无线携能通信系统中基于人工噪声的波束成形算法研究

Artificial noise-aided beamforming algorithm in simultaneous wireless information and power transfer systems

在存在多天线窃听者的情况下,研究了无线携能通信系统的物理层安全传输问题。传统上,人工噪声方案是一种保证物理层安全通信的有效策略,提出了一种人工噪声辅助的波束成形算法,以提高信息与能量联合传输的安全性。该算法在满足多项约束(接收端能量采集门限、信息泄露控制指标和发送功率)的基础上,通过优化波束成形预编码矩阵和人工噪声实现无线携能通信系统的物理层安全通信。在数学上该算法是一个非凸优化问题,不易求解。为此,首先引入最小均方误差接收算法和连续凸近似方法将其转换为凸的二阶锥规划子问题,然后对该凸问题进行迭代求解。仿真结果表明,该算法能够在保证窃听者无法解码信息的同时,实现信息和能量的联合传输,并且算法收敛速度快。

This paper investigated the physical layer secure transmission problem of a simultaneous wireless information and power transfer system by considering the existence of a multi-antenna eavesdropper. Traditionally, artificial noise （AN） scheme was an efficient strategy to guarantee transmission security at the physical layer. To improve the security of information and energy transmission, this paper proposed an AN-aided beamforming algorithm. By optimizing the beamforming precoding matrix and AN, the proposed algorithm could achieve secure transmission while meeting energy threshold at the receiver, information leakage control requirement at the eavesdropper, and power constraint at the transmitter. This optimization problem was non-convex and difficult to be solved. In order to get an iterative solution, this paper introduced minimum mean square error （MMSE） method and successive convex approximation to transform it into several convex subproblems which could be solved by second order cone programming （SOCP） method. Simulation results show that the proposed algorithm can not only disable eavesdropper to decode information but also achieve transmission of information and energy jointly. Also, the proposed algorithm has a good convergence.