In this paper, a novel intelligent reflecting surface (IRS)-assisted wireless powered communication network (WPCN) architecture is proposed for power-constrained Internet-of-Things (IoT) smart devices, where IRS is exploited to improve the performance of WPCN under imperfect channel state information (CSI). We formulate a hybrid access point (HAP) transmit energy minimization problem by jointly optimizing time allocation, HAP energy beamforming, receiving beamforming, user transmit power allocation, IRS energy reflection coefficient and information reflection coefficient under the imperfect CSI and non-linear energy harvesting model. On account of the high coupling of optimization variables, the formulated problem is a non-convex optimization problem that is difficult to solve directly. To address the above-mentioned challenging problem, alternating optimization (AO) technique is applied to decouple the optimization variables to solve the problem. Specifically, through AO, time allocation, HAP energy beamforming, receiving beamforming, user transmit power allocation, IRS energy reflection coefficient and information reflection coefficient are divided into three sub-problems to be solved alternately. The difference-of-convex (DC) programming is uesd to solve the non-convex rank-one constraint in solving IRS energy reflection coefficient and information reflection coefficient. Numerical simulations verify the superiority of the proposed optimization algorithm in decreasing HAP transmit energy compared with other benchmark schemes.
翻译:在本文中,提出了一个新的智能结构,反映表面(IRS)辅助无线电力通信网络(WPCN)结构,用于受电力限制的互联网电话智能设备,在这种设备中,IRS被用来在不完善的频道状态信息(CSI)下改进WPCN的性能。我们制定了混合接入点,通过联合优化时间分配、HAP能源束成像、接收信号成像、用户传输电力分配、IRS能源反射系数和信息反射系数,在不完善的 CSI和非线性能源收获模式下。由于优化变量的高度结合,所提出的问题是一个非康韦克斯优化问题,难以直接解决。为了解决上述具有挑战性的问题,我们采用了交替优化(AO)技术,通过调和优化变量来解决这个问题。具体来说,通过AO、时间分配、HAP能源成像成像、接受信号成形、用户传输电力分配、IRS能源反射系数和信息反射系数被分为三个子问题分数,因为优化变压变压的优化的优化的优化的优化的优化的节算法,将不相法的能源平压法的递解的递解的能源平压法化法的递解法。