Achieving high data rates in a distributed MIMO system

Abstract

A distributed MIMO system consists of several access points connected to a central server and operating as a large distributed multi-antenna access point. In theory, such a system enjoys all the significant performance gains of a traditional MIMO system, and it may be deployed in an enterprise WiFi like setup. In this paper, we investigate the efficiency of such a system in practice. Specifically, we build upon our prior work on developing a distributed MIMO testbed, and study the performance of such a system when both full channel state information is available to the transmitters and when no channel state information is available. In the full channel state information scenario, we implement Zero-Forcing Beamforming (ZFBF) and Tomlinson-Harashima Precoding (THP) which is provably near-optimal in high SNR conditions. In the scenario where no channel information is available, we implement Blind Interference Alignment (BIA), which achieves a higher multiplexing gain (degrees of freedom) than conventional TDMA. Our experimental results show that the performance of our implementation is very close to the theoretically predicted performance and offers significant gains over optimal TDMA. We also discuss medium access layer issues in detail for both scenarios. To the best of our knowledge, this is the first time that the theoretical high data rates of multiuser MIMO systems have been showcased in a real world distributed MIMO testbed.