π/4-DQPSK on microcellular radio channels with diversity and interference

A analyze the average bit error rate (BER) performance of π/4-shifted differential quadrature phase shift keying (π/4-DQPSK) in the presence of multiple independent cochannel interferers in frequency-nonselective fading environments. Nyquist shaped pulses are used and postdetection diversity combining is employed at the receiver. The use of both L-branch postdetection equal gain combining (EGC) and L-branch postdetection selection combining (SC) are considered. Two approaches for representing the cochannel interference are investigated. These are a Gaussian interference model and a synchronous interference model. The accuracies of both of these models are assessed by comparing their BER performances with precise BER results. The precise BER results are obtained by using a combination of analysis and simulation