Performance Analysis of Optimum Diversity Combining for Partially Coherent Frequency-Selective Fading Channel With Intersymbol Interference

The performance of coherent BPSK and QPSK systems in the presence of frequency-selective fading and carrier phase errors is analyzed. Frequency-selective fading channels are modeled as multipath Rayleigh, Nakagami- m, or Rician two-ray fading models wherein the presence of a delayed ray causes intersymbol interference (ISI). A diversity system with L-branches is used for signal detection using an optimum equal-gain-combining receiver. The effect of ISI on system performance is assessed using a truncated pulse train of the ISI signal. For Rayleigh-faded channels, the simulation result that demonstrates the influence of Doppler spread on system performance was also included. The following two performance criteria are considered: the average bit error probability and the signal-to-noise-ratio (SNR) gain penalty due to ISI.