Coded PSK signals over a nonlinear channel in a TDMA environment

The paper studies an improved scheme of a digital modem that transmits a convolutionally encoded eight-phase-shift keyed (C8PSK) signal over a nonlinear satellite channel in a TDMA environment. The results of computer simulation tests showing the effects of band-limiting, nonlinear distortion introduced by the HPA and the detection process at the receiver on the tolerance of the modem to AWGN are presented. The study also shows the performance improvements gained by using a baseband linearizer at the input to the modulator with HPA characteristics, and with different levels of output backoff in the HPA at the transmitter.