MSIM:合作被动波束设计 (Double-IRS Assisted Multi-User MIMO: Cooperative Passive Beamforming Design)

from arxiv, Early access in IEEE TWC (https://ieeexplore.ieee.org/document/9362274). We answer the following fundamental question: whether partitioning the IRS elements/subsurfaces into distributed but cooperative IRSs is superior to combining them as one single IRS or not. Efficient channel estimation (arXiv:2010.06155) and (arXiv:2011.00738)

Intelligent reflecting surface (IRS) has emerged as an enabling technology to achieve smart and reconfigurable wireless communication environment cost-effectively. Prior works on IRS mainly consider its passive beamforming design and performance optimization without the inter-IRS signal reflection, which thus do not unveil the full potential of multi-IRS assisted wireless networks. In this paper, we study a double-IRS assisted multi-user communication system with the \emph{cooperative} passive beamforming design that captures the multiplicative beamforming gain from the inter-IRS channel. Under the general channel setup with the co-existence of both double- and single-reflection links, we jointly optimize the (active) receive beamforming at the base station (BS) and the cooperative (passive) reflect beamforming at the two distributed IRSs (deployed near the BS and users, respectively) to maximize the minimum signal-to-interference-plus-noise ratio (SINR) of all users. Moreover, for the single-user and multi-user setups, we analytically show the superior performance of the double-IRS cooperative system over the conventional single-IRS system in terms of the maximum signal-to-noise ratio (SNR) and multi-user effective channel rank, respectively. Simulation results validate our analytical results and show the practical advantages of the proposed double-IRS system with cooperative passive beamforming designs.

翻译：智能反射表面(IRS)已成为一种有利于实现智能和可重新配置无线通信环境的有利技术,具有成本效益;IRS以前的工作主要考虑其被动波束成型设计和性能优化,而没有IRS之间的信号反射,因此没有暴露多IRS辅助无线网络的全部潜力;在本文中,我们研究一个双IRS辅助多用户多用户通信系统,与\emph{cooperate}被动波束化设计,以获取从IRS之间频道获得的多复制性波形收益;在与双和单反光链接共存的一般频道设置下,我们共同优化(主动)在基础站接收波形成型设计和性性能优化,从而不暴露多IR网络网络网络的全部潜力;我们研究一个双IR系统协助多用户的多用户多功能通信系统(分别安装在BS和用户用户之间)的双向干涉加音频波比;此外,对于单一用户和多功能用户系统设置的双向系统(我们分析S-S-S-S-S-A-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-S-