Practical MU-MIMO experiments using SDRs

This paper provides an overview of a testbed created using software defined radios (SDRs) for a Multi-User MIMO experiment, with guidelines for extension for similar experiments. We perform our experiments in ORBIT grid with multiple USRPs. The proposed experiment can be easily recreated using multiple USRPs and Octoclock-G to achieve synchronization among those. One of the main issues while working with multiple transmitters and receivers is synchronization. A technique to achieve the required synchronization on the ORBIT grid is described. A framework for estimating Channel State Information (CSI) across multiple receivers is provided. The various factors affecting the data such as the proximity of the users to one another, being in the line-of-sight of the transmitter, are addressed.