As a low-cost and low-power-consumption passive reflector, intelligent reflecting surface (IRS) can make a significant rate improvement by building a programmable wireless environment. To improve the rate performance and coverage range of wireless networks, an IRS-aided decode-and-forward (DF) relay network is proposed with multiple antennas at relay station (RS). To achieve a high rate, an alternately iterative structure (AIS) of maximizing receive power (Max-RP) at RS is proposed to jointly optimize the beamforming vectors at RS and phase shifts at IRS. Considering its high-complexity, two low-complexity Max-RP schemes of null-space projection (NSP) plus maximum ratio combining (MRC) and IRS element selection (IRSES) plus MRC are presented to reduce this complexity, respectively. For the former, NSP is used to separate the reflected signal from IRS and the direct transmitted signal from source and MRC is adopted to combine the two signals at RS. For the latter, the basic concept of IRSES is as follows: IRS is partitioned into M subsets of elements and adjusting the phases of all elements per subset make all reflected signals and the direct signal from source phase alignment (PA) at the corresponding antenna of relay. Simulation results show that the proposed three methods perform much better than the existing network with single-antenna relay in terms of rate performance. In particular, a 85% rate gain over existing scheme is achieved in the high signal-to-noise ratio region.
翻译:作为低成本和低功率消费被动反射器,智能反射表面(IRS)可以通过建立一个可编程的无线环境来大大提高率。为了改善无线网络的费率性能和覆盖范围,提出了在中继站安装多天天线的IRS辅助解码和前向(DF)中继网络。为了实现高接收率,提议在RS建立一个替代迭代结构(AIS),以尽量扩大接收电源(最大功率-RP),并在IRS上调两个信号。考虑到其高度兼容性,两个低兼容性无空间投影(NSP)的马克斯-RP计划,以及最大比率组合(MRC),提出了一套IRS-RPS解码和前向后向(IRS)中继器。对于前者,将反映的信号从IRS和源直接发送的信号(MRC)联合优化斯普斯卡共和国的两种信号。对于后者,IRSESESS的基本概念如下:IRSESS-R方案在S-RP(NP)和最大信号级组合组合组合中,所有SIM-S-SIMS-Servial 级的Servial 级的S-real 的S-resmal-resmal 的S-resmal 级,所有S-resmal-resmal-resmal 级的S-resmal-resm 级,所有S-resental 级的S-s-s-s-s