Abstract
A simple, exact expression for the probability distribution of differential phase noise is derived for calculating the average bit error rate (BER) of M-ary DPSK in frequency selective Rician fading. The irreducible BER due to multipath delay spread is evaluated for M = 2–16 assuming a double-spike delay profile of the Rayleigh faded diffused component and a spectrally raised cosine Nyquist filter response.