Performance Analysis of Large Centralized and Distributed MU-MIMO Systems in Indoor WLAN

Large MIMO systems are recognized as an effective technique of increasing the spectral and energy efficiency of wireless networks. The attractiveness of this technique for WLAN is that it can be an alternative approach to the densification of access points (APs) for providing high data rate wireless access and at the same time can potentially eliminate both the intra- and inter-cell interference problem in contrast to traditional networks. Here we consider large MIMO systems in indoor WLANs for multi-user MIMO (MU-MIMO) spatial multiplexing in the 2.4 GHz ISM band. The focus is on analyzing the behaviors of large MIMO systems with both centralized and distributed antenna system (CAS and DAS) architectures, especially highlighting the viability of achieving the optimum capacity performance using simple linear precoding techniques relying on large antenna arrays. The numerical results show that the optimum capacity can be closely approached with both CAS and DAS architectures when the number of AP antennas exceeds the users a few times. DAS is however found to be superior to CAS in that the required number of antennas is significantly smaller, and especially performs better in non-rich scattering channels.