1. Evaluating Time Diversity Performance on an On-Board Processing Satellite in Earth Station Downlink. Kufre Udofia & Ifiok Otung, ICRC, Faculty of Advanced Technology University of Glamorgan, Pontypridd CF37 1DL, Wales. United Kingdom (kmudofia@glam.ac.uk). 1 29/08/2015 12:24:1429/08/2015 12:24:14

2. Content Outline Introduction FMT TD Evaluation, Results and Analyses Discussions and Conclusions References Questions 229/08/2015 12:24:14

3. Introduction Fade Mitigation Technique FMT is a reliable and robust way of overcoming fading in real-time Increase development for high data rate multimedia services Congestion of conventional bands X, C and Ku Improve link performance Implementation necessary at Ka and V –bands 329/08/2015 12:24:14

4. Types of FMT 29/08/2015 12:24:144 Power Control Frequency Diversity Spatial/Site Diversity Time Diversity Satellite Diversity Antenna Diversity Signal Processing Adaptive Coding

5. Time Diversity (TD) Re-sending of signal until channel status allows it to pass through 529/08/2015 12:24:14

6. 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)

7. Problem Definition Evaluating 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 Bands Larger bandwidths and cost efficiency Reduced co-ordination problems due to decreased wavelength Propagation impairments are very prominent 29/08/2015 12:24:15

8. 8 Effects of Propagation Impairments Rain attenuation, melting layer, cloud, attenuation, tropospheric scintillation, depolarisation due to rain and ice Propagation Impairments Factors Fading, signal attenuation, increase in the sky noise temperature and intersystem interference 29/08/2015 12:24:15

9. Block View of the Link 9 Sparsholt is about 7.8Km from Chilbolton 29/08/2015 12:24:15

10. Analysis of Time Series of Sites 10 Rain attenuation time series for three UK sites measured at 20.7GHz on November 11, 2005. 29/08/2015 12:24:15 Earth location, separation distances, frequency and satellite earth link

11. 29/08/2015 12:24:1511 Cumulative distributions of measured rain attenuation for Chilbolton compared with the ITU-R 618v9 (predicted) model at 20.7 GHz with an elevation angle of 30 .

12. 29/08/2015 12:24:1512 Cumulative distributions of measured rain attenuation for Sparsholt compared with the ITU- R 618v9 (predicted) model at 20.7 GHz with an elevation angle of 30 .

13. 29/08/2015 12:24:1513 Cumulative distributions of measured rain attenuation for Dundee compared with the ITU-R 618v9 (predicted) model at 20.7 GHz with an elevation angle of 30 .

14. 29/08/2015 12:24:1514 Cumulative distributions for three sites measured at 20.7 GHz and the scaled distribution at 30 GHz at 30  elevation angle.

15. Evaluation, Results and Analyses Time diversity gain, time percentage, time delay Cumulative 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 delay For retransmission, the time shift per sample 1529/08/2015 12:24:15

16. Evaluation and Analyses (contd.) The pdf of the observed rain attenuation series for a satellite to earth link is given by 16 From a model for TD by Ismail & Watson developed for equatorial climate, a joint distribution is deduced to This is the percentage time exceeded for an effective or minimal attenuation, and is described by the function 29/08/2015 12:24:15

17. Effective attenuation, is the minimum of the two instantaneous attenuation values with time delay 17 Evaluation and Analyses (contd.) The gain is a function of delays and time percentages 29/08/2015 12:24:15

18. 18 Time diversity statistics at Chilbolton. This denotes gains achieved with outage probabilities at varying time delays

19. 29/08/2015 12:24:1519 Time diversity statistics at Sparsholt. This denotes gains achieved with outage probabilities at varying time delays

20. 29/08/2015 12:24:1520 Time diversity statistics at Dundee. This denotes gains achieved with outage probabilities at varying time delays

21. Discussions and Conclusions Relevant 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 services Electronic data broadcasting and file transfers 2129/08/2015 12:24:15

22. Discussions and Conclusions Access to the internet and data base E-commerce and re-mote teaching access such as the Open University TD as a fade mitigation scheme for broadcast satellite systems TD gain is a function of time delay and the time percentages The 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. 2229/08/2015 12:24:15

23. References 1. 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. 2329/08/2015 12:24:15

24. References 5. 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. 2429/08/2015 12:24:15

25. Thank you Questions Please