Differential detection of PSK signals in frequency selective Rayleigh fading channel

The error performance of differential detection of phase shift keyed (PSK) signals in a 2-ray frequency selective Rayleigh fading channel with additive white Gaussian noise is discussed. Unlike in a one-ray or flat fading channel, there exists an irreducible error floor even with static fading. In the worst case, this error floor is actually proportional to the inverse power split ratio among the two arrival rays. The results presented indicate that at a received signal-to-noise ratio of 25 dB and a target bit error rate of not more than 10^-2 (speech application), uncoded differential PSK (DPSK) will work well even under equal power split, provided that the relative propagation delay in two arrival rays does not exist one-fifth of a symbol duration. For channels with larger relative delays. DPSK will fail to provide the desired bit error rate, unless the signal power is increased, or more importantly, the channels exhibit highly asymmetrical power split. Simulation results for coded binary PSK with differential detection are also included