Fast link adaptation for opportunistic multiuser MIMO-OFDM wireless networks

This paper presents a practical scheme to exploit opportunistic multiuser multiple-input multiple-output (MU-MIMO) diversity in multicarrier systems using orthogonal frequency division multiplexing. The scheme is based on a multi-carrier user selection algorithm to schedule the users that should transmit simultaneously and a fast link adaptation (FLA) technique that, in light of the instantaneous channel state information (CSI), determines the most appropriate transmission parameters for each user. Numerical results based on parameters typically used in modern wireless local area networks (WLANs) show that, when compared to an opportunistic TDMA scheme, the proposed system can improve the system throughput performance by a factor proportional to the number of transmit antennas.