Performance analysis of 49-QPRS through nonlinear satellite channel in the presence of additive white Gaussian noise

This paper is concerned with the analytical performance analysis and evaluation of 49-ary quadrature partial response signaling (QPRS) when transmitted through a nonlinear satellite channel in the presence of additive white Gaussian noise (AWGN) in both the uplink and downlink channels. The main source of the nonlinearity is the traveling wave tube amplifier (TWTA) on-board the satellite. The transponder nonlinearities considered in this paper are due to: input amplitude-output amplitude conversion (AM/AM) and input amplitude-output phase conversion (AM/PM). The results are determined in terms of the dependence of average symbol error probability (Pe) upon the uplink and downlink signal-to-noise ratios (SNR) at different values of input back-off (BO) from saturation operation of the TWTA. Finally, the results showed that the appropriate values of the threshold levels and compensation phases at the receiver are highly correlated and can only be arrived at by minimizing the average symbol error probabilities