PATH AND SITE DIVERSITY RESTORATION TECHNIQUES FOR OPTIMUM PERFORMANCE OF MULTIMEDIA SATELLITE SERVICES IN A TROPICAL LOCATION

Abstract

Rain attenuation is the major propagation impairment for satellite systems operating at frequencies above 10 GHz. For optimum performance of multimedia satellite services in tropical region with high rainfall rate, an appropriate Fade Mitigation Technique (FMT) must be adopted. Among the FMTs, site and path diversity have been identified to limit the effect of rain fade most especially in the Ku-V band frequencies. In this study, 3 years of rain rate time-series measured by a tipping bucket rain gauges at four different locations within the Federal University of Technology Akure (FUTA), Nigeria Campus were utilized. The experimental sites are; Physics Main Building, Tropospheric Data Acquisition Network (TRODAN) garden and WASCAL building at the University Staff Quarters. Rain attenuation is generated from the result of the micro rain cells over each of the sites using Synthetic Storm Techniques (SST) by converting time-series of rain rate at a specified site into rain attenuation time- series to obtain the diversity gain. The micro scale site diversity is then presented for different site separation at different percentages of service availability for optimum satellite signals performance in the region. It is found that SST derived attenuation is consistent but overestimated in higher frequency bands. The simulated results shows that all the models considered underestimate the site diversity gain. The two models considered for the comparative studies underestimate site diversity gain at all separation distances. Provided all other factors are kept constant, the effects of baseline angle and frequency are found negligible. Apparently, the implementation of site and path diversity as a mitigation technique for the reduction of rain attenuation effect is a function of site separation distance between the diverse stations and elevation angle of the earth-satellite. The results show improved estimation capability of the proposed models at the tropical location.