Exploiting Opportunistic Multiuser Detection in Decentralized Multiuser MIMO Systems

This paper studies the design of a decentralized multiuser MIMO system for spectrum sharing over a fixed bandwidth, where the coexisting users independently update their transmit covariance matrices for individual rate maximization via an iterative manner. This design problem was usually investigated in the literature by assuming that each user treats the co-channel interference from all the other users as additional noise at its receiver, i.e., the conventional single-user decoding (SUD) for the MIMO channel is applied. In this paper, we propose a new decoding method for the decentralized multiuser MIMO system, whereby each user opportunistically cancels the co-channel interference from some or all of the other users via applying multiuser detection techniques, thus named opportunistic multiuser detection (OMD). This paper studies the optimal transmit covariance matrix for each user to iteratively maximize transmit rate with the proposed OMD, and shows the resultant capacity gains over the conventional SUD.