Multi-User MIMO Systems Using Semi-Orthogonal Space Division Multiplexing with Alamouti Code

In this paper, a multi-user multiple input multiple output (MIMO) system using semi-orthogonal space division multiplexing (semi-OSDM) and single-user QR-triangular detection with Alamouti code is studied. In this proposed semi-OSDM with STBC system, the transmit signals for each user are grouped into pairs and separately coded by using the standard Alamouti space-time code, while QR decomposition is used to make the signaling streams triangular so that the serial interference cancellation (SIC) can be utilized to maintain an accurate signal detection at the receiver. The bit error rate (BER) performance of the proposed semi-OSDM with STBC system outperforms the orthogonal space division multiplexing (OSDM) system as well as the semi-OSDM system, while exploiting a reduced complexity and stability when the correlation of the channel changes. Moreover, it largely reduces the complexity of the receivers.