Residual error based CSI feedback enhancement for downlink multiuser MIMO

In this paper, we consider a downlink (DL) multiuser (MU) multi-input-multi-output (MIMO) channel with linear precoding in advanced cellular systems. We propose a general residual error based channel state information (CSI) feedback framework to improve the MU-MIMO performance. In particular, we propose a simple form of the enhanced feedback, i.e., residual error norm (REN) feedback in addition to the conventional implicit CSI report, in the Long Term Evolution (LTE) cellular systems. We also illustrate mechanisms that the base station uses to exploit the proposed enhanced CSI feedback for rate-matching. The system level simulations demonstrate that the proposed residual error based enhanced CSI feedback with REN provides substantial system throughput improvements in both homogenous and heterogenous networks.