Iterative THP Transceiver Optimization for Multi-User MIMO Systems Based on Weighted Sum-Mse Minimization

We address the joint optimization of transmitter and receivers for a multi-user multiple-input multiple-output (MIMO) broadcast channel (BC) system under the assumption of perfect channel state information (CSI) at both transmitter and receivers. Tomlinson Harashima precoding (THP) is employed for interuser interference presubtraction and the mean square error (MSE) is minimized. Since the downlink problem is difficult to handle, we formulate an equivalent uplink problem by exploiting the duality between THP and decision feedback equalization (DFE). We present an iterative solution, which delivers suboptimum transmit and receive matrices as well as a suboptimum precoding order. The performance of the algorithm is studied theoretically and experimentally