Analysis of CQI Prediction for MU-MIMO in LTE Systems
The aim of this paper is to get an insight of Multi-User Multiple-Input and Multiple-Output (MU-MIMO) Channel Quality Indicator (CQI) prediction for Long Term Evolution (LTE) systems. MU-MIMO CQI predictions have been investigated for LTE Release 8 (rank one, Transmission Mode 5) and for LTE Release 9 (adaptive rank, Transmission Mode 8) at the link level. The relationship between CQI reporting and channel conditions is analytically analyzed and demonstrated. The tradeoff between the performance gain and the feedback overhead w.r.t. MUMIMO CQI prediction is investigated as well. The results have shown how MU-MIMO CQI prediction is influenced by channel correlation and that significant improvements can be achieved through rank adaption and receiver choice.