Impact of Feedback and User Pairing Schemes on Receiver Performance in MU-MIMO LTE Systems

This paper addresses the problem of feedback design for MU-MIMO (multi-user multiple input multiple output) transmission in 3GPP Long Term Evolution (LTE) systems. The CSI (channel state information)-based feedback introduced in the latest release of LTE, Rel-10 is adopted in MU-MIMO transmission and potential performance gains are demonstrated over Rel-8 CQI/PMI (channel quality indicator/precoding matrix indicator)-based feedback mechanism at the link level. The LTE downlink performance has been evaluated for various MU-MIMO feedback schemes and for low complexity receivers. The results have shown that the CSI-based feedback can make a significant tradeoff between receiver performance and complexity in MU-MIMO therewith reducing the design requirements for advanced receiver concepts.