Performance of FFH-GMSK signals with CSDD scheme in frequency-selective Rayleigh channels with CCI

A fast frequency hopping (FFH) spread spectrum technique (SS) using Gaussian minimum shift keying (GMSK) signals for data modulation and a centre sampling differential detector (CSDD) in restricted bandwidth (BW) Rayleigh channels is analyzed. The performance of the proposed system is analyzed in a two-path Rayleigh fading channel taking into account frequency-selective fading (FSF), 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 there is a significant improvement in the error rate performance by utilizing the frequency diversity inherent in the FFH system compared to other systems. Therefore, this system can accommodate more users than the others and a better spectrum efficiency can be achieved.