Performance of parallel combinatorial CDMA systems with side information

Abstract

This paper investigates the effects of using error-and-erasure decoding in coded parallel combinatorial spread spectrum (PC/SS) systems over Rayleigh fading channels. The PC/SS system is an advanced multi-code direct sequence spread spectrum system for high-speed data transmission. Our previous works have shown that the Reed-Solomon (RS) coded PC/SS systems provide significant improvement in error rate performance over conventional DS/SS systems. To achieve further performance improvement in the PC/SS systems, error-and-erasure decoding techniques are implemented in the RS coded PC/SS receiver. To obtain the erasure location information, a threshold for the signal-to-noise ratio is set at the correlator output. Numerical results show that the coded PC/SS systems with error-and-erasure decoding provides significant improvement in the bit error rate (BER). With errors-only decoding, the PC/SS systems cannot improve the error rate performance because of large SNR penalty introduced by coding. On the contrary, error-and erasure decoding still improves the performance of PC/SS systems under multiple access environment.