Linear detectors for multi-user MIMO systems with correlated spatial diversity

A multiuser CDMA system with both the transmitting and the receiving sites equipped with multiple antenna elements is considered. The multiuser MIMO channel is correlated at the transmitting and the receiving sites. Multistage detectors achieving near-linear MMSE performance with a complexity order per bit linear in the number of users are proposed. The large system performance is analyzed in a general framework including any multiuser detector that admits a multistage representation. The performance of this large class of detectors is independent of the channel correlation at the transmitters. It depends on the direction of the channel gain vector of the user of interest if the channel gains are correlated.