Advanced downlink MU-MIMO receiver for 3GPP LTE-A

Third Generation Partnership Project Long Term Evolution (3GPP LTE) provides potential of higher spectral efficiency by using multi-user multiple-input and multiple-output (MU-MIMO) system. Because of the coarse knowledge of channel state information at the transmitter (CSIT) under current standard, co-scheduled user equipments (UEs) may suffer large residual multi-user interference in MU-MIMO. In this paper, we investigate performances of various types of receivers in the cases where residual interference is not negligible. Interference ignoring receiver is expected to perform poorly in this scenario, and hence, we consider interference-aware receivers. Interference rejection combiner (IRC) and joint Max-Log-MAP receiver are considered as interference-aware receivers. In order to perform joint detection of the target and interference layers, UE needs to know interference modulation which current standard does not provide. Because of this, we consider modulation-estimation-based joint receiver as our advanced downlink MU-MIMO receiver. Performances of aforementioned receivers are investigated in several practically relevant cases. It is shown that modulation-estimation-based joint receiver can significantly outperform IRC or the joint receiver with assumption of fixed interference modulation.