Hayajneh Maymoona, Gulliver Thomas Aaron
Department of Electrical and Computer Engineering, University of Victoria, P.O. Box 1700, STN CSC, Victoria, BC V8W 2Y2, Canada.
Entropy (Basel). 2023 Jan 6;25(1):122. doi: 10.3390/e25010122.
In this paper, the security of two-way relay communications in the presence of a passive eavesdropper is investigated. Two users communicate via a relay that depends solely on energy harvesting to amplify and forward the received signals. Time switching is employed at the relay to harvest energy and obtain user information. A friendly jammer is utilized to hinder the eavesdropping from wiretapping the information signal. The eavesdropper employs maximal ratio combining and selection combining to improve the signal-to-noise ratio of the wiretapped signals. Geometric programming (GP) is used to maximize the secrecy capacity of the system by jointly optimizing the time switching ratio of the relay and transmit power of the two users and jammer. The impact of imperfect channel state information at the eavesdropper for the links between the eavesdropper and the other nodes is determined. Further, the secrecy capacity when the jamming signal is not perfectly cancelled at the relay is examined. The secrecy capacity is shown to be greater with a jammer compared to the case without a jammer. The effect of the relay, jammer, and eavesdropper locations on the secrecy capacity is also studied. It is shown that the secrecy capacity is greatest when the relay is at the midpoint between the users. The closer the jammer is to the eavesdropper, the higher the secrecy capacity as the shorter distance decreases the signal-to-noise ratio of the jammer.
本文研究了存在被动窃听者时双向中继通信的安全性。两个用户通过一个仅依靠能量收集来放大和转发接收到的信号的中继进行通信。中继采用时间切换来收集能量并获取用户信息。利用一个友好干扰器来阻止窃听者窃听信息信号。窃听者采用最大比合并和选择合并来提高窃听信号的信噪比。通过联合优化中继的时间切换比以及两个用户和干扰器的发射功率，使用几何规划（GP）来最大化系统的保密容量。确定了窃听者处信道状态信息不完善对窃听者与其他节点之间链路的影响。此外，还研究了干扰信号在中继处未被完美消除时的保密容量。结果表明，与没有干扰器的情况相比，有干扰器时保密容量更大。还研究了中继、干扰器和窃听者位置对保密容量的影响。结果表明，当中继位于用户之间的中点时，保密容量最大。干扰器离窃听者越近，保密容量越高，因为较短的距离会降低干扰器的信噪比。
