Sum-rate performance of large centralized and distributed MU-MIMO systems in indoor WLAN

Large MIMO systems are recognized as an effective technique for 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 cell densification for providing high data rate wireless access. 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) ar-chitectures. The analysis is based on extensive ray-tracing channel simulations, as well as an i.i.d. Rayleigh model. The numerical re-sults show that the optimum capacity can be closely approached with both CAS and DAS architectures when the number of Access Point (AP) antennas exceeds the users by a few times. DAS is found to be superior to CAS in that the required number of an-tennas is significantly smaller, and especially performs better in non-rich scattering channels which is the case of practical chan-nels reflected by ray-tracing simulations.