Performance of residue number system based DS‐CDMA over multipath fading channels using orthogonal sequences

Abstract

AbstractThis paper is concerned with a new direct‐sequence spread‐spectrum multiple‐access communication system based on the so‐called residue number system (RNS) or redundant residue number system (RRNS). The system operates in a multi‐path fading environment, and a RAKE receiver structure with maximum ratio combining is used for demodulation. Approximations to the error probabilities are given by using Gaussian statistics for the multiple‐access and the multipath interference. Concatenated codes employing residue number system product codes (RNS‐PC) as the inner codes and nonbinary Reed‐Solomon (RS) codes as the outer codes are adopted to improve the system performance. The performance of the system is determined for a range of different length RNS‐PC schemes. The results show that, for a given outer RS code and a given number of moduli of the inner RNS‐PC, the performance of the system can be optimized by varying the relative number of information moduli and redundant moduli of the inner RNS‐PC and the moduli's values.