In this article, a dual-hop amplify-and-forward (AF) multiple-input multiple-output (MIMO) relay communication system is studied. With a splitting (PS) protocol, the relay node harvests the radio frequency (RF) energy in the signals sent by the source node and utilizes the harvested energy to forward signals from the source node to the destination node. We aim at maximizing the source-destination mutual information (MI) through a joint design of the source matrix, the relay matrix, and the PS ratios under the source node power constraint and the relay node harvested energy constraint. We consider a general sum energy constraint at the relay node with different PS ratios across relay antennas, which includes existing works based on uniform PS or per data stream energy constraint as special cases. Moreover, a practical nonlinear energy harvesting (EH) model is adopted, where the harvested energy is bounded as the incident RF signal power increases. We establish the structure of the source matrix and the relay matrix, which simplifies the complicated transceiver design problem with matrix variables to a power distribution problem with scalar variables. Three approaches are proposed to efficiently solve the optimal power distribution problem. In particular, the first proposed algorithm solves the original nonconvex power allocation problem using the sequential quadratic programming, while the other two algorithms convert the original problem to convex problems by exploiting a tight upper bound and a tight lower bound of the objective function, respectively. Numerical simulations demonstrate that when the EH circuit works in the linear region, the proposed algorithms have a larger system MI than existing PS and TS based MIMO AF relay systems. The peak harvest power constraint plays an important role in choosing the location of the relay node.

中文翻译：

---

具有基于功率分配的能量收集中继节点的 AF MIMO 中继系统的收发器设计

在本文中，研究了双跳放大转发 (AF) 多输入多输出 (MIMO) 中继通信系统。通过分裂（PS）协议，中继节点收集源节点发送的信号中的射频（RF）能量，并利用收集的能量将信号从源节点转发到目的节点。我们的目标是通过源矩阵、中继矩阵和源节点功率约束和中继节点收集能量约束下的 PS 比率的联合设计来最大化源 - 目的地互信息（MI）。我们考虑了中继节点处具有跨中继天线的不同 PS 比率的一般总和能量约束，其中包括基于统一 PS 或每个数据流能量约束的现有工作作为特殊情况。而且，采用实用的非线性能量收集 (EH) 模型，其中收集的能量随着入射射频信号功率的增加而有界。我们建立了源矩阵和中继矩阵的结构，将复杂的带有矩阵变量的收发器设计问题简化为带有标量变量的功率分配问题。提出了三种方法来有效地解决最优配电问题。特别是，第一个提出的算法使用顺序二次规划解决原始非凸功率分配问题，而其他两种算法分别通过利用目标函数的紧上界和紧下界将原问题转换为凸问题。数值模拟表明，当 EH 电路工作在线性区域时，所提出的算法具有比现有基于 PS 和 TS 的 MIMO AF 中继系统更大的系统 MI。峰值采集功率约束在选择中继节点的位置方面起着重要作用。