In this paper, we propose a new dynamic IRS beamforming framework to boost the sum throughput of an intelligent reflecting surface (IRS) aided wireless powered communication network (WPCN). Specifically, the IRS phase-shift vectors across time and resource allocation are jointly optimized to enhance the efficiencies of both downlink wireless power transfer (DL WPT) and uplink wireless information transmission (UL WIT) between a hybrid access point (HAP) and multiple wirelessly powered devices. To this end, we first study three special cases of the dynamic IRS beamforming,namely user-adaptive IRS beamforming, UL-adaptive IRS beamforming, and static IRS beamforming,by characterizing their optimal performance relationships and proposing corresponding algorithms. Interestingly, it is rigorously proved that the latter two cases achieve the same throughput, thus helping halve the number of IRS phase shifts to be optimized and signalling overhead practically required for UL-adaptive IRS beamforming. Then, we propose a general optimization framework for dynamic IRS beamforming, which is applicable for any given number of IRS phase-shift vectors available. Despite of the non-convexity of the general problem with highly coupled optimization variables, we propose two algorithms to solve it and particularly, the low-complexity algorithm exploits the intrinsic structure of the optimal solution as well as the solutions to the cases with user-adaptive and static IRS beamforming. Simulation results validate our theoretical findings, illustrate the practical significance of IRS with dynamic beamforming for spectral and energy efficient WPCNs, and demonstrate the effectiveness of our proposed designs over various benchmark schemes.
翻译:在本文中,我们提出了一个新的动态IRS光学成像框架,以提升智能反射表面(IRS)辅助无线动力通信网络(WPCN)的总和。具体地说,对时间和资源配置的IRS级级转移矢量和静态IRS系统进行优化,以提高无线电传输(DL WPT)和无线信息传输(UL WIT)在混合接入点(HAP)和多个无线动力设备之间的下行传输(UL WIT)的效率。为此,我们首先研究三例动态IRS系统成像、即用户适应型IRS成形、UL-适应型IRS系统成形和静态IRS系统成形,通过描述其最佳性性能关系和提出相应的算法。 有趣的是,后两例的IRS阶段变异性转移,从而帮助将URS系统上流化系统实际所需的顶替电流数据信号信号信号信号化。 然后,我们提议一个动态IRS的内行优化框架, 也就是我们当前动态变动的变压变压的系统, 的变压结构将显示我们整个变动的变压的系统, 的变动的变压变压的变压的变压的变压, 将显示我们的所有的变压的变压的变压的变压的变压的变压的变压的变压的变压的变压的变压的变式的变式的变式的变式的变式的变式 。