Joint Beamforming and Time Switching Design for Secrecy Rate Maximization in Wireless-Powered FD Relay Systems
Joint Beamforming and Time Switching Design for Secrecy Rate Maximization in Wireless-Powered FD Relay Systems
复制标题
用于无线供电 FD 中继系统中保密率最大化的联合波束成形和时间切换设计
DOI：
10.1109/tvt.2017.2741491
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发表时间：
2018-01-01
影响因子：
6.8
通讯作者：
Yuan, Dongfeng
中科院分区：
文献类型：
--
作者：
Qiao, Jingping;Zhang, Haixia;Yuan, Dongfeng
本文重点关注无线供电全双工 (FD) 中继系统的安全传输，其中在存在单天线窃听者的情况下，多天线源借助 FD 中继与单天线目的地进行通信。假设FD中继具有无线能量收集功能，采用发射和接收天线以时间切换（TS）模式收集能量。由于本文的目标是通过联合设计能量波束成形向量、信息波束成形向量和TS系数来最大化系统保密率，因此提出了优化问题。所提出的问题被证明是非凸的，解决这个问题的挑战是同时解决三个变量。为了解决这个困难，提出了一种迭代算法，将公式化的优化问题转化为三个凸子问题，在此基础上导出波束形成向量的封闭解并获得TS系数。分析了迭代方法的收敛性。还进行了仿真以验证收敛速度和保密率方面的理论推导。结果表明，在 FD 中继中利用发射天线和接收天线进行能量收集的保密率性能优于仅接收天线的情况。此外，尽管天线之间存在环回干扰，但与半双工中继架构相比，FD中继始终能够大幅提高保密率。
This paper focuses on the secure transmission of wireless-powered full-duplex (FD) relay systems, where a multiantenna source communicates with a single-antenna destination with the help of a FD relay in the presence of a single-antenna eavesdropper. It is assumed that the FD relay is wireless energy harvesting-enabled, adopting both transmit and receive antennas to harvest energy in a time switching (TS) mode. As the objective of this paper is to maximize the system secrecy rate through jointly designing the energy beamforming vector, the information beamforming vector and the TS coefficient, an optimization problem is formulated. The formulated problem is proved to be nonconvex and the challenge to solve which is to concurrently solve out the three variables. To cope with this difficulty, an iterative algorithm is proposed to convert the formulated optimization problem into three convex subproblems, based on which the closed form solutions for the beamforming vectors are derived and the TS coefficient is obtained. Convergence property of the iterative method is analyzed. Simulations are also done to verify the theoretical derivations in terms of the convergence speed and the secrecy rate. Results reveal that the secrecy rate performance of exploiting transmit antenna together with receive antenna for energy harvesting at the FD relay outperforms only receive antenna case. Moreover, although there exists loopback interference between antennas, the FD relaying can always substantially boost the secrecy rate compared with half-duplex relaying architecture.