Asymptotic Analysis of Subspace Blind Multiuser Detection with Blind Channel Estimation

The analytical performance of the subspace-based blind linear MMSE multiuser detection algorithm in general multipath multi-antenna CDMA systems is investigated. In blind multiuser detection, the linear MMSE detector of a given user is estimated from the received signals, based on the knowledge of only the spreading sequence of that user. Typically, the channel of that user must be estimated first based on the orthogonality between the signal and noise subspaces. An asymptotic limit theorem for the estimate of the blind linear detector (when the received signal sample size is large) is obtained, based on which approximate expressions of the average output SINR’s and BER’s for both BPSK and QPSK modulations are given. Examples are provided to demonstrate the excellent match between the theory developed in this paper and the simulations results.