In this letter, we consider an intelligent reflecting surface (IRS)-aided wireless relaying system, where a decode-and-forward relay (R) is employed to forward data from a source (S) to a destination (D), aided by M passive reflecting elements. We consider two practical IRS deployment strategies, namely, single-IRS deployment where all reflecting elements are mounted on one single IRS that is deployed near S, R, or D, and multi-IRS deployment where the reflecting elements are allocated over three separate IRSs which are deployed near S, R, and D, respectively. Under the line-of-sight (LoS) channel model, we characterize the capacity scaling orders with respect to an increasing M for the IRS-aided relay system with different IRS deployment strategies. For single-IRS deployment, we show that deploying the IRS near R achieves the highest capacity as compared to that near S or D. While for multi-IRS deployment, we propose a practical cooperative IRS passive beamforming design which is analytically shown to achieve a larger capacity scaling order than the single-IRS deployment (i.e., near R or S/D) when M is sufficiently large. Numerical examples are provided, which validate our theoretical results.
翻译:在本信中,我们考虑了一种智能反射表面(IRS)辅助无线中继系统,其中使用解码和前方中继(R)将数据从一个源(S)传送到一个目的地(D),由M 被动反射元素协助。我们考虑了两种实用的IRS部署战略,即单IRS部署,其中所有反映元素都安装在S、R或D附近部署的单一IRS上,以及多IRS部署,其中反映元素分布在分别部署在S、R和D附近的三个独立的IRS上。在光线(LOS)频道模式下,我们用不同的IRS部署战略来描述增加IRS辅助中继系统M的能力缩放订单。关于单一IRS部署,我们表明在R附近部署的IRS达到与S或D附近部署相比的最大能力。对于多IRS部署,我们提出了一种实际合作的IRS被动成型设计,其分析显示能够实现比单一IRS部署(R/D)更大规模的能力缩放,当我们提供的是M/充分的理论结果时,S/NU。