This paper proposes a hybrid-relaying scheme empowered by a self-sustainable intelligent reflecting surface (IRS) in a wireless powered communication network (WPCN), to simultaneously improve the performance of downlink energy transfer (ET) from a hybrid access point (HAP) to multiple users and uplink information transmission (IT) from users to the HAP. We propose time-switching (TS) and power-splitting (PS) schemes for the IRS, where the IRS can harvest energy from the HAP’s signals by switching between energy harvesting and signal reflection in the TS scheme or adjusting its reflection amplitude in the PS scheme. For both the TS and PS schemes, we formulate the sum-rate maximization problems by jointly optimizing the IRS’s phase shifts for both ET and IT and network resource allocation. To address each problem’s non-convexity, we propose a two-step algorithm to obtain the near-optimal solution with high accuracy. To show the structure of resource allocation, we also investigate the optimal solutions for the schemes with random phase shifts. Through numerical results, we show that our proposed schemes can achieve significant system sum-rate gain compared to the baseline scheme without IRS.

中文翻译：

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自我可持续 IRS 授权的 WPCN 中的优化能量和信息中继

本文提出了一种在无线供电通信网络 (WPCN) 中由自持智能反射面 (IRS) 授权的混合中继方案，以同时提高来自混合接入点 (HAP) 的下行链路能量传输 (ET) 的性能到多个用户和从用户到 HAP 的上行信息传输 (IT)。我们为 IRS 提出了时间切换 (TS) 和功率分配 (PS) 方案，其中 IRS 可以通过在 TS 方案中的能量收集和信号反射之间切换或在 PS 中调整其反射幅度来从 HAP 的信号中收集能量方案。对于 TS 和 PS 方案，我们通过联合优化 IRS 的 ET 和 IT 相移以及网络资源分配来制定和速率最大化问题。为了解决每个问题的非凸性，我们提出了一种两步算法来获得高精度的近最优解。为了显示资源分配的结构，我们还研究了随机相移方案的最佳解决方案。通过数值结果，我们表明，与没有 IRS 的基线方案相比，我们提出的方案可以实现显着的系统总速率增益。