Influence of imperfect carrier recovery on satellite QPSK communication system performance

The purpose of this paper is to provide the theoretical approach for determ ining the bit error probability in detecting a coherent quaternary phase-sh ift-keyed signal transmitted over a soft-limited channel in the presence of the uplink and downlink noise, as well as the noisy carrier reference sign al. The uplink noise is considered in the specific way through the envelope variations and the frequency offset of the signal remitted by the satellit e station having influence on the variations of the phase-locked loop param eters in the receiving ground station, consequently on the probability dens ity function of the phase error, i.e. the average bit error probability. Th e downlink noise is also taken into consideration. The determined results a re based on the non-linear phase-locked loop model with primary emphasis on the degradations in the system performance produced by the imperfect carri er signal extraction. Copyright (C) 1994 John Wiley & Sons, Ltd.