Performance analysis of bandlimited DS-CDMA systems in Nakagami fading

Accurate performance analysis of asynchronous bandlimited binary DS-CDMA systems in Nakagami-m fading is considered. The fading is assumed to be flat and slow. The spectrum raised-cosine and Beaulieu-Tan-Damen pulse shapes are employed. A new accurate approximation for computing the bit error rate of bandlimited DS-CDMA systems employing random spreading sequences is proposed. A substantial computational complexity reduction is achieved. The well-known standard Gaussian approximation, Holtzman´s simplified improved Gaussian approximation, and the improved Holtzman´s Gaussian approximation are also considered. The accuracies of the approximations are assessed using Monte-Carlo simulation. For a system employing a deterministic sequence for the desired user and random sequences for the active interfering users, a characteristic function method is employed to derive exact BER results. The new Beaulieu-Tan-Damen pulse outperforms the spectrum raised-cosine pulse in all situations examined.