Massive multiple-input multiple-output (MIMO) and reconfigurable intelligent surface (RIS) are two promising technologies for 5G-and-beyond wireless networks, capable of providing large array gain and multiuser spatial multiplexing. Without requiring additional frequency bands, those technologies offer significant improvements in both spectral and energy efficiency by simultaneously serving many users. The performance analysis of an RIS-assisted massive MIMO system as a function of channel statistics relies heavily on fundamental properties, including favorable propagation, channel hardening, and rank deficiency. The coexistence of both direct and indirect links results in aggregated channels, whose properties are the main concerns of this “Lecture Notes” article. For practical systems with a finite number of antennas and engineered scattering elements of the RIS, we evaluate the corresponding deterministic metrics, with Rayleigh fading channels as a typical example.

中文翻译：

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Reconfigurable Intelligent Surface-Assisted Massive MIMO：有利传播、信道硬化和秩不足 [讲义]

大规模多输入多输出 (MIMO) 和可重构智能表面 (RIS) 是 5G 及以后无线网络的两种有前途的技术，能够提供大阵列增益和多用户空间复用。这些技术不需要额外的频段，通过同时为许多用户提供服务，显着提高了频谱和能源效率。作为信道统计函数的 RIS 辅助大规模 MIMO 系统的性能分析在很大程度上依赖于基本属性，包括有利传播、信道硬化和秩不足。直接链接和间接链接的共存导致聚合渠道，其属性是这篇“讲义”文章的主要关注点。