Zero-forcing based multi-user MIMO coordinated with user-wise joint transmit-receive diversity

Multi-user MIMO multiplexing and spatial diversity are indispensable techniques to improve the link capacity in a fading environment. In this paper, user-wise joint transmit-receive diversity (JTRD) is proposed for zero-forcing (ZF)-based multi-user MIMO. Two types of user-wise JTRD are considered and the design of ZF precoder/postcoder, which takes into account the role of JTRD, is presented. The achievable received signal-to-noise ratio (SNR) is analyzed and a simple but useful expression for the received SNR is derived for a 2-user case. The link capacity achievable by ZF-based multi-user MIMO coordinated with user-wise JTRD in an uncorrelated Rayleigh fading environment is evaluated by Monte-Carlo numerical computation and is compared with ZF-based multi-user MIMO coordinated with user-wise maximal-ratio transmitting and combining diversity (MRTCD).