The reconfigurable intelligent surface (RIS) is useful to effectively improve the coverage and data rate of end-to-end communications. In contrast to the well-studied coverage-extension use case, in this paper, multiple RIS panels are introduced, aiming to enhance the data rate of multi-input multi-output (MIMO) channels in presence of insufficient scattering. Specifically, via the operator-valued free probability theory, the asymptotic mutual information of the large-dimensional RIS-assisted MIMO channel is obtained under the Rician fading with Weichselberger's correlation structure, in presence of both the direct and the reflected links. Although the mutual information of Rician MIMO channels scales linearly as the number of antennas and the signal-to-noise ratio (SNR) in decibels, numerical results show that it requires sufficiently large SNR, proportional to the Rician factor, in order to obtain the theoretically guaranteed linear improvement. This paper shows that the proposed multi-RIS deployment is especially effective to improve the mutual information of MIMO channels under the large Rician factor conditions. When the reflected links have similar arriving and departing angles across the RIS panels, a small number of RIS panels are sufficient to harness the spatial degree of freedom of the multi-RIS assisted MIMO channels.
翻译:重新配置的智能表面(RIS)有助于有效改善终端到终端通信的覆盖范围和数据率; 与研究周密的覆盖范围扩展使用案例相比,本文件引入了多个RIS小组,目的是在分布不足的情况下提高多投入多产出渠道的数据率; 具体地说,通过操作员估价的自由概率理论,通过高层次的RIS辅助MIMO频道的无空间相互信息,在与Weichselberger的关联结构逐渐淡化的情况下,在有直接和反映的链接的情况下,获得与Weichselberger的相对结构的无源互通信息; 尽管Rician MIMO频道的相互信息是线性,作为天线数和信号到音频率的比例,但数字结果显示,它需要足够大的SNR,与Rican系数成正比,以便获得理论上保证的线性改进; 本文表明,拟议的多RIS部署对于改进大型RIM频道在RIS频道下的共同信息特别有效,在移动的大型空间因素面上,移动的MISIS-有类似联系。