Performance study of two optimal detectors of asynchronous CDMA systems

To date, most available CDMA systems are interference limited. Although many schemes have been proposed to reduce the effects of interferences, few of them are based on optimal criteria. The maximum likelihood sequence detector (MLSD) is one of the few detectors that is optimal. However, it has a complexity growing exponentially with the number of users, and is not implementable for many practical applications. This paper shows that, as long as the number of users in the system is kept moderate, the performance of the MLSD can be approached by a simple linear detector that is based on an optimal estimator.