Performance evaluation of differential pi /4-QPSK systems in a Rayleigh fading/delay spread/CCI/AWGN environment

An experimental study and performance evaluation results are presented of differential pi /4 quadrature phase-shift keying (QPSK) systems ( pi /4-DQPSK) in a Rayleigh fading and delay spread channel corrupted by additive white Gaussian noise (AWGN) and cochannel interference (CCI). The effect of time delay spread and the CCI on the bit error rate (BER) performance and the residual error floor of differential pi /4-QPSK systems is evaluated. The spectral spreading of bandlimited pi /4-QPSK systems due to nonlinear amplification is investigated. The beneficial effect of a hardlimiter in the receiver is investigated. The experimental results show that in a Rayleigh-faded channel, CCI and delay spread have significant impact on the BER performance and the residual error floor of differential pi /4-QPSK systems.<>