Equal-gain combining of multichannel DPSK in Doppler-spread Ricean fading

A method for computing the bit error probability (BEP) of multichannel differentially coherent phase-shift keying (DPSK) with equal gain combining in Doppler spread Ricean fading is given. It is based on Gauss-Chebyshev quadrature integration of the moment generating function of the decision statistic at the combiner output. The method allows nonuniform power delay profiles for the received multipath rays. Applications to multicarrier spread spectrum modulation and spread spectrum with RAKE reception systems are discussed. It is found that for moderate values of the Ricean K-factor (ratio of specular to diffuse fading signal power) an optimum order of diversity exists whereas, for large K-factors, diversity does not improve performance.