This paper studies the secrecy communication on wireless powered communication network (WPCN) in an orthogonal frequency division multiplexing (OFDM) system, where an energy harvest (EH) user sends confidential information to the hybrid access point (HAP) in the presence of a potential eavesdropper. We introduce a wireless powered cooperative jammer to improve the secrecy performance of this system. For the user and the jammer, we both consider the linear energy harvesting model and the nonlinear energy harvesting model. More specifically, the half-duplex WPCN is considered first. We study secrecy rate maximization problem by jointly optimizing the time allocation and the transmit power allocation for the HAP, the jammer and the user over sub-carriers. The nested form algorithm is proposed to solve the original non-convex problem, where one-dimension search method is used at the outer layer and a convex approximation algorithm by leveraging DC-based optimization is adopted at the inner layer. Then, the full-duplex WPCN is considered. We formulated the secrecy rate maximization problem and optimized the transmit power by using the DC algorithm and convex optimization. Simulation results demonstrate that the proposed scheme dramatically enhances the secrecy rate compared to the benchmark schemes.

本文研究了正交频分复用 (OFDM) 系统中无线供电通信网络 (WPCN) 上的保密通信，其中能量收集 (EH) 用户在存在潜在威胁的情况下向混合接入点 (HAP) 发送机密信息。窃听者。我们引入了一种无线供电的协作干扰器来提高该系统的保密性能。对于用户和干扰者，我们都考虑了线性能量收集模型和非线性能量收集模型。更具体地说，首先考虑半双工WPCN。我们通过联合优化 HAP、干扰器和用户在子载波上的时间分配和发射功率分配来研究保密速率最大化问题。提出了嵌套形式算法来解决原始的非凸问题，其中外层采用一维搜索方法，内层采用基于DC优化的凸逼近算法。然后，考虑全双工WPCN。我们制定了保密速率最大化问题，并通过使用 DC 算法和凸优化来优化发射功率。仿真结果表明，与基准方案相比，所提出的方案显着提高了保密率。