A Trace-Orthogonal Multi-User Space-Time Coding

In this paper, we propose a trace-orthogonal space-time coding (TD-STC) for multi-user systems. Based on the flexibility of linear dispersive codes (LDC), we apply it to broadcast channels in multi-user systems. According to the transmission rates of user's, we adaptively construct the transmitting space-time coding matrix. At the same time, we give the design criterion of the space time coding for multi-user systems. At the receiver, exploiting the characteristic of trace orthogonal, the complexity of decoder based on MMSE criterion will not increase apparently. Compared with orthogonal space-time coding (OSTC), our proposed TD-STC can greatly decrease the complexity of ML decoding instead of little performance loss. When in the lower SNP, the proposed scheme is better than the scheme when applying orthogonal space-time coding.