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Evaluating Time Diversity Evaluating Time Diversity Performance on an On-Performance on an On-
Board Processing Satellite Board Processing Satellite in Earth Station Downlink.in Earth Station Downlink.
Kufre Udofia & Ifiok Otung, Kufre Udofia & Ifiok Otung, ICRC, Faculty of Advanced TechnologyICRC, Faculty of Advanced Technology
University of Glamorgan,University of Glamorgan,Pontypridd CF37 1DL, Wales. United KingdomPontypridd CF37 1DL, Wales. United Kingdom
([email protected])([email protected]).
121/04/2321/04/23 01:26 AM01:26 AM
Content OutlineContent OutlineIntroductionFMT TDEvaluation, Results and AnalysesDiscussions and ConclusionsReferencesQuestions
221/04/23 01:26 AM
IntroductionIntroductionFade Mitigation TechniqueFMT is a reliable and robust way of
overcoming fading in real-timeIncrease development for high data
rate multimedia servicesCongestion of conventional bands X, C
and KuImprove link performanceImplementation necessary at Ka and V
–bands
321/04/23 01:26 AM
Types of FMTTypes of FMT
21/04/23 01:26 AM 4
Power ControlFrequency DiversitySpatial/Site DiversityTime DiversitySatellite DiversityAntenna DiversitySignal ProcessingAdaptive Coding
Time Diversity (TD)Time Diversity (TD)Re-sending of signal until channel
status allows it to pass through
521/04/23 01:26 AM
SampledTime Series
DelayedTime Series
st min5
st min10
snt min
min1 t
1 to 86400 samples represents seconds
delay
864001 2 3 4 5 6
864001
864001
864001
864001
Based on the idea that events are short-lived
Dependent on the re-transmission delay
More affordable when compared to site diversity and uses a single link unlike others
Provides high quality data rate multimedia services
Provides high quality of service (QoS) and an increase availability.
Able to combat large fading
Time Diversity (TD)Time Diversity (TD)
Problem DefinitionProblem DefinitionEvaluating time diversity performance
on an on-board processing satellite in earth station downlink. A fade mitigation process to combat effects of atmosphere on satellite-earth links at Ka and V bands, a case study is the UK.
7
Properties of Ka BandsProperties of Ka BandsLarger bandwidths and cost efficiencyReduced co-ordination problems due
to decreased wavelengthPropagation impairments are very
prominent 21/04/23 01:26 AM
8
Effects of Propagation Effects of Propagation ImpairmentsImpairments
Rain attenuation, melting layer, cloud, attenuation, tropospheric scintillation, depolarisation due to rain and ice
Propagation Impairments Propagation Impairments FactorsFactors
Fading, signal attenuation, increase in the sky noise temperature and intersystem interference
21/04/23 01:26 AM
Block View of the LinkBlock View of the Link
9
600.2Km
Dundee
Chilbolton
UFO-9 20.7 GHz Beacon Payload
RAIN
Cloud
Aup From Scaled
Frequency
Adown BEACON
Adown From Link
Earth-stations with Beacon Receivers
SignalDirections
Sparsholt is about 7.8Km from Chilbolton21/04/23 01:26 AM
Analysis of Time Series of Analysis of Time Series of SitesSites
10
Rain attenuation time series for three UK sites Rain attenuation time series for three UK sites measured at 20.7GHz on November 11, 2005.measured at 20.7GHz on November 11, 2005.
21/04/23 01:26 AM
0 1 2 3 4 5 6 7 8 9
x 104
-5
0
5Chilbolton
0 1 2 3 4 5 6 7 8 9
x 104
-1
0
1
Att
enuation (
dB
)
Dundee
0 1 2 3 4 5 6 7 8 9
x 104
-5
0
5
Time (seconds)
Sparsholt
Earth location, separation distances, frequency and satellite earth link
21/04/23 01:26 AM 11
Cumulative distributions of measured Cumulative distributions of measured rain attenuation for Chilbolton compared rain attenuation for Chilbolton compared with the ITU-R 618v9 (predicted) model with the ITU-R 618v9 (predicted) model at 20.7 GHz with an elevation angle of at 20.7 GHz with an elevation angle of 3030..
0 5 10 15 20 25 3010
-3
10-2
10-1
100
101
102
Attenuation (dB)
Tim
e A
bsci
ssa
is E
xcee
ded
(%)
Measured
ITU
21/04/23 01:26 AM 12
Cumulative distributions of measured Cumulative distributions of measured rain attenuation for Sparsholt compared rain attenuation for Sparsholt compared with the ITU-R 618v9 (predicted) model with the ITU-R 618v9 (predicted) model at 20.7 GHz with an elevation angle of at 20.7 GHz with an elevation angle of 3030..
0 5 10 15 20 2510
-3
10-2
10-1
100
101
102
Attenuation (dB)
Tim
e A
bsci
ssa
is E
xcee
ded
(%)
Measured
ITU
21/04/23 01:26 AM 13
Cumulative distributions of measured Cumulative distributions of measured rain attenuation for Dundee compared rain attenuation for Dundee compared with the ITU-R 618v9 (predicted) model with the ITU-R 618v9 (predicted) model at 20.7 GHz with an elevation angle of at 20.7 GHz with an elevation angle of 3030..
0 5 10 15 20 2510
-3
10-2
10-1
100
101
102
Attenuation (dB)
Tim
e A
bsci
ssa
is E
xcee
ded
(%)
Measured
ITU
21/04/23 01:26 AM 14
0 2 4 6 8 10 12 14 16 18 2010
-3
10-2
10-1
100
101
102
Attenuation (dB)
Tim
e A
bsci
ssa
is E
xcee
ded
(%)
20.7 GHz Chilbolton
20.7 GHz Sparsholt
20.7 GHz Dundee30 GHz Chilbolton
30 GHz Sparsholt
30 GHz Dundee
Cumulative distributions for three sites Cumulative distributions for three sites measured at 20.7 GHz and the scaled measured at 20.7 GHz and the scaled distribution at 30 GHz at 30distribution at 30 GHz at 30 elevation elevation angle.angle.
Evaluation, Results and Evaluation, Results and AnalysesAnalysesTime diversity gain, time percentage, time
delayCumulative distributions of rain attenuation at
time, t and (t+delay) are considered, based on a simple TD principle – retransmitted signals
Gain increases with increase in the delay and decreases with increase in the time percentage
Improves the fade margin per increased delayFor retransmission, the time shift per sample
15
ttTshift 21/04/23 01:26 AM
Evaluation and Analyses Evaluation and Analyses (contd.)(contd.)The pdf of the observed rain attenuation
series for a satellite to earth link is given by
16
)}({1})({ tApatAp From a model for TD by Ismail &
Watson developed for equatorial climate, a joint distribution is deduced to )}](),([min{1)]([ ttAtAptAAp T
This is the percentage time exceeded for an effective or minimal attenuation, and is described by the function )}(),(min{ ttAtAAA effT
21/04/23 01:26 AM
Effective attenuation, is the minimum of the two instantaneous attenuation values with time delay
17
Evaluation and Analyses Evaluation and Analyses (contd.)(contd.)
)}]1(),1([min{)1( sttAstAstAGTD )()1( tttAstAG TTD
TTD AtAG )(
The gain is a function of delays and time percentages
21/04/23 01:26 AM
21/04/23 01:26 AM 18
Time diversity statistics at Chilbolton. Time diversity statistics at Chilbolton. This denotes gains achieved with outage This denotes gains achieved with outage probabilities at varying time delaysprobabilities at varying time delays
0 2 4 6 8 10 12 14 16 1810
-3
10-2
10-1
100
101
102
Gain (dB)
Tim
e A
bsci
ssa
is E
xcee
ded
(%)
1 mins
5 mins
10 mins
15 mins30 mins
45 mins
60 mins
21/04/23 01:26 AM 19
Time diversity statistics at Sparsholt. Time diversity statistics at Sparsholt. This denotes gains achieved with outage This denotes gains achieved with outage probabilities at varying time delaysprobabilities at varying time delays
0 2 4 6 8 10 12 1410
-3
10-2
10-1
100
101
102
Gain (dB)
Tim
e A
bsci
ssa
is E
xcee
ded
(%)
1 mins5 mins
10 mins
15 mins
30 mins
45 mins60 mins
21/04/23 01:26 AM 20
Time diversity statistics at Dundee. This Time diversity statistics at Dundee. This denotes gains achieved with outage denotes gains achieved with outage probabilities at varying time delaysprobabilities at varying time delays
0 2 4 6 8 10 12 1410
-3
10-2
10-1
100
101
102
Gain (dB)
Tim
e A
bsci
ssa
is E
xcee
ded
(%)
1 mins5 mins
10 mins
15 mins
30 mins
45 mins60 mins
Discussions and Discussions and ConclusionsConclusionsRelevant to communications network
operators and system designers in the UK wishing to offer improved broadband
Relevant to the UK propagation research programme
Improvement of performance for wireless communication systems involving BSS
Video-on-demand servicesElectronic data broadcasting and file
transfers
2121/04/23 01:26 AM
Discussions and Discussions and ConclusionsConclusionsAccess to the internet and data baseE-commerce and re-mote teaching
access such as the Open UniversityTD as a fade mitigation scheme for
broadcast satellite systemsTD gain is a function of time delay and
the time percentagesThe study of TD gain on a single
downlink (OB Satellite to ES) and a subsequent study of a complete link, ES to Satellite to ES will lead to a complete evaluation of TD performance.
2221/04/23 01:26 AM
ReferencesReferences1. Watson, P.A., Ismail, A.F., Seng, P. A., Ja, Y. Y., Kamaruddin, H.
S., Eastment, J. D. & Thurai, M., (1998), ”Investigation of Rain Fading and Possible Countermeasures on Satellite-Earth Links in Tropical climates”, URSI-F Open Symposium, Aviero, Portugal, pp.3-7.
2. Fukuchi, H, (1992), “Slant Path Attenuation Analysis at 20 GHz for Time Diversity Reception of future Satellite Broadcasting”, URSI-F Symposium Colloque, pp.6.5.1-6.5.4, Ravenscar, UK.
3. Ventouras, S., Wrench C. L. & Callaghan, S. A., (2000), “Earth-Space Propagation, Measurement and Analysis of Satellite Beacon Transmissions at Frequencies up to 50GHz, Part 2: Attenuation Statistics and Frequency Scaling of Attenuation Values”, RCRU, CLRC Chilton, UK
4. Emilio Matricciani, (2006), “Time Diversity as a Rain Attenuation Countermeasure in Satellite Links in the 10-100 GHz Frequency Bands,” Department of Electronic and Information, Milan Polytechnic, Milan.
2321/04/23 01:26 AM
ReferencesReferences5. Ismail, A. F. & Watson, P. A., (2000), “Characteristics of
Fading and Fade Countermeasures on a Satellite-Earth Link Operating in an Equatorial Climate, with Reference to Broadcast Applications”, IEE Proc. Microwave, Antenna Propagation, vol.147, No.5, pp.369-373
6. Fabbro, V. and Castanet, L. (2006), “Characterisation and Modeling of Time Diversity in 20-50GHz Band,” Department of Electromagnetism and Radar, Unite of Research APR: Antenna and Radioelectric Propagations, Toulouse, France.
7. Fukuchi, H & Nakayama, T. (2004), “Quantitative Evaluation of Time Diversity as a Novel Attenuation Mitigation Technology for Future High Speed Satellite Communication”, IEICE Trans., vol.E87-B, pp.2119-2123.
8. “Propagation data and prediction methods required for the design of Earth-space telecommunication systems”, Recommendations ITU-R P.618-9, 2007, Geneva, Switzerland.
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Thank youQuestions Please