
between
reaches
Ka-band
in
be experienced
coupling
depolarization
horizontal,
atmospheric
such
polarization
polarization,
for a circularly
and
particles
can produce
to the local
a 45 ° tilt
imperfections
Non-spherical
is a function
45 °. Depolarization signal
antenna
particles.
Depolarization
frequency.
from
becomes
other
hand
m
ice
the link. l
Rain
and
ice depolarization
recommended
by
discrimination is defined
the
(XPD)
figure
typical
at 20 and
fading.
to an elevation
than
interference
about
by
and
due
COMBINED preceding
series
shows
the
techniques
distribution
to atmospheric
such
as the
the
cross-polar
particles;
the
of
precipitation
one ! m
XPD
the
at the
components seen
that
The
lowest
ACTS two
at the
frequencies two
different frequency
the
most the
signals are
frequencies
propagation
time
are
(ratio factors
components
series
for
availability
power
impairments
In Figure Figure
spectral
occur
event
3-10 power
3-11
shows
value
of spectral
identified ratio
are
the
through identified
of power
simultaneously.
This
at Clarksburg,
spectrum ratio
of the of the
components). the
spectral
with
the
contained
an this sheet
time
spectral It is ratio. gaseous
45M/TR01363_art data
Ka-
SS/L-TR01363 Draft Final Version
3-8 of the
the
affecting
recorded
Ilmdlld_g
Use or disclosure
to
control
amount
w
interference.
of a fade
can be easily
LCI_L
in
compared
to the
can
of logarithmic
of the
shown
that
through
climate
levels
importance
propagation
impairments
and
a rain
FACTORS
shown.
shown,
secondary
excessive
individual
of these
be surmised
applied
to avoid
and
attenuation
proportionately
OF PROPAGATION
3-9 where beacon
is
increases
outlined
of rain
is of
be taken
polarization,
3-8, it may
compensation
must
In general,
in Figure
in Figure
(3-3)
)
polarization
A comparison
depolarization care
polarization
of 40 °, circular
depolarization
fade
EFFECT
links.
is illustrated using
99%
subsections
satellite
angle
levels
when
caused
applied,
band
due
location.
depolarization
However,
3.7
30 GHz
3-8
empirical
..,, ( signal power in the wanted = lu log/ ..... signal power in the unwanted
pertains
greater
control
Figure
using
M
3-4 with
time
MD,
[17].
of a US mid-Atlantic
Figure
The
ITU
be predicted
as:
XPD
The
may
is subject
to the
restriction
on the
title
page.
11-gF_J7
w m
50
40 IIlll Ii1111 Illll IIIIII
IIIII ..... IIIII1_2°°"zI I]IIII iIItII]lll I IIIII 30 GHz
(dB)
Depo
20
larization
t_
0.01
0.1 Percent
Figure
3-8.
1 Time Ordinate
Distribution
of XPD
10 Exceeded
Not
100
at 20 and 30 GHz
i
,j,
m -lO
._
-15
!___o. --_o?_; r_
-25
k_
-30 " 16.00
18.00
17.00
19.00 Time
20.00
21.00
22.00
- UT
:
Figure
3-9. 27.5
Rain GHz
event
observed
ACTS
at Clarksburg.
beacon
signals
Signal
are shown;
attenuation
elevation
angle
on 20.2 and 39 °
I
..=.
UKJ IlI=_IE
SS/L-TR01363 Draft Final Version
gPdlI'f'lEl_g
3-9
45 Use
or
disclosure
of
the
data
contained
on
this
sheet
is subject
to
the
restriction
on
the
title
page.
M/TR01363/Part
1/-9,5,97
w
!
Powcr
Density dB/Hz M
i
-
fill
,....., ,,
IIII IIII
1_
-
IIII
I II
0.001
O.Ol
0.1
i
O.l Fouricr frequency
w==7, l
(Hz)
Figure 3-10. Power Spectra of the Fading Event Depicted in Figure 3-9
1.5 i
I .
gasl
_kkt llJllll Ii IIIii +_IIIA+ _ _tll. lJ,J,IIIII ! IIIII+ +IVflll_,,J+IJil IIII III I[llltr+wIeMlll IIII
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S
Power Density Ratio
I
IIIII lllllll II IIII .IIIII IIIIIII II IIII 11111lllllll II IIII
0.5
0 0.001
O.Ol
0.1
Fourier
Frequency
(Hz)
Figure 3-11. Ratio of Spectral Components at 27.5 and 20.2 GHz
!!¢=_¢_C=E
SS/L-TR01363 Draft Final Version
EiV'IFrlEI_I_
I..l'llqM_l-
3-10
45M/TR01063/Part Use
or disclosure
of the data
contained
on this
sheet
is sub_ect
to the
restriction
on the
title
page.
11- 9_97
absorption;
mid
frequencies
are produced
propagation
frequencies
factors
are
associated
with
by scintillation can
be
gainfully
cloud_
and
activity.
As such,
employed
when
rain
attenuation,
frequency
and
domain
implementing
higher
separation
fade
of
mitigation
techniques. 3.8
FADE
DYNAMICS
Dynamics
of fade
mitigation
techniques
In addition,
they
networks signal
--=2
need
relevant
Within
a precipitation
themselves
are
precipitation fade
level
level
is closer
Within
falls
the
gaps.
The
inter-fade event
event,
when
peaks
interval.
implementation
coding,
and
performance
or the time
intervals
resource
sharing.
objectives
of digital
interval
during
fade
episodes,
intervals
most
important
dynamic
between
of attenuation
of fade
are the
which
the
may
The
level
a longer the
considerably,
short
time
interval;
as
illustrated
time
fade level and
varies
span
exceeds
is followed
a given by
crossing
a given
precipitation in
threshold gap
peaks
separated
events
Figure
3-12.
A
ends
when
the
which
the
fade
and
a long
during
fade
value.
are called
intervals.
fade
the threshold
to the clear-air
there
duration,
threshold,
and
diversity,
specifying
a relatively
by
starts
event,
the
over
separated
below
Fade
design
modeling.
times
event
control,
the rate of change
to system
several
in the
when
links. a given
and
features
power
to be considered
exceeds
events,
threshold
of importance
satellite
attenuation fade
are
employing
employing
between
m
events
be
fade
several
short
episodes
and
relatively
Tropospheric
longer
scintillations
duration the gaps
time
are known
interval
often
several
short
as inter-episode
between
accompany
by
fade
events
precipitation
gaps
or
is the inter-
events,
and
the
Fade
Fade
duratio_
episodes
-4--------4_- -qt---I_ Interfade Fad interval
A
Fade
IJ
A
_
1
Fade
threshold
Time .,ml
Precipitation
event
Inter-event
interval
Precipitation event
m
Figure
3-12.
Features
Commonly:0sed
incharacterizing
Precipitation
Events _
z
l_
SS/L-TR01363 Draft Final Version
lii'VIB'rlEI_B
3-11
45M/TR01363_a Use
or disclosure
of the data contained
on this
sheet
is subject
to the
restriction
on the
title
page.
rt 1/- 9F0_7
above
features
need
Scintillations
are
separated
from
filter.
Filter
to be characterized relatively
slower
time
fast
in the
variations
variations
constants
both
produced
of the
order
presence
in
the
by
precipitation
and
signal
absence
of scintillations.
amplitude
and
particles
of 20 to 60 seconds
appear
these
using
can
be
a low-pass
to be adequate
m
for the
m
purpose
[20].
3.8.1
Fade
Duration
In general,
fade
given
threshold
fade
w
duration
is a function the
fade
of frequency,
duration
will
elevation
increase
angle,
with
and the
an increase
rain
type.
of frequency
At a and
a m
decrease
of the
elevation
approximately [23].
follow
Thus,
the
approximately
angle.
the
rain
frequency
given
Experimental attenuation
evidence
dependence
dependence
of
fade
show
that
these
on frequency
duration
dependencies
and
at a fixed
elevation
elevation
angle angle
is
U
by:
total number
of fades
with A > x dB at fl =(fl'_
I
2
/--I
total number
of fades
with A > x dB at f2
\ f2 J
(3-4)
[] where and
A is the
fade
depth
f is frequency.
(dB)
A more
and
x is the
rigorous
threshold
frequency
(dB)
scaling
at which law
the
may
be
fades found
are
counted
in [17].
The m
elevation
angle
dependence
at a fixed
frequency
may
be approximated
total number
of fades
> A dB at 01
sin 0 2
total number
of fades
> A dB at 0 2
sin 01
shown
above
by:
m
where The
0 is the elevation
elevations than
time
angle
where
one
rain
elevation The
role
IlIn_A_IB
is expected
by individual
contributes
to the
rain
fading
to hold cells.
process,
only
At low
thus
for moderate elevation
leading
to high
angles
to a more
more
F
complex
w
rain
type
in influencing
fade
Wide
rains
spread
duration tend
stems
to have
directly longer
from dwell
the
average
times
dwell
compared
to
threshold appears to be independent the number of fades increase with
of the
rains.
duration level.
of
the
parameters. distributed
is produced
often
structures.
average threshold
decrease
dependence
dependence.
of the
of rain
angle.
fading
cell
angle
thunderstorm
The the
elevation
(3-5)
The among
of fades exceeding This is due to the
fade
threshold
larger
time
a larger
a given fact that
without percentage
number
any
discernible
for which
of fades,
and
the
relationship
a lower lower
fade time
threshold
percentage
liYUTIB_g
t_D_t_
between
the
is exceeded at a higher
two is fade
SS/L-TR01363 Draft Final Version
3-12
M 45 M,tTR01363/Part Use
or di_losur¢
of tlu_ data
contained
on this
sheet
is subject
to the restriction
an the
title
page.
1]- _ir-o,g7
:
threshold
is distributed
duration
is given
most
fade
paths
and
and
in Figure
thresholds
with
observe
in the
fade
the
lasting
20 dB is less likely
An
than
to last more
duration
an hour
This
or three
of fade As
3-14
the
subject
other
20.2
for
for most severe
the
average
it is common
value.
for
2 min.
around
an example,
3-15
fade
to extremely
duration
average
and
of average
to be typical
of 3 dB; on the
times
in Figure
seems are
threshold.
example
of approximately
that
at a threshold
two
shown
[20].
spread
fade
An
duration
regions
The
of the
than
statistics
3-13
of those
as typhoons.
of fades.
fade
in Figure
decrease
more
number
average
exception
such
with
fades
3-13.
the
events
increases
a smaller
is evidenced
climates
widespread
value
among
hand,
This GHz
to
a fade
of
is illustrated
and
27.5
GHz,
respectively. The
measured
log-normal Shorter F
data distribution
duration
by a power-law
=
3.8.2
which
events,
duration
and
of fades
duration
produced
distribution
largely
exceeding
fades by
a given
composed
mainly
tropospheric
threshold of rain
scintillations,
can
to have
induced
a
fades.
be represented
[24]. Inter-Event
Intervals
intervals
is important
on interfered excessive
performance.
the
for longer
fades,
Inter-Fade
Information in
indicate
switch
Inter-event
occurrences intervals,
are of importance
in applications can
which
in network
have
pertain
management
a
as diversity
detrimental
to the and
such
return
effect period
reallocation
switching on
system
of precipitation
of resources
on a larger
scale.
20O
|6O
,°
/\
FadeAverage 120 Duration _oo
_
_
/_
6O
o
I
/
/
\/
\/
0
G_
0
w
Figure
3-13.
Average
Fade
Duration
at 20.2
GHz
SS/L-TR01363 Draft Final Version
m_
3-13
45 M/"r'R01363/P USe
or dJsclosur¢
of the
data contained
orl this
sheet
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to the
restriction1
on tl_ lille
pagt.
art 1/- 9_/:J7
+2
20 GHz Fade Duration Distribution
lOOOO __:__
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1000 =_
g t_
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100
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10
100
1000
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Durstion (see.)
K==i
Ul
Figure 3-14. Fade Duration Distribution at 20.2 GHz
I 27 GHz Fade Duration
--
-._t_
_-_-_--7__-LL_
L__SIES
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Figure 3-15. Fade Duration Distribution at 27.5 GHz
LI'II_/_I.
SS/L-TR01363 Draft Final Version
3-14
45Mf'rR01363]Part
1/-9,_97 e,..
Use
or
disclosure
of
the
data
contained
an
this
sheet
is
subject
to
the
restriction
on
the
titIe
page.
=
In
general,
rain
distributed
induced
[24].
scintillations, fade
duration.
from
data
collected
40 ° . It can fade
duration
inter-fade
are
expected
Figures using
be seen
thresholds
intervals
Short
however,
term
inter-fade
that
are
the
and
ACTS slope
3-17
characterized
by
intervals
and
changes
intervals
tropospheric
as found
the
compared
with
the
distributions
27.5 GHz; with
log-normally
from
interval
at 20.2
distribution longer
form
inter-fade
signals
are
resulting
a power-law
show
beacon
of the
inter-event
intervals
to follow
3-16
the
and
derived
elevation
fade
short-
angle
depth.
to those
is
Higher
at lower
fade
thresholds.
Frequency
and
relationships
given
3.8.3
of Change
Rate
In a manner attenuation been --m w
elevation
of
the
fade
duration.
fade
duration
to be log-normal
between
the
of change
of
reported
to
experiments
of inter-fade
intervals
may
be
attempted
using
the
of Attenuation
to rain
appears
rate
scaling
under
similar
observed
angle
statistics,
with
a median
positive-going for
the
distribution
of about
(fading)
attenuation date,
the
and
0.1 dB/s.
times
fade
of does
rate
of about
of change difference
s or
not
slopes
more.
appear
of has
(recovering) 10
slope
rate
Little
negative-going
integration
average
of the
In to
most
depend
o
significantly
on the
for integration with
fade
time
integration
level,
with
constants
times
below
a maximum
of the
order
10 s and
fade
of 10 s.
these
are
20 GHz Inter-fade
Much
associated
Duration
higher with
1 dB/s
fading
reported
are
observed
rates
being
scintillation
activity.
Distribution
100000
10000
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1000
dB t
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dB
----!1---6 dB
100
[
--o-10 dB1
0
= Z
--!---2
10
1
I0
100
1000
Inter-fade
Figure
3-16.
Inter
Fade
Interval
Interval
10000
100000
1000000
(sec.)
Distribution
at 20.2
GHz
SS/L-TRO 1363 Draft Final Version
3-15 =
45 M/TR01363/Part Use or disclosure
of the data contained on this sheet is subject to the restriction
on the title page.
1/-9/_97
27 GHz Inter-fade Duration Distribution 100000
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Figure 3-17. Inter Fade Interval Distribution at 27.5 GHz
m
I
i
Figures 3-18 and 3-19 show the cumulative distribution of fade slopes at 20.2 and 27.5 GHz for different fade thresholds. It is evident that the fade slope distributions are not sensitive to the fade threshold. Figure 3-20 shows a histogram of fade slopes at 20.2 GHz illustrating the symmetrical behavior of positive and negative going slopes.
Distribution of Fade Slopes at 20.2 GHz
_
m
J
w
i
Attenuation
•_
!--_-6dB !--/_--6- 8aB ["-'X'_
8- lOde
0.1 0
02
0.4
0.6
0.8
1
12
1.4
Fade Slope (dB/s)
Figure 3-18. Cumulative Distribution of Fade Slopes at 20.2 GHz
I..aI'_M_L
SS/L-TRO 1363 Draft Final Version
3-16
45 M/'r'R01363_anl Us¢ or disclosure
of the data contained
on this
sheet
is subject
to the restriction
on the title
page.
l-_BgJ7 i
Distribution
of Fade Slopes at 27.5 GHz
1001 ""0"--2
- 4 dB
I'--E]_4I'_'_
6 dB 6 - S dB
I,_-X-_ 8 - lOdB
="
0.1 1.5
0.5 Fade Slope
Figure
3-19.
Cumulative
2
(dB/s)
Distribution
of Fade
Slopes
at 27.5
Ghz
Fade Slope Histogram 10OO0O Attenuation 10OOO
2-4d8
I
1000
d Z
100
lo! 1: -1
-1.5
-0.5
0
0.5
1
1.5
Fade Slope (dB/s)
Figure
3-20.
Fade
Slope
I--DI A I--
Histograms
at 20.2
GHz
SS/L-TRO 1363 Draft Final Version
3-17
45M/TR01363/Part
M
Use
or
disclosure
of
the
data
contained
on
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sheet
is
subject
to
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restriction
on
the
title
page.
1/-
9/&97
3.9
RAIN
FALL
CORRELATION
Rain
fade
compensation
with
an understanding
OVER
implemented
LARGE
on the
AREAS
basis
of shared
resources
must
be designed m
Although
of the
detailed
across
a large
studied
to
simultaneity
information
area
gain
is not
on
easily
sufficient
of rain
simultaneous
modeled,
knowledge
fading rain
rainfall to
across
size
the
fading
on
patterns additional
over
satellite
coverage
area.
multiple
satellite
links
extended
areas
resources
can
required
for
M
be
fade
compensation. w
Meteorological throughout areas.
data the
Figures
Cleveland,
OH,
on
hourly
continental 3-21,
precipitation
from
USA
were
analyzed
and
3-23
show
3-22,
Los Angeles,
CA,
and
several
to derive the
joint
Washington,
rain
thousand
stations
fall correlation
probability
scattered
over
of rain
for
extended
three
I
cities:
DC. I
i
Joint Probability of Hourly Rainfall Exceeding R for Cleveland, OH, and a Second Site at a Distance D; R o: Rainfall at Cleveland, R l: Rainfall at Second Site
Ill
m 10
,. ,,
"K .
|,
M
,,
--4--R
= 0.0I
-m-"R
= 2.5 mm/h
"-_-R
= 5.0 mm/h
_R
= 10 mm/h
B
mm/h
== =_
!11
T.
Percent
Probability
-- _
_D
OA
.-
0.01 0
500
1000
1500 Distance
Figure
3-21.
Joint
Probability
as a Function
BPI_.C=m
of Rainfall
2000
Specified
for Cleveland,
Threshold
OH
SS/I_-TR01363 Draft Final Version
E_"_B'FEEarUlS
I_I"JI_/_L
3000
D (kin)
Exceeding
of Site Separation
2500
3-18
45M/TR01363/Pa Use
or disclosure
of the data containesl
on this
sheet
is subject
to the
restriction
on
the
title
page.
rt 1/-9_37
JointPrd:_0_ty d _ RainfalEx_ R for los Angeles,CA, anda SecondSite at a DistanceD;,Ro: P,_J at LosAngeles,RI: Rairt'aJI at SecondSite lO Z 5 mm/h
1
Percent Probability (Ro >= R and R1 >= R)I
0.1
=
f
O.Ol 0
500
1000
15(30
2000
2500
3000
Di_=nce D (km)
w
Figure 3-22. w
Joint Probability of Rainfall Exceeding Specified Threshold Function of Site Separation for Los Angeles, CA Joint Probability of Hourly Rainfall Exceeding and a Second
Site at aDistance
D_ R0- Rainfall
R forWashington,
at Washington,
10.
as a
DC,
RI: Rainfall at Second •-O--R i -I--R
= 0.01 mm/h = 2.5 mmlh
-.A--R
= 50 mm/h
-_-R
= 10 mm/h
-i
Percent Probability _1o >= R and >: R)
01
=
0
500
1000
1500
2000
2500
3000
z
Distance D (kin) w
Figure 3-23.
l.¢:31_h¢_1.
Joint Probability of Rainfall Exceeding Specified Threshold Function of Site Separation for Washington, DC
3-19
as a
SS/L-TRO 1363 Draft Final Version 45M/T'R01363/PartI/- 9/_7
Use or disclosure o[ the data contained on this sheetis subject to the restriction on the title page.
3.10
ANTENNA
In addition
WETTING
to rain
window
can
especially
produce
severe optics
to antenna
reflector
and
wetting
is significantly
the
hand
coating
measurements. antenna
fade
on the
wetting satellite
at results
higher
than
the
is
Fade
attenuation
of the
a smooth
for
can
of attenuation not
to feed
may
smooth
as
mitigation
techniques
contribution
can
that
be considered
are
the
by
the
for the
an error
ACTS
antenna
term
due
when
m
of 40 ° and
assumed
in the
in Figure due
signal
be
using
loss. wetting
z m u
3-25. to feed
application
for reflector
demonstrated account
angle
However,
reduce
can
at 20 GHz
attenuation
wetting.
feed
be modeled
is shown
be encountered
must
can
an elevation
It is seen
antenna
attenuation
surface
significantly
the
attenuation
wetting
to reflector
window
for
reflector
30 GHz. due
effect
the signal rate
and
Signal
wetting
rain
due
surface
[25].
3-24 shows
20 GHz
that
feed
reflector
Antenna
of 1.8 m and
levels
surface
signal
Figure
show
on
significant
reflector
The
3-27
antenna
as a function
attenuation
3-26
hydrophobic
[26].
diameter
Signal
of the
frequencies.
wetting
Figures
other
additional
techniques
A reflector
calculation.
wetting
at Ka-band
geometrical 80 °.
fading,
of a On
I
the
when
propagation wetting measuring
effects. the
link. B
I
w_
g
Antenna Gain R_uction Due to Reflector
g m
0
¸
-0.5
-1
Rdative Gain (dB) -1.5
-2 0
20
40
60
80
100
Rain me (ram/h)
Figure
3-24.
Antenna
Reflector
I.,I:31qM L
Wetting
Loss
at 20 GHz
SS/L-TR01363 Draft Final Version
3-20
45M/rR01363/Part
1/- 9/1_97 m
Use or disclosure
of the data
contained
on this
she_
is subject
to the restriction
on
the title
page.
w Feed Window Wetting Loss Feed Loss at 20 GHz
Elevation
Angle
-0.5 --40
°
_80
o
-I .5
Relative
C_n (dB)
.-,,.,.
-3.5 F
0
10
20
30
40
50
Rain Rate (nan/h) =--.
Figure 3-25. Antenna Feed Wetting Loss at 20 GHz
Antenna
w
Gain Reduction Due to Reflector We_ting; Reflector Loss at 30 GHz
.==
Elevation
Angle
Relative Gain (dB) -1.5 w
-2 0
20
40
60
80
1O0
Rain rote (mm/h)
Figure 3-26. Antenna Reflector Wetting Loss at 30 GHz w
_r-J_
U',_eEFrlz_MB
LE3Rt_L
3-21
SS/L-TR01363 Draft Final Version
m
45M,,TR01363JPart 11-9b_9'7 Use or disclosure of the data contained on this sheetis subject tothe restriction on the title page.
Feed Window Welxing Feed Loss at 30 GHz 0-
-0.5 He'cation .|
Angle
•
J
-1.5 m
-2 Relative
u
Gain (dB) -2.5
J
-3
m l
-3.5 m
-4 0
10
20
30
40
50 = m
Rain Rate(ram/h)
i Figure
3-27.
Antenna
Feed Wetting
Loss
at 30 GHz BE
im
i
Smp_Lt:E Ept_B'flS_It4_
LC31 L
3-22
SS/L-TR01363 Draft Final Version 45Mr'FRO1363/Part1/-9,_,_7
Use or disclosure of the datacontained on this sl_ef is subject to the restriction on the title page.
SECTION
4 m RAIN FADE
MEASUREMENT
TECHNIQUES
w
Rain by
fading rain
in the
received
in the Downlink
to overcome
the effects
this study
°.
baseband
their
ability
is concerned
by rain
on the
satellite the
remote w
the
satellite
Six
fade
terminals. while
at earth =__
speed
In all cases,
accuracy
can
be predicted
The
prediction
compensation, u m
this
cover
m
six fade
are
refers fade
and
to the
degradation frequency
downlink
fading
Frequency
scaling
accuracy
in the estimated
accuracy
Detailed
analysis FADE
fade
on
small
degradation degradation
accuracy
of
by the
uplink of
techniques
following
and
modem which
sections SNR
_are
made
in the
path.
accuracy
The
assumptions
can be found
study.
on a common
techniques,
of the
technique
BEACON
receiver
other
descriptions
for each
FROM
beacon
while
the
include
measurement
accuracy.
in
on-board
of this
Uplink
the
all fade
by rain
impact
is degraded
affects
pipe
from
downlink
and
estimates,
The
in detail
cost
performed
measurement
techniques.
two
resides.
scaling
Bent
techniques
of predicting
measurements
caused
satellites.
phase
implementation
equipment
of fading
fading
on bent-pipe
measurement
accuracy
on scaled
quickly.
ESTIMATING
six fade
path.
caused
uplink
to
downlink
impairments
measure
during
respect
architecture.
terminals
and
regenerative
with
in the
uplink
employed
measurement
are _covered
can
evalUated
of response
measurement
covered
not
been
at earth
quality.
and
be evaluated
to either
required
measurement
measurement
masks
satellites
of these
involves
procedure
measurement 4.1
process
is not included
measurement nature,
the
transponder
have
downlink
process.
and the
from
based
scaling
equally
where
of fades
are usually
evaluation
to the
link
pipe
rain
or downlink
increase
fade
bent
by
to be applied
regenerative
accuracy,
terminals
applied
power
of rain
caused
in the increase
fade,
a given
architectures,
terminals
regenerative
signal
will
caused
temperature
effective
maintain
techniques
measurement
techniques
for comparative
terminals.
w
the
and
satellite
comparisons
techniques
measurement
measurement
distinct
an
of the
terminal
as a degradation noise
evaluation
techniques
Also,
such
to produce
at earth
allows
while
combine
a comparative
measurement
path
accompanying
losses
at an earth
expressed
the
measurement
fades
enable
the
Criteria
fade
downlink
earth
and
propagation
with
architectures
uplink
is typically
received
is an indication
for two
to measure of fade
Fading
path
of excess
Switching,
Comparison
of a signal
degradation
techniques
with
power
Fading
propagation
degradation.
compensation
_,,_._:
path.
in decibels.
by rain
Since
in the
propagation
carrier
caused
m.
is a degradation
fade
Similar in the
in fade
appendix.
RECEIVER
m
Most
satellites
propagation on
global
estimate
generate
beacon
experiments. coverage the
level
signals
Beacon
horns.
signals
Beacon
of fading
which
are are
signals
on its path.
as carriers
typically can
The
used
be
absolute
for telemetry
transmitted
in the
monitored power
by of the
the received
data
and
downlink
VSAT
for band
terminal
beacon
to
signal
is
E line m
SS/L-TR01363 Draft Final Version
m_
LD_L
4-1
45M/FR01363/Part
Use
or
disclosure
of
the
data
contained
on
this
sheet
is slrbject
to
the
restriction
on
the
title
page.
1/-
9,5,97
compared signal
with
a clear-sky
is assumed
antenna band
feed
to be available
or LNB
This
the
is not
VSAT
equipment.
down
converter
and
though.
of detecting
circuitry
circuitry
to measure required
The
complexity
and
the
downconverted
beacon
required receiver
the
beacon
the
for beacon cost
of the
beacon
receiver
and
downlink
frequency
and
therefore
increases
of the signal
signal,
the
the
at the
output,
beacon
IF
circuitry
!
output.
cost
of the
a synthesizer
and
a beacon
signal.
the
LNB
production
m
without
receiver
to include
LNB
acquired
beacon
the
A beacon
to be within
band
is envisioned
power
tracking
Figure
loop
4-1 shows
I
= =
the
monitoring.
receiver the
carrier
provide
path.
is possible
be assumed
the
from
on the
reception
cannot must
circuitry
beacon
attenuation beacon
signals
signal
strength
and
equipment
within
beacon
to select
elements
Beacon
beacon
The
rain
to all terminals
Terminal
otherwise
basic
of the
to determine
modifications.
of all terminals
capable
reference
is dependent
frequency
to noise
upon
accuracy
power
the
of the
density
frequency
reference
of the
accuracy
mm
provided
beacon
signal
to at the
m m i
receiver
input.
determine
The
the
width
search
to acquire
of the
beacon
adequate exceeds
the beacon
tracking
capture
required.
The
approach,
where
tracking,
to
level the
more
measurements
PLL
while
performance
for
(from
IF ODU)
range
the
accuracy
band
signal. then
a static
beacon
of this
will
which
downlink
beacon
received
low.
range
involve
calculations.
tracking than
If the
from
search
An by
bandwidth
band
example
switched
then
repeated
a 1.2 meter
is filter
narrowed signal
and of
provide
algorithm
a simple
i
range
will
search
acquisition
must
capture
search
making
the
the
beacon PLL
setting
sophisticated
for signal
across
converted
beacon is less
be
can
up
down
synthesizer
a more
algorithm
synthesizer
the
receiver
is opened
processes
which
cost
then
and
bandwidth
beacon
PLL
symmetry
ACTS
over
receiver
of the
the
reference
If this search
PLL bandwidth
tuning
of the
frequency
of complexity
from
in section
L-band
and
complex
frequency
provided
of the
performance the
beacon
frequency
for power
computing beacon
VSAT
the
tracking antenna
is
8.1.1.
/ _ --_
Beacon
Down
Log Amplifier
Tracking PLL
Converter
Beacon Power
I Frequency Reference (from
Synthesizer
modem)
Figure
LDI'_AE_L
4-1.
Beacon
Receiver
Block
Diagram
4-2
SS/L-TR01363 Draft Final Version 45M/TRO 1363tPa rtII-gFJ:J7
Use ordisclosure ofthedatacontainedon thissheetissubjecttotherestriction an thetitle page,
Beacon w
signal
When
clear-sky
update
measurements
conditions
a database
contains thus
enabling
the
by
divided
by
downlink
fade
rain
the
beacon
degradation
4.1.1
Accuracy-
which
accuracy
dependent
estimate
a constant
Beacon
Receiver
of fade upon
the
from
system
estimates
generated
correlation
between
level
from
rain
and
current
are
the
rain
attenuation
to
time
be
of day
is
estimate.
A
measurement
by a
temperatures.
power
and
-day
in received
current
media
to
database
time-of
attenuation
signal
used
determined
attenuation
rain
beacon
rain
for
This
variations
path
the
the
noise
the
receiver. are
levels.
for
the
to generate
is determined
assumes
along
beacon
measurements
for diurnal
reference
level
by the
power
level
to correct
clear-sky
power
power
beacon
conditions
the
basis
beacon
reference algorithm
attenuation,
beacon
clear-sky
propagation
received
table
clear-sky
on a continuous
to exist,
average
estimation
When
look-up
The
are perceived
average
power.
degraded
are made
containing
a moving
beacon w
power
measurements
received
beacon
is power,
2_
beacon
w
z7
power
estimate
degradation
product
of all gain
will
directly
error
and
day
and
Beacon path.
power For
loss
beacon
and
beacon
power
terms
in the
power
error
level.
which
the
effectiveness
readings.
Since
spacecraft Table
to fade
the
algorithm
received
to ground
4-1 shows
contributes
of the
beacon
path,
power in any
of fade
measurement
accuracy
after
direct
comparison
result D/is
clear-sky
are an indication
is used calculated
conditions,
of the
with
other
to generate from Ts, and
the
rain fade
attenuation
rain
or fading
measurement
a degradation
the rain
D_A+10
m
term
time
of
attenuation,
A, the
downlink
techniques,
estimate
temperature,
on the
or
effective
system
noise
the
Approximations and constant LNB
log
fade
fade.
The
temperature
Tm. (4-1)
L + T.(1-
m
to
is the
variation
sources
measurement
used
corrections. readings
degradation, under
and
residual
baseline
accuracy
from
affect the
measurement w
measurement
_r[
in the above equation include insignificant feed losses, no gaseous noise and rain temperature. Errors in the degradation estimate are
attenuation
aD= ,+
(4-2)
,
w
E m
LD_k
SS/L.-TR01363 Draft Final Version
4-3
4SM/'FRO Use or disclosure
of the
data
contained
on this
sheet
is subject
to the
restriction
on the
title
page.
1363/Parl
II- 9r-_J7
Table 4-1. Term in Link Budget
Beacon Power Measurement
Maximum Variation, [dB]
Beacon Power
2.00
Satellite pointing loss
_+0.0005
Fade Estimate
Accuracy
m w
Residual Error, [dB]
Compensation Mechanism Beacon source aging is effectively removed by long term averaging of clear sky baseline.
0.01
Level fluctuations, AP Tare dependent on satellite orientation errors,
0.00
A[_], according to
m
I
m
w
Z_UP=--I2:AO/O_vmM)2[. Beacon is transmitted
on conus horn with 8_M
= 4°1 and variation 0.025 o is most significant
m
mispointing using autotrack.[27). Hourly quantization of clear sky baseline will remove all but 0.00003dB. Path loss Scintillation
_--_.1 +1.2128]
Long term averaging of clear sky baseline will reduce any range variation dependency to an insignificant level.
0.00
Low pass filtering of power readings will reduce scintillation to
0.04
[../.,=(,+ o,/o:)']I=--3
m
for scintillation,
I
(0o = 0.5 rod / sec filter comer. De-
polarization
-0.14 ( XPD, degraded to 15dB)
Depolarization associated with rain events is dominated by absorption. Rain causing a degradation in XPD to 15 dB, and resultant 0.14 dB copolar attenuation, would be associated with at least a 20 dB fade from absorption at 20 GHz. Depolarization associated with ice crystals will not be accompanied with absorption and will appear to the fade measurement system as a rain event.
0.07 m
i
I
Gaseous absorption
_+0.5[28]
Gaseous absorption is dependent upon relative humidity and air temperature. Both of these parameters will correlate with diurnal compensation of baseline and long term(seasonal) effects will be filtered out by clear-sky baseline averaging. Most significant errors will be caused by drastic weather changes (4 RH=20%, AT = 20 °) in a reasonably short time frame. Frequency scaling of error will cause overcompensation during periods of changing gaseous absorption and baseline compensation under compensates for long term changes.
0.3
Cloud Attenuation
-1.2
Dynamics of cloud attenuation are indistinguishable from light rain and frequency scaling is very similar.[28] Since it is desirable to compensate for cloud attenuation, fade measurement system should respond and therefor response is not an error.
0.0
Rain Attenuation
-2O
Response to rain attenuation is not an error. When attenuation exceeds dynamic range of beacon receiver, receiver will loose lock and high rain fade should be assumed.
0.0
_+0.04
Diumal variations in the satellite position relative to the earth terminal will be filtered out by diurnal compensation of clear-sky baseline. ( see
0.003
Feed window wetting is small when compared to rain attenuation at identical rain rates and will be overcompensated when frequency scaled. Two decibel wetting loss at 20 GHz would be scaled to 3.6 dB at 30 GHz while wetting loss for transmit signal should only be 2.7 dB. 0.9 dB is worst case error. Precipitation in the form of snow causes little atmospheric attenuation but a layer of melting snow or ice on the antenna surface can cause gradual deep fades. Heating systems or antenna covers are required in snowy environments.
0.9
Earth station antenna pointing error Earth station antenna efficiency
LD_L
-2.0
4-4
SS/L-TR01363 Draft Final Version 45 M/TR0136&/Pa
Use ordisclosure ofthed_a cont_ned on thissheetissubject totherestricfion on thetitle page.
rt 1I- 9r--_97
m
Table
4-1.
Term in Link
Measurement
Fade
Variation,
Estimate
Accuracy
(Continued) Residual Error, [dB]
Compensation Mechanism
[dB]
1.0
LNB gain variations with temperature are approximately -0.1 dB/K. Clear-sky baseline will compensate for seasonal changes and diumal compensation will remove a significant portion of the daily variations. Residual error will be related to worst case day-to-day temperature change at constant time of day. (assume 10°C)
LNB gain
1.0
Beacon receiver accuracy
= _
Power
Maximum
Budget :
Beacon
0.75
Expensive beacon receivers typically have 0.25 dB long term accuracy. Inexpensive circuitry to measure beacon power level should provide 0.75 dB long term accuracy without periodic calibration.
RSS Error in attenuation
All of the above fig.s are worst case errors which can be assumed to be equivalent to 2LVJ or 95% confidence values.
Average error
The mean square error, or lr"_,
Accuracy of degradation estimate
Look-up table uses fixed clear-sky system noise and rain media temperature and calculates degradation from rain attenuation estimate. (see text )
1.57
0.79
value is one half of the above result.
_+1.25dB
. =,
roll=
Assumed 230+10
rain
temperature,
K and
rain
Tm,
is 280+10
K, clear-sky
attenuation,
A,
is 5+0.79 summarized
dB.
system
The
noise
Beacon
temperature,
Power
fade
Ts,
is
measurement
w
technique
accuracy
calculations
are
appendix,
on pages
A-1 through
A-3.
estimate
is predicted
4.1.2
Response
to be +1.25
The
for
overall
dB for all three
the
three
satellite
uncertainty satellite
in the
architectures downlink
in the
degradation
architectures.
E
Logarithmic
m
Time
amplifiers
- Beacon are
Receiver
available
provide
which
times under I millisecond. When the degradation beacon receiver will lose lock. Such an occurrence and
the
duration
4.1.3 The
of this fade
Implementation beacon
independent Figure
- Beacon
receiver
fade
of the
satellite
4-1 are required
power
from,
synthesizer preliminary
the
estimate
beacon
by the beacon
parts
with
response
receiver margin, as a extended
receiver
elements
power
and Many
circuits
cost
i s unique
The
motherboard.
PLL integrated of the
accuracy
exceeds the beacon should be interpreted
technique
architecture.
unit
desired
acquisition
the fade
time.
Receiver
measurement
to measure
indoor
and receiver
will be prolonged
the
that
included must
exist
of the
are available
for a simple
in
analog
implementation
in the
blocks
in addition
components at low
cost.
beacon
is
shown
to, and derive including
Table
receiver
in
the
4-2 shows with
a
L-band
input. w
m ==lI=l, muII!
SS/L-TR01363 Draft Final Version
I_f"_l"R
LI31"_D_L
4-5
45M/TR01363/Patt 1/-S_'_J7 Use
or disclosure
of the
data
contained
on this
sheet
is subject,
to the
restriction
on
the
title
page.
Table
4-2.
Low
Cost
Beacon
Receiver
Parts
Cost m
Description
Manufacturer
-Part Number
Unit Cost ( Q=1000 )
L-band synthesizer PLL
Motorola
MC145201
$3.40
L-band mixer
TriQuint
TQ9172N
$4.14
L-band VCO
Motorola
MC12149
$3.03
IF synthesizer PLL
Motorola
MC145170
$2.05
Miscellaneous discrete
Various
Various
$5.00
Total
= $17
m i
u
m
The
beacon
impact
receiver
on the
yields.
modem
This
unit.
must
cost
over
impact,
quantities
are
much
increased
on
are
thousand
in production
from
based
costs
one
tested
arising
Development
spread
be
units
higher.
testing
a failure
estimated will
rate
to be
fade
therefore
time
and
of 10 -2 and
$120K
dominate
This
and
the
for
estimation
have
the
reduction
a unit
cost
the
modem
will
beacon
cost
technique
a slight of production
of $2K
This
unless
is expected
i
is $20 per
receiver.
impact
cost
cost,
production
to have
= =
BB
a cost =_
impact
of approximately
$157
on units
produced
in quantities
of one
thousand. m
4.2
ESTIMATING
Most
earth
provide digital
terminal
beacon
control
voltage
significant reading
into
algorithm
baseline
for
temperature
fade
measurement
to predict
the
satellite
and
fade
A_!
same
- Modem
architecture estimation
process
of these
The
seasonal
the
degradation
and
from
an
in section
factor
The
voltage
estimation them
the
fade
system
for
to u
whether
reading.
assumed 4.1.1
AGC
compares
may
is
modem
determines
and
to the
degradation the
and
algorithm
AGC
of these
A fade
variations.
current
to
is similar
samples.
path
analog
voltage
samples
measurements
downlink
as described
current
estimation This
fade
noise
and
the beacon
receiver
pipe
Voltage
estimates and
satellite
process.
in Appendix bent
from
downlink
AGC
of degradation
summarized backed-off
the
voltage
to follow
fading
the
circuitry
a record
control
a signal
to
modem
technique
of
measurement
the
the
controlled
technique.
Accuracy accuracy
the
level
are
to the
measurement
absolute
on
which
input
from
time-of-day.
baseline
estimates
via
current
at the
fade
of AGC
experienced
clear-sky
is used
rain
the
amplifiers
estimated
This
maintains
history
is being
the
also
estimate
4.2.1
recent
be
Fade
gain
power
the
fade. and
the
fading
can
it measures
VOLTAGE
variable
circuits.
measured
AGC
(C+N)
fading
intervals
tracks
clear-sky
gim,
the
at regular
algorithm
noise
(AGC)
in that
from
MODEM have
plus
Downlink
receiver
calculated
The
carrier
converter. gain
FROM
demodulators
constant
automatic
the
FADE
The
A, on
satellite
will
based
upon
performance received
pages exhibit
A-4
modem
AGC
as well
as the
C+N
power
level
through
A-6,
uplink
power
for
voltages AGC
each
variations
are
voltage
accuracy satellite which,
lS'V'IFI'I_IB
4-6
dependent
on
measurement calculations
are
architecture. when
A
combined
SS/L-TR01363 Draft Final Version 45M/TR01363/Pa rtI i-9,5/97
Use or disclosure of thedata contained on this sheetis subject to the restriction on the title page.
with
satellite
gain
measuremenL
will
uncertainties
is
transponder
a
and
improved
variations affect 1.14
the
4 dB, the
links
dB
operating
is shown
downlink
in
processing dB and
with
between in Figure
variations
downlink:carrier
uncertainty
of 0.66
relationship
(4-3) which
tl_e
on-board
uncertainty
For satellite
and
the
The
received
carrier
will
limit
dB respectively
concatenated C+N
power.
satellite
0.65
similar
coding
power
and
combined
fading
can
power
effect
of these
A
variations
the
with
beacon
power.
these for
and
to the
received
clear-sky
saturated
and
provide
carrier
power.
link
be approximated
margins by
of
Equation
4-2 below.
1.00
(C/N)cs =9 dB Tm = 280 K
0.90
0.80
Ts = 240 K 3 (C+N)
0.70
= 1.5 dB
_0.60 U
_ 0.50
m
0 N
=
0.40
_
0.30 0.20
0.I0
0.00 0
1
2
3
4
5
6
7
8
9
10
Rainattenuation, A, [dB] Figure
4-2. Effect
of Carrier
plu s Noise
Power
Uncertainty
on Estimated
Fade
=_ w
I
(C+N)'r=(C+N)¢_-A+IOI°g
"
T_
" (4-3)
( C + N).
= clear
( C + N) I = faded
sky carrier carrier
A, T m, & T, as previously
plus noise
plus noise
power
power
defined.
=_
w
LD L
SS/L-TR01363 Draft Final Version
4-7
45M/TR01363/Paa 1/-9r-J97 Use or disclosure
of the data
contained
on this sheet
is subject
|o the
restriction
on the
title
page.
Received
carrier
uncertainty
plus
in the
downlink
noise
power
estimated
degradation
uncertainty
of 1.14 dB creates
attenuation.
and
This
results
in
a
attenuation
a relatively
estimate
degradation
large
is used
uncertainty
of
+1.75
dB
to estimate
3.94
dB.
W
=
This m
uncertainty
is much
techniques
and
4.2.2
modem
modem
fade
0.001
estimation the
passing overhead,
the
with
delays
4.2.3
less
than
modem
-
of the
complexity
further
of the
carrier with
fade
Fade
rate limited
received
be around
and
from
5 fade
measurement
investigation.
estimates
AGC
control
voltage
and
will
Modem
AGC
Voltage
be read
noise
For
coding
and
A typical follow
any
from
is typically
circuitry
power.
the the
requirements
loop
for the AGC
300 ksymbols/s.
AGC
can
whenever
by the processing
concatenated
the
estimates
to
to respond
loop
W
to
modem
reasonable
AGC
of
0.01
a QPSK
I
=_.._ m
framing bandwidth
propagation
phenomena
E
10 ms.
Implementation
Implementation
carrier.
high
of 384 kb/s,
1.5 kHz
other
can provide
rate as it is undesirable
rate will
the
Voltage
technique
in the rate
by technique
The bandwidth
symbol
symbol
be around
AGC
to a received
algorithm.
an information
would
Modem
fluctuations
provided
measurement
at an arbitrarily
modem
instantaneous
fade
is tuned
circuitry
times
-
those
measurement
demodulator
fade
than
this
Time
AGC
demodulator the
eliminates
Response
The
higher
modem
and
AGC
fade
measurement
a possible
slight
impact
only
an additional
technique
on modem
has very
parts
cost.
low
impact
on
Demodulators
have
--=
r_
AGC
loops
record
in place
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4.3
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ESTIMATING
Downlink performance performed first path
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unless
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clear-sky
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parameters under
AGC
FADE
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estimated
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ERROR directly
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type[29].
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PSEUDO-BIT
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4.3.1
Accuracy
BER
Pseudo-error
an actual
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channel
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zone
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measurement
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in Figure
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Figure
variations There
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through
A-9,
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average 4-4).
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to be 1.06 dB for the
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about
measure
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estimate
dB for the
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value
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BER measurement.
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LNB
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4-3.
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Pseudo Ideal
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confidence
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measurements generate
rate,
four
input
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circuitry
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to be less
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cost
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comparators
parts
units.
desired require
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measurement
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in a cost
production
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desired
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generate
measurement unit
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latches
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the
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process
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while
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measurement
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symbol
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cost
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for
impact
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unit. 4.4
ESTIMATING
On systems (BER)
modem
the
Channel
comparing
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utilize
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occurs
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divided
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within
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by
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FROM forward can
carrier
BER error
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to noise
ON CHANNEL correction, to estimate
power
ratio
bit error rate is measured
re-encoded
data
are corrections the bit count
with
performed
to determine
CODED
measurements path
loss
degrades
of channel due
and
by re-encoding
a delayed
DATA
the
rate
attenuation.
As
decoder
correction
rate
the decoded
version
of the
original
by the decoder.
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corrections
the channel
bit error
to rain
channel channel
data
and
data.
Any
are counted
and
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4.4.1
Accuracy
The
accuracy
upon
the
of fade
correlation
accuracy.
Effects
compensation Efforts
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through of
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channel
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to reduce
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the
of fade
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error
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errors.
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combined
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effective
ratio
accuracy
measurement
can include
Appendix
error,
estimate
BER
antenna
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to noise
is dependent
in
i
overall
dB
for the
bent pipe
and on-
respectively.
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- BER
from
required
to accumulate response
and
uncertainty.
Eb/No
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attenuation
gain
never
of signal
channel BER is measured in less than 17 milliseconds.
the
rain
antenna
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satellite
and
sources
combine
BER measurements
BER and
C/N
measurement
Assuming obtained
stream
channel
of error
in the
satellites
and
channel
variations,
principle
error
pipe
Response
gain
Data
from
downlink
sources
BER,
the
processing
4.4.2
between
these
shows
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generated
satellite
square
measuring
Channel
estimates
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mean
board
out
A-12
from
which
errors,
to filter
errors
- BER
Coded
Data
on a 384 kb/s carrier the above accuracy can For lower baseband data rates more time would
statistics.
time
Channel
On
high
is significantly
rate
data
streams,
such
as a 90Mb/s
be be
R
TDM
lower. W
4.4.3
Implementation
This
technique
on the
the
framing limited
can be utilized
recovered
measuring
- BER
data.
from
independent
If FEC
is not
BER of a known
bits in a TDM number
can also be implemented
In this
error
Coded
Data
of satellite
utilized
sequence
system.
of bits for
Channel
such case
access
a similar as the
unique
response
measurement.
schemes
technique
times
All forms
because
can
word
will
it operates
be implemented
in a TDMA
be much
of this fade
system
longer
due
estimation
i
by or
:
to the
technique
on the satellite. w
Circuitry
required
to implement
this
circuitry,
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a channel
estimate
the
the
integrated devices,
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circuits which
from
presumably
circuitry,
a comparator,
therefore
no additional
circuitry
should
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cost
measurement
$50 per
unit
cost
less
of $2K,
results
circuitry
reside
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error
with
in a cost
impact
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test
units.
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failures
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and
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to
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decoding.
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have
built-in
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bit
counter.
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measurement per
of $2 per unit. than
the
rates
Viterbi
a channel
this
to be less
of 1,000
data
modem,
and
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is estimated
production
counter
the
include
bit counter For
encoding
within
associated
than
technique
measurement.
for convolutional
a channel parts
estimation
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BER
already
generate
for total
error
channel
are available
fade
unit
technique. which,
Development resulting
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cost
This
for a unit cost
in a cost factors
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for the
impact
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is $52 per
unit.
w
ll=l,
SS/L-TRO 1363 Draft Final Version
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I.,DI'_U_L-
4-12
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the
title page.
1/- 9FJ97
:
For
higher
rate
impacts
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counters The
systems,
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relatively
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impact.
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when
circuitry
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technique 4.5
for bit rates ESTIMATING
Virtually
every
multiplexing
frame or burst
constitute
3%
on these
bits
estimates
FADE
satellite
reference
25 Mb/s
time
then
the
the
impact
on the results
some
and
error
encoded
data.
incremental
cost
circuitry
of this
and
fade
estimation
bits
to indicate
carrier
frequency
overhead
reference,
provide
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a-priori
of these
fades
PATTERN
terminals.
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estimation
overhead
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terminal
counters
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fade
DATA
phase
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carries
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ON KNOWN
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bit
of decoding
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communication
boundaries,
because
data
FROM
task
to complete The
BER and
circuitry,
the
statistics
required
algorithm.
above
with
BER
channel
compare
compared
is still
compensation
to measure
circuitry,
to accumulate
A microprocessor
implement
circuitry
can
knowledge
bits
easily
typically
be
of their
performed
content.
Fade
measurements.
m
4.5.1
Accuracy
BER
measurements
- BER
from
Known
performed
on
Data
Pattem
known
data
patterns
are
of any
power
measurements
of channel
m_
quality w
and
do
technique
for
uncertainty SNR
M
m
BER m
channel
on
is 0.01
Figure
+1.06 the
+ 40%
A,
4.5.2 Since
measurement tolerance interval
pages saturated
or 0.10 seconds
to LNB
to the
that
of 0.01
the
indicates
through
bent-pipe,
the
dK
upi_
and
A-15.
The
pattern
the
This
error
in the
_+0.50 dB for the backed
coded
data,
encoded
decoder.
interval
uncertainty
the
of 3x10 -4 after
un-coded
downlink
and
is not
Reed-Solomon
from
of +0.5
channel
confidence
This
variations
to a BER
the
95%
Reading
in Eb ]NO with
the
gain
data
corresponding
that
measurement.
BER from
known
(10 -10 - 10 -11) after
< BER < 0.014.
A-13
- BER
measurement
measured
is similar
level
for QPSK
the
A 40% measured curve
is combined
of with
uncertainties
in Eb/No
in
degradation
estimate
is
off bent-pipe
and
+0.49
dB for
satellite.
Time
time on
BER
associated
processing
BER
free
the
immune
Assume
at a BER
or 0.006
Response the
quality
an uncertainty
on
dB for the
on-board
signal
quasi-error
measuring
accuracy
is therefore
measurements.
uncertainties
Appendix
absolute
fading
received
and
4-4 yields
additional
the
is operating
decoder
tolerance
on
estimating
pseudo-BER
the
Viterbi
rely
in the
and
and
not
from
Known
is performed
is required BER
to for
on only
provid_e
Pattern a small
acceptable
a 384 kbit/s
for a 3% known
Data
pa_ern
stream
fraction
of the
accuracy. requires
To a 1,200
achieve bit
bits, the
40%
measurement
SS/L-TR01363 Draft Final Version 45M/TR01363/Part
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Use or diaclosure o/the data contained
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content.
4-13
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channel
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on the title page.
1/- _lr-J_'
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4.5.3
Implementation
This
fade
when
the
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measurement
from
technique
demodulator
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only
is locked
to the
knowing
the
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provide
desired
meaningful
data
stream.
degradation The
estimates
demodulator
will
not wi
have
the
advantage
procedure.
This
modem.
Any
basis
by
The
cost
of fade
measurement
known
the modem
data
associated
in the
provide
with
degradation
technique
pattern
to either
current
this
does
not
aggregate
or verify
technique
the
any
additional
add
stream
proper
during
is monitored
operation
is only
that
link
of the
acquisition parts
on
to the
a continuous
communication
associated
with
lib
link.
the
expense
equal
to the
of R
developing from
a process
Channel
to accumulate
Coded
Data
fade
the BER statistics measurement
and
can be assumed
BER
technique. N
4.6
ESTIMATING
Measurements used
of signal
to estimate
power
FADE
ratio
FROM
power
path
loss
degrades
SIGNAL
to noise
due
power
to rain
according
TO NOISE ratio
(SNR)
attenuation.
to the
following
RATIO
As
within
fading
the
occurs
modem the
can
carrier
also
be
to noise
Ill
formula. m
C
Ndegredation
in decibles
= 10log
+ A
T,
(4-5) _I u
T, = System
noise
temperature
A = Rain attenuation
under clear
sky conditions
in decibels
l
T m = Rain temperature w
The
first
term
accounts
and
the
second
term
for
several
accounts
system
degradation,
for the
clear
increase
in system
for the
sky
noise
is approximately
signal
noise
attenuation.
temperatures
1.5 times
power
higher
The
in Figure than
the
rain
caused above
by
rain
absorption
relationship
4-6.
The
induced
is plotted
effective
fade,
or
w
attenuation. w
=_en=this and
technique
SNR
high, Within If we
is implemented
degradation
essentially the assume
equal
modem QPSK
on the
is one
because
to the
earth
the data
baseband with
satellite,
the noise surface
signal no inter
the
scaling
temperature
between
"seen"
by the
rain
attenuation
satellite
is always
temperature. to noise
symbol
ratio
w
can
interference
be calculated the
signal
from
data
samples.
to noise
ratio
is
(DIl+le)
SNR 22(1
= + Q=)_(ZItI+IQI)Z
(4-6)
w
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12
Rain Attenuation,
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Where
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Q
are
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from
4-6.
I-channel
signal
the
C/N Fading
and
to noise
above
14
16
18
20
A (dB)
Caused
by Rain
Q-channel
data
measurement
Attenuation
samples.
and
assumptions
signal
to noise
Fade on
estimates
the
are
receiver
noise
graph.
E= Z
4.6.1
w
Accuracy
The
accuracy
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of fade upon
measurement include
m
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errors.
correlation
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residual
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from
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Effects
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generated
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contribute
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appendix,
of error
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ratio
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variations,
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antenna
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measurement
pages
to noise
downlink
gain
sources
to fade on
signal
decouple
satellite
out these
will
and
power
never
rain
to noise
attenuation
gain
and
antenna
be completely
uncertainty. through
signal
These
A-18,
for
the
is
effective
uncertainties three
satellite
=
architectures. be
The
1.03 dB for the
+0.42 °--
the
to Noise
estimates
accuracy.
uplink
pointing
- Signal
dB for the
4.6.2
overall backed-off
on-board
Response
Assuming
Signal
uncertainty
Time
bent
in less
than
required
to accumulate
pipe
processing
downlink
satellite,
satellite
- Signal
to Noise
obtained
in the
10 milliseconds. statistics.
On
dB for
the
saturated
is predicted bent
to
pipe
and
Ratio
on For
+0.43
estimate
architecture.
to Noise
is measured
degradation
a 384 kb/s lower
high
carrier
baseband
rate
data
the
data
above
rates
streams,
such
more
accuracy time
can would
as a 90 Mb/s
be be
TDM
m
SS/L-TR01363 Draft Final Version
I3"Y'EFr_
LC3RM_L
4-15
m 45M/'FR01363/Par111-9_/97
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the
data
contained
on
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sheet
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subject
to
the
restriction
on
the
title
page.
stream below
the response 10 milliseconds
4.6.3
time trades with implementation can be obtained at low costs.
Implementation
This
technique
can
- Signal
be utilized
on the baseband satellite.
signal.
Figure
4-7 shows
a hardware
TDM
environments.
are
required
only
successive microprocessor calculates logic which
may
a few
estimation
times
I
access
technique
implementation
times
samples
SNR
per
function are
and
takes
schemes
can
also
because
be
read
into the
it operates
implemented
to control
to obtain
by
accumulating
the
to interface
fade
FIFO with
of the
symbol
FIFO
data
loading
fact
on the
rate. the
required the
perform
modem.
The
high
SNR
are
I
the
number
SNR
required
rate
readings
memories
A sufficient
algorithm.
and
and
that
(FI_O)
compensation
the
in TDMA
First-In-First-Out
channel
the
the
can function
advantage
The
at the
implements
required
which
second.
processes
is included be
response
_z
of satellite
implementation
must
then the
device
This
which data
fade
case
Ratio
independent
This
In this
I
only
element
to Noise
cost.
of
accuracy.
A
summations,
m
i
A programmable
other
terminal
ancillary cost
i
functions
impact
of this
i
_I
I-channel D/A
m
Demodulator Data
==
Samples
Baseband __
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_
,
Signa_
= =
Q-channel D/A
Logic
Programmable Device
I [
I
I
I-channel FIFO
Q-channe_ FIFO
I Memo_
Figure
4-7.
Signal
_{
to Noise
I
I Processor
Ratio
|
t
Measurement
Hardware w
w
LD_L
SS/L-TR01363 Draft Final Version
4-16
45M/TRo Use or disclosure
of the data
contained
on this
sheet
is subject
to the
restriction
on
the
title
page.
1363/Part
1/-9FJ,97
w
circuitry
is estimated
to be approximately
circuit.
The
processing
modem
with
no parts
due
to a 10 -3 test
Fade
measurement
the
per
fade
was
for further
rate
for the
cost
fade
OF FADE
MEASUREMENT
with
The
production
is $2 for unit
to be
into
$80K
combined
yields
costs
which
the
of $2K.
adds
$80 to
impact
of this
techniques
were
cost
are
TECHNIQUES
summarized
as indicated.
higher
reduced
circuitry
units.
integrated
to be incorporated
with
is estimated
memory
to be $94.
its performance
improve
FIFO
is assumed
of 1000
is estimated
speed
associated
cost
quantities
investigation
a low
measurement
development
techniques
for
burden
technique
because
will
The
measurement
selected
factor
requirement.
for production
SUMMARY
selected
handling
circuitry
cost
six fade
data
failure
measurement
4.7 The
unit
and
$12
in Table
The
beacon
is independent production
4-3.
power
of satellite
volumes.
The
Three
measurement architecture
Modem
technique and
AGC
the
technique
cost was
=
excluded Coded
based Data
upon
and
poor
BER from
BER from
channel
coded
will
most
certainly
SNR
technique
was
predicted Known
data
was
Data
and
also
based
Table
4-3.
Summary
The
Pattern
selected
be employed included
accuracy.
technique
to represent
many
modems
upon
low
of Fade
Pseudo-BER,
cost
are very
similar
group
because
this are
BER
available
impact
Measurement
and
with good
from
Channel
in performance. channel this
coding
feature.
The
accuracy.
Techniques
Accuracy of Degradation Estimate Cost to Implement
Speed of Response
Bent Pipe/ Backoff
Bent Pipe/ Saturated*
On-board Processing
Selected for Experiment
$157
0.001 sec
1.25
1.25
1.25
v"
Modem AGC Level
$92
0.01 sec
3.94
2.17
2.17
Pseudo BER
$57
0.02 sec
1.06
0.50
0.50
Channel BER from a Known Data Pattern
$52
0.10 sec
1.06
0.50
0.49
BER Monitoring from Channel Coded Data
$52
0.02 sec
1.04
0.46
0.45
v"
Modem Signal to Noise Ratio
$94
0.01 sec
1.03
0.43
0.42
,/
Technique Satellite Beacon
w
=--
* Assumes that overdrive is maintained through all uplink fades. Otherwise bent-pipe with pack-off accuracy is more appropriate.
=_
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4-17
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45M/FR01363/Part Use or disclosure
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an this sheet is subject to tht restriction an the title page.
1/-_5/g7
i
a_
i
i
:
=
SECTION For
satellite
degrade
=
systems
the
it is necessary
some
of rain
power
routing,
and
control,
power
amplifier,
and
In a bent-pipe
active
for
at earth
will
can
in a year
(e.g.,
A number
rate
and
active
lens
be evaluated
site
FEC
and
the
and
satellite fade
transponder,
diversity
code
array,
Ku-
of rain
satellite
diversity,
severely
or to implement
or on board
overdriven
information
These
events
carriers
levels.
margin,
array,
all
stations
(i.e., frequency
phased
amplifier).
rate
through
changes,
matrix
and
or multiport
compared
in this
section.
MARGIN
satellite,
carrier-to-noise
margins
link
network),
(i.e.,
multimode
built-in
rain
of time
at acceptable
techniques
terrestrial
LINK
sufficient
availabilities
in which
durations
techniques
include
sharing
BUILT-IN
total
link
diversity
back-up
downlink
5.1
the
bands
significant
compensation
techniques
uplink
for
to allocate
fade
to maintain
compensation
in frequency
performance
Ka-bands),
in order
w
operating
carrier
form
S -- RAIN FADE COMPENSATION
for a carrier ratio
transmitted
at B is given
1
1
c
from
earth
station
A to earth
station
B, the
by [6], [7] 1
I
=
1
1
C
+ C
(5-1)
where (C/N)total
= total
carrier-to-noise
ratio
(dB)
(C/N)up
= uplink
carrier-to-noise
(C/I)up
= uplink
carrier-to-interference
C/IM
= carrier-to-intermodulation
(C/N)down
= downlink
carrier-to-noise
(C/I)down
=
carrier-to-interference
ratio
(dB) ratio ratio
(dB)
(dB)
ratio
(dB)
--J ==:
Equation
(5-1)
can also
d0wnlink
be expressed
as
(C/N)u p
(Cll)_
(C/N)wt. ,
10
io
=10
lo
+10
1o
ratio
(C/IM)
_o
+10
(dB).
(C/N)ao, _
+10
_(C/I),_,,=
_o
+10
_o
(5-2)
or
(C/l)d,,_
+10 (C)
total
=-101og[10
F6 +10 (cn)o_
(cm),
i_ +10 (C,_M)
_o
+ 10
I0
(5-3) .
w
EDgE
SS/L-TR01363 Draft Final Version
5-1
45MfI"R01363/Part2/- 9,_,_/ Use
or
disclosure
of
the
data
contained
on
this
sheet
is
subject
to
the
restriction
on
the
title
page.
As seen
from
the
total
that
the
Equation
(5-3), if one
carrier-to-noise link
ratio
is limited
of the
five ratios
is almost
by this
equal
component.
becomes
to this
ratio.
In operational
much
smaller
than
In this
case,
it is often
satellite
the
others, termed
w
systems,
depending
on a
bit rate,
modulation
and
=_
number
of factors
coding,
required
such
as service
requirements
in terms
BER
performance,
and
availability;
of carrier
i
and
high-power
parameters the
amplifier
(e.g.,
total
(HPA)
saturation
carrier-to-noise
flux ratio
link
size;
climate
density,
conditions
EIRP,
can be limited
earth
and
than
antenna
diameter
earth
stations;
satellite
at
G/T);
by more
station
and one
interference
environment,
i
component. i
In general,
a link
or system
availability.
A high
transponder,
the
margin
the
depends
system
the
the
is allocated
margin
transponder
lower
on
margin
is required
capacity
capacity.
factors
to a link
a high
is a function
As
mentioned
for
seen
to provide
link
of the
from
earlier.
in order
availability.
system
Equation
this
in which
link
In a bent-pipe
margin:
(5-3),
In a system
a specified
the
higher
nonlinear
carriers
the
function
are
allocated i
margins BER
to provide performance
Since
Therefore,
it is not
realized
had
the
allocated
and
adaptive
basis
It should
be noted
input
fixed
periods that,
almost
downlink
fade,
only
the
last
rate)
service
and
downiink
the
two
region
there
nonlinearities margin
(C/N)down, larger
than
since and
are
are
equal
the
an
uplink
affected. in the
fade
since
only
fixed.
could
have
been
margins
U
been
spacecraft
larger
on
an
the
nonlinear uplink
would
not fade,
the last
two
distortions
affect the
equally
components
margin
uplink
set in the due
is normally
downlink
For
a
since data margin
In a single-carrier-per-
is normally
margin
would
(intermediate
nominal
[30].
fade
system
IM
region.
(C/I)down.
the IDR
system,
the
linear
uplink
and
for
backoff
in the
an
the
transponder
minimize
is set
than
total
to
since
11 dB, respectively
The
the
(C/N)down,
INTELSAT
input
LD__
BER is
and/or
backoff
margin
much
(Here,
[31].)
threshold
fixed
in order
As an example,
For a downlink
margin
input
is normally
transponder
dominant
region
C/IM,
to 7 dB and
total
smaller
carrier
capacity
which
stations
system
(C/I)up,
Ku-band
the
operation,
carrier
to the
margin
(C/I)down.
the system
earth
quasi-linear
is no IM impairment.
become
or had
the
the
fades.
individual
(C/N)up,
in the
margin
the
equal
components
operation,
since
in
the
downlink
transponder
system
set
the
offered
rain
than
capacity
in a multicarrier-per-transponder
is normally
equally
in the
by
availability,
assigned,
allocated
provided
link
better
permanently
been
of severe
is normally
margin
much
an increase
not
margins
Consequently,
uplink
are
to achieve
margins
at a specified
conditions,
margins
possible
during
impairment.
affect
clear-sky
these
additional
backoff
BER performance
is, under
performance.
The
a threshold
the margin
saturation
to TWTA larger (C/N)up, is normally
or SSPA than
the
(C/I)up, much
are affected.
SS/L-TR01363 Draft Final Version
5-2
45 M/TRO 1363/Pa rt2/- _r--r'_7 Id_ or disclosure of the data contained
on this sheet is s_lb_ect to the restrictic,n
on the title page.
w
In an OBP
satellite,
information
for a carrier
BER performance
transmitted
at B, BERi, BERi
r
from
is given
= BERiu
earth
station
A to earth
station
B, the
by [13]
+ BERid
(5-4)
where BERiu
= uplink
BERid
= downlink
BERiu
is a
noise in Equation
carrier
power
3-dB
(C/N)up
and here
interference (5-3).
carrier
in system
BERid
uplink
noise
components
thermal
of downlink
(C/I)up,
that
In a special
to uplink
advantage
BER.
noting
and
shown
ratio
of
It is worth
downlink
BER
information
function
(C/I)down.
the
information
situation
noise
and
power
margin
do
can
not
in which
or
is equal
and and
up
like
the
ratio
those
of uplink
tO Cdown/(Ndown+Idown),
noise
as compared
(C/N)down components, add
Cup/(Nup+Iup),
thermal
be realized
of
interference
accumulate
interference,
to downlink
a function and
and
interference,
to a similar
close
situation
to
using
a
W
bent-pipe
satellite.
system
In a link,
margin.
performed
From
conditions
carrier,
the
(5-4),
from
at the
allocation
uplink
Equation
independently
climate
the
the
transmit
or downlink the
allocation
allocation and
of a large
fixed
built-in
link
associated
with
margin of
of a fixed
receive
earth
downlink
is always
a fixed
uplink
downlink For
may
reduce
a large the
than
margin
margin,
stations.
margin
larger
the
can
be
depending
on
downlink
carrier
TDM
information
rate.
"mU
Therefore,
while
complexity
and
the
Ka-band
system
(much
OVERDRIVEN
possible, from
about
and
technique
a network,
margins OBP
SATELLITE
satellite,
an earth
example,
than
margin
region in the
such
(i.e.,
4 dB
Ku-band,
+4 dB to -3 dB.
The
0.5 dB for a TWTA
high
uplink
same
level.
fades
can
the
in the
can
reduce
fixed
margins
adversely
affect
of large
Ku-band)
the
transponder
more
a 7-dB
fade
in the
will
uplink
while degradation
operating
due
as
will
reduce
in downlink
by operating keeping
to high
the
uplink
to transmit
saturation)
reduction
Therefore,
the
due
TWTA
beyond
corresponding [18]).
effects
operation,
or
be tolerated
Consequently,
requirement
and
the in the
satellites.
to minimize
that
is simple,
TRANSPONDER
in order
station
the
required
in a single-carrier-per-transponder
overdrive
from
larger
in bent-pipe
In a bent-pipe m
cost
capacity
5.2
the
the
downlink
to an
shown
uplink
is set
EIRP
fade
into
overdrive
on
the
the
5-1.
For point
is small
EIRP
it is
carrier
operating
in the carrier
well
in Figure
TWTA
carrier
TWTA
fades,
a high-power point
the
rain
(e.g., region,
at about carrier
the BER
w
5-3
m m
SS/L-TR01363 Draft Final Version 45 M/'rR01363JPatt2/-
Use or disclosure
of the data contained on this sheet is subject to the restriction on the title page.
_,97
Overdrive Saturation
Region
I
Quasi-Linear Region
_ ==
TWI'A Operating Point
O o
Linear Region
m
_
(._ :3
/
O
m
w
Input Backoff
Figure performance limited
5-1.
is almost in
the
Transponder negligible.
uplink.
(dB)
TWTA
(It has
This
Operation
been
is normally
in Overdrive
implicitly the
assumed
case
in
Region
here
that
g
the
link
is not
single-carrier-per-transponder
operations.) This
technique
is only
transmitted
through
saturation.
Here,
the
(i.e.,
BER
performance evaluated
and
technique
is not
suitable
a single
for
systems
transponder
nonlinear
for
TWTA
effects
performance,
accounted
in which
in the
whose
[32],
power
a single
[31]
operating
due
spectrum
system
design
high-power
to
the
point TWTA
is set on
re-growth,
etc.)
associated
link
and
carrier
is
i
beyond
the
must
carrier be
:_ u
fully
budgets.
This =
multiple 5.3
(CDMA)
carriers
UPLINK
POWER
CONTROL
power
adaptive
control
basis
another
carrier this
beam
and
and
In an open-loop own
transmit
a closed-loop its
own
LD L
due
to severe
carrier.
downlink
fade.
this
and
technique
operations
the
carrier
measurement, The
amount
can
uplink in the
of uplink
Depending availability
with
FDMA
or code-division
IM impairments.
in which
continuous
same
on the of beacons,
be implemented
EIRP
power
satellite and
is adjusted
downlink, adjustment beam the
in three
of the
on
station
different
of
is estimated
configurations
earth
an
power
(i.e.,
locations
ways:
in
open-loop,
feedback-loop. system
(e.g.,
carrier,
and
system
(e.g.,
transmit
communicating.
the
coverages)
coverages,
closed-loop,
on
or of the
measured
multicarrier
is a technique
based
connectivities the
in commercial
access
Uplink
from
useful
carrier
in a non-loopback
needs
to rely
in a global as well
It is preferable
beam),
an earth
on a measurement
of the
beam
or loopback
as carriers
from
to estimate
the
other uplink
beam), earth power
station
cannot
downlink an earth
beacon s_tation
stations adjustment
5-4
receive
with
fade.
can
it is on
the
SS/L-TR01363 Draft Final Version 45M/rR01363/Part2/-
Use or disclosure of thedata contained on this sheet is subject to the restriction on the title page.
In
receive
which based
its
9Fa97
--4 B
•
fade
measurement
measurement
of of the
associated
of
latter
variations
at an earth
one
is not
in carrier
station
affecting
a feedback-loop
system
control
station
through
the
EIRP's.
It is implicitly
beams.
Among
other
accurate
instead
due
backoff the
earth
beam
of all carriers
stations
which
the
and
carrier
downlink
transmitted
and
a west-to-east in one
uplink
since
input
being
it receives
undergo
same
in carrier
upiink
carrier
in an east-to-west powers
of
to variations under
simultaneously
the
beam,
carriers
output
(e.g.,
monitors
these
backoff
fadings and
fadings
and
(i.e., rain
received).
beam),
beam,
the
In
a central
and
commands,
to adjust
their
uplink
w
resources
fadings
has
power,
bit
to estimate can
Appropriate adjust
the
control
accuracy compensated. 5.4 Over
the
years
terrestrial
then
could
coded
rain
fade
data,
and
to measure
in the
which
before
carrier
to the
ground uplink
it can
receive
techniques
satellite, uplink
two
EIRP.
signal-to-noise
the
downlink,
and
undergoes
measurement
In an OBP
satellite
segment
delays
its uplink
in the
(i.e.,
ratio)
one
of the
powers affected
can last
be two
of all carriers. earth
stations
to
accordingly. by
[28].
channel
space
station
propagation
selected
simultaneously
more
to increase
be sent,
occur
an earth
three
the
not
requires
adjustments.
powers
A summary
at frequencies ==_
dB
DIVERSITY
from
COMSAT
- November
technique
of +2.5
of the
conducted
May
one
station
on board
carrier
last
does
round-trip
power
can
rain
In addition,
two
uplink
was
the
control
ratio
be used
uplink
during
power
error
that
two.
any one
the
experiment
ACTS
central
commands
their
first
at least
the
here
systems, the
satellite,
techniques
An
than
from
In a bent-pipe
used
three
to wait
instructions
=
the
segment
beacon
assumed
1994
It was
Laboratories
to evaluate
found
be
maintained
of key
ACTS
at Clarksburg,
the
that,
under
and
uplink
experiments
feasibility most
of the
of
up
described
using
open-loop
conditions,
fades
was
Maryland
uplink
a power to
15
dB
control could
be
in [33].
TECHNIQUES
various
diversity
above backup,
about and
techniques
10 GHz.
orbital
have
These
diversity.
been
include
Some
proposed
for mitigating
frequency
of these
diversity,
techniques
are
rain site
fading
diversity,
briefly
discussed
below. 5.4.1
Frequency
Rain
attenuation,
proportion that GHz
Diversity
to the
at 11 GHz. for
expressed square Figure
to mitigate
systems
or separate
of the
rain
dB,
increases
frequency.
5-2 shows
a mid-Atlantic
be used
in
Rain
therain elevation
fading
at Ka-band may
out
weigh
the
attenuation
attenuation
location;
antennas
with
angle
is 40 °.
approximately
at 20 GHz
distributions
frequencies, any
frequency
advantage
frequency
requirement offered
by this
w mP.A.Iml
5-5
diversity of complex
or disclosure
of the
data
contained
on this sheet
30 can
feed
technique.
45 M/TR Use
times
SS/L-TR01363 Draft Final Version
_sYECll-r==_9
LDI=_dI_L
three
at 4, 6, 11, 14, 20, and
Although the
is almost
in
is subject
to the restriction
on the
title
page.
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Figure
5-2.
Cumulative
Frequencies
5.4.2
Site
The
experiments
a significant
improvement 10 km,
separation conventional
together Finite than the
the
size
rain
and
diversity
in link gain
Figure function
and level.
the
The
[17]which angle joining
5-3
40 °
I
and
requires as the
the
two
5-4 show
of single
site
may
the
predicted
attenuation.
use
of
the
diversity
gain
is the
the
be predicted site
parameters; and
exceeds,
applied
site
in the
satellite
link.
connecting
them
by distances
larger
projection
At the
using
the
model
low
elevation
gain end
and
is the
radio
on
single
30 GHz, site
the
as single
at the
same
recommended
orientation
at 20 and
of the
taken
angle,
path
fades.
quantified
between
both
of the
diversity
difference
to
strong
is normally
sites,
baseline
proportional
relatively
two
separation, the
is inversely
in combating
between
frequency,
sites
hil
that
20 °, the
a single
separated
cell size
effective
the
attenuation
input
shown
below
and
site-
diversity
and
Diversity
at sites
average
Diversity
gain
20 ° have
angles
stations
fading
Site
approaches,
to support
earth
fading the
with
diversity
elevation
about
intensity
rendered.
can be highly
joint
For
two
rain
availability.
above
stations
up the
In general,
advantage.
link
separation
earth
of rain
of severe
proportionately.
in uncorrelated
availability
presence
site
20 kin.
dedicated
size.
or diversity
attenuation
line
results
intensity
orientation the
cells
cell
ITU-R
Angle
non-uniformity
angles
as the
the benefits
rain
Improvement
the
to outweigh
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improving
elevation
in setting
average
probability
at Different
Elevation
In the
to increase
two
involved
in
about
appear
and
diversity.
rapidly
beyond
requires
of rain
diversity
Location;
storms,
with
increases
cost
appears
the
site
paths
saturating
sense
rain
advantage
requirements
In general,
of
in site
on earth-space
diversity
Attenuation
U
extent
are exploited
has
about
for a Mid-Atlantic
horizontal
a storm
diversity
of Rain
Diversity
limited
within
Distribution
the
base
angle
the
by
between
earth
surface.
respectively,
attenuation
line
very
as a little
SS/L-TRO 1363 Draft Final Version
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5-6
45 M/TR01363/Pa
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on this
sheet
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on
the title
page.
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r 12
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10
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Figure 5-3.
Diversity
Gain at 20 GHz as Function
of Site Separation q
Diversity Gain at 30 GHz
s..,..
14
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20
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of Site Separation
SS/L-TR01363 Draft Final Version
i_Pdu'rM
L¢3_1.
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or disclosure
of the data
contained
on this
sheet
is subject
to the
restriction
on the title
page.
a rt2/- 91e,97
diversity low
gain
is predicted.
attenuation
levels
This
are
is due
rather
widely
to the
fact
that
precipitation
spread
and
both
sites
structures
will
producing
experience
similar
levels
of attenuation. 5.4.3
= =
Back-up
Site
diversity
and
an
Terrestrial
as described
inter-link
involving
ratios
in the
facility.
low-cost
activity
Network
As
terminals
and
the
previous such,
such
availability
subsection
site
requires
diversity
is not
as VSATs.
However,
of free
on a VSAT
time
two very
dedicated
earth
attractive
VSATs
do not
may
stations = m =
to applications normally
be gainfully
have
high
employed
with m
site be
diversity
to overcome
connected
fading
together
conditions.
take
of site
by
the
fading.
using
VSAT
advantage
replaced
rain
the
sites
terminals
terrestrial
must
diversity.
terrestrial
VSAT
network
have
The
network
located
to implement
separation
cost
distances
of full
usage,
time
which
in a metropolitan traffic
in excess
dedicated
is close
area
sharing
under
of about
interconnect
to the
average
10 km line
raining
can
to
U
is now
time
a l
of the
I
order
of 10%.
benefits 5.5 In
In this
through
INFORMATION
RATE
specified
link
method
systems,
diameters
(or very
efficient
modulation
sky
degraded
and
concatenated
the under
most
earth
small
aperture
and
Due
to operational
rain
fades,
one
power,
of the
two
basic
the third
constraints,
simplest
rain
by one
half,
and
C-band
and
code
the
it is essential conditions
and
convolutional
In
very
small
that
power
(i.e.,
systems,
i
clear-
the inner
J
power.
frame.
with
Ku-band
use
of
code)
is
also
effects
techniques
caused
would
fixed.
reduced
w
m
the
bandwidth rate
and
a
services.
compensation FEC
to provide
in a TDMA
antennas
to mitigate
occupied
slots
all weather
of multimedia
fade
and
under
in order
economic
bandwidth
Therefore,
(RS) outer
provision
time
low-cost
(VSATs)). be used
further
utilized
carrier
is the
employ
in current
cost
normally
include
resource
will
mitigation,
CHANGES
resources
terminals
rate,
fade
resources.
RATE
conditions
Reed-Solomon
transmission
can be reduced
CODE
techniques
in the
and
FEC
In fact,
especially
rain
of ground-segment
stations
FEC
(e.g.,
besides
fading
then
weather).
up",
carrier
AND
is used,
coding
"catching
sharing
systems,
performance
TDMA
Ka-band
rate
of arrangement,
can be gained
communications
If the
type
Thus,
by one
by
severe
be to keep the
half.
the
information
As an example,
=_ w
a clear-sky rate
64 kbit/s
3/8
steps and
FEC
is at least more
receive
keep
1 dB
carriers, stations,
carriers,
the
extra
at the end the
3/4
The
FEC
carrier
possible
can
be switched,
additional
fade
from
FEC
it may
and
the
information
time burst
rate
reduction
be difficult service
reserved of each
rate
slots
not
be
3/4
end
by carriers
of the
twice
the
achieved
frame. time
suffering
fades
transmit
5-8
TDMA
in order
required
_ the data contained on this sheet is subject to the restrictionon the titlepage.
from
to the
SS/L-TR01363 Draft Final Version 45 M/T'R
Use or d_Iosur¢
and
can be allocated
example, be
half
employing
employing
above will
combined by one
at the
In a system
slots
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to a 32 kbit/s
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N_
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fades, from
rate
to 3/8).
this
seamless.
to be used
or at the unchanged,
from
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information
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under
margin
5 dB at a BER of 10 -8 (i.e., 3 dB from
than
continuous
either
carrier.
rate
01363/Pa
rt2/- 9F.J97
reserved
time slots.
the frame
overhead
which
Implementation traffic
The establishment
parameters,
transmission
climate conditions
Downlink
among
E
amplifiers
(HPAs) within
Linear
2) those
on the
earth
station
and availability,
and
1) those HPAs
for sharing
satellite
available
by the satellite.
involving operated
linear
Two
mode
general
high
in saturation.
RF
power
Candidate
the following.
methods lens array
•
Active
transmit
phased
or matrix
amplifier
(MPA)
(ATLA) antenna
array
(ATPA)
antenna
mode amplifiers
Multimode amplifiers Code and data rate changes mode
methods
in sections
discussed
5.5.
is provided Preamble
The satellite
and the multimode
5.6.2 through
in section
methods 5.6.1
transmitted
include
transmit
order,
of
&[36]).
carriers involving
Active
Saturated
part
depends
parameters,
link performance
methods
are considered:
•
The linear
_
sharing
these categories
mode
and
candidate
downlink
Multiport
• •
L
addresses
and
required
constitutes
or OBP satellite
configurations
(e.g., see [34],[35]
•
2.
w
a bent-pipe
slots in a frame
SHARING
the several
of power
=
u
sharing
categories
1.
in either
parameters,
POWER
power
methods
capacity.
beam
at earth stations
DOWNLINK
power
satellite
of time
the system
of this technique
requirements,
5.6
reduces
of a pool
5.6.4 and 5.6.6.
A comparison
in section
method
are discussed
The code and data rate change
of the DC power
requirements
here, in
method
of the linear
was mode
5.6.5.
and System
system
amplifier
for which
Assumptions power
sharing
is here considered
is one which
is accessable
w
by a large capacity filings
number
of individual
and low per-user with
the Federal
will serve
their
each beam
covering
On the average,
given
and
cost.
corporate
In conformity
COmmunications coverage
a separate,
rain occurs
areas distinct within
users. with
Therefore,
all of the current
Commission using
a very
(FCC),
large
glm,
high
Ka-band
of this system
of narrow
"spot"
beams,
sub area. any single
spot
beam
will vary with the location of the area were discussed in section 3.0.
area no more
than
about
five
rainfall simultaneously. Also, of the year) of the rainfall that
covered
by the spot
beam.
These
SS/L-TR01363 Draft Final Version
md_a
I,.CI_L
both
multimedia
the satellites
number
percent of a year. All spot beam areas will not experience the intensity, frequency, and time of incidence ( e.g., season is experienced characteristics
it is to have
5-9
45 MFrR01363/Pa Use or disclosure
of the data contained on this sheet is subject to the restriction
on the title page.
rt2J- _-a07
It is evident, that
the
then,
available
attenuation. would
spot
beam
have area.
of rain-induced the
allowed
on
average,
sharing, relative
This
large
the
99%
power
can
to be large fixed,
would
to the and
sharing,
satellite
be used the
power
power
would
Or,
are
99.9%
it is not
link
less
would
be fixed within
frequently
a
EB
than
of the
(at the
availability,
the
all levels
fraction
closure
so
signal
raining
the
to link
is desired
to overcome
to occur margin,
weather-related
time,
l
required
typically,
at Ka
m
of the time. the available
power
generated
smaller
f'Lxed power
margin
is provided
need cover only the measurement time between fade measurement
beam
be sufficient
relative
ideally,
such that a much
beams
rain-induced
spot
when
a fixed
be over-powered
advertised
to each
predicted
with
spot
to overcome
needed
which
outage.
among
allocated
margin
those
power
as needed
power
to the
except link
link
is equal
between
With needed
power
weather-related that
of sharing
power
attenuation
quality)
band,
a means
satellite
Without
and
link
that
on the satellite
can be allocated
in each beam.
error and the change in attenuation and the initiation of sharing.
level which
The smaller occurs
as
m
margin
during
U
the I
5.6.2
Multiport
(or
Matrix)
Amplifiers m
5.6.2.1
Multiport
A multiport linear
beams.
amplifier
amplifiers,
separate
Amplifier
input The
INPUT PORTS
(MPA)
and ports
generic
Introduction consists
of an
a K x N output of the
form
MPA.
matrix. The
of an MPA
M x K input The
M channels
N output
is shown
matrix,
ports
in the block
K individual
to be transmitted
connect
to N
diagram
of Figure
' E> 2 i>
• •
arrive
separate
at
transmit
5-5.
2 • •
OUTPUT PORTS
N
M
INPUT MATRIX
Figure
N
matched
5-5.
HIGH POWER AMPLIFIER,c (HPAs)
Top-Level
Diagram
OUTPUT MATRIX
of Multiport
9708293
Amplifier
13Y!B'I"l_M6
I.I=II_/_L
SS/L-TR01363 Draft Final Version
5-10
45M/l'RO1363/Part2/-_ Use or disclosure
o/the data contained on this sheet is sub_t
to the restr_tion an the title page.
i
Signals
in one
channel
uniform
amplitude
shifters,
to the
power
input
power-divided
units,
divider.
from
each
of the K outputs of the K amplifiers
of the
other
M-1
represented
in and
amplified
signals
into
signal
units
is easily
the
and
one
corresponding
power
ports
Each
by the
of amplifier
of the various
of the M input
is amplified
are proportionally that sharing
at one
of a separate
outputs
all M signal w
arrive
are
passed
of the divider where
input
by all K individual merely
by setting
amplifier
while
maintaining
multiport
are sent,
via phase with
The composite Thus,
achieved
a K-way,
it is summed
channels.
amplifier.
through
signal,
all M input amplifiers.
the
signals It is seen
relative
linear
the
drive
levels
operation
of all
amplifiers. The
M distinct
ports,
are,
way
divider
summed
the
arriving
from
passed
is then
with
signal
The
in turn,
input K units and
output
their
vector
sum
numbers.
originated
input
from
port
the
port
each
n.
Thus,
amplifiers.
As
the
originated paths
where
it is
a result,
the
this sum
originated from
through
a phase
port
shift
the
such
that
rational
connection
amplifier
M.
both
can be other
a routing
multiport
of an N-
K of which
be imparted
M input
output ports
K which
or not
of the
output
different
whether
each Each
signals,
traversed
implementations,
output
K-1
the
In certain determines
of the
different
may
sum
m and
of MK
I have
dividers.
other
therefore,
or zero.
event,
the
so on through
port
one from
power to one
from
consists
2, and
and,
is unity
In any
between
port
port
matrices
shifter,
outputs
output
outputs,
uniform
a phase
power-divided
which
K amplifier
K N-way
via
1, K from
input
of the
through
routed,
at each
port
at each
can
exists route
the
_r
signals
from
The
one of M input
attraction
amplifiers output.
of
the
ports
MPA
among
several
If the drive
level
into
the
MPA
to one
lies
in
signals
or more
its
and,
the MPA
of the N output
ability
to
secondarily,
share
the
to route
ports. power
of
inputs
of any one of the signals
several
to more
is reduced,
matched
than the
a single
output
level
=--
of that
signal
amplifiers w
may
from
is maintained
be shared
among
by adjusting linearizer,
their i.e.,
noise
power
The
discussion
Paul,
and
prepared
satellite
relative
input
presented
here
of SAIC USAF
the use
communications
of matrix
from
being
levels.
draws
saturation
amplified,
from
In this regard,
approximately liberally
Matrix
and
reduced.
If the
to achieve whatever
it is our
Missile
or multiport
from
Amplifier Systems amplifiers
operation
linearity, input
opinion
at, say 4 dB to 4.5 dB OBO
achieve
entitled
Space
correspondingly
backoff
optimized could
D. Cole
be
all the signals
(NPR))
for the
investigated
at a fixed
an LTWTA,
ratio
will
the
channel, that
(to achieve
of the power merely
a TWTA close
and
to 20 dB
35% to 40% efficiency. a 1993
report
and Routing Center
[37] by X.T. Vuong,
System
(SMC).
in future
(MARS)
The
X-band
supporting (7-8
H.
which
GHz)
was study
military
payloads.
5-11
SS/L-TRO 1363 Draft Final Version 4$M/rRO 1363/Pa_./-
Use or disclosure
of the data contained
an this sheet is subject to the restriction on the title page.
9597
5.6.2.2 The
Non-Ideal
following
First,
what
factor.
considerations makes
Since
multiport
reduce
amplifier
not
pose
less
limitation
amplifiers
efficient
beams
in saturated
optimized
for high
efficiency
discussed
in section
5.6.5.
mode.
in both
a reduced-power
As noted
optimized
for
high
efficiency
saturation.
Therefore,
a dual-
there,
is very
however,
nearly
the
or multi-mode
plan
think
of using
the same
TWTA
and
linearity
cannot
a dual-mode
saturation,
N
as
TWTA
a single-mode
be used
is
TWTA
of a dual-mode
as for
w
TWTs.
an amplifier
at nominal
TWTA
U
at H g
in an MPA.
i
Finally,
the
output
components
of the
significant
if the
However,
the
hybrid
to the
multiport
The
may
possible
than
major
at Ka band
multiport
amplifier?
Four
facets
of the
that
the multiport port
in regard
and
second,
implementation
1.
Insertion
2.
Effect
of errors
output
matrix,
and
3.
Effects
of HPA
failure
4.
Effects
of HPA
non-linearity
I-DI'_aE_i,.
not
addition
to
losses.
These
microwave
eliminated
if the
require
losses
separate
is realized
of the can
phase using
arriving
arrived provide than
Since
be accomplished
M signals
and at more
comgining
multiplexer.
a corresponding
amplifier
losses
be
shifters.
a Butler
or
hybrids.
can
individually
insertion
and
matrix
an output
of the
the
combiners
using
from
I
single on many
routing
at the
amplifiers
at low
power
level
M input
ports
of the
receive
antenna
different
of signals
one relative
the
receive from
power
beam
or
beams.
It
a single
input
level.
Issues
questions
practical
combining
is, each
originate
one output
In
all multiplexing
That
Implementation
two
are
does
of signals
that
are
are combined
region,
matrix.
lossless.
using
losses
linear
be a multiplex
5.6.2.3
is realized
amplifier
input
to more
there
signals
amplifier
is also port
where
in their
prior
may
matrix
the multiport
operate
is not
matrix,
combining
matrix
Also,
matrix
loss of the
output
in amplitude
to a multiport how
many
issue
are
amplifier
individual
discussed
are,
amplifiers
by Vuong,
first,
is the
implementation
can be shared
Paul,
and
in a single
Cole:
matrix and
phase
I
of
Usually,
for 20-GHz mode
= =
to be
width
of the system.
In this
mode
all signals
The required
mode.
Onemight
described.
also be a limiting
amplifies
are common
in linear
just
may
be broadband.
of I GHz
operate
capability
simultaneously
on the frequency
as bandwidths also
sharing
in the first place
it must
depends
must
than
attractive
amplifiers
bandwidth
any
the near-ideal
amplifier
of the K individual
K individual
usually
may
by all of the N transmit
the individual
The
the
each
transmitted
this will
Considerations
settings
resulting
from
the
input
matrix,
HPAs
5-12
SS/L-TR01363 Draft Final Version 45 MrrR01363/P
Use or disclostare of the data contained on this sheet is subject to the restriction on the title page.
ar t2J-9F--_T/
Summary
discussions
Regarding
the number
Cole:
"to
have
ports
N must
restriction,
not
issues
are given
of amplifiers,
desired
does
the
not
can be shared,
among
number
seem
below.
K, that
orthogonality
exceed
of fitting
output
the
output
of amplifiers
to be a limit
K amplifiers
into
the
of amplifiers
required
according
K:"
ports,
That
to K other and
to serve
a given
the
that
of the
providing
Paul,
number
is, K > N.
than
spacecraft
to Vuong,
the
and
of output
Other
than
obvious
this
physical
requisite
input
and
matrices.
=
As
for the
number
number K will
amplifier;
=
the
there
limitation .
of these
depend
upon
carriers
that
by
of the
each
upon
Y, the
total
weather.
values
of N and
X using
5-1).
Further,
Table
these
5-2 gives
four
resulting
KP L is the
power.
Note
increased
given
to these
be uniformly
Supposing W,
the
and
a sense
values
for
value
linear
per beam
multiport
X, the
MPA
number
of
contributed per
calculated
link budget
required
the
power
the
of K, it was
carrier
by
upon
from
the
downlink for
several
shown
in Table
(i.e., Y=N).
on the equation
and
to each
could
MPA;
PL, the
K = (62"x
RF power
clear-weather
X carriers
required
served
a Ps of 6.2 W (see
or
provided
the
power the
of K based
linear
upon
a single
+ 6.2*(N-X))
by the
fades;
of PL and
assume
power
by 10 dB over
power not
that
Ps, the
of beams,
of beams
served
high
upon
values
available
number
of carriers
To get
KP L = (62"X
where
and
calculations
the
total
experience
K amplifiers;
in clear
the
number
simultaneously
carrier
N,
number
+ 6.2*(N-X))/PL,
62"X + 6.2*(N-X)
of the
value
X carriers
of 6.2 W.
is the
that
required
experience
In actual
high
practice,
be distributed
among
them
in any
of 120 W, the
PL values
used
here
linear
the
RF
fades
total
proportion,
is
excess it need
distributed.
a saturated
HPA
50 W correspond
power to HPA
output
back0_ffs
of 6.8 dB,
of 25 W, 31.6
5.8 dB,
4.8 dB,
and
W,
39.8
3.8
dB,
respectively. From
Table
downlink fully
5-2, rain
one
areas
fades.
third
probability of the
approximately
it is apparent Even
of the beams
that
rain
world.
occurs For
80% of the
that
for the
an
MPA
smaller
P_. values,
are experiencing in any the
given
higher
downlink
provides
high beam
values beams
a--Dr_a_L
significant link
closure
downlink
no more
than
of PL,
service
experience
capability
high
in all beams
fading. about
rain
this
5% of the
contained
on this
sheet
with
time
the
for most
when
up
to
SS/L-TR01363 Draft Final Version 45 M/FR
of the data
when
fades.
5-13 Use or disclosure
counter
occurs
Contrast
is maintained
to
is subject
to the
restriction
on the
title
page.
01363/Pa
r t2J- 9Fo,_7
Table 5-1. Link Budget for Ka-band Demod-Decode/Recode-Remod Payload Transmiffing 60 Mb/s per 0.6-deg Beam into 70 cm receive terminal m
Ka-band budqet assuming a rate 3/5, K=7 convolutional code concatenated with a rate 0.9216 R-S block code. On-board decoding. Required Eb/No values are taken from CyberStar filing with the FCC (9/29/95)._ ..... 0,3841 60.00|Midis I FECcoderatp= 0.55 I R-S code rate=; 0.92 Link burst (dat_ bits) rate 20,001 User terminal elev. anqle 20.00,[de:1 I _3onv. code rate= 0.60 35786.00! 3578..6.001kr_ I Modulation= _I Hz/=svm/sec=: 1.5( Satellite altitude
t Earth
radius
Slant range
6378.00 39554.46
J
Total xm|tt__l_owe
6378.00 39554.46Ikm Downlinkl
Uolink 1.00 0.00 0.70 1.02
dbeam
Tx antenna diameter TX antenna beamwidth Antenna efficiency Transmission fr.e.quency Aqtennae_ain Pointin._,EOC & lin_ IOS,S l EIRP per userI Free space loss Atmos, loss R._ainloss I Path Loss Rx antenna diameter Rx antenna beamwidth
0.
43.80 213.79 1.00 0.00 21 4.79 0.65 1.1 0
0.5;
4.041W 6.06idBW
Tot RF pwr/bm13.14 I # active beamsl128 ..... Total downlink mar.qip / beam, dB 0.00
1.781m
Array
dia.=21/if(GHz)*BW(deg));
Direct
radiating elements with taper
600',
E
dl_j
i
with taper
/
1
NASA Hdbk p. 6-7_foi elev. angle x 1.22 1
55.001% 40,60]dBi I
i
I
Uplink signal bandwidth (MHz)= I
1 52]_j
75.48 1.00 1.50 301.18!K 15.28
1
i User rx bw (°) 1.52
0.53 dB 40.07 dB 75.48!K K dB dB
dB/K dBW -120.57 -203.81 dBW 83.24 dB-Hz 15.00 92.78 82.79 dB-Hz 200.00 _dB 82.79 dB-Hz 77.78
I
3.561
I ==
211T28 dB 0.70]m
LNA+ noise figure 2,16 TSySTr (in rain_ at flan.o.e) 600.34 _ G/T 12.41 Received siqnal (flange,. rain)!_ .-_130.80 -200.82 kT, in rain (if any) 70.01 C/No I 15.00 Link interference (C/I) 70.84 Link interference_C/Io___ 67.40 C/(No+Io) I 200.00 Rain-induced c ross_0_o_l 67.40 C/(No+Io+Xo)I 55.84 Link data rate (dB-Hz) 8.00 Recl'd Eb/No lw/impI, loss 1 A._vailable m .ar.qin
I
I Downlink si_lnal bandwidth (MHz)=I 81.3_ Total RF pow_erradiated (assumed), W= 400
55.00!% 19.70 GHz 48.69 dBi 4.10 dB 50.65 dBWi 210.28 dB 1.00 dB 0.00 dB
60.00 29.50 44.50 0.70
Antenna efficiency 55.00 Antenna peak gain 43.42 Pointing loss & polar, mis,. 3.23 40.19 I Gain at antenna flange .... 290.00 Rx clear-=sky ant. noise tem__. N/A Rx rainy-sky ant. noise temp.__ Line loss I 1.00
'1
km
1
I _lear Skv: I Ta=17.89+280*(1-10^(-Latmos/10) Rainy Sky: I ITa= 1"7.89+280"
(1-10^(-
i
(Latmos+Lrain)))
J I Including C/IM from active antenna amplifiers C/Io = C/I+10*LOG10(Rb) in data bandwidth
L
Circular polarization. In data rate bandwidth.
5.OOIde O.O01dB
i
i
N_
SS/L-TRO
LD_I.
5-14
Draft
Final
1363
Version 1
45 M/TR01363JPa Use
or disclosure
of the data
contained
on this shee_
is subj¢_
1o lk¢ restriction
on the
title page.
rt2J- 9F_97
w
Table
5-2.
No. of Amplifiers,
K, to Support
for X of Y (=N)
10-dB
Power
Increase
Carriers
a. PL =25 W N=20
N=30
N=50
N=60
N=80
N=100
N=120
X
K
X
K
X
K
X
K
X
K
X
K
X
K
7
21
10
30
16
48
20
60
27
80
33
99
40
119
8
23
11
32
17
51
21
62
28
83
34
101
41
121
b. PL =31.6
W
N=20
N=50
N=30
N=60
N=80
N=100
N=120
X
K
X
K
X
K
X
K
X
K
X
K
X
K
9
2O
13
29
22
49
27
60
36
80
45
99
54
120
10
22
14
31
23
51
28
62
37
81
46
101
55
121
w
_r..a
c. PL =39.8
W
N=20 " 2
N=30
N=50
N=60
N=100
N=80
N=120
X
K
X
K
X
K
X
K
X
K
X
K
X
K
12
20
18
30
30
50
36
60
48
80
60
100
72
120
81
61
101
73
121
_:
13
22
19
32
31
52
37
62
49
d. Pt =50 W N=20
N=30
N=50
N=60
N=80
N=100
N=120
X
K
X
K
X
K
X
K
X
K
X
K
X
K
16
21
24
31
40
51
48
61
63
80
79
101
95
121
17
22
25
32
41
52
49
62
64
82
80
102
96
122
w
LDI'_/_I,,,
SS/L-TR01363 Draft Final Version
5-15
45 M/TR01363/Part2/Use
or disclosure
of the
data
contained
_a this
sheet
is subject
to the
restriction
on the
title
page.
9_J7
Obviously,
during
matched
any
to the
system
expected
implementation
broad
area
the
rain
linear
statistics
power
such
per
that
amplifier
total
would
power
per
be
MPA
is
minimized. I
5.6.2.3
Insertion
The multiport
Loss
amplifier
amplifiers,
K, is given
waveguide
rather
given
does
of the Output
output
Matrix
matrix
consists
of k stages
by K=2 k. It is assumed
than,
for example,
that
squareax
this
of hybrids,
output
or a printed
matrix
network.
where
the number
of
would
be realized
in
The
output
U
loss figure m
here
not
include
the waveguide
for connecting
the
N output
ports
with
the
N m
antenna
beam
0.5 dB per 0.5-dB For
input
stage
loss per
an
MPA
ports
nor
is estimated stage
with
does
it include
at 19 GHz
estimate
when
at X-band
128 amplifiers,
the
output
realized
(7.5 GHz)
there
would
dB.
This
zonal
filters.
as a hybrid
given
ring.
by Vuong,
be 7 stages
A value (This
Paul,
of ring
of 0.4 dB to compares
and
to a
Cole.)
hybrids,
m m
or an
output m
matrix
loss
of
including
approximately
filter,
transmit
of about
phased
antennas
array
depend
lower
efficiency
3.0 0.5
dB for
antennas.
upon
the
either
the
However,
use
of SSPAs
is to be
compared
active
as will rather
to
transmit
lens
be mentioned
than
an
output
array
below,
TWTAs
and
loss,
or
these
would,
not
the
active
two
active
therefore,
m
have
amplifiers. m
5.6.2.4
Phase
and
Amplitude
Deviations
A concern
associated
with
MPAs
is the
ability
aside
from
intended
phase
shifts,
and
amplitude
output
matrices
and
themselves. the
Certainly,
vector
sums
at unwanted i.e.,
high
means
In the
tolerance
investigated analysis.
by The
undertaken random while
"worst design
a cost-effective
a defacto
worst
and case
Paul, case
to "consider amplitude results
of [an MPA]
loss,
Ka-band
and
output
case,
phase
and
Cole
tracking in both
is the
easier
the nominal
provide
its components,
that
reflect
information these
sum
at unwanted
primary
had
the
that
been
it creates means
of
sum
inserted
in
after
signal
analysis The
use
the
specifications
was Carlo
analysis
upon
was
statistically
components."
to create may
paths
a Monte
Carlo
based
of typical
is safe
and
Monte
Also,
specifications
be too
tight
for
to meet
in
manner."
N_
LD_L
ports,
A non-unity
several
performance the
to zero
is one of the
a worst-case
system
sum
neither
I,o = oo dB.
among
analysis.
paths,
words,
loss
AC = 0 dB and
of these
will
filings.
input
K amplifiers
other
multimedia
In
phase,
of the
the
matching
A non-zero
reuse
paths
match
ports
I_o.
insertion
multiple
amplitude
AC, as if an ohmic
deviations
may
the
isolation,
Frequency
and
analysis
ports.
port-to-port
no degradation,
amplitude
MPA
identical
amplitude
and
at the
schemes.
and
phase
at wanted
in all of the
Vuong,
in order phase
reuse
ideal,
on
to unity
nearly
through
to phase
close
signals
reduces
capacity
beams
amplifiers.
the
beams,
in frequency
achieving wanted
sum
ability
very
component
nor
in unwanted
as the
without
of the
ports
interference
The
as well
to achieve
5-16
SS/L-TR01363 Draft Final Version 45 M/TR01363/Pa
Use or disclosure of the data contained on this sheet is subject to the restriction on the title page.
rt2J'-9FJ97
The
results
analyses
w
of these
are
in Figures
summarized
amplitude
deviation
(degrees).
same
5-10.
Note
amplitude).
When
nature
logarithmic
+ c_) dB, and
_))
The
dB.
respect
values
5-6 and
that
ratio,
they
the
aG
through
Monte
ratio the
are
no
and
analysis
- a)),
is c_
longer
the
where
overdeviation
underdeviation
allowable
a = maximum allowable
due
nominal to the
allowable becomes
the
same
phase
allowable
(A is the
same
worst-case
is summarized
overdeviation
which
approximately
The
Ao = maximum
maximum
are
5-10.
Carlo
maximum
allowable,
to dB,
of AG ÷ and
The
5-6
AG = 20 log(1/(1
voltage
underdeviation
maximum
5-7.
figures,
in voltage
function; the
in Figures
in relative
converted
20 log(1
shown
In these
deviation
as the maximum
of the
are
in Figures
5-8 through
allowable the
analyses
is
carrier nonlinear
becomes
AG ÷ =
AG" = 20 log(1/(1
when
r_ is small
with
to unity.
WORST CARRIER POWER DEGRADATION (dB) 5O
(9 w 0
INPUT MATRIX/HPN
OUTPUT
MATRIX
40
Z 0
w
3 dB
-1- 20
2
cO U.l o9 "1o.
1
<
:
0.5
z
0
0.5
1
1.5
2
2.5
3
3.5
MAX. GAIN DEVIATION _G (dB) Figure
5-6.
Maximum
Contours
of Worst-Case
Allowable
Phase Matrix,
Carrier
Deviation HPAs
Power
be and Gain
or Output
97o8294
Degradation Deviation
_C Versus _G of Input
Matrix
i
SS/L-TR01363 Draft Final Version
m_
La_L
5-17
45M/TR01363/Part2/-_Ir-_97 Use or disclosure
of the
data contained
on this
sheet
is subject
to the restriction
on the
title
page.
-
WORST PORT - PORT ISOLATION (dB)
!
12
-- -- - INPUT MATRIX / HPA OUTPUT MATRIX
15 dB
l
BB
O LU Ct v
m I
z O \ > LU O
\
2O
6 o
I
\ \ \
LU 09 ,<
\
-112.
\
IBII
\ 25
\
\
\
\ \
m
\ \
3O
\ \
m
t 0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8 b
MAX. GAIN DEVIATION AG (dB)
Figure
5-7.
Contours
Maximum
of Worst-Case
Allowable
Phase
Input
Matrix,
Port-Port
Deviation HPAs
97o_9s
Isolation
be and Gain
or Output
Iso Versus
Deviation
AG of
Matrix
L
m
Vuong,
Paul,
and
found
that
the
been
same
made,
results
from
worst
generated
case
indeed
redundancy
indentical
were
failure
is the
of L out
therefore,
also
state,
expected
for any
mathematically
that
K= power
isolation that
results
K= power the
for K=4,
"It is reasonable
8, and
of 2. No attempts
worst
case
16
to extrapolate
port-port
w
have
isolation m
of 2."
HPAs
provided,
HPA
e the
failures
isolationof
of K vectors,
of K HPAs
AC = 20 logl0(K/(K-L))
port-to-port
They
for any
decreas sum
worst-case
are
Redundant
port_.and port
results to prove
Providing
"wanted" wanted
Cole
to be identical.
however,
are
5.6.2.5 If no
and
them
reduce
the
the"unwanted"
all aligned
is given
would
in phase.
power
ports.
Therefore,
The
available
at the
power
at the
the reduction
in power
by:
dB
LI=II'_M_L
SS/L-TR01363 Draft Final Version
5-18
45M/TFt01363/Part2/-gFJ97 Use or disclosure
of the data
contained
on this
sheet
is s=,.b_ect to the
restriction
on the
title
page.
u
CARRIER POWER DEGRADATION (dB) MONTE CARLO SIMULATION RESULTS L_ 90 LU
a
80
z 0
70
--
AVERAGE AVERAGE
+ 2*SIMGA 2 dB
2 dB
6o > w D
-- -
50 -
1
,17- 4o w
"lco
N
30 -
\
N
\
0.5
UJ
\
< I
-L
20
0-
_
10
\ \0.2 I,
_
I I
0
I!
I
t
0
| I ,.l
\
t
I
1
, 3
2
i
,
t
4
,
Figure 5-8. Degradation
Contours
of Average
AC Due to Random
i
5
0.2 i
6
MAX. GAIN
m
_ I ,
DEVIATION
and (Average
Deviations
i
7
i
I
8
i
,
i
9
,
i
10
_
11
AG (dB)
12 9708296
+2 x Sigma) of Carrier
in Characteristics
Power
of Input Matrix, HPAs
or Output Matrix (K --- 8 and # Monte Carlo Cycles = 20,000)
The isolation the best
case,
would still uncancelled. associated
at unwanted
ports
the L failed
HPAs
cancel except In the worst isolations,
depends
upon
would
pairwise
be paired
cancellation
such
of the K vectors.
that the remaining
In
K-L vectors
when L is odd, in which case a single vector would remain case, L vectors would remain uncancelled and be aligned. The
which
establish
the upper and lower bounds,
are:
L
I_o (best case)
I_o (worst
case)
=
20 logl0(K-L)
dB
where
L is odd
=
oo
dB
where L is even
=
20 Iogl0((K-L)/L)
dB
u
A table
of values
dependence m
upon
of AC and
I,o taken
K and L is given
and output matrices reduction in power
from
in Table
Vuong,
5-3.
Note
Paul,
and
that for large
Cole
showing
their
K and
for ideal
input
(i.e., phases set according to ideal MPA theory), both the worst-case and the worst-case isolation are probably acceptable. Nevertheless, it
w
would
m
be prudent
to provide
switching
is accomplished
perturbed
when
redundant
redundant
amplifiers.
so that the desired units
are brought
EDgE
phase
Care
must
relations
used in how
among
output
the associated vectors
are not
into use.
5-19
SS/L-TR01 363 Draft Final Version 45M/TR01363/Part2/-gr'o/97
Use or disclosure
of the data containtd
an this sheet is subject to the restriction on the title page.
ISOLATION VS INPUT MATRIX/HPA CHARACTERISTIC MONTE CARLO SIMULATION RESULTS
DEVIATIONS
15
i
m
AVERAGE -- -- - AVERAGE - 2*SIGMA
I
2O dB !
(.9 LU E3 v
\
m
\
Z
O
\20 dB
> UJ t7 111
i
25
< I
BIB
\25
<
g
30 \30 t \35
I i_
35 II 0
0.5
1
1.5
2
2.5
3
3.5
MAX. GAIN DEVIATION _G (dB) Figure
5-9.
Contours
Due to Random
of Average Deviations
and (Average
+2 x Sigma)
in Characteristics
(K = 8 and # Monte
Carlo
Cycles
9_0829_ of Port-Port
of Input
Matrix
Isolation
Iso
or HPAs
= 20,000)
m
LDI' M L
5-20
SS/L-TR01363 Draft Final Version 45M/TR01363/PartPJ-9FJ97
Use or disclosure ofthe da_a contained on this sheet is s_bject to the rest_'_c_ionon the titlepage.
I
ISOLATION
VS OUTPUT MATRIX/HPA CHARACTERISTIC MONTE CARLO SIMULATION RESULTS
DEVIATIONS
15
--
AVERAGE
-- -- - AVERAGE
12-
- 2*SIGMA 20
L9 LU E3 v
2
.
z
_o \ \20 > uJ E3
\
w
m
25
I
I 09 LU 09 < "1-
I I I
30
\
w
35
35 I
I
0
1
0.5
1.5
2
MAX. GAIN DEVIATION
Figure
I
IIIII I
0
5-I0.
Contours
of Average
Iso Due to Random
Deviations
and (Average
2.5
Carlo
I
+2 x Sigma)
Cycles
I
I
3.5
3
AG (dB)
in Characteristics
(K = 8 and # Monte
!
9708298
of Port-Port
of Output
Matrix
Isolation
or HPAs
= 20,000)
SS/L-TR01363 5-21
Draft Final Version 45 M/TRO
Use or disclosureof the data contained on this sheetis subjecfto the restriction on the title page.
1363/Part2/-
_r-_7
Table
5-3.
Effects
of HPA
Failure
on Carrier
Power
and Port-to-Port
Isolation
L, No. of Failed HPAs
K, No. of Original HPAs
AC (dB)
Min. I,o (dB) (worst case)
Max. I,o (dB) (best case)
1 2
4
9.5 0.0
9.5
4
2.5 6.0
1 2 3 4
8 8 8 8
1.2 2.5 4.1 6.0
16.9 9.5 4.4 0.0
16.9
i
Oo
BIB
OO
14.0 OO
BI
23.5
1 2 3 4
16 16 16 16
0.6 1.2 1.8 2.5
23.5 16.9 12.7 9.5
1 2 3 4
32 32 32 32
0.3 0.6 0.9 1.2
29.8 23.5 19.7 16.9
29.8
64 64 64 64
0.1 0.3 0.4 0.6
36.0 29.8 26.2 23.5
36.0
oo
22.3
BB
oo
i II
co
29.2 lib
5.6.2.6 The
Effects
effects
of HPA
of HPA
OO
m
35.7 BII OO
Nonlinearity
nonlinearity
can
be
summarized
in the
following
statements,
per u
Vuong, (1)
Paul,
and Cole:
When
frequency
performance
reuse
is better
is
than
not
that
employed,
of conventional
the
MPA
amplifiers
intermodulation operated
noise
at similar
output
backoffs. (2)
When
frequency
performance performance (3)
When the
is worse
intermodulation
of inter-port
is than
as the number
the number
contrast,
reuse
the MPA
fully that
intermodulation
output
for a conventional noise
may
MPA
intermodulation
amplifiers,
in the system
per MPA
intermodulation
the
of conventional
of carriers
of carriers noise
employed,
but
becomes
(or channel) amplifier
noise
approaches
their
large. is small system
not be negligible
(i.e.,
1, 2, or 3),
is negligible. due
to the
By
existence
products.
m_
5-22
SS/L-TR01363 Draft Final Version 45 M/TR01363/Pa
Use or disclosure of the data contained an this sheet is subject to the restriction an the title page.
rt2/- 9FJ,97
u
5.6.3 An
Active active
Transmit
transmit
Lens Array
lens
comprise
the RF lens.
of a proof
of concept
array
(ATLA)
The fourth
antenna
is a feed
has
array.
antenna
in Figure
of radiating
elements
launches
of power
modules,
(1)
A fiat array
(2)
A corresponding
5-11,
four
These
major
sections,
sections,
shown
three
of which
in an artists
sketch
are: the far-field
spot
beams.
w
signal
power
delay
line.
of the
lens.
(3)
Signals
(4)
The
array to the
Collectively,
arrive
receive
elements separate
transmitted
from
feed
array.
the
delay
at the modules
physically
the
radiating
horn
space
from a single
in the
feed
lines
from
are
the
Each
fed,
horn.
for each
radiating
element,
module
contains
an amplifier
power
of the modules
individual
lens.
feed
one
receive
in turn, Each The
from
far-field beam
constitute
the
supplies
center
elements
at their
inputs.
an
of feed
horns
array
beam direction
is created is fixed
by
and
a
portion
that
by
the
the
location
is
signals of
array.
m
i
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ARRAY FEED
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Figure
m
5-11.
Active
Transmit
Lens
Array
Antenna
Concept
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5-23
SS/L-TRO 1363 Draft Final Version 45M//1:_01363/Pa_2/-
u
Use or disclosure of the data contained on this sheet is subject to the restriction on the title page.
9r-_97
The
attraction
of the
in principle,
a major
forming
network
determined Both
the
thus
heat
ATLA
difficulty is
by the ATLA
the
and
the
each
dissipation
which
forming
ATPA
lend
all
array
and
carrier
ATPA
beams
data
rates
se, are
concept
required.
is avoided.
Thus,
The
with
beam
directions
structure.
to solid
challenge.
per
simultaneously
lens
themselves
a common
transmitting
networks,
in the
forms
of the feed
remains
problem
no beam
encountered
lens
geometry
dissipation
of beams
is that
m
state
power
For large
in the
amplifiers
arrays,
60 to 100
(SSPAs);
creating
Mb/s
several
range,
tens
the
u
power
is acute. IBm
These As
two
similarities
such,
closer
the
look
above
it does
As
the
not
specifically,
large
number
of the
the
means
total
that
Active
Based
on work
array
(ATPA)
more
than
done
Phased
to the
slightly
ATLA
less than
also. the
A
t
ATPA
modules.
for
two
that
a large
technology
of the
At Ka band,
reasons.
First,
number
relatively require
is cost
small a large
as noted
the
of such
lens
small
above,
size
available
number
a
of
is required
power
itself
to create
m
ii
in Ka-band
of modules
BB
the
to achieve
space.
elements.
few
the Each
from and
topological
BFNs
separate
phased
these
indicated
in the current
Even
32 beams
built)
is fewer
than
physical
FCC
this
not In
filings,
is only one
use
states
with
of the
numbers in Table at this
that
limited
of beams
juncture;
also in are beam
which
it has
a
created
to 32 beams
5-4, 16 beams
of
from
Iridium are
of the
shown
number just
satellite up
antenna
corresponding
As the
that
confirmation
difficulty
are
overwhelming
per
for
in a physically
as there
It is believed
M-Star
The
beam,
elements.
phased
of ATPAs
practical.
be summed
48 beams
conceptual
transmit
the
each
becomes
a clear
terms
multimedia
for all but
for
for
antenna
task
filing
that
of outputs
must
Iridium,
Although
antenna
one
16 beams.
for
indicative.
Ka-band
is shown
achieves filing
The
array.
that
of the
the
certainly
(note
BFN
grows,
arrays).
capacity,
each one
for an active
is not
number
each
FCC
aperture
(BFNs),
same
from
work
it is known
same
to feed
the
phased
are
the
Globalstar (from
in a single
have
elements
viewpoint.
the
[38],
networks
an output
all other
16-beams
from
forming must
on engineering
(20 GHz)
beams
beam BFN
antenna
and
at Ka band
Furthermore,
outputs
Array
for Globalstar
a relatively
small
created
power
beams
are comparable.
networks. ATLA
the
weights
applies
weighs
to the
Second,
their
order,
ATLA
forming
means
of high-power
antenna
in creating
three
indicated
Transmit
arises
achieves
hundred
is
that
power.
5.6.4
beams
tens
the
that
beam
elements
mean
show
several
beamwidths.
ATPA
to a first
impediment
modules
narrow
the
estimate,
the multiple
radiating
desired
likely
a major
of
corresponding
SSPAs
have
and
weight
would
ATPA,
and,
the
ATPA
at weight
because with
of the ATLA
are
is small. not
been
of the systems.
m
mp/M¢_!
SS/L-TR01363 Draft Final version
I'V'I_TEM_
LC:I_I--
5-24
45M/'i'R01363/Pa Use or disclosure
of t_ data contained
on this sheet is subject to the restriction
on the title page.
rt2/- _,97
m
Table
i
5-4.
Representative
System
m
Astrolink
Ka-band
Systems
CyberStar
of Beams
per Satellite
NetSat 28
Spaceway
Teledesic
Voice Span
L-M
SS/I_
NetSat 28
HAC
Teledesic
AT&T
No. Beams
192
27
1000
48
64
64
The
Comparison results
of
approaches Mb/s
which
a first-cut
beam
into
a 70-cm
(i.e.,
are shown
is assumed Table
5-5.
SSPA
in Table
(assumes
DC
required and
receive
transmit 5-6.
For the
for
for
are shown
for the
the
128 beams
is taken
multiport
of 50.65 48.7
power
Table
phased
amplifier,
and
in Table
from
active
three
there
a required 5-5.
5-1.
array
sharing 60
For each
The number and
the active
is an active
amplifier,
of the 128 beams.
for Three
EIRP
MPA)
dBW
modules)
for each
DC
terminal
EIRP of 50.65
Power
required
total
antenna,
ground
to be a TWTA, Total
of
ATPA
the per-carrier
elements
array
DC Power
analysis
antenna,
approach,
of active lens
of Total
(ATLA
per
sharing
Transmit dBW,
dBi peak
Parameter
Power-Sharing
128 0.6-deg
spot
Approaches beams
with
gain)
ATLA
ATPA
MPA
Loss to EOC
3.0 dB
3.0 dB
3.0 dB
Output loss (w/filter)
1.1 dB
1.1 dB
3.7 dB
48.7 clBi
48.7 dBi
48.7 dBi
6.05 dBW
6.05 dBW
8.65 dBW
(4.03 W)
(4.03 W)
(7.33 W)
515.8 W
515.8 W
938.2 W
14%
14%
45%
3685 W
3685 W
2085 W
Antenna peak gain Req'd RF pwr per beam at HPA output r
Number
Company
5.6.5
__=
with
Total Req'd RF pwr (=128 x above line) HPA linear mode efficiency Total DC Power
_=_
m
Table
5-6.
Number
of Active Three
Transmit
Sharing
Modules
Technic
(or Elements)
for
ue
w
Parameter
ATLA
ATPA
MPA
1.0 W
1.0 W
25 W
HPA OBO, assumed
4.09 dB
4.09 dB
5.33 dB
RF power per transmit module
0.39 W
0.39 W
7.33 W
Number of active transmit modules
1323 (=515.8/0.39)
1323 (=515.8/0.39)
128 (=no. of beams)
Diameter of array, approximate at 19.2 GHz (see Appendix B)
43 antenna elements 69 inches (at 2.6_, spacing)
43 antenna elements 69 inches (at 2.6_, spacing)
Rated RF power per transmit module, assumed
m
LC:IIRbC_L-
N/A
SS/L-TR01363 Draft Final Version
5-25
45M/'rR01363/Patt2/-9_,97' Use
or disclosure
of the data
contained
on this
sheet
is subject
to the
reslriction
on
the title
page.
The
power
dissipated
is indicated
in Table
power the
is the
sum
transmit
60 W/ft
and
size
5-7 based
of the
modules
2. A value
the
of the corresponding
on plausible
power
efficiencies
dissipated
themselves.
The
of 45 to 50 W/W
radiator
in the radiator
would
for the
output size
SSPA
loss
shown
be reflective
for each
and
and the
technique
TWTA
power
assumes
of current
sharing
units.
This
dissipated
by
a radiator
capacity
of
BIB
capability. L--
What
can
be concluded
array-type the
sharing
two
from
the
technique
primary
above
is about
contributors
comparison? twice
to DC
that
power
First,
required
the
power
required
for an MPA
differences,
i.e.,
for a large
technique.
HPA
That
efficiency
and
ml
is, of =_ _I
output
I
circuit 4-dB
losses, output
array
circuit
requires
reject
Second,
MPA the
solar
SSPAs
power,
for the
additional
arrays
dominates. same
power
to generate
Therefore, EIRP
per
dissipation
the
beam,
of the
increased
even
with
is half
that
array-type
power
and
nearly
a
of the im
techniques
larger
radiators
to []
of the
radiators,
spacecraft
about array-type
the
optical
solar
weight
Table
must
(heat
reflectors
(OSRs)),
1600
embedded
a nominal
arising
Dissipated
Parameter
from
DC
subsystem
In the
radiators these
is approximately
Size
into
the
the
lifetimes
MPA
lib
pound is
comparison,
with
the
BI]
technique.
face
44 lbs (=1.6
Sharing
skins
and
Therefore,
is approximately
for the Three
per
12 year
2, or 1.6 lb/_.
considerations
and Radiator
radiators
160 lbs more.
honeycomb
is 5 gm/in
the
above
than
weighing
in aluminum
and
for Watts
with
power
subsystem the
value
satellites weight.
weight
power
nominal
W more
a power
larger
of integrating
A current
subsystem
by the larger
difference
Power
into
pipes
occasioned
weight
5-7.
generate
the
geosynchronous
power
translate
panels
difference total
large
of total
nominally,
radiator
on
with difficulty
be obtained.
subsystems pound
associated
the increased
may
techniques
would,
weight
to mention
configuration,
10 W per
This
increased
not
solar-power
The
the
of the
the heat.
larger
For
efficiency
loss,
larger
estimate
for
lower
techniques.
also
An
the
the
x 4.6 x 6). 200
lbs.
A
Techniques
ATLA
ATPA
MPA
Total DC power (per Table 5.6-2)
3685 W
3685 W
2085 W
Power dissipated at transmit module
3169 W
3169 W
1147W
.r
Power dissipated in output loss Total RF power dissipated Required radiator area Dimensions of two radiator panels
116W (=516 x (1-10"° 11))
116W (=516 x (1-10-°"))
538 W (=938 x (1-10°3'))
3285 W
3285 W
1685 W
55 sq. ft. (=3285/60)
55 sq. ft. (=3285/60)
28 sq. ft. (=1685/60)
4.6 x6 ft. (two)
4.6 x 6 ft. (two)
4.6 x3 ft. (two)
SS/L-TR01363 Draft Final Version
m_
5-26
45M/TRO1363/Part2/-95B7 Use or disclosure of the data containt, d on this sheet is subject to the restriction
w
on the tit_ page.
m
complete
comparison
multiple
beam
comparison
of mass
reflector
favors consideration
than
reflector
are
100 beams even cost
the
input
good
and
array
antennas
with
the
for use
of the
The cost
to a reflector
to make
the
themselves
MPA.
versus
It is believed
the
that
this
antenna.
is the cost
antennas.
include
postulated
reflector
compared
further of
antenna
the
Another
should
multiple
on the
output
systems.
Active
difference
beam
promise
matrices
arrays
would
much
It would
of beam
MPA
would
to achieve
near
more
expensive
for arrays
configuration.
of arrays for the
are
be magnified
steering not
with
be
and
50 to
magnified
shaping.
narrow
the
The
difference
appreciably. 5.6.6 A
Multimode
multimode
operated
amplifier
is designed
at saturation
saturation
level.
that beam
could
The
Amplifiers
DC
as well
Thus,
so as
as when
if it is not raining
be run at reduced
power
operated
required
in the area
output
to run the
at selected
power
amplifier
maximum
output
of a given
while
power
spot
be reduced
levels
beam,
still operating
would
efficiency below
the
near
in the
when this
amplifier
peak same
for
efficiency. proportion
w
(assuming
no loss
application
to an
manner,
the
much This
less
the
total
than
is fed, usual
DC
would typically,
by
efficiency,
it also
multimode
would
HPA.
gain
cannot
be only
and used
for
rain.
be shared
antennas
redundant
for In this
and
(MBAs)
amplifiers
forming and
with
can
or
could
relatively
be
to very
little
on the
linearity.
enhancement. a single
carrier
to
implement. little
In other
Therefore,
in
networks
with
level
each
to be provided
simple
power
effect
where
switching
the output
linearity
in systems
beam
beam
very
be available
above.
It allows
has
would
is experiencing
I-tPAs
multiple
drops
and
area
satellite
large
feature
power
whose
is straight-forward
the
be used
output
as discussed
require
multimode
drops
TWTA
amplifier
not
sharing,
the
to the
for reflector
a single
does
power while
allocated
be ideal
is the to a beam
this sharing,
fashion,
accomplish
connected
power
without
However,
efficiency)as
amplifier
technology
beam
in overall
the
loss
in
words,
a
multimode
per HPA.
w
In almost tube
the
amplifier
(TWTA).
(TWT)
power
output
High w
all instances,
capacity,
directly
into
the higher
and
much
one high
efficiency
of choice
for this
Especially
higher
of the power
HPA
at Ka band,
efficiency
required HPAs.
architecture
than
system Thermal
TWTAs
are
solid
for
be a traveling
are capable
state
characteristics control
would
power the
considerations
of much
greater
amplifiers
target on
wave
the
system, satellite
(SSPAs). translates also
favor
TWTAs.
r__
One
might
off the reduced
m
[--G_K,.
suggest
drive drive
level. levels,
that
reduced
However, this
output because
approach
power
of the
amplifier
is not
practical.
HPA
operating The
be achieved efficiencies
necessity
by merely fall
backing
drastically
for multimode
operation
SS/L-TR01363 Draft Final Version
5-27
45M/rR01363/Part2/Use or disclosure of the data contained on this sheet is subject to the restriction
with
on the title page.
9FJ97
is seen
by
noting
the
of a single-mode operated
tube
with
As a result TWTA
efficiencies
in Table
5-8.
for representative
These
of efficiency,
even
the
dissipated
power
to a TWT
efficiency
loss,
efficiencies
though
stays two
power
relatively
other
the
gain
of the
TWT
increases.
Although
to determine
the
input
backoff
corresponding
TWT
level.
would
also
efficiencies OBO,
Second,
drop.
EPC
for saturated
where
the
total
the
efficiency
efficiency
TWT
power
attraction
of the
varies
loads
are
levels
a 20-GHz
TWT
with
of a single-mode
reduced
(at least not
m
to a given power
range
of 92%
to 94%.
EPC
efficiency
would
reduction
conditioner power
in
IE;
of multimode
desired
processed
the
levels
a calibration
the
is reduced,
output
in theory)
a problem,
electronic
in the
consumption
consumption
accompany
TWTAs.
power
to the
effects
and
output
assume
power
constant.
TWTA
be required
contribute
the
a single-mode First,
output
carrier.
loss
decreases,
tube
shown
a single
of this
In addition
approximate
(EPC)
level. At will
in
for the
Typical large
W
EPC
values
drop
m
of
to as low
.=..
BB
as 86% to 88%. It
should
be
noted,
contemplating
use
adjusting
the
decrease
For
any
by
For
at least will
and
would
need
[Below
to operate would
determined
Also,
the
a single-mode
TWT
applies
whether Table
This
made
above
the
Point
gain the
Backoff
reduces
the
gain
would
(OBO)
power.
The
inch
in the
per
of a single-mode
TWT
would
around
When EPC
30 dB,
a certain to be
signal
reduced
TWT
a
current
of the
the
cause
as the
have
as well.
by
to drop
receiver
TWT,
voltages output
being
could
track
processed
efficiency
Efficiencies
m m
gain
in the
drive It
through of the
W
TWT
transmitted.
efficiency the
the
minimum
offset
l
when
achieved
the
requires
regarding
TWT
reductions adjusted
usually
ground
considered
reduces
gain
phase
be
continues
tube
Single-Mode
Output
tube
the
or a multimode
TWT Operating
the
the
the the
Representative
TWTA),
change
whether
to a multimode
power
in turn,
because
must
output
threshold,
perturb
statement
in a single-mode 5-8.
a cliff
also
range,
a certain
seriously
perturbation.
drops,
power
properly.]
likely
to be
off
which,
geometry,
a 10 dB output
fall
For
through
physical
dB.
basically
in order
circuits
30
TWT
density
given
effects
(a multimode
in the
current
is reduced.
efficiency level
current
other
TWTA.
voltages
in effective
density drop
operating
circuit.
that
of a multimode
in cathode
reduction TWT
however,
this EPC
power
for level
will drop. at Several
Levels
Approximate
TWT Efficiency
0 dB OBO (saturation)
58%
3 dB OBO
40%
10 dB OBO
15% 2%orless
20 dB OBO
I,.,¢:11_/_1..
SS/L-TR01363 Draft Final Version
5-28
45M/'rR01363JPart2/Use or disclosure
of the data contained on this sh_
is subject _o the restriction an the title page,
_97 J
To
date,
multimode
realized.
w
To
approaches, =
:
power
and
modem
offer
dB, and
of the
The
resulting
EPC
so that
never
been
-
of the
will
efficiency more
for each
mode.
through
a warm-up
than
just
implemented.
period
unacceptable.
Also,
considerations,
to date,
the
perceived
benefits
For
example,
in the
required
for
TWTAs
using
system
...
and
prior
consequent
ACTS
that the
program,
an operational
advantages
TWT
0 dB, 3
range
The
has,
would
either
EPCs
turn-on
be
must
one
be cycled is about
would
likely
heavier. never
3 be
These
used
because
mass. the
dual-power
study
knowledge,
period
much
of the
in parallel,
and
is almost
and
very
15% to 25%.
to our
signal
TWTA
of 3 dB,
of from
together
typical
efficiency
the complexity
[39] "compared
The
using
For example,
Rather,
separate
on-line
complexity
employing
a 10-
built
nominal,
drop
transmitted
study
technology."
major
come
approach
added
other
While
with
power
This
envision
the
of that
were
6 dB.
by increasing
a multimode
a 1988
system
current] no
EPC
meant
driver.
an output
on line. to
multiple
have
exceeded
is adjusted.
must
to coming
do not offset
offer[ed]
tubes
of which
an efficiency
might
disruption
this
[then
One
been
program.
theoretically, voltage
not
efficiency
Over
opinion
not
impractical.
on Marisat
successful
6 dB, expect
anode
EPCs
flew
range.
Over
the
for and
is not the
power
occur.
However,
The
levels
can be increased,
successfully
minutes.
L
of power
has
a very
It is our
(none
levels
have
independent
is completely
achieved
power
was
steps
power
band
10 dB is desired.
been
baselined
Marisat
span
loss of efficiency
was
in output at Ka
voltage
have
in output
TWTA
the number
is a function
commandable
span
span
mitigation
of at least
for space
6 dB OBO modes.
Apparently,
w
the
necessary
fade
difference
tubes
triple-mode
the
rain
using
mode
technology),
an L-band
little
level
range
triple
with
significant
a power
dB output dual
TWTAs
found
spacecraft
TWTAs that
"the
compared
to a conventional
transmitted
signal
resources
or fixed
ACTS
power
dual-power
... fixed-power
system." It should
be stated
when
changing
mode
TWTA.
taken
down.
point,
the
that the
For
perturbations
EPC,
to the
as mentioned
a very
large
earlier,
power
but
change
also
will
when
(>6 dB),
the
be experienced
changing
carrier
modes
would
not
only
in a multi-
likely
have
to be
=
It might
warm-up
also
cycle
be necessary would
to turn
be initiated
off
and
the
all high
voltage
overall
in the
downtime
EPC.
At
would
be about
power
appears
this 3
minutes.
i
In summary,
the
be infeasible.
For changes
with the
data data
Note, during
and rate
code and
however, the
multimode
ACTS
rate
TWTA less
than
changes
(>6 dB) changes
6 dB, a multimode up
rate
for such
a multimode
and
has
TWTA
in output might
to 16 dB of rain
introducing
development
development
large
to provide
simultaneously that
for
not been
one-half
forward tube
be used
fade
in conjunction
mitigation error
at Ka band
by
correction was
to
not
halving coding.
successful
reinitiated.
--= !
i.,D_L
SS/L-TR01363 Draft Final Version
5-29
45MtTR01363/Part2/-gF_97 Use or disclosure
of the data contained on this sheet is su_ect
to the restriction
on the title page.
5.6.7
Conclusions
for Downlink
It is concluded
that
power
of many
tens
active
transmit
sharing
(ATLA)
and
the
the
multiport
Power
Sharing
amplifier
of downlink
(MPA) beams.
phased
array
of total
beams.
offers
significant
In contrast,
(ATPA)
promise
the active
antennas
would
for downlink
transmit find
lens
array
application
only
MPA
after
m
for
relatively
smaller
numbers
considered
engineering
is believed
to be feasible
feasible
at X band
design at this
(7.5 GHz).
rate
changes,
is also
rate
nor need
for synchronization
the
effort,
feasible.
time.
As The
prove
This
feasible
Vuong,
discussed
Paul,
in section
advantage of code
of the and
data
is not
to say that
at Ka band and
Cox
MPA
(20 GHz).
concluded
5.5, power is there
rate changes
the
sharing
Nevertheless, that
an MPA
by code
is no disruption at the
will,
transmitter
and
it was data
to data and
m
at
receiver. I
W m
i
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SS/L-TR01363 Draft Final Version
5-30
45M/TR01363/Par12/-_J7 Use or disclosure
of the data contained on this sheet is subject to the restriction
on the title page.
SECTION
To limit in the
the
and
weather
rate the
COMSAT
ATM
6.1
ATM
ATM
was
rate
initially
developed
Networks that
of ATM
wide-area,
and
for
for
the
use
the
for rain are
ABR
fade
traffic.
attenuation
is This rate
during
binary
feedback.
implementing
Forum
information
end-to-end
destination
ATM
This
bad-
feedback, section
compensation,
also
using
the
(ALAs).
as
it could is that
relay.
A cell
in Figure
6-1, is 53-bytes
bytes
referred
long,
local-area
bear
the
of which
area
as well.
Among
Integrated
and
but
higher,
Indeed,
to integrate
or associate
fixed-format
the
Broadband
one
of the
in a seamless
soon major
manner
domains.
name
a fixed-size,
to as payload.
local
for
of 155 Mbps
an 0i_portunity
and which
solution
at bit rates
in the
it represents
is just
mode
operating
be employed
metropolitan-area,
of cell
a transfer
(B-ISDN)
to all technologies
are
which
the
OVERVIEW
advantages
notion
mechanisms links
considered
source
configuration
connections,
to compensate
controls
Accelerators
of ATM
satellite
technique
virtual
FoR ATM'S ABR TRAFFIC
control
for
feedback
and
Link
realized
Common
change
The
system
Digital
it was
feedback
mechanisms
feedback,
discusses
Services
m
code
on performance
several
these
conditions.
explicit
the
of congestion
of adopting
evaluates
reduction
w
impact
process
section
6 -- FADE COMPENSATION
first the
five
themselves
packet. bytes
advantages
are
with
ATM
is the
The
ATM
cell,
headers
and
the
remaining
packet
structure
of such
a rigid
as shown
are:
(1)
Ease
(2)
Higher
(3) (4)
Lower
per-packet
Easier
buffer
and
low
cost
per-packet
of implementation processing queuing
of cell
processing
in VLSI
chips,
speed, delay,
and
allocation.
u
The
disadvantages
ATM)
and
more
suited
contributes
are bandwidth
processing
overhead
to larger, to lower
but exacerbates
inefficiency for many
variable-size and
less
(i.e., an unavoidable
types
frames.
variable
the disadvantages
of traffic The
network
above
bulk
relatively
latency
mentioned
(e.g.,
and
for some
9.4 percent data
small easier
transfer)
size allocation
traffic
of the
overhead
in
which
are
ATM
ceils
of bandwidth,
types.
m
=
=
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SS/L-TR01363 Draft Final Version
6-1
45M/FRO1383/Part2/- 96_
w
Use
or
disclosure
of
the
data
CrOntained
on
this
sheet
is su_ect
to
the
restriction
on
the
title
page.
# of bits
,i,6131,I,I
4
384
UNI m m
NNI I_..,
J
Header (5 bytes)
I-
r]--_
Payload
(48 bytes)
UNI: NNI:
User Network Interface Network Node Interface
VCI: PT:
Virtual
Channel
Payload
Type
GFC: VPT:
Generic Flow Control Virtual Path Identifier
CLP: HEC:
Cell Loss Priority Header Error Control
Figure
6-1.
ATM
Cell
Identifier
I
z I
Format m
There
are =numerous
dedicated
media;
transmission
propoSals-0n
in a ring,
dual-bus,
infrastructure;
dedicated
media
optimized
for
switches;
and
etc.
connecting local
how
area
or star
An
data
switches
to
switch
Cells = migh(
topology;
emerging
local
over
synchronous
in a star
switches
are interconnected
relayedi
appears
equipment
the
be
over
paradigm
terminal
networking;
these
ATM
are
or
to be switch-centric topology
with
to a local
switch
to wide-area
arbitrary
[] m
or asynchronous
connected
in a relatively
shared
I
ATM
topology.
The
local m
connections transmission
protocol,
ATM
ceils
link.
To identify
in the the
are
table
and
must
requires cells.
and
set
Associated
up
usage
type
is established.
maximum
This
the in
each
ratio
will
sounds
time, which
rate).
Once
fairly
table
the
simple
and
the
user the
I-Dl'_a_,l,,
the or prior
quality
will
with provide
information
is carried
is performed
outgoing
to actual
The
routing
allocated. transmission
identification of service
by reading
path.
dynamically
service but
an ATM
(QoS)
This of ATM
(VCI)
to accept
is established, as long the
provider
a description
is willing
a connection
in concept,
switching
in a transmission
is assigned,
parameters,
such
are determined.
user
desired
routing
as the
details
of the (e.g.,
there user
of how
when
is an stays
the
the
service
average
within
connection desired
data
agreement
user-network
his
rate
and
that
the
constraints. agreement
45M/TR01363/Pa of the data contained on this sh_
and
is
SS/L-TR01363 Draft Final Version
6-2 Use or disclosure
m
asynchronous
protocol.
transmitted
contains
channel
the
or
a synchronous
and
pre-assigned
a virtual
specified, etc.
via
a cell,
to be established
connection,
synchronous
to determine
will be negotiated
within
provide
which
receives
either
(CLR),
a
connections
a label
routing
are
either
in a sequence
switch
advance,
of service
data
cell,
connection
At that
constraints
each
parameters
In ATM,
via
inter-switch
an ATM
with
cell loss
network
route
consulting be
the
the
typically
contiguously
When
as allowable
the
and
an end-to-end
traffic
are
multiplexed
cell header.
label
the
a
is subject to the restriction
on the title page.
rt2/-gFu,_7
w
reached,
what
happens
how agreements
are coordinated
shape terminal its User-Network definitions 6.1.1
across
in this area, but there ATM Service
Constant
(2)
Real-Time
(3)
Non-Real-Time
(4)
Available
(5)
Unspecified
applications
many
switches,
how
of the agreement, the switch
can help
is a great
deal more
to do.
defines
five service
categories
[40]:
Bit Rate (CBR), Variable
Bit Rate (rt-VBR),
Variable
Bit Rate (nrt-VBR),
Bit Rate (ABR), and Bit Rate (UBR)
categories and those
non-real-time
possibly
end
Categories
currently
(1)
service
fail to live up to their
traffic, etc. are complex, numerous, and contentious. The ATM Forum, in Interface (UNI) specification, has taken the first steps in providing some
The ATM Forum
ATM
if any of the parties
service
may
be arranged
which classes
do not.
into
Real-time
are nrt-VBR,
two
groups:
service
classes
ABR, and L_R.
Table
those
supporting
real-time
are CBR and
rt-VBR.
The
6-1 provides
the attributes
=¸;::¸7
of the ATM service
categories Table 6-1.
H_
Service Category
Typical Traffic Type
CBR
Voice or video
[41]. Attributes
of ATM Traffic Categories
Cell Switching Priority
Bit Rate
Delay Sensitivity
Target CLR for CLP=0
High
Constant
Yes
1.7 E-10
rt-VBR
Yes
Image or compressed video
Medium
1.0 E-7
Bursty
nrt-VBR
No
w
L_
ABR
Data
Low
Bursty
No
1.0 E-7
UBR
Data (email, fax, file transfer)
Low
Bursty
No
No target
.,.j.
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BYtC'rI_MII3
6-3
SS/L-TR01363 Draft Final Version 45M/TR01363/Pa
Use or disclosure
of lhe data contained
on this sheet is subject to the restriction on the title page.
rt2/- _a/E/
6.1.1.1
Constant
The CBR
service
and video
Bit Rate supports
by providing
constant
cell
requires
a predefined
traffic
cell
rate,
connections timing
which
The
equivalent
and
cell
such
rate
(PCR),
and
Cells
typically
specifies
the
delay
(CTD)
cell
as voice
can be characterized
to its PCR.
contract
maximum
applications
traffic
to a peak
A CBR
(CDV),
real-time
recovery.
capacity a QoS.
variation
and
corresponds
dedicated
are guaranteed delay
line
end-to-end
arrival
pattern
(CLR),
leased
transfer
by a
therefore,
conforming
it
to this
cell
loss
= = m
ratio
as the
QoS
=_ m m
parameters. 6.1.1.2 The
Variable VBR
service
multiplexing. two
Bit Rate supports
Based
on traffic
sub-categories,
real-time
referred
applications
applications.
The
services.
VBR
(SCR).
The
nrt-VBR
Compared
requires
to the
stringent
traffic and
requirements
delay
requirements,
which the
bit
rate
amount
capacity
which
contract
specifies
an
network
is further
The
rt-VBR
service
as
packetized
is equal
for
CDV
CTD,
is intended
for
and
to PCR
category and
rate
not
a mean
H
lib
as CDV.
does
only
U
is pre-
cell
as well
BB
=
as data
sustainable CTD
Z m
video
equivalent
nrt-VBR
and
into
such
CLR,
the
divided
voice
to the
acceptable
statistical
applications
of capacity
categories,
from
service
such
average
the
benefit
for non-real-time
a constant
service
can
VBR
nrt-VBR.
is intended
rt-VBR
on
and
variable
where
an
CBR
applications
service
to CBR,
rt-VBR
bursty
to as rt-VBR
with
In contrast
reserved,
BI
place
CTD
is
iW
ensured. 6.1.1.3
Available
Similar
to nrt-VBR,
mail,
the
ABR
fax transmission,
minimum
which
cell
rate
cannot adapt
effectively
characterize
traffic
rates
ABR
service,
if the
then
no packets
The
UBR
service
not
require
priority are used
services
such
to minimize
service
traffic
(MCR),
behavior
flow
in a certain
difference
For
from
VBR's
applications
establishment
protocol.
in response
for a
to the
to support
indication
way
as e-
is a guarantee
at connection
control
such
as opposed
is designed
due to a congestion
the
but
example,
ABR
network.
to feedback
In the
flow
control,
dropped.
is intended
for applications
response.
Furthermore,
end-system
whatever
through
rate
applications
Bit Rate
non-real-time
goes
cell
ABR
for data
The main
cell
a feedback
behaves
category
it to the
is suitable
Telnet.
their
be intentionally
Unspecified
the
the
be reduced
source
6.1.1.4
to tolerate
and
following
may
will
willing
category
as minimum
In addition,
their
leaving
known
SCR.
transmission
thus
service
file transfers,
throughput,
average
can
Bit Rate
the
network.
as electronic cell
and
to handle.
cell
loss
Therefore, mail
tolerant
UBR
is ideally
to delay
on the CLR
With
the network
or low-tariff
loss at the expense
are
no guarantees
applications
capacity
which
this can
suited
file transfers.
the
user
at the
to low-cost
Practically,
do
are offered,
service,
provide
and
instant
and
large
low-
buffers
of delay.
SS/L.-TR01363
W_
LlCi_L
Draft
6-4
Final
Version
45M/TR01363JPar12/-9_97 Use
or disclosure
of the data
contained
on this
sheet
is sub_ect
to the
restriction
on the
title
page.
is
m w
w
6.1.2
ATM
To support
w
ATM
Adaptation
the multiplicity
adaptation
layer
of user information
(AAL)
is defined
within
a common
ATM
Type
1: intended
to provide
connection-oriented,
CBR traffic.
(2)
Type
2: intended
to provide
connection-oriented,
rt-VBR
(3)
Type
3/4:
ABR,
and
Type
5: This
original AAL The
Type
reassembly, 6.1.3 The
already
and connection_less,
nrt-VBR,
out
Simple
of concerns
and
Efficient
about AAL
the
complexity
(SEAL),
and
for Type
it performs
3/4.
Its
a subset
of
of the a
AAL
desired
is to map
application.
numbering,
error
user
information
The
AAL
functions
and
transmission
protection,
into
ATM
cells
include
in the
most
segmentation,
of timing
information.
Layer
layer
provides
existing
bytes
connection-oriented
traffic.
functions.
sequence
ATM
grew
was
3/4
for
ATM
to provide
protocol
purpose
form
the
traffic.
name
primary
suitable
intended UBR
cell structure,
for five classes of user information:
(1)
(4)
w
Layer
for the
virtual
of data.
The
circuits
functions
transparent among
transfer
of ATM
communicating
users.
performed
(1)
Multiplexing
of ATM
(2)
Cell
relay
(3)
Cell
delineation
(4)
Payload
(5)
Selective
cell discarding
(6)
Cell
shaping
(7)
Enforcement
by the ATM
layer
service
data
All ATM
units
SDUs
(SDU) are
over
simply
48
include:
connections
L J m
and
routing
type
discrimination
M
=
rate
of traffic
contract.
,
u
6.1.4 The
Physical physical
of two (TC)
layer
sublayers: sublayer.
specifying
the
extraction
of
received
provides the
The
decoupling, w
layer
Header from
used for cell uncorrectable
Physical PM
physical timing
the header errors
ATM
cells
Medium
sublayer
the
information.
ATM
(HEC) into
services
sublayer
and
physical
TC
sublayer
dependent
performs and
of the
layer.
verification,
Convergence
the
such
insertion
delineation, and
system.
multiple-bit-error
It consists
functions
and cell
transmission
single-bit-error correction and in the cell header are discarded.
ATM
the Transmission
characteristics,
generation
frames
to the
medium
transmission
The
Check layer
(PM)
performs
medium,
Error
transportation
mapping The
detection.
HEC
as and
cell
rate
the
cells
field
Cells
is
with
w
m
HVIFrIg_WS
LDRb_,L.
SS/L-TR01363 Draft Final Version
6-5
45 M/TRO Use
or disclosure
of the
data
contained
an this sh_t
is subject
to the restriction
on the
tith_ page.
1363_a
r_J'- 9_97
Currently,
there
are
two
major
(1)
Based
on Plesiochronous
(2)
Based
on Synchronous
groupings
of physical
Digital Digital
Hierarchy
layer
protocols
for ATM:
=
u
(PDH)
Hierarchy
=
(SDH). m m k
PDH
is basically
the
PDH,
the
U.S.,
though the
Mbit/s),
the
DS-1
derived
and
of the
DS-3
optic
framing
structures
Mbit/s),
is STS-1 resulting
multiplying
OC-48
sublayer
the
(2488.37
performs
ATM
multiplexing higher
than
rate
OC-1.
by
N
To transport
mapping
of the
Mbit/s),
Forum
SONET
has
cell
first
in In
(6.312
defined
a set level
structure
(155.52
cell
DS-2
a way
into
the
by
SDH
was
is carried
SONET
over
rates
over
[]
of framing
of the
Mbit/s),
streams
defined
in PDH.
synchronous
OC-3
levels
region.
system
defines
The
STS-1
ATM
ATM
(1.544
defined
Higher
(e.g.,
geological
five
u
those
the
are
with
ATM
standards.
When
There
transmission
(SONET).
is called
Mbit/s)). the
cells.
Mbit/s).
basic
DS-1
to carry
Network
service
vary
The
multiplexing
(51.84
levels
(139 Mbit/s).
at rates
and
system.
(64 kbit/s),
division
Optical
speeds,
the
by
streams
these
DS-0
DS-4
time
transmission
with
are
and
data
hierarchy
achieved
hierarchy
Synchronous
medium,
associated
synchronous
to carry
telephony
Mbit/s),
transmission
framing
digital
bit rates
(44.736
from
formats,
TC
the
is a flexible ITU-T
existing
levels
DS-3
for the SDH
the
fiber
(STS-N)
OC-12
are
[] N
(622.08
SDH/SONET,
SDH/SONET
m l
the
frames.
All
H m m
l
timing
and
synchronization
functions
are
performed
by
the
SDH/SONET
transmission
systems. u
6.1.5 The
ATM Traffic ATM
layer
defines
sophisticated balance
set a high
network
of traffic
service
do
not
resources
in a way
this
the
case, usage
ATM
are The
four
(1)
Traffic
(2)
Quality
(3)
Connection
(4)
Conformance
(5)
Congestion
there
are
traffic
parameter
at
distributed
full
management
procedures.
for
be high,
but traffic
Traffic
Another
the
QoS
building
be
available
because
all
capacity.
unacceptable
and
switch
to
i
is to allocate
requires
functions
modules,
blocks
will
management
management interface
than
a low
connection
operate option
a
is to
example,
of every to
by
challenge
For
PCRs
connections
controlled The
utilization.
capacity.
more
among
categories
is uneconomical
effective
elements.
and
is reserved
always
will
service
network
option
operate
Therefore,
typically
functions
This
utilization
of all network
node
module.
in which
of ATM
maximum
if capacity
quality.
periods.
participation
with
continually
network
set
management
service is expected
a high
connections
a comprehensive
quality
utilization
achieve
peak
Management
during end-to-end
procedures
fabric,
In
and
at an a control
are:
descriptors,
of Service
parameters,
admission
control
monitoring
and
(CAC), enforcement,
and
control.
w
LD L
SS/L-TR01363 Draft Final Version
6-6
45MJTR01363JP Use
or disclosure
of the da ha con tained
on this
sheet
is sx_ect
to the
restriction
on the
title
page.
a r t2/- 9F_37
u
6.1.5.1
Traffic
A traffic
descriptor
service
elements:
Source
Source
:
guarantee
Traffic
Maximum
Burst
Size
connection
set
varies
directional
connection
which
descriptor
specify
The
CDVT
the
and
has
a set
need
is a network
be the
or the
pattern
of a given
of placing
several
virtual
6.1.5.2
Quality
of Service and
of
for each
direction.
CLP_0+I
traffic.
Jitter
on a single
are
for
caused
key
SCR
and
conveyed
at
A sustained
each
Source
of the
two
expected
PCR,
category.
a measure
is typically
the
descriptors
service
resource has
describes
traffic
descriptors
provides
connection.
circuits
QoS is measured
same
that
set
a
(CDVT).
parameters
traffic
aggregate
descriptor
These
within
proper
descriptor
which
connection's
of connection
to ensure
Tolerance
parameters
The
a connection
A traffic
Variation
needs.
on the
not
cell traffic,
of
MCR.
depending
departure
ATM
a set
required
network.
Delay
connection
(MBS),
sets
CLP_0
is
Cell
to which
are
an ATM
and
Descriptor
guidelines
descriptors
QoS across
Descriptor
utilization
can
bandwidth Traffic
the
Traffic
up
the
adhere.
bandwidth
the
Descriptors
defines must
and
that
=
category
allocation
The
Parameter
direction. traffic
jitter
by the
biNote
descriptors
in the
cell
inter-
multiplexing
effect
connection.
Parameters specified
(1)
Cell Delay
Variation
(2)
Maximum
Cell Transfer
(3)
Cell Loss
(4)
Cell Error
(5)
Severely
(6)
Cell Misinsertion
in terms
of the following
parameters:
(CDV), Delay
(Max
CTD),
w
Ratio
(CLR),
Ratio
(CER),
w
! -
Of
these
six
Errored
QoS
Cell Block Rate
basis.
CER,
guarantees
to meet
for
currently
supported
(SECBR),
only CMR,
CDV,
and
by the ATMF for the
UNI
max
SECBR
all connections.
4.0 provides mechanisms and the network.
and
(CMR).
parameters,
connection
Ratio
CTD, take
and
Specification Signaling
4.0.
negotiation
of CDV,
QoS
parameters
are
agreement
between
CLR
default
are
values
specified
of individual In addition, max
CTD,
the and
on
which QoS ATMF CLR
the
a per-
network
parameters
is
LTNI Signaling
between
the
user
! •
The
traffic
descriptors
representing
and
a mutual
specifies
its connection
network
agrees
descriptors
to provide
the
and
QoS level
the
a set
the
main
user
and
of QoS
specified
components the
network
parameters
in this
in each
of a traffic provider.
contract The
direction,
user
and
the
contract.
w
I..1I:3_1.
SS/L-TR01363 Draft Final Version
6-7
L 45 M/TR01363JPa Use
or disclosure
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6.1.5.3
Connection
Connection
Admission
connection
set-up
accepted one
Admission Control phase
or denied,
and
is established.
connection
in the
certain
bandwidth
nodes
are active
the
is the set of actions
order
to determine that
involves
path
traffic
(CAC)
to ensure
CAC
along
included
in
Control
traffic
If a connection
to the
participants
the
the
of CAC.
are not
descriptors
Each
node
affected
the
is accepted,
along
the
and
the path
when
QoS
be
a new by
each
requirements
network
reject
U
allocates
all intermediate
can
the
can
required
and
The end-systems
during
request
bandwidth/capacity
request
connection.
by the network
a connection
connections
determining
contract.
capacity
whether
existing
to support
taken
the
ATM
connection I
request The
if it can not meet
set
of
depends
traffic
on
bandwidth
the
to
connections,
and
ATM
service
PCR
account
utilization
meets
required
the
existing
For
CAC
PCR.
the
simplest
CAC
The
conservative
a connection
multiplexing
this
as PCR,
for accepting
resources
gains
prefer
connection,
as well
the
bandwidth
Service using
CAC
for
CBR
providers
can
the
lower
algorithms
a connection
and
required
is appropriate
powerful
traffic
request
allocates
in VBR
or refusing
for VBR
of
algorithm
for VBR connections.
providers
new
for
computation
Although
Service
of the
indicated
Therefore,
connection.
of network QoS
parameters
statistical
SCR, as well
optimizes the
each
to be overly
than
QoS
category.
of significant
rather
into
for
QoS parameters.
category.
for each
it proves
parameter,
ensures
the
to
categories:
will
credible,
the
In
addition,
a unique
rt-VBR,
result
I
the
This m
network
agreed
QoS
of
L_
B
be
CBR,
I
which
request.
that
as maintaining
SCR
connection.
descriptors.
optimal
descriptors
the
advantage
take
defined
is different
equivalent
take
the
algorithm
nrt-VBR,
in efficient
needs
to
algorithm
ABR
and
allocation
factor
in all
is required
UBR.
Ensuring
of network
of
the
for _each that
each
bandwidth.
standard
of
the
of these
Thus,
traffic
five
m w
service
algorithms
how
M
refined
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algorithms
are will
6.1.5.4 When the
Conformance a network
ceils
been
conformance
achieve
this
conforming the QoS
of the
a Usage
Parameter
with
and takes
conforming
Parameter Control
(NPC)
it commits
generic
cell
Recommendation to the
network
of other
Control process
(UPC)
action
rate
algorithm
traffic
the
traffic
on these
connections. process
at the NNI
to provide
1.371 and
source
polices
appropriate cells
is allocated.
and Enforcement
theoretical
respect
the
bandwidth
connection,
the ITU-T
objective, ceils,
efficiently
an ATM
to the
by both
how
Monitoring
carries
conforming
selected
define
by
determine
at the
the
(GCRA).
ATM
cells
and
connection
to prevent
The compliance UNI
(Network-to-Network
and
QoS
to all
The GCRA
has
TM 4.0 specification
descriptors of the
agreed
them
the
CDVT.
to detect from
enforcement
optionally
to
by
To non-
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a Network
Interface).
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The
CAC
and
congestion
w
The
while
CAC
while
uses
the
the
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When
connection, For
=
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to allocate
from
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of all current
making
isolated
to the
buckets
thus
two
one
from
connections.
bandwidth/capacity,
sure
the
another,
are
(fill
that
rate
can
traffic and
conforms
are
leaky
the
to
not affected
the
relay
and
at a higher
highest
rate
may
PCR0,
rate
PCR
limit
(size
being
and
the
and
actually
PCR1
each
parameter
bucket)
example,
service
buckets:
to police
increment
of the
(for
with
frame
algorithms
burst
is used
cascaded,
three
bucket
parameters:
rate
descriptor
carrying
require
leaky
has
of cells
traffic
connections
and
more
compliant
number
one
leaky
ATM
or
mechanism of the
than
multiple
descriptors
users
to protect
objectives
connections,
one
bucket
inverse
more
example,
traffic
leaky
corresponds
bucket).
network
implements
to the
parameter
of the
way,
together
users.
process
corresponds
the
work
performance
descriptors
In this
Each
must
network
polices
"misbehaving"
connection.
the
traffic
descriptors.
A UPC/NPC
functions
meeting
UPC/NPC
the traffic by any
UPC/NPC
of the
SCR)
for a
policed
first.
define
three
SCR0.
,
6.1.5.5
Congestion
There
are
two
control.
down
Discard
(EPD)
it actually When
can
until
and
the
network
with
re-transmissions
This
drastically
reduces
a cell level.
data
packets
ABR
and
which
have
UBR
traffic
flow
control
packet
Type
prevents
reactive
congestion
control
technique,
congestion
is detected,
sources
are requested
Discard
(PPD)
a state
by
traffic by the
5 connections,
preventive
the
EPD
are
fixes
levels the
on a packet
by the
sender.
which
EPD
cells
caused
congestion
as increasing
requests.
discarding
useless
are
of congestion
re-transmission
to be re-transmitted
of AAL
technique
and
In a reactive
experience
more
than
more
control
control
occurs.
Packet
generate
of flooding
and
preventive
the end of congestion.
Partial
quickly
control:
a preventive
for congestion.
A network
cell loss
before
or stop transmission
Packet
examples.
of congestion names,
actions
is monitored
to slow
categories by their
appropriate
network
r
general
As indicated
by taking
Early
Control
transfer
and
used
of
problem
level
rather
of corrupted
PPD
are
especially
applied
to
for this packet
traffic.
Feedback used
to guarantee
objective
the
is to
mechanisms QoS
reduce
are
of existing
the
overall
considered
reactive
connections traffic
in case
in a way
that
control
techniques
network the
which
capacities
network
run
never
can be
low.
The
reaches
an
informs
the
w
undesirable traffic stop
sources increasing
feedback for g
state
the
flow other
of congestion.
of impending or slow
As mentioned congestion;
down
control
mechanism
services.
Section
their
previously,
on receiving
traffic.
Table
is mandatory 6.2 provides
the
this 6-2
for the a summary
ATM
information,
indicates ABR
that
network the
traffic
sources
implementation
service
category
and
of several
feedback
flow
of a optional control
mechanisms.
m
SS/L-TR01363 Draft Final Version
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6-9
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6.2
ABR FEEDBACK
ATM has essentially error
rates
noisier rain
such
than fades.
margins
as those
These are
used
therefore
wasted
adaptive
fade
in
satellite
be severely
to severe
cell loss.
of source maintain
Thus,
an acceptable
this adaptive
rate
no feedback
information
links.
experience
severe
may
rate
link
not
rain attenuation.
satellite
be
"ill
resource
[] u
This is
operations,
and
I
utilization, code
rate
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links which
may
m
reduction,
for use in satellite
as
To improve
techniques
as information
proposed
such
and built-in
for bad-weather
To improve
such
have been
of satellite as coding
low
are inherently
impediments
these
condition.
networks
added
such
be reserved
media with
degraded.
The use of the information for rain fades with
from
However,
links which
approaches control
suffer
approaches
must
transmission
Satellite
performance
links.
clear weather
power
often
non-adaptive
resources
stable
fiber cables.
the
satellite
compensation
and uplink
and
reduce
for satellite
during
for use over very
systems
links,
IN RAIN FADE COMPENSATION
by optical
impediments
attractive
significant
otherwise
wired
often
because
designed provided
of satellite
economically
change
been
terrestrial
performance
FLOW CONTROLS
reduction
and
mechanisms
code
to dynamically
this fade compensation rates
for active
performance.
rate adjustment
rate change
ABR
technique
technique
control
the source
requires
connections
over
The ABR feedback
control
an adaptive a fading mechanisms
It
to compensate rate can lead adjustment
satellite
link
to
will provide
_m am
capability.
Table 6-2.
m L_ BB
Feedback
Controls
for ATM Traffic u
Service
Service
Category
Feedback Guarantee
g
Control
CBR
Capacity for PCR, Max CTD and CDV
Optional
VBR
Capacity for SCR, Max CTD and CDV for rt-VBR, Mean CDV for nrt-VBR
Optional
:: = m
Capacity
UBR
Mandatory
for MCR
Nothing
K.DI'_A_I-
Optional
SS/L-TR01363 DraftFinal Version
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45M/TR01363/Part2/Use or disclosure
of the data
contained
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restriction
on the
title
page.
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6.2.1
ABR
There
w
are
Feedback
essentially
participating
ABR
activation
the typical
terrestrial
buffer
traffic
being
certain
ceils
sent
earth
fade
where
station marked
that will
by their
Section
Binary
Feedback
be used
require
6.3.2
requests
discusses
the
ABR
from
are based
satellite.
can
a system
message
to a switch
the
The
is different
controls
relayed
over
would
ATM.
is then
adjustment
This
congestion
each
condition.
by a notification
equipment.
the feedback
enable
channel
triggered
for transmission
However,
controls
rate to a satellite
message
of rate
this
feedback
compensation
The processing
with
where
is assumed
The notification
are appropriately
networks
with
At the
sources
on ABR
switch,
to adjust
the
also be accomplished
configuration
integrated
that
system
at
integrates
configuration
in
detail.
6.2.1.1
End-to-End
Binary
feedback
is a flow
Forward
Congestion
data
header
cell
destination
= ....
mechanism
station's
to the
station.
satellite greater
earth
[40],
its information
implementation,
rates.
earth
control
thresholds.
information the
the
Mechanisms
mechanisms
to adapt
of a feedback from
Control
three source
originated
switch
Flow
control
mechanism
Indication
(EFCI)
as "congestion
end-system
where
bit
in the
experienced"
which
receives
until
data
a network
Payload
cells
the
end
with
element
Type
marks
Indicator
of a congestion
EFCI=I
may
that
satellite
the
(PTI)
notify
Explicit
field
of the
duration.
The
the
source
end-
k_a
system
of congestion
The
source
notification
cells
which
are
Figure
to zero
rain
sends
a fade
Upon with
direction
backward bits
to one.
The
transmission
rate.
Note
cells/sec When reduced
received per
a backward by
during
the
Figure
6-3.
cell,
that
the
RM
destination The
is attenuated).
Management
a satellite cells
(RM)
Under
the EFCI of data
the
transmit
active
ABR
cells
earth
the
bit set sent.
station
connection.
The
cells.
end-system
turns
The
congestion received
may
use
this
generate
of these
link.
with
number
consecutive
may
rate
the
for all data
destination "N"
to the
supporting
end-system
cell.
over
all of its data
is activated,
switch
the last
destination
link
of Resource
proportional
to backward.
if the
use
the
of ABR traffic sends
bit to one
bit changed
a forward
connection
to the
RM
the
compensation
the EFCI
is set to one
equal
having
r_
message
(DIR)
RM cell
control
end-system
and
of a forward
sources
destination.
at a frequency
detected
by setting
reception the
are
notification
responds
traffic through
feedback
a source
RM cells
fades
the
by the
the binary
inserts
Once
switch
around
condition,
and
to inform
is accomplished
turned
6-2 depicts
clear-weather
I
(e.g.,
the
RM cell around
indication data
(CI) bit of the
cells
had
information
backward
backward
their
EFCI
to lower
RM
cells
RM
cells
cell
transmission
its
without
is limited
to 10
[40].
RM
cell
a rate
decrement
signaling
phase.
with
CI=I
factor The
is received, (RDF).
simplified
LD_L
The flow
the RDF
source factor
diagram
is a negotiated
of this
procedure
of the data contained
on this sheet is subject to the restriction
is
parameter is shown
in
SS/L-TR01363 Draft Final Version
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rate
on the title page.
E 3-ts3
Satellite _j
fade notificationr.Al_rn
/ n
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h
u
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D
Data Cell with EFCI=!
Figure 6-2.
Data Cell with EFCI=0
End-to-End
[_RM
Binary Feedback
Cell
j
Flow Control
/ Yes (i.e., data cells)
I
SOURCE
Cells (data and RM)
w
If Fading SET PT--01x
, ATM Switch RM cells)
i
DESTINATION: 1. EXAMINE DATA CELLS 2. IF PT=01x THEN 3. MODIFY RM CELLS BY SETTING CI=I 4. TURN RM CELLS AROUND TO SOURCE
CI= 1: Reduce ceil sending rate gradually NI=I: Do not increase ce]l sending rate
r
Cl=0 & NI=0: Increase cell sending rate gradually
Backward
Figure 6-3.
N
Simplified
Flow Diagram
of End-to-End
RMs
Binary Feedback
UPII_R'IEaMB
Control
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6.2.1.2
Explicit
Because
Rate
Feedback
of a gradual
explicit
rate
rate feedback
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cells
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at any
allows
desired
to network
conditions
status
along
their
Specifically,
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them
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can have based
access
the
to forward
on available
element
capacity
should
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each Any
and
increase
if a more
stringent
sources
element
to request
and
PCR).
can
react
value
Hence,
situation
cell
RM
cells
the
ABR
rate (ECR) no
result
is encountered
sources
mechanism
However,
would
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to congestion
along
explicit
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ABR
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generates
condition.
since
feedback,
effectively
element
to modify
congestion
congestion
binary
network
RM cells
ECR
end-to-end
periodically
intermediate
impending the
MCR
end-system
backward
and
ever
ABR
the
network
between
since
connection.
by
for any
rate (i.e.,
is adaptive
paths'
dictated
in
path values
network
the
somewhere
and
loss
of
along
the
path. Figure
6-4 depicts
flow
control
an over-the'satellite
mechanism.
A
by
the
compensation
reducing
ABR
transmit
connection
earth
information
using
station
rate
the
explicit
detects
on the
rain
satellite
rate feedback
fades
link.
and
as a
activates
A fade
notification
ABR
connection.
w
message
is sent
The switch w
bit and
responds
ECR
.=,
rate
in the
to the
diagram
when
RM cell
the value
earth
they
with
ECR
value
station
by inserting
field)
a backward F
by the
in the
feedback
pass
CI=I,
field.
the
field
switch
source
and
in Figure
direction.
adjusts
destination
active
into RM cells
backward
end-system
the
the
information
forward
of a forward
is shown
supporting
control
in the
Similarly,
ECR
of this procedure
to the
its cell
end-system
RM
cell
with
the CI receiving
transmission
adjusts CI=I.
(setting Upon
rate
to
its transmission
The
simplified
flow
6-5.
m
6.2.1.3
Virtual
VS/VD
Source
is essentially
connection
the
segmented
sourced
by
the
virtual
source,
and Destination explicit
at several
source
(VS/VD)
rate
feedback
intermediate
end-system.
Feedback
Each
flow
network adjacent
control
mechanism
elements. ABR
The
control
first
for ABR
segment
an
ABR
segment
is sourced
is by
a
=
segment,
BIB$
Which
except
of the
destination
turned
around
the
assumes last,
the
is terminated
end-system. and
forward
RM cell
CI field
is set to one
received
by a virtual
not
behavior
is changed and source
from the
by a virtual
Forward
forwarded
ECR
of the
to the
RM next
"forward" field
are removed
source
end-system.
destination, cells
received
segment
of the
to "backward."
which by
from
the
assumes
a virtual
connection. When
is set to an appropriate
Each
ABR the
behavior
destination The
are
DIR bit of the
congestion
value.
control
occurs,
Backward
the
RM cells
connection.
i.
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m
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Figure 6-4.
['_RM
Cell with CI--O
Explicit Rate Feedback
--']Data
h
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Flow Control k
ira--.
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i
If fading
SET
Forward
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If fading
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ATM Switch
Figure 6-5.
Simplified
m
RMs
]t'
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DESTINATION
_
Backw
Flow Diagram of Explicit
Rate Feedback
Control
m
LI31"4/_L
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w
Figure
6-6
flow
control
ABR
segments.
system,
m
depicts
The the earth
information
rate
around
value
detects satellite
receiving
RM
that
cells
the
destination destination
cells cells
simplified
flow
then
the
Switch
from
diagram
source
reducing
the
RM
cells
satellite). 1 and
rates
CI bit turned
Switch
sets
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of this procedure
the
I modifies
receiving
transmission
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the
Switch
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a fade
1 (i.e.,
over
Upon
cell
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by
sends
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controlled
destination
Switch
transmitted
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separately
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by
coming
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for
for the
message,
RM
VS/VD
destination
station
terminated
set
three
activates
earth
not
end-systems
The
and
are
end-system
into
source
notification
of RM
fields
the
virtual
vlrtual
The
ECR
and
the
fades
link.
1. Upon
in the ECR.
6.2.2
rain
CI
for the
specified
the
the
and
destined
and
2 becomes
using
is divided
1 becomes
end-system
the
source
Switch
connection
connection
source
examines
the
Switch
station
for
to the
ATM
ABR
ABR
on
to Switch
ECR
The
ATM
A transmit
and
over-the-satellite
mechanism.
and
message
an
equal
RM with
cells CI=I,
to the
is shown
2
value
in Figure
6-7.
Assessments
Table
6-3 compares
the
feedback
flow
control
mechanisms
using
criteria
such
delay
refers
as response
w
delay,
cell
time
rate
beginning
end-system The
rate
request arrival flow
adjustment when
method,
the
earth
of a particular adjustment the
transmission
of the control
congestion mechanisms
station
ABR
method rates
and
reliability. decides
connection
criterion explicitly
notification is provided
The
response
to compensate
receives
assesses
message
at the
in the
following
fading
a "congestion
a given
or relatively.
for
control
The last criterion An
until
refers
evaluation
elapsed
the
notification"
feedback
source.
the
source
message.
mechanism to the of the
to
reliable feedback
paragraphs.
•2 _]
_C)--_
fade notification
Satellite
/
® Figure 6-6. VSND
Feedback
Flow Control
SS/L-TR01363 Draft Final Version
IRl_=eM_m
6-15
45 M/I'R01363/Part2/-_16_7 Use or disclosure of the data contained on this sheet is sttbject to the restriction
on lhe title page.
VIRTUAL DESTINATION
(VIRTUAL) SOURCE
± =_
No (e.g., Data) I RM cells + Data cells
T
N
RM)
Backward RMs
SET ECR>MCR
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Forward RMs
DESTINATION ]GENERATE] ECR>MCR c'T'= RM 1
(VIRTUAL)
Dm---o VIRTUAL
Backward RMs
SOURCE m
Figure
6-7.
Table
Simplified
6-3.
Flow
Assessments
Diagram
of VSND
Feedback
of ABR
Feedback
Flow
Control
Controls = u
Criteria
Binary
Feedback
ECR
Feedback
VS/VD
Feedback
Source
Response
Two satellite
hops
One satellite
hop
Negligible
Negligible
Delay Destination Response
One satellite
One satellite
hop
hop
DelaY.r,., Rate
Gradual
Actual
Actual
Low
Better
Setting
Low
Reliability
(ES waits for data/RM cells, some of which may be lost or corrupted)
(ES waits for RM cells some of which
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may be lost or
corrupted)
RM cells
to notify ABR source and destination) w
rw
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6-16
SS/L-TR01363 Draft Final Version 45M/TR01363/Part2J-_FJ37
Use or disclosureof the data contained on thissheet is subject to the restriction on the title page.
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6.2.2.1
Response
Delay
w
For the end-to-end destination delay
from
(approximately
would
Therefore, propagation In the
Delays
due
delay
RM
of
the
a data
station
cell with
is a single
to processing
reacts
a backward
response
it takes
earth
If the destination
receive
the
the time
transmit
240 ms).
negligible.
system
feedback,
end-system
assumed
upon
celI
EFCI=I
satellite
and
hop
terrestrial
this
data
cell,
with
CI=I
one
end-to-end
binary
feedback
at the
propagation
propagation
receiving
marked
to arrive
the
are
source
end-
satellite
delay
later.
is two
satellite
hop
delays.
explicit
feedback, the
binary
rate
feedback,
as shown
current
state
station
to source
Similar
to the
transmit
ceils
the
in Figure
of the
destination
6-2.
link since
response
delay
However,
the
the
of backward
delay
source
is the
is much
same
faster
RM cells
as the
in adapting
from
the
binary
its rate
transmit
to
earth
is insignificant.
w
explicit
accomplished of feedback
w
desired
by the
turned-around
control
is the same
6.2.2.2
Rate
since
other
tO the two
the
binary
approach. may
to request
in the
source
As shown
first loop
in Figure
of the
end-system
end-system
ABR
from
6-6,
path.
the
to this
is
The delay
transmit
earth
mechanisms.
feedback
control
It is therefore
exceed
an ABR
immediately.
destination
feedback
previously,
delays
time
RM ceils
Method
reduction
the
is almost
information as the
rate decrease
rate
rate
Adjustment
mentioned
transmission
feedback,
at any
station
As
rate
the
not
fade
mechanism
effective
duration.
against
The
explicit
uses
the
short
term
rate and
gradual fading VS/VD
w
feedback rates
mechanisms
on any
ABR
however
allow
connections
for the
based
on the
actual
specification
satellite
link
of desired
capacity
under
transmission different
fading
conditions. 6.2.2.3 The
Reliability binary:
feedback
mechanism
successfully
propagate
The explicit
rate
backward feedback adjusts transported experiencing
control
by a terrestrial
rate
satellite
mechanism by a faded
therefore
transmission
rain
the
transported
mechanism its
through
feedback
RM cells
is less
appears based link
reliable twice
in the
before
is more return
to be more on
since
loop
reaching
reliable
satellite
not
the
link must
contained (i.e.,
control the
than
favorable,
information first
feedback
since
source binary
must
end-system. feedback,
but
survive.
The VS/VD
the source
end-system
in feedback
transported
cells
control
by the
satellite
ceils link
fades).
LD_L
6-17
SS/L-TRO 1363 Draft Final Version 45 M/TR01363]Pa
Use or disclosure
of the data contained on this sheet is subject to the restriction on the title page.
rt2J-9F_97
= m
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6.2.2.4
Recommendation
Practical
considerations
mechanism
networks.
mechanism rate
viewpoint mechanism
its
the
feedback
above
discussions,
transmission
link
request. to
terrestrial
reduce links
the
due to its long The
mechanism
request
From
explicit
delay
and
that
rate
of backward
accomplishes
a
It is superior
to the
transmission
the request
rate
end-to-end delay
and
binary gradual
explicit
rate
rate
delay
by the
for the
the
the this
explicit
the
virtual
_I I
VS/VD
ability
to
source's
from
it is not reliable
and
transmitted
i
feedback
since
feedback,
feedback
is reliably
time,
to
transmission
However,
in a critical
feedback
compared
specification.
response
can be generated
large
is acceptable
to the
explicit
are
mechanism
RM cells
negligible
a given
delays
response
explicit
Similar
implementing
the
feedback
is degraded.
source
in
propagation
source
rate
and
on the arrival
satellite
part the
response
depends
important where
approach. of
an
networks,
is unacceptable
decrease
while
play
in satellite
terrestrial
u
rate that
the
source
lip
via
destination. i
6.3
SYSTEM
COMSAT which rate
CONFIGURATION
Laboratories
facilitates
manufactures
the
adaptation
transmission
and
Mbit/s
but
do
shown
in Figure
sources
are connected
FOR
signal
not
an ATM of ATM
any
modified
Link
traffic
conditioning
implement
6-8,
IMPLEMENTING
Accelerator
over
functions of the
versions
to the switches
FADE
satellite
feedback
of ALA-2000
through
TM, model systems.
to output
ABR
data flow
units
physical
COMPENSATION
links
ALA-2000 The
at rates
control
will
be
running
TM
[42],
ALAs
perform
of up
to 8.448
mechanisms.
[]
As
required.
The
ABR
at standard
rates
such m
as 51.84
Mbit/s
155.52
Mbit/s
Mbit/s
over
interface
over
OC-1
lines.
(STS-3).
The
ALAs
DS-3
proposed
lines.
Another
The are
switches
are
connected
possible
interconnected
to the
system
switches
via via
links
configuration
would
links running make
running
at
at 44.736 use
of the
w
in [43]. Standard Rates El, DS1, DS3 ....
ABR source
V
MODEM
ABR source
MODEM rl u
i
MODEM ABR source
Figure
6-8.
System
Configuration
for Implementing
Fade
Compensation
SS/L-TR01363 Draft Final Version
6-18
45M/'rR01_3/Part2/-0_a_d'/ Use
or disclosure
of the
data
contained
on this
sheet
is subject
to the
restriction
on
the
title
page.
SECTION
In order must
for
be given
J
selected
to several
required
to
common
resource
addressed .
the
invoke
the
fade
mitigation
system
related
mitigation
pool
approach
defining
to selecting
the
to operate
aspects.
These fade
for fade
without
REQUIREMENTS
schemes
scheme,
required
adequately
general
7 -- SYSTEM
include
system
system
compensation
compensation. the
successfully
overall
parameters
margin,
range,
Most
system
consideration
and
of these
affect
size
issues
requirements.
that
setup of
the
cannot
An
fade
time
be
outline
mitigation
of a
is given
below. 7.1
SYSTEM
MARGIN
System
margin
is directly
largely
a function
elevation
angle.
in terms =--
takes
of
care
through allow quality
measurement,
Link
quality
associated pertain this
to the process
statistical fade
the
results
link
this
must
have
the
been
derived
estimation
around
5 dB
and
error
the
into the
fade
beacon
estimation
error
to the
is of the
must the
measurement
link
errors
of the
techniques
to the
and
in the
margin.
up-link.
7-1 shows In this
the
of +0.5
dB.
figure
down-link
at Clarksburg, fade
scaling
frequency
Figure
against
down-link
order
margin with
Some
measurements
is proportional
available
or down-link)
is plotted
the
essentially
portion
are introduced
down-link
and
compensation.
typical
clear-sky
is
be considered
associated
(up-link
the
may
clear-sky
presented.
errors
in turn
provided
is the
fade
6 and
This
allocation
The
the
frequency
from
ACTS
fixed
margin
were
down-link
from
The
inaccuracies
approach,
be factored
up-
margin
Section
at one
scaling
the system
implemented.
techniques
In this
is to be
for invoking in
quality
of frequency
between
the
discussed
service
dynamic
being
time required
frequency.
and
ratio
that
fades
other
the
measurement
measurement the
behavior
the
the was
different
to measuring
scaling
seen
and
estimation with
value
attenuation,
requirements.
component.
and
schemes
the
mitigation
a dynamic
conditions
signal
availability
in which fade
and
compensation
for clear-air
service
climate
implementing
clear-sky
fade
to the
rain
component
of the
the
the
When
of a fixed
related
and
MD. for
Most
fade; It is
down-link
compensation
_=_
techniques period
have
some
allocated
for
appropriate m
margin
of 2 s, the
additional
applying
fade
The
duration
to
time ensure
implementation has
ceased.
threshold
overheads the
overhead
must
to avoid
is I dB. time
of
of around
short
them
Another
larger
than
rate factor
the
can
with
n provides
fades
which
to
of 0.5 dB/s that
must
and
with
handled wait
a hysteresis cause
by time
around the
this
fade
an
an overhead
be accounted
associated be
the time
ensure
compensation
a suitable
may
During
and
the
time
This
delays).
intact,
for which
0.5 dB together
duration
stay
a fade
duration
margi
(signaling
must
resources.
implementation very
link
be significantly
utilization
margin The
is the
with
Assuming
required
compensation
adequate
the
be allowed.
margin
must
associated
for in
is invoked. the
overhead
including after the
the
an fade
clear-sky
compensation
to
L_
LDI'_M_I,.
SS/L-TR01363 Draft Final Version
7-1
_m
45 Use
or
disclosure
of _he
data
contained
on
this
sheet
is
subject
to
the
restriction
on
the
title
page.
M/TR01363/Pa
r t2/-
9F._97
kick-in the
and
out.
following
The
clear-sky
margin
may
be assigned
using
typical
values
to account
for
factors:
-
gaseous
-
link-quality
-
time
-
frequency
-
fade
u
absorption
(- 1 dB)
measurement
delay
error
in applying scaling
dB)
compensation
error
compensation
(-1
within
b
(-
1 dB)
the clear
implementation
sky
margin
margin
(- 0.5 dB)
(- 0.5 dB) y ± m
A
contribution
required the
under
overall
other tie-up made The
from
each
worst
case
system
hand,
a very
valuable
factor
conditions;
cost,
and
low
value
as such
dynamic
the
schemes
impairments.
Figure
together
to
e.g.
4 dB.
Clear-sky
margin
pessimistic
fade
arrive
value
the
two
has
should
compensation
between
at the
to kick-in opposing
fixed
a direct
margin impact
be avoided.
on
On
the
too frequently
requirements
and
must
be
w
margin.
component
compensation
added
the
A trade-off
fixed
be
an overly
can cause
resources.
in selecting
can
of must
the
link
margin,
be determined
which
on
the
is
basis
available
of
rain
(30 GHz)
and
through
and
other
the
fade
propagation .I
(20 GHz) system
cumulative noise
7-2 and
7-3 show
distributions
temperature
up-link
for different
fade rain
of 200 K is assumed
climates
in the
down-link
degradation
for an elevation
down-link
angle
degradation
W
of 20°; a
calculation. m
m
w
1.5
Fade
Raio m
1
0
4
8
12
16 .m
20.2
Figure
7-1.
Distribution
GHz Attenuation
of the Fade
Ratio
(dB)
Between
27.5
and 20.2
GHz
w
w
SS/L-TR01363
LC:U_M_L
Draft
7-2
Final
Version
45M/TR01363/Part2/-9_97 Use
or disclosure
of the data
contained
on this
sheet
is subject
to the
restriction
on the
title
page.
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Attenuation Rain
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Angle
for Different
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Down-Link
Ordinate
Degradation
Rain
Zones;
100
Exceeded
Distributions
Elevation
at 20 GHz
Angle
for Different
20 °
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LaI'_L
SS/L-TR01363 Draft Final Version
7-3
45M/TR01363/Part_Use
or
disclosure
qf
the
data
contained
on
this
sheet
is subject
to
the
restriction
on
the
title
page.
9_97
The
calculation
gaseous for
the
the
ITU
Table
is based
absorption scintillation rain 7-1
99.7%. 20 °, and
shows
sky
margin
up
to about
region
reduced
service
The
response
time
required
the
margin
such
levels;
at elevation
to be the
worst
10 dB of compensation, even
P may
at 99.7%
require
distributions
99%, angles
case.
it is seen
below
that
and about
a clear
rain
level.
additional
99.5%,
Assuming
availability
either
for
climates
Operation
clear-sky
in
margin
or
TIME
time
for fade
for the
compensation
selected
fashion
has
fade
of the control
hops.
other
techniques the in
fade
level
on the
other
also
setting-up the
by
time
clear-sky
time
the
hand
(of the
point will
satellite
margin
suffer
link
must
and
be
the
and
of the
must
stay
in
since
processing
required
a minimum
times
implemented
of milliseconds)
power
time
control delay
order
intact,
adjusted
synchronization
control
order
where
setting-up
the
signaling Power
measurement
at the
require
of the
method.
response
determined
power
During
is a function
compensation
the smallest
is essentially
included
be considered
as region
Closed-loop
factor
can
include
figures.
availability
to operate
and
of 0.6 m is assumed
degradation
in the
three
expected
approximately
determination
seconds.
not
for
errors
diameter
down-link
shown
model
availability.
time
Most
P are
K can be accommodated
climates
loop
are
an antenna
and
required
shown
prediction
scintillation; Attenuation
systems
RESPONSE
response
total
of 4 dB and
rain
for
the
calculations
heavier
an open
tropospheric
attenuation
B, D, F, H, K, M, and
Ka-band
the
ITU-R
calculation.
regions
Most
7.2
and
on the
to
is applied.
of two of one
and
meet
the
the
the
satellite
to several time
set-up
delay time
requirements.
Table
7-1.
Link
Margins of 99%,
Rain
Required 99.5%,
for Availability
Times
and 99.7%
Up-link"Margin (dB)
Down-link Margin (dB)
Zone
99%
99.5%
99.7%
99%
99.5%
99.7%
B
2.5
3.2
3.8
2.6
3.1
3.6
D
3.9
5.0
6.1
3.9
4.7
5.5
F
5.4
7.2
9.0
5.1
6.3
7.4
H
6.4
8.6
10.7
5.7
7.2
8.5
K
8.7
11.8
14.6
7.8
9.7
11.4
M
10.6
14.5
18.3
8.7
11.1
13.3
P
16.5
23.0
29.3
12.4
16.3
20.0
w
I..PJlRM I..
SS/L-TR01363 Draft Final Version
7-4
45 Mrr R01363JPa Use
or disclosure
of the
data
contained
on this
sheet
is subject
to the restriction
on the
title
page.
r_2/- 9_F37 m
7.3
COMPENSATION
The
fade
RANGE
compensation
range
compensation
being
power
is a function
control
selected.
The
HPA
capacity
in turn
data
rate
reduction,
on
little
cost
impact
margin not
be
handled
by
recourse
of service
of the
high
is a function
the
by
As an example
other
that
any
of the
may
be made
the
amplifier
Referring
compensation
the range capacity
earth
range
available
ratio,
to Table
7-1, and
assuming
required
fade
described
clear-sky
margin
and
to provide
station.
has
for very
a clear-sky
compensation
in Section
fade
for up-link
at the
reduction
the
of the
available
compensation
techniques the
capability
of the
climates
to increasing
and
(HPA)
Fade
is a function
rain
cost
compensation
of its cost.
hand,
for heavy
the
power
its implementation.
of 4 dB, it is seen
situations, levels
on
is determined
6.
may In such
acceptable
availability.
r_ =_ rw
2-.2"
=__
=
w
w
SS/L-TR01363 Draft Final Version
7-5
45 M/TR 01363JPa rt2J'-_-_,97 Use or disclosure
of the data contained
¢,n this sheet is subject to t_
restric_ic,n an the title page.
Ill
U
F
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_
D
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mE W
m
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SECTION
Three focus
experiments on low cost
achieve The
higher fade
w
availability
measurement
terminal.
The
compensation
consists
coupled
information
with
ATM rate
stream
changes
to
demonstrate
rate
experiment
and
satellite
transmission
two.
presented
on
Each
experiment
in the following
8.1
FADE
link
traffic
over
cost
associated
by rain of
three
rain
low
cost
impact
with
code
rate
The
information
This
experiment
conduct
of an
information will
satellite
conducting
final
rate
traffic.
compensated
a
changes
and
the
on Fade
code
for
fade
experiment.
the
to
attenuation.
utilizing
the
a plan
experiments terminals
availability.
reducing
ATM
is described,
of the
three
improve
carrying
ATM
caused
convolutional
compensation
links
of
an estimate
shown
fade
first two Ka-band
compensation
for dynamically
enabling
The small
a relatively
fade and
to
COSTS
performance
with
control
reductions
a mechanism
occur
the
is a rain
power
study. enable outages
be implemented
staged
thereby
the
can
ESTIMATED
service
compares
experiment
of
demonstrates
traffic
by reducing
which second
AND
as part of this which will
experiment
techniques
experiment w
have been planned hardware modifications
average
measurement small
8 m EXPERIMENTS
link
of
the
experiment
is
of each
experiment
is
sections.
MEASUREMENT
EXPERIMENT
- OVERVIEW
w
r
The
fade
measurement
and
response
rate
from
time
experiment of three
compares
low-cost
fade
the
relative
measurement
accuracy,
implementation
techniques.
Beacon
cost
power,
bit error
-
w
channel
selected
r__
for
suitability
coded
this of
data
and
experiment.
the
signal
This
technique
for
to noise
selection
fade
measurement
is based
low-cost,
upon
independent,
techniques
the user
have
analysis
of Section
premises
terminals.
been 4 and The
v
performance
of the
the techniques
=--
The
proposed described
Lewis
Research
carrier
which
random
bit the
controller
fade
allowing
fade
is best
upon
m
and
three
them
measurement by
starting
Center
sequence
Ground
developed
control
system
for 90%
of the
by
experiment
LET
by
bit error
the
(NGS)
COMSAT
under
to provide
less
conditions.
the
Evaluation
Terminal
controlled,
QPSK
Link
a power
rate
modem test
uplink
contract than
implementing
in Figure
The
27 GHz
identical
by
is shown
is fed
modem.
Station
is expected
source,
a satellite
generated
under
setup
signal The
can be compared
simultaneously
experiment at the
by
techniques
to run
(LeRC).
is generated
NASA
measurement
input
set.
power
is provided
326402
[28].
0.5 dB signal-level
The
experiment (LET)
This
variation
at
modulated
is a 384 kbit/s
Uplink
beacon
NAS
8-1.
pseudo-
control
based
by
power
the
uplink at the
power satellite
duration.
_m _l_i
B'YEclrl!MS
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SS/L-TR01363 Draft Final Version
8-1
z
45M/'r'R01363/Part,JUse
or
disclosure
of
the
data
contained
on
this
sheet
is
subject
to
the
restriction
on
the
title
page.
9_B7
Beacons Satellite
Beacons Ill
Terminal Propagation
VSAT Terminal
_'_
Terminal
Receiver 27 GHz Beacon
q
Station*
Uplink power control
L_ ]_
27 GHz Beacon Receiver*
[
I
t
Beacon Receiver Modem
Receiver 20 GHz Beacon
q
BR
tim
Reference Degradation
]
BERTestSet
measurements
IB
estimators COMSAT
Data Archive
NASA
Laboratories
Lewis
Research
Center miR
* Propagation equipment
conditions performing
at LeRC are monitored and recorded on a continuous basis. NGS this function is not included in experiment cost and requirements.
m
The
signal
Figure
8-1.
transmitted
by
at IF by the microwave VSAT
site
both
the
rain
rate,
output Each VSAT
the LET is received
switch
matrix
into
Experiment
by the
the E-08
Maryland.
path
to the
VSAT
site by the co-located
uplink
and
downlink
temperature
from
modem
Measurement
Clarksburg,
downlink
in
Fade
the
and
VSAT
performing of the
is split
simultaneous
three
fade
at the and
BER
measurement
systems
are
site will to the
coded will
data
run
towards
which
also low
and
the
monitor
instantaneous
be monitored. cost
beacon
SNR
fade
independently.
the
on
will
including
m
switched
monitored
terminal
conditions
VSAT
mode,
is directed
conditions
provided
fro m
in HBR
which
propagation
=_= _P
Diagram
satellite
beam
Meteorological
speed,
terminal
spot
Propagation
beacon. wind
ACTS
Block
The
LNB
receiver
and
m m I
a
measurements.
A computer
at the
site will:
•
Read
beacon
•
Read
BER
Eb/No
from
from
•
Read
•
Maintain and
signal
SNR
coded
results data
from
results
the low-cost
from
the
beacon
receiver.
and
calculate
modem
J
received
reading.
results
calculate
continuous
channel
each
a table
measurement
from
the modem
of hourly the
w
clear-sky
downlink
and
calculate
baselines
degradation
received for each
estimated
Eb/No fade
from
each
measurement
from
each
reading. technique
technique
on
q
a
basis.
w
SS/L-TR01363 LG_I--
Draft
8-2
Final
Version
45 M/TR01363/Part2/-gF_97 Use or disclosure
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data contained
on this
sheet
is su_ect
to the
restriction
on tht
title
page.
m iiBll
•
Read
downlink
propagation
w
•
Maintain
a record
,
fading
Read
and record
The experiment
measurements
propagation
from
the co-located
for each fade processing baseline establishment
parameters
used
in calculations
and
technique.
a WWV receiver and append time stamps to data effects on the uplink from LeRC to be correlated with data.
meteorological
should
results,
for each fade measurement
Read the current time from records to allow propagations
•
reference
of measurement
estimates
NGS generated L
uplink
terminal.
degradation •
and
parameters
run for sufficient
at the VSAT site.
time to establish
reliable
algorithm and should encompass several phase. The cost estimates assume that
clear-sky
baseline
data
rain events following the the duration of the data
.--4
collection
phase
is between
determine
the relative
the fade measurement still remains
2 and
performance utilizes
significant
3 months.
The
of the three
existing
development
data
fade measurement
equiPment effort
collected
and resources
which
must
Fade Measurement
Experiment-
Beacon receivers are designed and tend to be far to expensive $2K. w
=
A beacon
acquisition time VSAT terminals. receiver.
=
These
receiver
whenever
performance
there
to perform
effort
the
and suggests
a
Low Cost Beacon Receiver
sacrifices
some
must be developed specifications have parameters
Table 8-1.
Although
possible,
be undertaken
to
to provide control signals to antenna positioning systems for application in a VSAT terminal priced to sell around
which
and features, Preliminary
be analyzed
techniques.
experiment. The following text describes the required development method to achieve the required development at reasonably low cost. 8.1.1
will
performance,
in terms
of accuracy,
for fade measurement applications in been established for the low cost beacon
are shown
in Table 8-1.
Low Cost Beacon Receiver
Performance
Requirements Parameter
Requirement
Accuracy
i_0.80 dB
Acquisition bandwidth
50 kHz
Acquisition time
3 seconds
!
Input frequency range
1385+.05 MHz
Input beacon level
-20 to -40 dBm
i =llll
Beacon modulation types
BPSK
Threshold C/No
_
40 dB/Hz
EI'VIFIt'8_II3
SS/I..-TR01363 Draft Final Version
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45M/'FR01363/_a Use
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_[ tk_
data
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title page.
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9F_,97
A beacon
receiver
threshold
of 43 dB/Hz
10 dB at 20 GHz
link
the
budget allows
receiver
is shown operation
will
lose
in Table through
lock
and
8-2.
The
beacon
10 dB fades.
will
receiver
During
re-acquire
when
the
fades
sensitivity in excess
of
signal
returns
from
that
no more
than
lib
the
fade.
The
10 dB of uplink will
provide
communications
selection
of this
compensation
is based
is reasonable
meaningful link
threshold
beacon
power
upon
in a low
the
cost
measurements
conclusion
terminal
and
whenever
the
beacon
acquisition
receiver of
the
is possible.
Table
II
Beacon Receiver Link Budget at Threshold
8-2.
Carrier Frequency, F
20.19
GHz
20 GHz Beacon EIRP
18.50
dBW
Modulation Loss
1.20
Single tone EIRP
17.30
dBW
38,500
km
Path Loss, Lp
210.31
dB
0.95
dB
10
dB
Rain Attenuation, Lr
280
Rain Temperature, Tm
m g
K
-203.96
Flux Density at Earth Terminal
w
dB
Satellite Slant Path Range, S
Clear Sky Attenuation
m m
dBW/m 2
.n.
45.18
Antenna Gain, Gr
dB
257.74
Antenna Noise Temperature, Tant Pointing Loss
0.10
dB
Feed loss, L
0.20
dB
Feed Transmission, a
0.95
LNA Noise Temperature, Tlna
145.00
K
Ambient Temperature,
290.00
K
404.19
K
To
System Noise Temperature, Ts G/T
19.11
dB/K
C/No
43.55
dB-Hz
VSAT terminal phase noise
71.70
dB-Hz
C/No total
43.55
dB
C/No required
43.00 O.55
dB dB
Margin
....
m u
K
w
m
m
m
u
lu:l,m_cm
SS/L-TR01363 Draft Final Version
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LDI'4/ L
8-4
45M/TR01363]Part2./-_*97 List or disclosurt af tht data contained
an this sheet is subject to the restriction
on the title page.
m
A block
diagram
estimates
of section
frequency
to bring
nominal have
L
of the beacon 4.1.3 the
70 MHz.
a 5 kHz
loop
in Figure
phase-locked
bandwidth.
The loop
of
frequency
of the
beacon
additional
acquisition
10 dB,
signal
with
the
(SNR)L
level
beacon = Ps
f0_ generation
The L-band
( RF unit loop
signal
be
This
ACTS
8-2.
used
to noise
LO = 18.8 GHz
to within
of performance and existing
filter
ratio,
is just
known
of the cost
synthesizer
is a tracking
is 3 dB which
must
circuitry.
was
beacon
The second
fading
months
is shown
which
downconverted
1), at downlink
of several
receiver
adequate
VSAT
) at 1350
MHz
to a
is estimated
to
using
Equation
for acquisition.
6 kHz should
is set to a fixed
which
calculated
impact
to be acquired be achievable
(8The
without for periods
terminal.
B,
P,, 2BL
Ps = signal
power
PN = noise
power
(8-1)
=--
at PLL input
B i = PLL input bandwidth, B L = PLLbandwidth,
(2 MHz)
(5 kHz)
m
w
70-2:1 L-band input 1350 MHz
Beacon Power
Oe ,or
---¢,:) vco( ) 12s0
.m
0.455 +0.005
VCO +
z
Frequency PLL Synthesizer
=,._
PLL Frequency Synthesizer
_
10 MHz Reference
Figure
8-2.
Low
Cost
Beacon
Receiver
Block
Diagram
=--
7_
I..DRb(_I..
SS/L-TR01363 Draft Final Version
8-5
m 45 Use
or
disclosure
of
the
data
contained
an
this
sheet
is
subject
to
the
restriction
on
the
title
page.
M,/TR01363_art2J'-
_FJoJ7
8.1.2
Fade
Measurement
A modem
capable
estimates
must
found
be
which
Therefore and
of performing
which provide
it is necessary
modify
A search
the
from
to procure
two
and
other
measuring
there
is no guarantee
the
because data
samples.
converter,
in parallel,
carrier
distort
the
SNR the
in the
the
fades
signal
BER
fade
by the
are
in fact and
timing
approach
to be less
two
data I
desirable
from
of the the
of
coded
fades
between
w
readily
capability
channel
estimating
has
measurement.
alternative
performance
circuits
are
measurement
deemed
fade
modems
quality
BER from
was
and SNR
Modems
The
measurements,
modems
symbol
data
data
satellite
technique.
measurements.
implementation
and
SNR
with
SNR
from that
recovery
experiment
a modem
coded
available
coded
one measuring
fades
Differences
by the
channel
simultaneous
running
channel
of commercially
link quality
BER
Modifications
BER from
measure
it to perform modems
Modem
simultaneous
obtained.
no modems
available
Experiment-
identical
m
analog,
A/D
modems
may
m
results. I
The
circuitry
Modem
required
firmware
requirements. and
SNR
data
8.1.3
Fade
must
8-3 shows
rate.
The
These
requirements
statistics
to the
the link
modulator
consistent
with
the
system
convolutional
code
modulation are
NEWTEC provides and
Table
8-4.
for the
This
LET
data
estimate
link
framing
carrying
channel
coded
The
outer
VSAT
data
terminal
channel
data
The
was
I
digital a rate
3/4
rate
after
performance
manufactured
=
by
to noise
density
of 61.8
rate
QPSK
modulation
with
m a
modulation
symbol
terminal
which
carrier
and
includes
code. VSAT
information
Institute's
coding
block The
required
274 ksymbol/s
coding
Standards
services.[44]
The
a 384 kb/s
channel
274 ksymbols/s.
Belgium.
dB
< 10 -10.
Experiment
fade
M
handling
Budgets
to VSAT
COMSAT's
BERi
data
4-7.
u
(204,188)
is approximately
Measurement
estimate
- Link
Reed-Solomon,
to provide
Fade
A cost
and
in Figure
additional
of BER from
Telecommunications
sound
to
the
the reporting
to perform
of 4.4 dB for the
is expected
8.1.4
with
meet
is shown
computer.
for the
European
measurement
to
include
budget
for
fade
modified
experiment
of Antwerp,
Es/No
be
Experiment
applicable
CY
SNR
is assumed
broadcasting
parameters
also
Measurement
Table
QPSK
to implement
measurement is based
- Cost
Estimate
experiment
upon
is provided
modifications
for planning
to a modem
which
purposes
in
is currently
in w
production section and
(COMSAT 8.1.2.
All hardware
compensation
modifications In
addition
Laboratories
to
modifications
experiments required the
are
to implement modem
CL-107).
data
The
modifications
required included the
handling
to perform
in this
fade
estimate.
compensation
firmware,
software
required both
the
were fade
must
and are
be
in
measurement
Software experiment
described
not
written
firmware
J
included. for
the w
m_
LD_L
8-6
SS/L-TRO 1363 Draft Final Version 45kVT'RO 1363JPart2/-_d97
Use or disclosure of thedatacontained on this sheet is subject to the restriction on the title page.
=
Table 8-3.
Fade Measurement
Experiment
w
Carrier Frequency, F LET EIRP Backoff
29.00 GHz 75.00 dBW 42.00 dB Tr
Carrier frequency, [F] Fixed beam e.i.r.p, at saturation Backoff
Pointing loss Single tone e.i.r.p. Distance to satellite, Path Loss, Ls
0.50 dB 32.50 dBW
Satellite pointing loss e.i.r.p. Distance to VSAT, IS]
S
Clear Sky Attenuation, Rain Attenuation, Lr L__
Channel
Polarization G/T
loss, Lp
Transponder
bandwidth,
Received
Link Budget
Downlink
Uplink =
Communications
38,000 213.29 0.50 0
km dB dB dB dB 0.50 23.10 dB/K 900.00 MHz 69.91 dB
Lc
B
C/No
19.28 65.00 26.00 0.22 38.78 38,500 209.85 0.50 0.00 275 0.00 0.13 45.58 0.50 77.59 71.57 67.23 61.80
Path loss, [Lp] Clear sky attenuation, [Lc] !Rain attenuation, [Lr] Clear sky noise temperature, Rain fade, [Lf] Polarization loss
ITs]
Antenna gain Pointing loss Down]ink C/No VSAT downconverter Combined C/No C/No
required
phase noise
(CBER=10E-4)
Mar_n
Table 8-4.
Cost Estimate
GHz dBW dB dB dBW km dB !dB dB K dB dB dB dB dB-Hz dB-Hz dB-Hz dB-Hz
5.43 idB
for Fade Measurement
Experiment
DEVELOPMENT COST Beacon Receiver Modem Modifications
40 K 46 K
EQUIPMENT COST Modem (2+0 spare) Beacon Receiver
48 K 4K
EXPERIMENT COST Experiment design Design reviews Testing Data collection Data analysis and reporting
8K 8K 10K 10K 6K
TOTAL
$180 K
m
N
iP/iFrlS_lS
LDI'_/_I--
SS/L-TR01363 Draft Final Version
8-7
m
45M/TR01363/Part2/Use or disclosure of the data contained on this sheet is su_ect
to the restriction
on the title page.
_-_97
computer
to collect
implement
the
data,
store
degradation
costs
are included
8.1.5
Fade
data,
implement
calculations
in the experiment
for
design,
the
both
clear-sky
fade
testing
baseline
measurement
and
data
algorithms
and
techniques.
collection
These
w
categories. H
The
schedule
of the
for the
experiment
8.2 The
Measurement
FADE fade
Experiment-Schedule
Fade
Measurement
is expected
compensation
Low
cost
experiment
tend
8-3.
The
duration
months.
m
experiment
compensation
terminals
in Figure
- OVERVIEW
utilizes
a fade
VSAT
ten
EXPERIMENT
to implement
terminals.
is shown
to be approximately
COMPENSATION
measurement
Experiment
hardware
technique
to be limited
suitable
on transmit
from for
EIRP
the
low
fade
cost
U
VSAT
at Ka-band
due
to
m lID
the
fact that
solid
cost
effective
held
in reserve,
additional
state
amplifiers
to counteract either
in the
channel
compensate
for
transmitting
and
frequency
power
of
fading
entirely
form
of unused
capacity rain
cost
which
transitions
with
Due
terminals
during
between
code
control.
if code
requirements
code
rate
rates.
output
or frequency
required
the
with
power
slots
be
to
rapidly
uplink
time
would
attenuation.
receiving
increases
for
changes
This
power.
It is not
Bandwidth
can
slots,
to accommodate
rates
are
u
changed
coordination
to
between
it is desirable
experiment
be
to limit
demonstrates
El
the the --I
effectiveness
of code
employed
to
availability
with
rate
limit
the
changes, rate
reduced
of
combined code
with
rate
limited
transitions,
(4 dB)
in
uplink
achieving
power
high
control
satellite
w
link
margin.
--= g
Allocation satellite
of reserved channel
bandwidth
requires
the
while
existence
maintaining
a fixed
of a TDMA,
FDMA,
symbol FDM
duration
or TDM
on
system
the with V
1 Experiment 2 Beacon
Design
I
2
3
.A
(2E)
_..
4
5
6
7
8
9
10 w
Legend:
Receiver
&
(1 E)
V
Modifications
A
(m)
V
E=Engineer T=Technician m
3 Modem
A
4 Testing
(1E+IT)
V
m
A
5 Data Collection
(1E)
V (1E)
/K_._V
6 Data Analysis
(1E)
/K...._V
7 Reporting
--7 w
Figure
I_lpl/_C=m
8-3.
Schedule
for Fade
Measurement
Experiment
SS/L-TR01363 Draft Final Version
EP_tIl"lS_ei
LC:iRM_L
u
8-8
45M/TR01363/Part2/Use or disclosure
of the
data
contained
_
this
shed
is subject
to the restriction
on the
title page.
9_B/37
reserved
r
capacity.
management
system,
information
rate
including
the
fade
to be run
with
the
low
and
to the
site
through
BER
test
set
for the
signal
at the
to be
with
evaluated,
complexity
and
8.5 dB
of degradation
power
control,
rate
1.5 dB of compensation Code
information
rate
carrying Fade
BER
when
from
and
power allowing
measurements
will
Channel
3/4
and
channel
feeds
Coded
cost
of
to rate
3/8
information
rate
control
transition
the
experiment
be performed
Data
The
computer. the
and
or
by
SNR
fade
by
is split
based
compensation
and beacon
data
or
upon
one
commands.
the S_
BER
The
to the test
set
LET-modem randomization
ETS 300 421.[44]
segment
to the VSAT-modem.
•
DLPC
commands
to be sent
•
Code
by the
commands
and data
and
techniques.
commands
VSAT-modem
to the
beacon
outputs
measurement
These
commands
cost
experiment
fade
ULPC
transition
power
measurement
•
rate
fed to the low
demodulates
fade
The
performs
is best
clock
in following
space
availability
provides
Specification,
ACTS
the
experiment
LET-modem.
provided
is absent
between
high
in effect.
and
is very
sections.
The
is identical
to that
experiment.
coded
the
are
link
achieves
is not
channel
The
duplex
LET-modem
to the
hardware
controller
compensation
Broadcasting
coding
power
4 dB and
The
signaling
The
The
of the
bits
Video
measures
channel
of only
upconverter.
VSAT-modem
estimates fade
VSAT
in Cleveland.
of data
Digital
uplink
compensation
(160 b/s)
LET
receiver
from
required
rate
signaling
by the
The
BER
degradation
the
the
in Cleveland.
code
measurement
beacon
site
a margin
site
experiment.
except
Operation
rate
the
compensation
LET
sequence
with
fade
fade
with
LET
in a low
received
functions
m
approximately
modems.
at the
multiplexing,
described
outputs
achieve
compensation.
compliant
output
either
system
will
experiment
operates
at 384 kB/s
modulator
the
Z r_
ACTS
of the
modem.
the
measurement
multiplexes
coding
The
a bandwidth
in conjunction
additional
of 4 dB of uplink
of the
a pseudo-random
Details
compensation the
receiver,
diagram
by starting
provides
and
beacon
9.5 dB of fade
frames,
performed
without
compensation.
over
is required
and
described
m
fade
a computer
VSAT
requiring
circuits.
8-4 is a block
similar
the
be
not
delay,
continuous-mode
cost
by
will
approximately
3 dB
will be performed
Figure
W
providing
signaling
measurement
allows
combination
contributing
either
This
experiment
transitions
experiment
management.
the
two
of the transitions
of propagation
with
transitions
cost rate
reductions.
compensation
rate
the
code
bandwidth
compensation code
limit the
effect
demonstrating The
To
may
receiver
and
VSAT-
measurement
results
to
also
fading
by
measure
The
computer
except
it may
system.
The
performs only
all
calculate
computer
also
include:
to the LET-modem.
VSAT-modem.
m
m_
L¢I_L
SS/L-TR01363 Draft Final Version
8-9
m
45M/TR01363/Part_J-9F_97 Use
or disclosure
of the data
contained
on this
sheet
is subject
to the
restriction
on the
title
page.
Beacons
q
I
Satellite
1
Propagations Terminal
i__" t_ Link Evaluation Terminal
Terminal
U
Local VSAT
w
27 GHz Beacon Receiver LET-Modem Fade
I
U
Estimation
VSAT-Modem
20 GHz Beacon Receiver
Signalling
!
w
BER Test Set Computer Data
BER Test Set
J
/
i
Recordation
Beacon Receiver Algorithm B
Figure
8-4.
Fade
Compensation
Experiment
Block
Diagram J i
The
VSAT-modem
implements and
the
rate
modem
data
with
at
communications also
be
the
provide
fade
demodulated,
are also
8.2.1
Fade
Multiplexing modem.
The
MPEG-2
for
BER
LET site.
beacon
test
monitored
Return
Fade
set
for
the
channel
sequence,
BER
LET
at the and
are
also
of th_ channel
at the
_0
site.
The
LET
site
signaling
J
data
to
channel
of signaling packet
channels
information
utilized
_=_
and Coding
information
and
w
i
- Multiplexing and
w
VSAT-
estimates
VSAT-to-LET
computer
i
channel
the
or one
for errors
A
recovered
with
receiver
The
by
The
and
in Cleveland.
signaling
multiplex
8.2.2.
a pseudo-random
techniques.
implemented
Experiment
multiplexing
to the
and
LET-modem
to be multiplexed
either
at Cleveland.
of the
to the
sources
clock,
upon
by the computer
coding
also
returned
based
is also rain
Compensation
transport
set
to the
in section
is routed
measurement
algorithm
recorded
and
test
commands
as described
recovered
demultiplexed
compensation
activity
BER
site
DLPC
VSAT-modem
trafficked
LET
channel
compensation
the
signals
algorithm
VSAT-modem
sig-naling
generated
fade
from
The
the
generated
being
ULPC,
transition
monitoring.
synchronous
The
code
demultiplexed
performance
will
implements
streams
by ETS 300 421
is performed is shown
by
each
in Figure
consists
8-5.
of an eight-bit u
sync
byte
packet
followed
creating
by what
187 eight-bit shall
data
be called,
bytes.
The
for purposes
sync
byte
of this
is inverted
report,
on every
a master
frame.
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sequences
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8.2.2.
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and
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during
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8-6
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bit rate
The
Figure
fades,
impact
for
link
convolutional
are compliant is not specified
of VSAT
the
operating
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with
downconverter
phase
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3/4
Reed-Solomon
ETS 300 421 except
in ETS 300 421.
rate
that
optional which
rate
3/8
interleaver is significant
systems.
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SS/L-TRO 1363 Draft Final Version
8-11
45 M/I"R01363/Part2/Use
or
disclosure
of
th¢
data
contained
on
this
sheet
is subject
to
the
restriction
on
the
tit_
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8-12
SS/L-TR01363 Draft Final Versio_lT 45M/TRO 1363,'1Pa rt2/- 9FJ_J7
Use or disclosure of thedatacontainedon thissheetissubjecttotherestriction on thetitle page.
W
8.2.2 Fade
Fade Compensation compensation
implemented experiment
initiated. processor
by cost.
control
the margin
algorithms
and
by a microprocessor
are performed Power
Experiment-
the
is used
VSAT
modifications
is continuously with
Signaling system
For this experiment,
modem
link margin
maintained
in an actual
the modem.
to limit
compensation
to maintain
is no longer
signaling
within
computers
Fade
Fade Compensation
through
shallow
full transmit
power
This process is shown in Figure 8-7 for a rain event algorithm has determined that a code rate transition
be
functions
thereby
by both
fades then
these
and
performed
would
reduce
computers.
of up to 4 dB. When
a code
rate
at Clarksburg. is required.
transition
is
The VSAT It signals the
new code rate to the VSAT modem, CR=Ri. Each modem maintains two parameters, its current transmit code rate, Rtx, and its current receive code rate, Rrx • The VSAT-modem sends
the next signaling
the new code
rate.
frame
at the prior
The LET-modem
VSAT Processor
receives
code rate
with
this frame,
code rate
bits,
the subsequent
VSAT Modem Code Rate = R i
_1
R0 and R1 set to 6 master
frames
of
LET Modem Rate = R i
lhx-- %
-- ..
P,_ -- Ri_ 1
lhx= %
i
tl_ = Ri I_
m
Rate=Ri
m
Encoded
at Rate = R i
w
2 * ( propagation
m
delay) + Signalling flame period < Delay < 2 * ( propagation + 3 * ( Signalling frame period )
delay )
750 ms < Delay _97
Use or disclosure
of the data contained on this sheet is subject to the restriction on the title page.
APPENDIX
A m FADE MEASUREMENT TECHNIQUE RESULTS
ERROR ANALYSIS
Bent Pipe with Back-off Low Cost Beacon Receiver Residual Error, [+dB]
Source of Error
Comments
Beacon power fluctuations at receive terminal
0.31
Fade estimate errors caused by satellite beacon power and pointing errors are much less than propagation effects. Propagation effects are dominated by frequency scaling of gaseous absorption.
Receive antenna pointing errors and efficiency variations
0.90
Dominated by inaccurate frequency scaling of feed window wetting.
Receive gain fluctuations
1.00
Residual error will be related to the worst case day-today temperature change at a constant time of day.
Beacon power level measurement accuracy
0.75
Expensive beacon receivers can provide _+0.25 dB accuracy. Accuracy of low cost receiver is estimated to be _+0.75dB.
RSS Error
1.57
Mean square error
0.79
Half of two sigma value.
Degradation estimate accuracy
_+1.25dB
Beacon receiver measures fading on path while comparison is performed on accuracy of degradation estimate. Terminal must assume system and sky noise temperature and calculate degradation from fade measurement.
'
= .....
Worst case values above are interpreted as two sigma values. Error is less than value 95% of time.
=__ r__ _
I3'V'IB"I"I!EI_II_
IL-131=4/ 1.
SS/L-TR01363 Draft Final Version
A-1
45M/TR01363/Pa Use or disclosure
of the data
_ont_wd
on this
sheet
is subje_
to the restriction
on the title
page.
rt 3/'- 9F_,97
Bent Pipe with Back-off ..
T
Automatic Gain Control Signal Measurement Residual Error, [+dB]
Source of Error Transmit power variations across frequency band
1.50
Transmit power variations over temperature
0.50
Accuracy of uplink compensation
i
Uplink transmit power variations with frequency are approximately _+1.5dB. Typically +_2dB from -40°C to 50°C. Time of day correction removes all but the worst case day to day temperature variation at constant time-of-day which is approximately _-+0.5dB/10°C.
1.00
Satellite motion
Comments
If signal is not regenerated on the satellite then uplink fading must be compensated for at the transmit station. Downlink C/N and BER will be affected by residual fade.
0.33
Received signal power fluctuations caused' by satellite motion are more significant for narrow beam antennas. _+0.05° satellite orientation error produces _-H).33dB signal level variation at receive terminal in 0.3 ° beam.
Satellite gain variations across frequency band
0.50
Satellite gain variations at a fixed frequency
0.50
Downlink propagation effects
0.31
Propagation effects are dominated by frequency scaling of gaseous absorption.
LNA gain fluctuations
1.00
LNA gain variations affect signal and noise equally.
RSS of worst case errors
2.28
Error is less than this value 95% of the time.
RSS error
1.14
L_
u i
=--
i L--
i
Gain variations across the transponder do not affect (C/N)up but (C/N)down is affected. Apply half of the typical error for a link with (C/N)up = (C/N)down.
N
Thermal gain variations of the transponder do not affect (C/N)up but (C/N)down is affected. Apply half of the typical error for a link with (C/N)up = (C/N)down.
i
i
RMS error or one sigma error. ,
,,,.,
Mean square error in fade estimate
1.75
[Eb/No] clear-sky =9 dB
Mean square error in degradation estimate
3.94
Fade =2.+.1.75 dB, Tm=280 __.10,Ts=230!-_10
w
A-2
SS/L.-TR01363 Draft Final Version 45M/TR01363JPart3/-9/5/97
Use or disclosureaf th¢data containedon this sheet is subjt,ct to the rt,striction on the title page.
i
Bent Pipe with Back-off Pseudo-Bit Error Rate Source of Error
•
=
Comments
Transmit power variations across frequency band
1.50
Uplink transmit power variations with frequency are approximately _+1.5dB.
Transmit power variations over temperature
0.50
Typically _+_2 dB from -40°C to 50_C. Time of day correction removes all but the worst case day to day temperature variation at constant time-of-day which is approximately _+0.5dB/10°C.
Accuracy of uplink compensation
1.00
If signal is not regenerated on the satellite then uplink fading must be compensated for at the transmit station. Downlink C/N and BER will be affected by residual fade.
Satellite motion
0.33
Received signal power fluctuations caused by satellite motion are more significant for narrow beam antennas. •+0.05° satellite orientation error produces _-4-0.33 dB signal level variation at receive terminal in 0.3 ° beam.
Satellite gain variations across frequency band
0.50
Gain variations across the transponder do not affect (C/N)up but (C/N)down is affected. Apply half of the typical error for a link with (C/N)up = (C/N)down.
Satellite gain variations at a fixed frequency
0.50
Gain variations across the transponder do not affect (C/N)up but (C/N)down is affected. Apply half of the typical error for a link with (C/N)up = (C/N)down.
Downlink propagation
0.31
Propagation effects are dominated by frequency scaling of gaseous absorption.
LNA gain fluctuations
0.00
LNA gain variations affect signal and noise equally.
Fade measurement
0.50
Channel BER=0.01,95%
RSS error
2.11
Square root of the sum of the worst case errors.
Mean square error
1.06
Mean square or one sigma error.
effects
accuracy
confidence interval is 0.5 dB.
N_
SS/L-TR01363 Draft Final Version
A-3
45 M/'I"R01363/Pa Use or disdosu_
of tht _,,
_tained
on this
sheet
is subject
to the
rtst_ti_
on tl_ title
p=ge.
rt 3/- 9FJ97
i
Bent Pipe with Back-off Bit Error Rate Measurement I
on Channel Coded Data Source of Error
Comments
Transmit power variations across frequency band
1.50
Uplink transmit power variations with frequency are approximately +1.5 dB.
Transmit power variations over temperature
0.50
Typically +_2dB from -40°C to 50°C. Time of day correction removes all but the worst case day to day temperature variation at constant time-of-day which is approximately _+0.5dB/10°C.
Accuracy of uplink compensation
1.00
If signal is not regenerated on the satellite then uplink fading must be compensated for at the transmit station. Downlink C/N and BER will be affected by residual fade.
Satellite motion
0.33
Received signal power fluctuations caused by satellite motion are more significant for narrow beam antennas. _+0.05° satellite orientation error produces _+0,33dB signal level variation at receive terminal in 0.3 ° beam.
iI
=a
l M
Satellite gain variations across frequency band
0.50
Gain variations across the transponder do not affect (C/N)up but (C/N)down is affected. Apply half of the typical error for a link with (C/N)up = (C/N)down.
Satellite gain variations at a fixed frequency
0.50
Thermal gain variations of the transponder do not affect (C/N)up but (C/N)down is affected. Apply half of the typical error for a link with (C/N)up = (C/N)down.
I
J
Ial
I
Downlink propagation effects
0.31
Propagation effects are dominated by frequency scaling of gaseous absorption.
LNA gain fluctuations
0.00
LNA gain variations affect signal and noise equally.
Fade measurement accuracy
0.30
Channel BER=5E-4, 95% confidence interval is 0.3 dB.
RSS error
2.07
Square root of the sum of the worst case errors.
Mean square error
1.04
Mean square or one sigma error.
U I
, i,.
L_ w
w_I
=
LD L
A-4
SS/L-TR01363 Draft Final Version 45M/TR01363/Par13/-9Fu,97
Use or discbsure of thedata contained on this sheet is subject to the restriction on the title page.
J
=
Bent Pipe with Back-off Bit Error Rate Measurement from Known Data Pattern Comments
Source of Error Transmit power variations across frequency band
1.50
Uplink transmit power variations with frequency are approximately _+1.5dB.
Transmit power variations over temperatu re
0.50
Typically -+2 dB from -40°C to 50°C. Time of day correction removes all but the worst case day to day temperature variation at constant time-of-day which is approximately _-+0.5dB/10°C.
Accuracy of uplink compensation
1.00
If signal is not regenerated on the satellite then uplink fading must be compensated for at the transmit station. Downlink C/N and BER will be affected by residual fade.
Satellite motion
0.33
Received signal power fluctuations caused by satellite motion are more significant for narrow beam antennas. -+0.05° satellite orientation error produces __+0.33 dB signal level variation at receive terminal in 0.3 ° beam.
Satellite gain variations across frequency band
0.50
Gain variations across the transponder do not affect (C/N)up but (C/N)down is affected. Apply half of the typical error for a link with (C/N)up = (C/N)down.
Satellite gain variations at a fixed frequency
0.50
Gain variations across the transponder do not affect (C/N)up but (C/N)down is affected. Apply half of the typical error for a link with (C/N)up = (C/N)down.
Downlink propagation effects
0.31
Propagation effects are dominated by frequency scaling of gaseous absorption.
LNA gain fluctuations
0.00
LNA gain variations affect signal and noise equally.
Fade measurement accuracy
0.50
Channel BER=0.01, 95% confidence interval is _+0.5dB.
Total Error
2.11
Square root of the sum of the worst case errors.
Mean square error
1.06
Mean square or one sigma error.
:i
SS/L-TR01363 Draft Final Version
A-5
45M/TR01363/Part3/test or disclosurt
o_ tht
_ta
cont_,_
on this skttt
is s._tct
to tht
fish'S:lion
_
t_
tit_. _,_.
$F_,_7
Bent Pipe with Back-off Signal to Noise Ratio Measurement
m
Comments
Source of Error Transmit power variations across frequency band
1.50
Uplink transmit power variations with frequency are approximately _+1.5dB.
Transmit power variations over temperature
0.50
Typically +_2dB from -40°C to 50°0. Time of day correction removes all but the worst case day to day temperature variation at constant time-of-day which is approximately _--K).5 dB/10°C.
J
i
H
Accuracy of uplink compensation
1.00
If signal is not regenerated on the satellite then uplink fading must be compensated for at the transmit station. Downlink C/N and BER will be affected by residual fade.
.=,.
Satellite motion
0.33
Received signal power fluctuations caused by satellite motion are more significant for narrow beam antennas. _+0.05° satellite orientation error produces _+0.33dB signal level variation at receive terminal in 0.3 ° beam.
m
Satellite gain variations across frequency band
0.50
Gain variations across the transponder do not affect (C/N)up but (C/N)down is affected. Apply half of the typical error for a link with (C/N)up = (C/N)down.
Satellite gain variations at a fixed frequency
0.50
Thermal gain variations of the transponder do not affect (C/N)up but (C/N)down is affected. Apply half of the typical error for a link with (C/N)up = (C/N)down.
m
m m
== b
Downlink propagation effects
0.31
Propagation effects are dominated by frequency scaling of gaseous absorption.
LNA gain fluctuations
0.00
LNA gain variations affect signal and noise equally.
Fade measurement accuracy
0.10
For Eb/No > 5 dB, 95% confidence interval is 0.1 dB.
RSS error
2.05
Square root of the sum of the worst case errors.
Mean square error
1.03
Mean square or one sigma error.
lmm,aJ_!
_
LD I..
A-6
SS/L-TR01363 Draft Final Version 45M/'I'R01363/Pad3/-gFj97
Use or disclosure of the data contained
on this sheet is subject to the restriction on the title yage.
.lk.=
Bent Pipe with Saturated Transponder Low Cost Beacon Receiver Residual Source of Error
Error, [_+dB]
Comments
Beacon power fluctuations at receive terminal
0.31
Fade estimate errors caused by satellite beacon power and pointing errors are much less than propagation effects. Propagation effects are dominated by frequency scaling of gaseous absorption.
Receive antenna pointing errors and efficiency variations
0.90
Dominated by inaccurate frequency scaling of feed window wetting.
Receive gain fluctuations
1.00
Residual error will be related to the worst case day-today temperature change at a constant time of day.
Beacon power level measurement accuracy
0.75
Expensive beacon receivers can provide _-+0.25dB accuracy. Accuracy of low cost receiver is estimated to be _+0.75dB.
RSS Error
1.57
Mean square error
0.79
,
Degradation estimate accuracy
i
,
Worst case values above are interpreted as two sigma values. Error is less than value 95% of time.
_+1.25 dB
Beacon receiver measures fading on path while comparison is performed on accuracy of degradation estimate. Terminal must assume system and sky noise temperature and calculate degradation from fade measurement.
SS/L-TR01363 Draft Final Version
m_
LDl b¢ l,.
A-7
45MfT'R01363/Patt3/-gra_7 Use or disclosure
of the data
contained
an this
sh_t
is subject
to the
restriction
on the
title
page.
u
Bent Pipe with Saturated Transponder Automatic Gain Control Signal Measurement
Im
Residual Source of Error
Error, [_+dB]
Comments
Transmit power variations across frequency band
0.15
Uplink transmit power variations with frequency of _+1.5dB will be reduced to approximately _-K).15dB in saturated transponder.
Transmit power variations over temperature
0.05
Uplink transmit power variations with temperature of _+0.5dB will be reduced to approximately _-K).05dB in saturated transponder.
Accuracy of uplink compensation
0.10
..
Uplink compensation errors of _+1.0dB will be reduced to approximately _.1 dB in saturated transponder. n.
Satellite motion
0.33
Received signal power fluctuations caused by satellite motion are more significant for narrow beam antennas. _+0.05° satellite orientation error produces _--*-0.33 dB signal level variation at receive terminal in 0.3 ° beam.
Satellite gain variations across frequency band
0.50
Gain variations across the transponder do not affect (C/N)up but (C/N)down is affected. Apply half of the typical error for a link with (C/N)up = (C/N)down.
Satellite gain variations at a fixed frequency
0.50
Thermal gain variations of the transponder do not affect (C/N)up but (C/N)down is affected. Apply half of the typical error for a link with (C/N)up = (C/N)down.
Downlink propagation effects
0.31
Propagation effects are dominated by frequency scaling of gaseous absorption.
LNA gain fluctuations
1.00
LNA gain variations affect signal and noise equally.
RSS of worst case errors
1.32
Error is less than this value 95% of the time.
RSS error
0.66
RMS error or one sigma error.
Mean square error in fade estimate
0.95
[Eb/No] clear-sky =9 dB
Mean square error in degradation estimate
2.17
Fade =5-+1.5 dB, Tin=280 -+10, Ts=230-+10
,,in
_
i,l.,.
SS/L-TR01363 Draft Final Version
15"Yu"rl_l_lS
A-8
45M/TRo Use or disclosure
_f the
data contained
on this
shert
is subject
to the restriction
on the title
page.
1363/Part3/-_-_J7
t
u m
!il
m
w
Bent Pipe with Saturated Transponder Pseudo-Bit Error Rate Source of Error
r
•
N
Comments
Transmit power variations across frequency band
0.15
Uplink transmit power variations with frequency of +1.5 dB will be reduced to approximately :L-0.15dB in saturated transponder.
Transmit power variations over temperature
0.05
Uplink transmit power variations with temperature of _+0.5dB will be reduced to approximately _+0.05 dB in saturated transponder.
Accuracy of uplink compensation
0.10
Uplink compensation errors of _+1.0dB will be reduced to approximately _-_+0.1 dB in saturated transponder.
Satellite motion
0.33
Received signal power fluctuations caused by satellite motion are more significant for narrow beam antennas. _+0.05° satellite orientation error produces _+0.33 dB signal level variation at receive terminal in 0.3 ° beam.
Satellite gain variations across frequency band
0.50
Gain variations across the transponder do not affect (C/N)up but (C/N)down is affected. Apply half of the typical error for a link with (C/N)up = (C/N)down.
Satellite gain variations at a fixed frequency
0.50
Gain variations across the transponder do not affect (C/N)up but (C/N)down is affected. Apply half of the typical error for a link with (C/N)up = (C/N)down.
Downlink propagation effects
0.31
Propagation effects are dominated by frequency scaling of gaseous absorption.
LNA gain fluctuations
0.00
LNA gain variations affect signal and noise equally.
Fade measurement accuracy
0.50
Channel BER=O.01,95%
RSS error
0.99
Square root of the sum of the worst case errors.
Mean square error
0.50
Mean square or one sigma error.
"
confidence interval is 0.3 dB.
g'V_a'rlm_qEi
LI:31" B£ I..
L
SS/L-TR01363 Draft Final Version
A--9
45M/TR01363/Patt3/-_J97 Use or disclosure of the daLa c_ntained
on this sh_
is subject to the restrlction
on the title paSe.
Bent Pipe with Saturated Transponder Bit Error Rate Measurement m
on Channel Coded Data Source of Error
Comments m
Transmit power variations across frequency band
0.15
Uplink transmit power variations with frequency of _+1.5dB will be reduced to approximately _+0.15 dB in saturated transponder.
Transmit power variations over temperature
0.05
Uplink transmit power variations with temperature of _+0.5dB will be reduced to approximately _+0.05dB in saturated transponder.
BIB
Accuracy of uplink compensation
0.10
Uplink compensation errors of _+1.0dB will be reduced to approximately _+0.1dB in saturated transponder.
IBIB
Satellite motion
0.33
Received signal power fluctuations caused by satellite motion are more significant for narrow beam antennas. _-_-+0.05 ° satellite orientation error produces -+0.33 dB signal level variation at receive terminal in 0.3 ° beam.
Satellite gain variations across frequency band
0.50
Gain variations across the transponder do not affect (C/N)up but (C/N)down is affected. Apply half of the typical error for a link with (C/N)up = (C/N)down.
Satellite gain variations at a fixed frequency
0.50
Gain variations across the transponder do not affect (C/N)up but (C/N)down is affected. Apply half of the typical error for a link with (C/N)up = (C/N)down.
Downlink propagation effects
0.31
Propagation effects are dominated by frequency scaling of gaseous absorption.
LNA gain fluctuations
0.00
LNA gain variations affect signal and noise equally.
Fade measurement accuracy
0.30
Channel BER=5E-4, 95% confidence interval is 0.3 dB.
RSS error
0.91
Square root of the sum of the worst case errors. ,,
Mean square error
0.46
m
U
I
:
c
m
Mean square or one sigma error.
w
A-10
SS/L-TR01363 Draft Final Version 45M/TR013_art3/-9_g7
Use or disclosure o/the _,,
c_tained on this sheetis subject to therestriction on tile title pa_e.
I
Bent Pipe with Saturated Transponder Bit Error Rate Measurement from Known Data Pattern Source of Error
Comments
Transmit power variations across frequency band
0.15
Uplink transmit power variations with frequency of +1.5 dB will be reduced to approximately _+0.15dB in saturated transponder.
Transmit power variations over temperature
0.05
Uplink transmit power variations with temperature of _+0.5dB will be reduced to approximately _-_+0.05 dB in i saturated transponder.
Accuracy of uplink compensation
0.10
Uplink compensation errors of +_1.0dB will be reduced to approximately _-+0.1dB in saturated transponder.
Satellite motion
0.33
Received signal power fluctuations caused by satellite motion are more significant for narrow beam antennas. +-0.05° satellite orientation error produces _-*-0.33dB signal level variation at receive terminal in 0.3 ° beam.
Satellite gain variations across frequency band
0.50
Gain variations across the transponder do not affect (C/N)up but (C/N)down is affected. Apply half of the typical error for a link with (C/N)up -- (C/N)down.
Satellite gain variations at a fixed frequency
0.50
Gain variations across the transponder do not affect (C/N)up but (C/N)down is affected. Apply half of the typical error for a link with (C/N)up = (C/N)down.
Downlink propagation effects
0.31
Propagation effects are dominated by frequency scaling of gaseous absorption.
LNA gain fluctuations
0.00
LNA gain variations'affect signal and noise equally.
Fade measurement accuracy
0.50
Channel BER=0.01, 95% confidence interval is +-0.5 dB.
Total Error
0.99
Square root of the sum of the worst case errors.
Mean square error
0.50
Mean square or one sigma error.
"_= ....
r__
L_ L
w
m
w
m
I.DI= .I L
A-11
SS/L-TR01363 Draft Final Version 45M/TR01363,_Pa
Use or disclosure _f tl_ ,_ta con_aln_
_'Itl_ sheet issu_ect to _he testricfion on _he riflepage.
rt 3/- 9r--_97
Bent Pipe with Saturated Transponder Signal to Noise Ratio Measurement Source of Error
Comments
m I
Transmit power variations across frequency band
0.15
Uplink transmit power variations with frequency of +_1.5dB will be reduced to approximately +-0,15 dB in saturated transponder.
Transmit power variations over temperature
0.05
Uplink transmit power variations with temperature of __+0.5 dB will be reduced to approximately _-K),07dB in saturated transponder.
.=
Accuracy of uplink compensation
0,10
Uplink compensation errors of +_1.0dB will be reduced to approximately _-+O.1dB in saturated transponder.
U
Satellite motion
0.33
Received signal power fluctuations caused by satellite motion are more significant for narrow beam antennas. _-+0.05 ° satellite orientation error produces _-+0.33dB signal level variation at receive terminal in 0.3 ° beam.
i
n i=
n ill
U
Satellite gain variations across frequency band
0.50
Gain variations across the transponder do not affect (C/N)up but (C/N)down is affected. Apply half of the typical error for a link with (C/N)up = (C/N)down.
i
Satellite gain variations at a fixed frequency
0.50
Gain variations across the transponder do not affect (C/N)up but (C/N)down is affected. Apply half of the typical error for a link with (C/N)up = (C/N)down.
U
Downlink propagation effects
0.31
Propagation effects are dominated by frequency scaling of gaseous absorption.
N m
LNA gain fluctuations
0.00
LNA gain variations affect signal and noise equally.
0.10
For Eb/No > 5 dB, 95% confidence interval is 0.1 dB.
RSS error
0.87
Square root of the sum of the worst case errors.
Mean square error
0.43
Mean square or one sigma error.
w
Fade measurement
accuracy
m
m
_
Q'Ytn"l_lm
LDREJC L
A-12
SS/L-TR01363 Draft Final Version 45M/TR01363/Part
Use ordisclosure oft_ _ta conralned on thisskeetissubject totherestri_ti_ on thetizle pa_.
3/-gFoB7
On-board Processing Low Cost Beacon Receiver Residual Source of Error
Error, [_+dB]
Comments
Beacon power fluctuations at receive terminal
0.31
Fade estimate errors caused by satellite beacon power and pointing errors are much less than propagation effects. Propagation effects are dominated by frequency scaling of gaseous absorption.
Receive antenna pointing errors and efficiency variations
0.90
Dominated by inaccurate frequency scaling of feed window wetting.
Receive gain fluctuations
1.00
Residual error will be related to the worst case day-today temperature change at a constant time of day.
Beacon power level measurement accuracy
0.75
Expensive beacon receivers can provide _-+0.25dB accuracy. Accuracy of low cost receiver is estimated to be -+0.75 dB.
RSS Error
1.57
Worst case values above are interpreted as two sigma values. Error is less than value 95% of time.
Mean square error
0.79
w
Degradation estimate accuracy
_+1.25dB
w
Beacon receiver measures fading on path while comparison is performed on accuracy of degradation estimate. Terminal must assume system and sky noise temperature and calculate degradation from fade measurement.
w
m
SS/L-TR01363 Draft Final Version
A-13 L__
45 M/TR01363/Pa
w Use or disclosure
of the data
contained
on this
sheet
is su_ect
to the restrictio_
on the
title
page.
rt3/- 9,5_'/
On-board Processing Automatic Gain Control Signal Measurement
m
Residual Source of Error
Error, [_+dB]
Comments
Transmit power variations across frequency band
0.00
Uplink transmit power variations will not affect downlink power.
Transmit power variations over temperature
0.00
Uplink transmit power variations will not affect downlink power.
Accuracy of uplink compensation
0.00
Uplink compensation errors will not affect downlink power.
Satellite motion
0.33
Received signal power fluctuations caused by satellite motion are more significant for narrow beam antennas. _+0.05° satellite orientation error produces _-H3.33dB signal level variation at receive terminal in 0.3 ° beam.
m
Satellite gain variations across frequency band
0.50
Satellite gain variations at a fixed frequency
0.50
Downlink propagation effects
0.31
Propagation effects are dominated by frequency scaling of gaseous absorption.
LNA gain fluctuations
1.00
LNA gain variations affect signal and noise equally.
RSS of worst case errors
1.31
Error is less than this value 95% of the time.
RSS error
0.65
RMS error or one sigma error.
Mean square error in fade estimate
0.95
[Eb/No] clear-sky =9 dB
Mean square error in degradation estimate
2.17
Fade =?__.1.5dB, Tm=280 __.10,Ts=230!-_10
LIl31 =C L
Gain variations across the transponder do not affect (C/N)up but (C/N)down is affected. Apply half of the typical error for a link with (C/N)up = (C/N)down. Thermal gain variations of the transponder do not affect (C/N)up but (C/N)down is affected. Apply half of the typical error for a link with (C/N)up = (C/N)down.
SS/L-TR01363 Draft Final Version
A-14
45 M/TRO 1363/Pa rt3/'-_Vg"/ Use or disclosure
of the data contained on this sheet is subject to the restriction
on th_ title page.
m
U
m
m
U
On-board Processing Pseudo-Bit Error Rate Source of Error
w
Comments
Transmit power variations across frequency band
0.15
Uplink transmit power variations with frequency of _+1.5dB will be reduced to approximately _+0.15dB in saturated transponder.
Transmit power variations over temperature
0.05
Uplink transmit power variations with temperature of _+0.5dB will be reduced to approximately _+0.05 dB in saturated transponder.
Accuracy of uplink compensation
0.10
Uplink compensation errors of _+1.0dB will be reduced to approximately _+0.1dB in saturated transponder.
Satellite motion
0.33
Received signal power fluctuations caused by satellite motion are more significant for narrow beam antennas. _--H).05 ° satellite orientation error produces _-+0.33dB signal level variation at receive terminal in 0.30 beam.
Satellite gain variations across frequency band
0.50
Gain variations across the transponder do not affect (C/N)up but (C/N)down is affected. Apply half of the typical error for a link with (C/N)up = (C/N)down.
Satellite gain variations at a fixed frequency
0.50
Gain variations across the transponder do not affect (C/N)up but (C/N)down is affected. Apply half of the typical error for a link with (C/N)up -- (C/N)down.
Downlink propagation effects
0.31
Propagation effects are dominated by frequency scaling of gaseous absorption.
LNA gain fluctuations
0.00
LNA gain variations affect signal and noise equally.
Fade measurement accuracy
0.50
Channel BER=0.01, 95% confidence interval is 0.3 dB.
RSS error
0.99
Square root of the sum of the worst case errors.
Mean square error
0.50
Mean square or one sigma error.
w
w
-.==_
w m_
LC:IIRM L
SS/L-TR01363 Draft Final Version
A-15
w
45 M/I'_ Use
or disclosure
of the data
contained
on
this sheet
is su_ect
to the
restriction
on
the title
page.
01363JPa
rt 3/- _'/
On-board Processing Bit Error Rate Measurement ii
on Channel Coded Data Source of Error
Comments
Transmit power variations across frequency band
0.00
Uplink transmit power variations will not affect downlink power.
Transmit power variations over temperature
0.00
Uplink transmit power variations will not affect downlink power.
Accuracy of uplink compensation
0.00
Uplink compensation errors will not affect downlink power.
Satellite motion
0.33
Received signal power fluctuations caused by satellite motion are more significant for narrow beam antennas. _+0.05° satellite orientation error produces _--H).33 dB signal level variation at receive terminal in 0.3 ° beam.
ill
Ill
il
Satellite gain variations frequency band Satellite gain variations fixed frequency
across
at a
0.50
0.50
Gain variations across the transponder do not affect (C/N)up but (C/N)down is affected. Apply half of the typical error for a link with (C/N)up = (C/N)down. Gain variations across the transponder do not affect (C/N)up but (C/N)down is affected. Apply half of the typical error for a link with (C/N)up = (C/N)down.
Downlink propagation effects
0.31
Propagation effects are dominated by frequency scaling of gaseous absorption.
LNA gain fluctuations
0.00
LNA gain variations affect signal and noise equally.
Fade measurement accuracy
0.30
Channel BER=5E-4, 95% confidence interval is 0.3 dB.
RSS error
0.89
Square root of the sum of the worst case errors.
Mean square error
0.45
Mean square or one sigma error.
lira
im
llll
U
N_
A-16
SS/L-TR01363 Draft Final Version 45 M/'fR01363/P
Use or disclosure _ the data contained
on this sheet is subject to the restriction on the title page.
a rt 3/- 9r.J97
On-board Processing Bit Error Rate Measurement from Known Data Pattern Comments
Source of Error
w
Transmit power variations across frequency band
0.00
Uplink transmit power variations will not affect downlink power.
Transmit power variations over temperature
0.00
Uplink transmit power variations will not affect downlink power.
Accuracy of uplink compensation
0.00
Uplink compensation errors will not affect downlink power.
Satellite motion
0.33
Received signal power fluctuations caused by satellite motion are more significant for narrow beam antennas. _+0.05° satellite orientation error produces _-_+0.33 dB signal level variation at receive terminal in 0.3 ° beam.
Satellite gain variations across frequency band
0.50
Gain variations across the transponder do not affect (C/N)up but (C/N)down is affected. Apply half of the typical error for a link with (C/N)up = (C/N)down.
Satellite gain variations at a fixed frequency
0.50
Gain variations across the transponder do not affect (C/N)up but (C/N)down is affected. Apply half of the typical error for a link with (C/N)up = (C/N)down.
Downlink propagation effects
0.31
Propagation effects are dominated by frequency scaling of gaseous absorption.
LNA gain fluctuations
0.00
LNA gain variations affect signal and noise equally.
Fade measurement accuracy
0.50
Channel BER=0.01,95%
Total Error
0.98
Square root of the sum of the worst case errors.
Mean square error
0.49
Mean square or one sigma error.
w
=
1.,
confidence interval is _+0.5dB.
m_
I-1:31=J./ L
A-17
SS/L-TR01363 Draft Final Version 45M,'TRO1363/Part3/-9FJ97
Use or disclosure of thedata c_ntained on this sheetis subject to the restriction on the title page.
iil
On-board Processing Signal to Noise Ratio Measurement
m Comments
Source of Error Transmit power variations across frequency band
0.00
Uplink transmit power variations will not affect downlink power.
Transmit power variations over temperature
0.00
Uplink transmit power variations will not affect downlink power.
Accuracy of uplink compensation
0.00
Uplink compensation errors will not affect downlink power.
Satellite motion
0.33
Received signal power fluctuations caused by satellite motion are more significant for narrow beam antennas. _--H).05 ° satellite orientation error produces _--K).33 dB signal level variation at receive terminal in 0.3 ° beam.
m
I
Ill
m
Satellite gain variations across frequency band
0.50
Gain variations across the transponder do not affect (C/N)up but (C/N)down is affected.
Satellite gain variations at a fixed frequency
0.50
Gain variations across the transponder do not affect (C/N)up but (C/N)down is affected. Apply half of the typical error for a link with (C/N)up = (C/N)down.
Downlink propagation effects
0.31
Propagation effects are dominated by frequency scaling of gaseous absorption. Apply half of the typical error for a link with (C/N)up = (C/N)down.
LNA gain fluctuations
0.00
LNA gain variations affect signal and noise equally.
Fade measurement accuracy
0.10
For Eb/No > 5 dB, 95% confidence
RSS error
0.85
Square root of the sum of the worst case errors.
Mean square error
0.42
Mean square or one sigma error.
II
I
m
interval is 0.1 dB. Ill
m
m
i
_
SS/L-TR01363 Draft Final Version
B'Y'B'IrlmMa
LD L
A-18
45M/r'R01363/Part3/Use or disclosure of the data contained
on this sheet is subject to the restriction
on the title page.
9Fu/97
I
APPENDIX
Hexagonal
array
hexagonal
array
area is about
B -- HEXAGONAL ARRAY NUMEROLOGY AREA FOR CIRCULAR ELEMENTS
numerology of circular
array
19, 37, 61, 91, 127,
the
number k=l
expressed
The
n=7,
as a function
the
hexagonal
hexagonal where The
active
horn
apertures,
total
area
areas
between
a
of the
i
the
feed
k=3
for
be inscribed of the
feed
array
array
feed
feed w
n_n_, for regular
of active
hexagonal
on a principal
diagonal
area
area
of a
to total
diagonal
fill areas of the
are 7,
hexagonal
= 2k+1
n=37,
etc.
within
the
The
diameter
circle.
of an individual
feed
is equal
With
active
Each
this
nomenclature,
n may
be
horns)
(1/2)
- 3 (one-sixth
D h D h cos(30
0.16125
(Dh/2)
the
area
plus
the area,
with area
such
circle
that
no
is equal
part
of the
to (2k+1)
[= 6(1+(k-1)/2)k
of a single
feed
area
by
taken
horn all
Ai, is obtained
vertices of a single
°) - (3/6)_(Dh/2)
2 = 0.0513275_
of this
of all of then
interstitial
triangle
circle
D h,
horn.
2 is the area
such
of an equilateral
smallest
to the area
A h = _(Dh/2) is the
horns.
(area
=
that the ratio
active
+ 1
or nA h, where
of the
of the
of k as:
diameter
area
of elements, of elements
for n=19,
is outside
D h is the
numbers number
fill area
area
calculation
It is determined
on principal
k=2
n = 6(1+(k-1)/2)k
Let
by
as:
of elements
for
horns.
followed
arrays. total
etc.
can be defined
where
feed
0.91 for large
In a hexagonal area
is presented
AND ACTIVE
horn
aperture.
of the
The
interstitial
as follows:
at the centers feed
+ 1] feed
of three
adjacent
aperture)
2
(Dh/2)
2
L
It is easy a functional i
=
to count
the
number
relationship
with
of interstitial k.
The
result
areas, of this
i_,for each effort
hexagonal
array
and
establish
is:
= 6k 2
=
SS/L-TR01363 Draft Final Version
B-1 r_
45 M/I"R01363/Pa Use or disclosure
of the
data
contained
on this
sheet
is subject
to the
restriction
on
the
title
page.
rt3/- _-J97
The ratio
Ra/t of active
Ra/t
=
area
(active
to total
area of a hexagonal
area) / [(active
area)
array
+ (interstitial
is then
given
by:
area)] U
h +
6k2Ai]
=
nAh/[nA
=
n_(Dh/2)2/[n_(Dh/2)
=
[6(l+(k-1)/2)k
=
[3k 2 + 3k + 1]/[3.308k
b.--
2 + 6k 2 0.0513275 + 1]/[6(1+(k-1)/2)k
_(Dh/2)
2]
g
+ 1 + 6k 2 (0.0513275)]
2 + 3k + 1] m
Values
for Ra/t are given
To obtain the
an array
diameter
wavelengths,
of the
in Table
with the
1323 array
diameter
I
B-1.
active
elements,
is 43
feed
may
the value
horns.
For
of k should
be about
any
feed-horn
given
21.
Therefore, spacing,
in
be calculated. I
For example,
if horn
spacing
is 2.6 wavelengths
at 19.2 GHz,
the array
diameter
is given
by: []
array
diameter
= 43 x 2.6 (11.785/19.2) = 68.6
m
inches
inches m
u
LD_L
SS/L-TR01363 Draft Final Version
B-2
45M/'FR01363/Part Use
or disclosure
of the
data
contained
on this
sheet
is subject
to the
restriction
on
the title
page.
3/- _-,J37
w
Table
B-1.
Table
of Values
of ILa/t for
k=1,2,
..., 6
n (number regular
of feeds
hexagonal
Ra/t in
(number
grid
array)
of interstices
within hexagonal
611+(k-1)/2]k+1
(ratio of active
area
to total area of
regular
array)*
grid array) 6k 2
0
1
0
1
1
7
6
0.9579
2
19
24
0.9391
3
37
54
0.9303
4
61
96
0.9253
5
91
150
0.9220
6
127
216
0.9197
7
169
282
0.9180
8
217
384
0.9167
9
271
486
0.9157
10
331
600
0.9149
11
397
726
0.9142
12
469
864
0.9136
13
547
1014
0.9131
14
631
1176
0.9127
15
721
1350
0.9123
16
817
1536
0.9120
17
919
1734
0.9117
18
1027
1944
0.9114
19
1141
2166
0.9112
20
1261
2400
0.9110
21
1387
2646
0.9108
22
1519
2904
0.9106
23
1657
3174
0.9105
24
1801
3456
0.9103
25
1951
3750
0.9102
m
Ra_ = [3k 2 + 3k + 1]/[3.308k 2 + 3k + 1]
w
SS/L-TR01363 Draft Final Version
B-3
45MfTR01363JPart3/Use
or disclosure
of the
data contained
on this
sheet
is subject
to the restriction
on the
title
page.
9F_7
=,.,=.
in
I
i i
If
i
I
i
I
I
I I
•
w
w
qjuf
LF_
U E_ L_
U
w
w
z
im
m
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REPORT
DOCUMENTATION
PAGE
FormApproved OMB
Public
reporting
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for this
collection
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aws r.gnway, butte 12o4, /_l=ngton,v_ 1. AGENCY
USE ONLY
information
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is Ostimeted
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to average
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1 hour
zo wa.snlngton
per
response,
inclu_ng
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time
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utrectorate
for
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In fi_tetlorl
No. 0704-0188 searching
Operations
and
existing
Reports,
data
1215
sources,
Jefferson
ZZZtZZ'43orx,and tO me unee o= Management and Budget. Paperwork Reduction Project (0704-0188), Washington. DC 20503.
(Leave blank)
2. HEPORT
DATE
3. REPORT
TYPE
December 1997
4. roLE ANDSUB'ffr'L/_
AND DATES
COVERED
Final Coal]actor Report S. FUNDING
NUMBERS
Rain Fade Compensation for Ka-Band Communications Satellites 6.
WU-315-90-2C NAS3-27559
AUTHOR(S)
W. Carl Mitchell, Lan Nguyen, Asoka Dissanayake, and Brian Markey 7. PERFORMING
ORGANIZATION
NAME(S)
AND ADDRESS(ES)
8. PERFORMING ORGANIZATION REPORT NUMBER
r
Space Systems/LORAL 3825 Fabian Way Palo Alto, California 94303--4604 9.
SPONSORING/MONIT()RING
_.GENCY
E-11024
NAME(S)
AND ADDRESS(ES)
10.
National Aeronautics and Space Administration Lewis Research Center Cleveland, Ohio 44135-3191 11.
SUPPLEMENTARY
SPONSORING/MONITORING AGENCY REPORT NUMBER
NASACR_97-206591 SS/LTR01363
NOTES
W. Carl Mitchell, Space Systems/Loral, 3825 Fabian Way, Palo Alto, California 94303-4606; Lan Nguyen, Asoka Dissanayake, and Brian Markey, COMSAT Laboratories, Clarksburg, Maryland. Project Manager, Clifford H. Arth, Space Communications Office, NASA Lewis Research Center, organization code, (216) 433-3460. =
,
12a.
DISTRIBUTION/AVAILABILITY
STATEMENT
12b.
DISTRIBUTION
CODE
Unclassified - Unlimited Subject Category: 17 This
publication
13. ABSTRACT • z
is available
(Mexlmum
Distribution: from
the NASA
Center
for AeroSpace
Information,
Nonstandard (301)
621-0390.1
200 words)
This report provides a review and evaluation of rain fade measurement and compensation techniques for Ka-band satellite systems. This report includes a description of and cost estimates for performing three rain fade measurement and compensation experiments. The first experiment deals with rain fade measurement techniques while the second one covers the rain fade compensation techniques. The third experiment addresses a feedback flow control technique for the ABR service (for ATM-based traffic). The following conclusions were observed in this report; a sufficient system signal margin should be allocated for all carriers in a network, that is a fixed clear-sky margin should be typically in the range of 4-5 dB and should be more like 15 dB in the up link for moderate and heavy rain zones; to obtain a higher system margin it is desirable to combine the uplink power control technique with the technique that implements the source information rate and FEC code rate changes resulting in a 4-5 dB increase in the dynamic part of the system margin. The experiments would assess the feasibility of the fade measurements and compensation techniques, and ABR feedback control technique.
J
I7
=
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14.
SUBJECT
TERMS
lS.
NUMBER
16.
PRICE
OF PAGES
== =
ACTS; Rain fade;Ka-band; Satellites 17. SECU_T'f CLASSIFICATION OF REPORT
Unclassified NSN L.
7540-01-280-5500
18. SECURITY CLASSIFICATION OF THIS PAGE
Unclassified
CODE
A08 19. SECURITY CLASSIFICATION OF ABSTRACT
20.
MMrrATION
OF ABSTRACT
Unclassified Standard Form 298 (Rev. 2-89) Prescribed by ANSI Std. Z39-18 298-102
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