volume | PIER Journals

Abstract

This study builds on the earlier work by Odedina and Afullo on Multipath fading in Durban. Their work was based on multipath measurements in Durban over a 6.73 km Line-of-Sight (LOS) link. This submission uses the geoclimatic factor approach and ITU-R recommendations P530-14 to obtain the multipath fading occurrence in five cities in South Africa, including Durban. Three-year radiosonde data is used in estimating the percentage of time that a certain fade depth is exceeded and hence outage probability due to atmospheric multipath propagation, assuming the given fade depth leads to the received signal falling below the squelch level. We employ the Inverse Distance Square technique to estimate point refractivity gradient not exceeded for 1% of the time in the lowest 65 m above the ground for five locations within South Africa. Standard error of the mean and confidence interval for both annual averages and seasonal averages of point refractivity gradient is calculated to reflect possible deviation in the given readings. These values of point refractivity gradient obtained are used in determining the geoclimatic factor K. The results presented show monthly, seasonal and annual variation of both point refractivity gradient and geoclimatic factor K. The results confirm that the geoclimatic factor K is region based. The percentage of time a given fade depth is exceeded for a single frequency increases rapidly with increasing path length. This is due to the fact that as the path length increases so do the multiple reflections leading to multipath propagation, which can result in either signal enhancement or multipath fading. A comparison of fade depth and outage probabilities is made with the earlier work in Durban and Rwanda in Central Africa.

1. Grabner, M., V. Kvicera, P. Pechac, and M. Mudroch, "Multipath fading measurement and prediction on 10 GHz terrestrial link," Proceedings of IEEE 15th Conference of Microwave Techniques, 2010. Google Scholar

2. Bogucki, J. and E. Wielowieyska, "Empirical season's fading's in radio communication at 6 GHz band," Journal of Telecommunications and Information Technology, Vol. 2, 48-52, 2009. Google Scholar

3. ITU-R "Propagation data and prediction methods required for the design of terrestrial line-of-sight systems," Recommendation of ITU-R P.530-14, Geneva, 2012. Google Scholar

4. Olsen, R. L., T. Tjelta, L. Martin, and B. Segal, "Worldwide techniques for predicting the multipath fading distribution on terrestrial LOS links: Comparison with regional techniques," IEEE Transactions on Antennas and Propagation, Vol. 51, No. 1, January 2003. Google Scholar

5. Olsen, R. L. and T. Tjelta, "Worldwide techniques for predicting the multipath fading distribution on terrestrial LOS links: Background and results of tests," IEEE Transactions on Antennas and Propagation, Vol. 47, No. 1, January 1999. Google Scholar

6. Odedina, P. K. and T. J. Afullo, "Clear air signal level measurements for microwave line-of-sight link application in South Africa," SAIEE Transactions, Vol. 101, No. 4, 132-139, December 2010. Google Scholar

7. Adediji, A. T. and M. O. Ajewole, "Vertical profile of radio refractivity gradient in Akure, south-west Nigeria," Progress In Electromagnetic Research C, Vol. 4, 157-168, 2008. Google Scholar

8. Tjelta, T., et al. "Correlation of observed multipath occurrence with climatic parameters derived from radiosondes, surface stations, and numerical models," CLIMPARA, 85-92, Ottawa, Canada, April 27-29, 1998. Google Scholar

9., http://www.sa-venues.com/no/weather.htm. Google Scholar

10. Fashuyi, M. O., "A study of rain attenuation on terrestrial paths at millimetric wavelengths in South Africa," Ms.c. Thesis, University of KwaZulu-Natal, 2006. Google Scholar

11. Fashuyi, M. O., P. A. Owolawi, and T. J. O. Afullo, "Rainfall rate modelling for LOS radio systems in South Africa," Transactions of South African Institute of Electrical Engineers (SAIEE), Vol. 97, No. 1, 74-81, March 2006. Google Scholar

12., http://www.bdb.co.za/kimberley/climate.htm. Google Scholar

13. Lystad, S. L., et al. "Interpolation of clear air parameters observed at non-regular observation locations," CLIMPARA, 15-26, Ottawa, Canada, April 27-29, 1998. Google Scholar

14. Li, J. and A. D. Heap, A Review of Spatial Interpolation Methods for Environmental Scientists, 137, Geoscience Australia, Record 2008/23, ISBN 978-1-921498-282.

15. Freeman, R. L., Radio System Design for Telecommunications, John Wiley & Sons, 1997, ISBN 978-0-471-75713-9.

16. Odedina, P. K. and T. J. Afullo, "Use of spatial interpolation technique for determination of geoclimatic factor and fade depth calculation in Southern Africa," Proceedings of IEEE AFRICON Conference, Windhoek, Namibia, September 26-28, 2007. Google Scholar

17. Abu-Alman, A. and K. Al-Ansari, "Calculation of effective earth radius and point refractivity gradient in UAE," International Journal of Antennas and Propagation, Vol. 2010, 1-4, doi. 10.1155/2010/245070. Google Scholar

18. Odedina, P. K. and T. J. Afullo, "Estimation of secondary radioclimatic variables and its application to terrestrial LOS link design in Southern Africa," Proceedings of IEEE AFRICON Conference, Wild Coast Sun, South Africa, September 7-10, 2008. Google Scholar

19. Al-Ansari, K. and R. A. Kamel, "Correlation between ground refractivity and refractivity gradient and their statistical and worst month distribution in Abu Dhabi," IEEE Antennas and Wireless Propagation Letters, Vol. 2, 233-235, 2008. Google Scholar

20. ITU-R "The radio refractivity index: Its formula and refractivity data," Recommendation of ITU-R P.453-9, Geneva, Switzerland, 2003. Google Scholar

21. Dabideen, A. S., M. Gopichund, and T. J. Afullo, "Radio refractivity distribution and duct and fading occurrence measurements in kwazulu-natal," Transactions of South African Institute of Electrical Engineers (SAIEE), Vol. 96, No. 2, 121-132, June 2005. Google Scholar

22. Odedina, P. K. and T. J. Afullo, "Multipath propagation modeling and measurement in a clear-air environment for LOS link design application," Southern Africa Telecommunication Networks and Applications Conference Proceedings, Ezulwini Swazi, Royal Spa, Swaziland, August 31-September 2, 2009. Google Scholar

23. Djuma, S., "Clear-air microwave signal prediction on terrestrial paths in Central Africa using existing models,", Ms.c. Thesis, National University of Rwanda, September 2012. Google Scholar

Mr. Mike Omondi Asiyo

Prof. Thomas Joachim Odhiambo Afullo