Performance analysis of bandlimited DS-CDMA systems with diversity receivers over Nakagami fading channels

The average bit error rate of an asynchronous bandlimited binary DS-CDMA system with three diversity combining receiver schemes over Nakagami-m fading channels is studied. Maximal ratio combining, predetection equal gain combining and predetection selection combining are considered. Random spreading and flat slow fading are assumed. The spectrum raised cosine and Beaulieu-Tan-Damen pulse shapes are employed. The standard Gaussian approximation for the multiple access interference is used for the performance analysis giving a closed-form expression for the BER of maximal ratio combining. Characteristic function and approximate Fourier series methods are used for the performance analysis of equal gain and selection combining schemes, respectively. Our results are valid for arbitrary diversity orders and arbitrary Nakagami fading parameters. The Beaulieu-Tan-Damen pulse outperforms the spectrum raised-cosine pulse in all situations considered.