The Internet of Things (IoT) is expected to provide ubiquitous wireless machine-type communication devices and extensive information collection, resulting in an unprecedented amount of privacy and secrets exposed to the radio space. Security issues become a major restriction on the further development of IoT. However, secure transmissions in IoT are challenged by low complexity limitation and massive connectivity demand, especially by the use of short packets, which are expected to satisfy the delay requirement in ultra-reliable low-latency communications. Physical layer security can be employed without the constraints of packet length and number of connections. Nevertheless, due to the limitations of complexity, not all existing PLS techniques can be adopted in IoT. Non-orthogonal multiple access (NOMA) is a promising technique for increasing connectivity and reducing delay. Assuming an eavesdropper (Eve) is capable of the same detection capability as legitimate users, this article further exploits the inherent characteristics of NOMA to secure short-packet communications in IoT networks without introducing extra security mechanisms. Both downlink and uplink NOMA schemes are introduced to secure transmission by deliberately increasing the co-channel interference at Eve, which can be viewed as a special cooperative jamming strategy. Simulations show that in both uplink and downlink, although secrecy performance deteriorates in short-packet communications, the performance gains of NOMA over traditional orthogonal multiple access are significant. Finally, we analyze the challenges and future trends in this emerging area.

中文翻译：

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物联网中由NOMA协助的安全短分组通信

物联网（IoT）有望提供无处不在的无线机器类型的通信设备和广泛的信息收集，从而导致无线电空间暴露出前所未有的隐私和秘密。安全问题成为物联网进一步发展的主要限制。但是，物联网中的安全传输受到低复杂度限制和庞大的连接性需求的挑战，特别是通过使用短数据包，这有望满足超可靠的低延迟通信中的延迟要求。可以采用物理层安全性而不受分组长度和连接数量的限制。然而，由于复杂性的限制，并非所有现有的PLS技术都可以在物联网中采用。非正交多址访问（NOMA）是增加连接和减少延迟的有前途的技术。假设窃听者（Eve）具有与合法用户相同的检测能力，本文将进一步利用NOMA的固有特性来保护IoT网络中的短数据包通信，而无需引入额外的安全性机制。引入了下行链路和上行链路NOMA方案来通过故意增加Eve处的同信道干扰来确保传输安全，这可以看作是一种特殊的协作干扰策略。仿真表明，在上行链路和下行链路中，尽管在短数据包通信中保密性能会下降，但NOMA相对于传统正交多址访问的性能提升是显着的。最后，