Hybrid QRM-MLD-MMSE with SIC Adaptive Multiuser Detection for SDMA-OFDM Systems

The multiuser detection (MUD) at the receiver end of the Space Division Multiple Access aided Orthogonal Frequency Division Multiplexing (SDMA-OFDM) systems is very crucial for receiver design technologies. Due to the detailed search mechanism, the maximum likelihood (ML) MUD that provides optimal performance is limited to a dramatically increased computational complexity. The QR decomposition with M-algorithm maximum likelihood detection (QRM-MLD) MUD reduces the computational complexity compare with the computational complexity of ML MUD. The minimum mean squared error (MMSE) MUD with low complexity exhibit poor performance. MMSE-successive interference cancellation (SIC) MUD with almost the same complexity provides better bit error rate (BER) performance than linear MMSE MUD. In this paper, Hybrid QRM-MLD-MMSE with SIC adaptive multiuser detection has been proposed for signal detection. The simulation results show that the proposed method significantly reduces the complexity of the system and controls the BER performance of the system at the desired level.