BER improvement of CSDD scheme in frequency-selective Rayleigh channels with CCI using an efficient decision feedback technique

The effect of an efficient decision feedback (EDF) technique proposed to improve the bit error rate (BER) of Gaussian minimum shift keying (GMSK) signals with a centre sampling differential detector (CSDD) in restricted bandwidth (BW) Rayleigh channels is studied. The performance of the CSDD scheme is analyzed in a two-path Rayleigh fading channel taking into account frequency-selective, carrier random frequency shift, intersymbol interference (ISI), Doppler frequency shift, cochannel interference (CCI) and additive white Gaussian noise (AWGN), while the receiver (RX) rejects a specified amount of adjacent channel interference (ACI). For the interference, we adopt a model which includes N statistically independent faded CCI. It is shown that the CSDD scheme is sensitive to frequency offset and the ISI is partially eliminated by using the conventional decision feedback (CDF) technique. In the present modification the ISI is drastically eliminated by using the EDF technique resulting in the minimization of probability of error. Numerical results show that the RX structure under consideration yields a superior performance in narrow band channels where the conventional differential detector (CDD) becomes unusable