In this paper, we consider the precoder design for an under-loaded or critically loaded downlink multi-user multiple-input multiple-output (MU-MIMO) communication system. We propose novel precoding and decoding schemes which enhance system performance based on rate splitting at the transmitter and single-stage successive interference cancellation at the receivers. The proposed successive null-space (SNS) precoding scheme utilizes linear combinations of the null-space basis vectors of the successively augmented MIMO channel matrices of the users as precoding vectors to adjust the inter-user-interference experienced by the receivers. We formulate a non-convex weighted sum rate (WSR) optimization problem, and solve it via successive convex approximation to obtain a suboptimal solution for the precoding vectors and the associated power allocation. Our simulation results reveal that the proposed SNS precoders outperform block diagonalization based linear and rate splitting designs, and in many cases, have a relatively small gap to the maximum sum rate achieved by dirty paper coding.
翻译:在本文中,我们考虑了一个载量不足或载量过重的多用户多投入多输出(MU-MIMO)通信系统的预编码设计;我们提出了新的预编码和解码计划,根据发报机的分率和接收器的单阶段连续取消干扰,提高系统性能;拟议的连续的空域预编码计划使用连续扩充的用户中不断扩增的MSIMO通道矩阵的空基矢量的线性组合,作为调整接收器所经历的用户间互不干涉的预编码矢量;我们制定了非convex加权总和率(WSR)优化问题,并通过连续的convex近似法加以解决,以获得预编码矢量和相关功率分配的亚最佳解决办法。我们的模拟结果表明,拟议的SNS预编码器在基于线性和分率分解设计而成形的区块外,在许多情况下,在脏纸编码达到的最高总和率方面差距相对较小。