An equicorrelation-based multiuser communication (ECBMC) scheme for direct-sequence code-division multiple-access (DS-CDMA) systems is presented. The ECBMC receiver has low computational complexity that is comparable to that of the conventional detector. By using the equality of cross correlations, the ECBMC scheme can completely eliminate multiple-access interference (MAI) in a synchronous single-path DS-CDMA network. The system performance is independent of the number of active users. The scheme is extended to include the effects of multipath fading. It is able to suppress a major portion of the MAI. This proposed ECBMC scheme is quite attractive for an MAI-dominant environment.

This paper presents a multiuser detection scheme based on cell diversity for DS/CDMA systems. This scheme may be employed when multiple base stations can receive the signal from a mobile. Each participating base station uses a decorrelator to remove multiple access interference and obtains the decision statistic for each user. It then quantizes the decision statistic and transmits it to a central processor. Based on these received quantized cell decision statistics, the central processor determines the received bit for each user. The quantizer proposed here is a MMSE log likelihood ratio quantizer, and is obtained via a Lloyd-Max type of algorithm. The decision-making rule at the central processor is derived based on multisensor signal detection theory. Numerical results show that significant performance improvement over single cell multiuser detection can be obtained at a moderate cost in terms of additional signal processing and communication bandwidth.