In this paper, we study a general multi-cluster wireless powered communication network (WPCN) with user cooperation under harvest-then-transmit (HTT) protocol where the hybrid access point (HAP) as well as each user is equipped with multiple antennas. In the downlink phase of HTT, the HAP employs beamforming to transfer energy to the users. In the uplink phase, users in each cluster transmit their signals to the HAP and to their cluster heads (CHs). Afterward, the CHs first relay the signals of their cluster users and then transmit their own information signals to the HAP. The aim is to design the energy beamforming (EB) matrix, transmit covariance matrices of the users and time allocations among energy transfer and cooperation phases in order to optimize the max-min and sum throughputs of the network. The corresponding maximization problems are non-convex and NP-hard in general. We devise iterative algorithm based on alternating optimization (AO) and then the minorization-maximization (MM) technique is used to deal with the non-convex sub-problems with respect to (w.r.t.) the EB and covariance matrices in each iteration. We recast the resulting sub-problems as a convex second order cone programming (SOCP) and quadratic constraint quadratic programming (QCQP) for the max-min and sum throughput maximization problems, respectively. We also consider imperfect channel state information (CSI) at the HAP and CHs and non-linearity in energy harvesting (EH) circuits. Numerical examples show that the proposed cooperative method can effectively improve the achievable throughput in the multi-cluster wireless powered communication under various setups.

翻译：在本文中,我们研究一个通用多组无电源通信网络(WPCN),由用户根据收成后传送协议合作,由混合接入点(HAP)和每个用户配备多天线。在HTT下行阶段,HAP使用光束向用户传输能源。在上行阶段,每个组的用户将其信号传送给HAP和分组负责人(CHs)。随后,CHs首先转发其组用户的信号,然后将自己的信息信号传送给HAP。目的是设计混合接入点(EB)矩阵设计能源组合(EB)矩阵,传输用户的变异矩阵以及能源转移与合作阶段之间的时间分配,以便优化网络的最大值和总和值。相应的最大化问题是非convex和一般的NP-硬性。我们根据提议的调整(AO),然后将小化-饱和化(MMM)技术用于处理非cional QQUM(EB) 子变压(Orality-Ax),然后在E-C-C 解算法下,通过电序(Ws-C-ral-ral-ral-ral-ral-ral-ral-ral-ral-st) 进行。