Performance Analysis of 49-QPRS Through Nonlinear Satellite Channels in the Presence of Gaussian Noise and Cochannel Interference

Abstract

This paper is concerned with the analytical performance analysis and evaluation of 49-ary Quadrature Partial Response Signaling when transmitted through nonlinear satellite channel in the presence of Additive White Gaussian Noise and Co-channel Interference ; in both uplink and downlink channels. The main source of the nonlinearities is the Traveling Wave Tube Amplifier on-board of the satellite. The transponder nonlinearities considered in this paper are due to : input amplitude-to-output amplitude conversion and input amplitude-to-output phase conversion. The cochannel interference results from interferers in the passband of the coherent ,receiver. The results in terms of the dependence of the average symbol error probability upon the uplink and downlink , signal-to-noise ratio's and Signal-to cochannel interference signal ratio's at different values of Back-Off from saturation operation of the Traveling Wave Tube Amplifier on-board of the satellite are illustrated. The results showed that the Back•Off value is the dominant factor in determining the system performance .The appropriate values of the threshold levels ; d"s and compensation phases ; W's at the receiver are highly correlated and can only be arrived at by minimizing the average symbol error probability .