In this paper, we study a covert Internet of Things (IoT) system. Compared with conventional IoT systems that apply cryptography and information-theoretic secrecy approaches to secure the transmission, our considered IoT system adopts the covertness technique and intends to hide the legitimate transmission from the observant adversaries. In the IoT system, the IoT devices randomly transmit the collected data to their associated IoT gateways (GWs). In the meantime, the adversaries attempt to detect the existence of legitimate transmission based on their received signal power and launch hostile attacks accordingly. To avoid being detected by the adversaries, the IoT system applies uplink power control to achieve covert legitimate transmission. Moreover, to distort the observation of the adversaries so as to mislead their decisions, we propose an artificial noise (AN)-assisted covert communication design, where the AN is transmitted by in-band full-duplex (IBFD) IoT GWs as a jamming operation. We formulate a Stackelberg game to study the interaction between the adversaries and the legitimate entities including the IoT GWs and IoT devices, where the legitimate entities, as the leaders, decide on the powers of legitimate and AN transmissions at the upper level and the adversaries, as the followers, aim to minimize their detection errors at the lower level. Thereafter, considering the large scale of IoT system, we further cast the Stackelberg game into a mean-field Stackelberg game and incorporate the stochastic geometry and statistical channel model to capture the location heterogeneity and channel dynamics among and of the system entities, respectively. In the performance evaluation, we verify the practicability of the mean-field Stackelberg game. Moreover, we demonstrate the effectiveness of AN in improving the transmission covertness.

中文翻译：

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隐蔽物联网系统中的平均场人工噪声辅助和上行链路功率控制

在本文中，我们研究了一个隐蔽的物联网 (IoT) 系统。与应用密码学和信息论保密方法来保护传输的传统物联网系统相比，我们考虑的物联网系统采用了隐蔽性技术，旨在向敏锐的对手隐藏合法传输。在物联网系统中，物联网设备将收集到的数据随机传输到其关联的物联网网关（GW）。同时，攻击者试图根据其接收到的信号功率检测是否存在合法传输，并据此发起恶意攻击。为了避免被攻击者发现，物联网系统应用上行功率控制来实现隐蔽的合法传输。此外，为了扭曲对手的观察以误导他们的决定，我们提出了一种人工噪声 (AN) 辅助的隐蔽通信设计，其中 AN 作为干扰操作由带内全双工 (IBFD) 物联网 GW 传输。我们制定了一个 Stackelberg 博弈来研究攻击者与包括 IoT GW 和 IoT 设备在内的合法实体之间的交互，其中合法实体作为领导者决定上层和攻击者的合法和 AN 传输的权力，作为追随者，他们的目标是在较低级别上最小化他们的检测错误。此后，考虑到物联网系统的大规模，我们进一步将 Stackelberg 博弈转化为平均场 Stackelberg 博弈，并结合随机几何和统计通道模型，分别捕捉系统实体之间的位置异质性和通道动态。在性能评估中，我们验证了平均场 Stackelberg 博弈的实用性。此外，我们证明了 AN 在提高传输隐蔽性方面的有效性。