Cooperative relaying can be introduced as a promising approach for data communication in the Internet of Things (IoT), where the source and the destination may be placed far away. In this paper, by taking a variety of realistic hardware imperfections (HWIs) and channels estimation errors (CEEs) into account, the secrecy performance of a three-hop cooperative network with a source, a destination and two consecutive amplify-and-forward (AF) relays is investigated. The relays are considered to be untrusted, i.e., while they are mandatory helpers for data transmission, they may overhear the received signals. We adopt the artificial noise injection scheme, to keep the source message secret from being captured by the untrusted relays. Given this system model, a novel closed-form expression is obtained in the high signal-to-noise ratio (SNR) regime for the ergodic secrecy rate (ESR) performance over Nakagami-m fading. Our simulation results highlight that the secrecy performance of the system is improved when the tolerable HWIs are distributed beneficially across the transmission and reception radio-frequency (RF) front-ends of each node. Our work reveals that unlike the ideal case, the realistic scenario of non-ideal hardware with CEEs faces with the secrecy rate ceiling. Finally, under a constraint on the total energy consumption which is applicable for battery-limited IoT equipment, we maximize the achievable secrecy rate. Our results highlight the importance of the destination's jamming cooperation and the first relay's role on the secrecy performance.

中文翻译：

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具有硬件缺陷和物联网信道估计错误的三跳不可信中继网络


协作中继可以作为物联网 (IoT) 中数据通信的一种有前途的方法引入，其中源和目的地可能放置在很远的地方。在本文中，通过考虑各种实际硬件缺陷（HWI）和信道估计误差（CEE），具有源、目的地和两个连续放大转发的三跳协作网络的保密性能（ AF）继电器进行了研究。中继被认为是不可信的，即，虽然它们是数据传输的强制助手，但它们可能偷听接收到的信号。我们采用人工噪声注入方案，以保证源消息的秘密不被不可信中继捕获。给定该系统模型，在高信噪比 (SNR) 范围内获得了 Nakagami-m 衰落的遍历保密率 (ESR) 性能的新颖封闭式表达式。我们的仿真结果表明，当可容忍的 HWI 有益地分布在每个节点的传输和接收射频 (RF) 前端时，系统的保密性能会得到改善。我们的工作表明，与理想情况不同，具有 CEE 的非理想硬件的现实场景面临着保密率上限。最后，在适用于电池有限的物联网设备的总能耗约束下，我们最大化了可实现的保密率。我们的结果强调了目的地干扰合作的重要性以及第一个中继对保密性能的作用。