Reconfigurable intelligent surface (RIS) has recently drawn intensive attention due to its potential of simultaneously realizing high spectral and energy efficiency in a sustainable way. This paper focuses on the design of efficient transmission methods to maximize the uplink sum throughput in a RIS-aided multi-user multi-input multi-output (MU-MIMO) system. To provide an insightful basis, the channel capacity of RIS-aided MU-MIMO is theoretically analyzed. Then, the conventional transmission schemes based on orthogonal multiple access are presented as the baseline. From the information-theoretic perspective, we propose two novel schemes, i.e., \textit{joint transmission} based on the semidefinite relaxation of quadratic optimization problems and \textit{opportunistic transmission} relying on the best user selection. The superiority of the proposed schemes over the conventional ones in terms of achievable rates is justified through simulation results.
翻译:最近,可重新配置的智能表面(RIS)由于具有以可持续的方式同时实现高光谱和能源效率的潜力而引起人们的高度关注,本文件侧重于设计高效的传输方法,以便在一个由RIS辅助的多用户多用户多投入多产出产出(MU-MIMO)系统中最大限度地增加上链路和输送量。为了提供一个有见地的基础,对RIS辅助的MU-MIMO的频道能力进行了理论上的分析。然后,基于正方位多重接入的常规传输计划被作为基准。从信息理论的角度来看,我们建议了两种新颖的计划,即:根据对二次优化问题的半确定性放松和依赖最佳用户选择的\textit{机会性传输}。从可实现的比率来看,拟议计划优于常规计划,通过模拟结果是有道理的。</s>