Low Complexity Near Optimal Multiuser Detection Scheme for SDMA-OFDM System

SDMA (Space-Division Multiple Access) is a MIMO (Multiple-Input and Multiple-Output) based wireless communication network architecture which has the potential to significantly increase the spectral efficiency and system performance. So far several multiuser detection (MUD) schemes like Zero Forcing (ZF), Minimum Mean Square Error estimation (MMSE), ordered successive interference cancellation (OSIC) and maximum likelihood (ML) detection have been proposed by various researchers. Among them, maximum likelihood (ML) detection scheme provides the minimum bit error rate (BER). However, the complexity of ML detection increases exponentially with the constellation size of modulation and number of users. The M-algorithm combined with QR decomposition (QRD-M) can be substitute to ML detection due its low complexity and it´s near optimal performance. In this paper the complexity of QRD-M scheme is compared with ML by means of number of foundational operations and the elapsed time.