Downlink MIMO-RSMA with Successive Null-Space Precoding
arXiv:2107.08294 · doi:10.1109/TWC.2022.3173463
Abstract
In this paper, we consider the precoder design for an underloaded or critically loaded downlink multi-user multiple-input multiple-output (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 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 optimization problem for the precoding vectors and the associated power allocation for the proposed SNS-based MIMO-rate-splitting multiple access (RSMA) scheme. We obtain a suboptimal solution for this problem via successive convex approximation. Moreover, we study the robustness of the proposed precoding scheme to imperfect channel state information (CSI) at the base station via derivative-based sensitivity analysis. Our analysis and simulation results reveal the enhanced performance and robustness of the proposed SNS-based MIMO-RSMA scheme over several baseline multi-user MIMO schemes, especially for imperfect CSI.
arXiv comment16 pages, 16 figures, one table; two-column final version. This article is the journal version of arXiv:2101.01147 and has been accepted for publication by the IEEE Transactions on Wireless Communications
References in corpus (11)
- Rate-Splitting Multiple Access for Downlink Communication Systems: Bridging, Generalizing and Outperforming SDMA and NOMA
- Evolution of NOMA Toward Next Generation Multiple Access (NGMA) for 6G
- The MIMO Iterative Waterfilling Algorithm
- Matrix Inversion Using Cholesky Decomposition
- Performance Indicator for MIMO MMSE Receivers in the Presence of Channel Estimation Error
- Uplink and Downlink MIMO-NOMA with Simultaneous Triangularization
- Precoder Design and Statistical Power Allocation for MIMO-NOMA via User-Assisted Simultaneous Diagonalization
- What is the gradient of a scalar function of a symmetric matrix ?
- Rate-Splitting Multiple Access for Multi-antenna Downlink Communication Systems: Spectral and Energy Efficiency Tradeoff
- Successive Null-Space Precoder Design for Downlink MU-MIMO with Rate Splitting and Single-Stage SIC
- Study of Linear Precoding and Stream Combining for Rate Splitting in MU-MIMO Systems