Learning-Based Adaptive IRS Control with Limited Feedback Codebooks
Learning-Based Adaptive IRS Control with Limited Feedback Codebooks
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DOI：
10.1109/twc.2022.3178055
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发表时间：
2021-12
影响因子：
10.4
通讯作者：
Junghoon Kim;Seyyedali Hosseinalipour;Andrew C. Marcum;Taejoon Kim;D. Love;Christopher G. Brinton
中科院分区：
文献类型：
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作者：
Junghoon Kim;Seyyedali Hosseinalipour;Andrew C. Marcum;Taejoon Kim;D. Love;Christopher G. Brinton
智能反射表面由可配置的元原子组成，通过设计反射系数来改变无线传播环境。我们考虑一个实际的设置，其中（i）的IRS反射系数是通过调整嵌入在元原子的可调元件配置，（ii）的IRS反射系数的入射角的传入信号的影响，（iii）的IRS部署在多径，时变信道，和（iv）从基站到IRS的反馈链路具有低的数据速率。传统的基于优化的IRS控制协议依赖于信道估计并将优化的变量传送到IRS，由于信道估计的困难和低反馈速率，传统的基于优化的IRS控制协议不适用于这种设置。因此，我们开发了一种新的自适应码本为基础的有限反馈协议，只有一个码字索引被转移到IRS。我们提出了两种自适应码本设计的解决方案，随机邻接（RA）和基于深度神经网络策略的IRS控制（DPIC），这两种方案都只需要端到端的复合信道。我们进一步发展了几个基于RA和DPIC的增广方案。数值计算表明，数据速率和平均数据速率在一个相干时间大大提高了我们的计划。
Intelligent reflecting surfaces (IRS) consist of configurable meta-atoms, which can change the wireless propagation environment through design of their reflection coefficients. We consider a practical setting where (i) the IRS reflection coefficients are configured by adjusting tunable elements embedded in the meta-atoms, (ii) the IRS reflection coefficients are affected by the incident angles of the incoming signals, (iii) the IRS is deployed in multi-path, time-varying channels, and (iv) the feedback link from the base station to the IRS has a low data rate. Conventional optimization-based IRS control protocols, which rely on channel estimation and conveying the optimized variables to the IRS, are not applicable in this setting due to the difficulty of channel estimation and the low feedback rate. Therefore, we develop a novel adaptive codebook-based limited feedback protocol where only a codeword index is transferred to the IRS. We propose two solutions for adaptive codebook design, random adjacency (RA) and deep neural network policy-based IRS control (DPIC), both of which only require the end-to-end compound channels. We further develop several augmented schemes based on RA and DPIC. Numerical evaluations show that the data rate and average data rate over one coherence time are improved substantially by our schemes.