A combined analytical model on the bit error performance of a DS-CDMA wireless communication system in presence of Doppler shift, timing error and frequency offset

In this paper a composite analytical model of DS-CDMA wireless communication system considering multipath Nakagami fading along with Doppler frequency shift, tracking jitter, local oscillator frequency offset and multi-access interference (MAI) for different PN sequences is presented. The analysis presents the development of a novel approach to find the pdf (probability density function) of the signal to interference plus noise ratio (SINR) at the output of Rake receiver considering combined influence of fading, timing jitter and Doppler frequency offset etc with maximal ratio combining (MRC) scheme. Performance results are evaluated in terms of average bit error rate (BER) at the output of MRC receiver by averaging the conditional BER over the pdf of SINR. The results are presented in term of BER for Gold and m-sequence codes and different system parameters. Analysis shows that increasing independent multipath detection ability of rake receiver improves SINR performance and mitigates the effect of Doppler frequency shift.