This paper investigates a multiuser downlink communication system with coexisting intelligent reflecting surface (IRS) and classical half-duplex decode-and-forward (DF) relay. In this system, the IRS and the DF relay interact with each other and assist transmission simultaneously. In particular, active beamforming at the base station (BS) and at the DF relay, and passive beamforming at the IRS, are jointly designed to maximize the sum-rate of all users. The sum-rate maximization problem is nonconvex due to the coupled beamforming vectors. We propose an alternating optimization (AO) based algorithm to tackle this complex co-design problem. Numerical validation and discussion on the superiority of the coexistence system and the tradeoffs therein are presented.
翻译:本文调查一个多用户下行链路通信系统,该系统与智能反射表面(IRS)和传统的半双倍分解和前向(DF)中继系统并存。在这个系统中,IRS和DF中继系统相互作用,同时协助传输。特别是,在基地站(BS)和DF中继系统进行主动光束成型,以及在IRS中继系统进行被动光束成型,共同设计是为了最大限度地提高所有用户的总和率。总和最大化问题由于同时成形的矢量不同,是非电解的。我们建议采用基于交替优化的算法来解决这一复杂的共同设计问题。我们提出了关于共存系统和其中的利弊的数值验证和讨论。