M-ary continuous phase frequency shift keying transmissions through nonlinear channels in additive Gaussian noise and cochannel interferences

The problem of evaluating the performance of M-ary continuous-phase frequency shift keying (CPFSK) signals transmitted through an arbitrary bandpass nonlinearity (BPNL) in the presence of additive Gaussian noise (AGN) and cochannel interference (CCI) is considered. The proposed nonlinear channels are two-link satellite channels. The satellite system consists of a ground transmitter, a satellite repeater, and a ground receiver. The system is evaluated according to the symbol error probability (SEP), taking into consideration the up and down link Gaussian noise, nonlinear characteristics (AM-AM and AM-PM) of the traveling-wave-tube amplifier, and CCI in the uplink before the nonlinearity. The technique used in calculating SEPs yields an expression for any level of M=2 (M is an integer) for CPFSK transmission with signal-to-noise ratios as parameters. SEPs are derived for the binary, quaternary, octernary, and duoocternary CPFSK signals. Although this model is not as efficient as the CPSK model in power or in bandwidth, it is easier in terms of generating the transmitted signals, and it is simpler in the receiver design