Performance bounds for decorrelator detectors in a QS-CDMA system

A linear decorrelator detector is considered for use in a quasi-synchronous code-division multiple access (QS-CDMA) system. A QS-CDMA communication system is considered in which decorrelators are employed for multiuser detection at the base station. For long code lengths, the evaluation of bit-error rate can be computationally expensive, due to the need for exhaustive search to determine the worst case relative delays. An upper bound on the error rate based on eigenvalue bounds is presented for the linear decorrelator detector, and which can be computed solely in terms of the maximum cross-correlation between codes and the number of users.