Bounds on MMSE multiuser detection for CDMA

Minimum-mean-square-error (MMSE) linear multiuser detector considers multiple access interference (MAI) and background noise asymptotically Gaussian for large number of users in asynchronous code division multiple access (CDMA) system. For this asymptotic condition, the available results in literature have been derived for two-user case. In this paper, we have proposed a general formula to calculate upper bound on normalized cross-correlation (NCC) for arbitrary number of users. Under near-far situation, Chernoff upper bound on error probability of MMSE multiuser detector is presented. Its proof based on divergence theorem and study of leakage coefficients imposes minimum bound on signal-to-noise ratio of desired user (SNRD).