Modeling and simulation of land mobile satellite propagation

SUMMARY MODELING AND SIMULATION OF LAND MOBILE SATELLITE PROPAGATION Land-Mobile Satellite Systems (LMSS) offer more economical mobile communication services relative to terrestrial radio systems such as cellular and private mobile radio. In reali2ation of mobile satellite communication, the most important problem is occurance of fading depth (F) due to tree shadowing and multipath propagation effects. As the system is power-limited, F is a very critical factor in link design processes. In this work, a new approach is indroduced to LMSS propagation model in order to determine fading depth. For this purpose, during a period of six months in 1993, L-band propagation measurements were made for 14 different types of trees. The average tree attenuation is found to be 11 dB. On the other hand, rician and rayleigh propagation factors are about 15 dB. Using these measured parameters, a propagation model has been designed and this model has been adapted to Eastern Black Sea Region of Turkey. For this region the probability of the received signal to exceed -26 dB relative to the direct component is found to be 99 % In this case, fading depth (F) is determined as 26 dB for the region. Because of high density of trees and increasing urbanization, fading depth is considered to be the highest in Eastern Black Sea Region. As a result, as far as the LMSS is concerned, this region has the worst propagations conditions in Turkey. Key Words: Land Mobile Satellite System, satellite link design, tree attenuation, multipath propagation, fading, fading depth, propagation measurements, propagation model. VII