S-BAND LMS PROPAGATION CHANNEL BEHAVIOR FOR DIFFERENT ENVIRONMENTS, DEGREES OF SHADOWING AND ELEVATION ANGLES

Experimental Land Mobile Satellite (LMS) propagation data have been pr ocessed in order to characterise the behaviour Of this channel under n arrow-band transmission conditions for difficult environments, degrees of shadowing and elevation angles. Measurements were carried out at S -band. The transmitter was located on a small plane flying parallel to the road with elevations ranging from 40 degrees to 80 degrees For th e analysis of the received amplitude series, they were classified, for each environment and elevation angle into three different States acco rding to the degree of shadowing experienced. This was done in order t o develop a Markov chain based propagation simulator [1]. The global ( slow + fast) signal variations within each State are modelled using th e Loo distribution (Rice + Log-Normal) [2]. Average distribution param eter values for each State, elevation angle and environment type are r eported. Also average State probabilities, slow variations' correlatio n lengths and other parameters are presented. Finally, a software impl ementation is described based on a Markov chain + Loo distribution mod el that is capable of reproducing the complex envelope variations in t he received signal due to shadowing and multipath.