A Reed-Solomon coded DS-CDMA system using noncoherent M-aryorthogonal modulation over multipath fading channels

摘要

The performance of Reed-Solomon (RS) coded direct-sequence codendivision multiple-access (DS-CDMA) systems using noncoherent M-arynorthogonal modulation is investigated over multipath Rayleigh fadingnchannels. Diversity reception techniques with equal gain combining (EGC)nor selection combining (SC) are invoked and the related performance isnevaluated for both uncoded and coded DS-CDMA systems.n“Errors-and-erasures” decoding is considered, where thenerasures are based on Viterbi's (1982) so-called ratio threshold testn(RTT). The probability density functions (PDF) of the ratio associatednwith the RTT conditioned on both the correct detection and erroneousndetection of the M-ary signals are derived. These PDFs are then used forncomputing the codeword decoding error probability of the RS codednDS-CDMA system using “errors-and-erasures” decoding.nFurthermore, the performance of the “errors-and-erasures”ndecoding technique employing the RTT is compared to that ofn“error-correction-only” decoding refraining from usingnside-information over multipath Rayleigh fading channels. As expected,nthe numerical results show that when usingn“errors-and-erasures” decoding, RS codes of a given codenrate can achieve a higher coding gain than without erasure information