On the performance of phase-shift-keying systems

An analytical procedure is developed for multiphase, M-ary Coherent Phase Shift Keying (CPSK) by means of which the detection efficiency of the system when it is subject to additive Gaussian noise, intersymbol interference (ISI), and imperfect carrier-phase estimation can be determined. A simple formula is given for the case of a large SNR which calculates the combined penalty due to ISI and noisy phase recovery. A rigorous method is developed for calculating the error rate, in the presence of ISI and additive Gaussian noise, for the inherently nonlinear case of multiphase Differential Phase-Shift Keying (DPSK) detection. Using these analytical techniques, it is possible to compare the performance of CPSK and DPSK and examine various parameter trade-offs. Numerical examples are given to illustrate the methods presented.