Performance analysis of multi chip/data rate DS-CDMA signals over multipath Rayleigh fading channels

Abstract

This paper investigates the Probability error (P e ) performance of Multi-Chip/Data Rate Direct Sequence Code Divisions Multiple Access (MCDR/DS-CDMA) systems over multi-path Rayleigh fading channels. Two chip waveforms, raised cosine (RC) and an orthogonal wavelet, are compared numerically in terms of the Pe. The results represent that the wavelet based system significantly outperforms the RC based system in terms of the P e . On the other hand, the wavelets have greater bandwidths than the RC waveforms. Thus, two systems are also compared in terms of the capacity (the number of users per Hertz) for the same P e level. The results for the capacity show that the wavelet based design has 3% and 41% more capacity than the RC based system for the medium and low rate users, respectively, while the RC based system provides 7% higher capacity than the wavelet based system for high data rate users. Since the average power of wavelets is zero, they can utilize a Single Side Band (SSB) transmission. With the SSB transmission, the wavelet based system has 86%, 106% and 182% more capacity for the high, medium and low data rate users, respectively.