Non-Linear Precoding for 5G NR

Abstract

Non-linear precoding gained attention recently in 3GPP (the third generation partnership project) as a possible technique to improve the performance of multi-user multiple input multiple output (MIMO). In this paper, research and standardization activities related non-linear precoding for 3GPP are described. Implementation, performance evaluation of nonlinear precoding and analysis of 3GPP specification impact are presented in this paper. Both system and UE throughput evaluation results, conducted at both 5GHz and 30GHz, demonstrate that non-linear precoding yield superior performance compared to linear precoding. In addition, two novel non-linear precoding based transmission schemes which require lower computational complexities than conventional non-linear precoding schemes are proposed. The first scheme separates UEs into linearly precoded and nonlinearly precoded UEs, reducing computational complexities required by non-linear precoding. The second scheme is a precoding scheme which intentionally introduces inter-UE interference through linear precoding and implements nonlinear precoding to remove inter-UE interference; multi-user diversity gain and reduction in computational complexity are obtained simultaneously. Finally, new abstraction performance metrics for the proposed schemes are presented. The simulation results demonstrate that the proposed methods outperform linear precoding techniques and offer a tradeoff between computational complexity and throughput performance.