Abstract

By considering an adversary jammer in a communication network, we investigate the secrecy performance of a cooperative wireless network comprised of a source, a destination and an untrusted amplify-and-forward relay. We assume that either the source or the destination, as well as the jammer are equipped with large-scale multiple antennas systems, while the rest are equipped with a single-antenna. To prevent the untrusted relay from intercepting the source message, the destination sends an intended jamming noise to the relay, which is referred to as destination-assisted cooperative jamming. On the other hand, the role of the jammer is to disturb the communication by transmitting jamming signals toward the untrusted relay. Given this system model, novel closed-form expressions are extracted for the ergodic secrecy rate (ESR) with Rayleigh fading channels. We further evaluate the ESR at high signal-to-noise ratio (SNR) and then determine the high SNR slope and power offset of the ESR to get some insights into the network. Next, with the aim of maximizing the instantaneous secrecy rate, we derive new closed-form solutions for the optimal power allocation (OPA). Numerical examples depict that the presented OPA considerably improves the system secrecy rate compared to the equal power allocation (EPA) which reveals the priority of our optimized network. We also illustrate that by increasing the number of jammer antennas, the ESR performance of both the OPA and EPA is reduced. The results state that unlike the EPA technique, increasing the number of source antennas enhances the ESR of the proposed OPA technique which reveals the priority of our OPA.

中文翻译：

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在存在敌方干扰机的情况下表征不可信中继网络

摘要

通过考虑通信网络中的攻击者干扰，我们研究了由源，目的地和不受信任的放大转发中继组成的协作无线网络的保密性能。我们假设源或目的地以及干扰器都配备了大型多天线系统，而其余设备都配备了单天线。为了防止不受信任的中继截获源消息，目标向中继发送了预期的干扰噪声，这称为目标辅助协作干扰。另一方面，干扰器的作用是通过向不受信任的中继发送干扰信号来干扰通信。有了这个系统模型，使用Rayleigh衰落通道提取遍历保密率（ESR）的新颖封闭形式。我们进一步在高信噪比（SNR）下评估ESR，然后确定ESR的高SNR斜率和功率偏移，以获取对网络的一些见解。接下来，为了最大程度地提高瞬时保密率，我们推导了用于最佳功率分配（OPA）的新闭式解。数值示例表明，与等功率分配（EPA）相比，本文提出的OPA大大提高了系统的保密率，这揭示了我们优化网络的优先级。我们还说明，通过增加干扰天线的数量，OPA和EPA的ESR性能都会降低。结果表明，与EPA技术不同，