As the number of connected devices is exponentially increasing, security in Internet of Things (IoT) networks presents a major challenge. Accordingly, in this work we investigate the secrecy performance of multihop IoT networks assuming that each node is equipped with only two antennas, and can operate in both Half-Duplex (HD) and Full-Duplex (FD) modes. Moreover, we propose an FD Cooperative Jamming (CJ) scheme to provide higher security against randomly located eavesdroppers, where each information symbol is protected with two jamming signals by its two neighbouring nodes, one of which is the FD receiver. We demonstrate that under a total power constraint, the proposed FD-CJ scheme significantly outperforms the conventional FD Single Jamming (FD-SJ) approach, where only the receiving node acts as a jammer, especially when the number of hops is larger than two. Moreover, when the Channel State Information (CSI) is available at the transmitter, and transmit beamforming is applied, our results demonstrate that at low Signal-to-Noise Ratio (SNR), higher secrecy performance is obtained if the receiving node operates in HD and allocates both antennas for data reception, leaving only a single jammer active; while at high SNR, a significant secrecy enhancement can be achieved with FD jamming. Our proposed FD-CJ scheme is found to demonstrate a great resilience over multihop networks, as only a marginal performance loss is experienced as the number of hops increases. For each case, an integral closed-form expression is derived for the secrecy outage probability, and verified by Monte Carlo simulations.

中文翻译：

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通过协作混合双工干扰增强多跳物联网网络的保密性能


随着连接设备的数量呈指数级增长，物联网 (IoT) 网络的安全性提出了重大挑战。因此，在这项工作中，我们研究了多跳物联网网络的保密性能，假设每个节点仅配备两个天线，并且可以在半双工（HD）和全双工（FD）模式下运行。此外，我们提出了一种 FD 协作干扰（CJ）方案，以针对随机定位的窃听者提供更高的安全性，其中每个信息符号都受到其两个相邻节点（其中一个是 FD 接收器）的两个干扰信号的保护。我们证明，在总功率限制下，所提出的 FD-CJ 方案显着优于传统的 FD 单干扰（FD-SJ）方法，其中只有接收节点充当干扰器，特别是当跳数大于 2 时。此外，当信道状态信息 (CSI) 在发射机处可用并且应用发射波束成形时，我们的结果表明，在低信噪比 (SNR) 下，如果接收节点以 HD 运行，则可以获得更高的保密性能并分配两个天线用于数据接收，只留下一个干扰器处于活动状态；而在高信噪比下，FD 干扰可以显着增强保密性。我们提出的 FD-CJ 方案被发现在多跳网络上表现出强大的弹性，因为随着跳数的增加，只会出现边际性能损失。对于每种情况，都会导出保密中断概率的积分封闭式表达式，并通过蒙特卡罗模拟进行验证。