This paper employs hybrid automatic repeat request (HARQ) to assist the cognitive non-orthogonal multiple access (NOMA) scheme for secure transmission in Internet of Things networks where the security-required (SR) users with high-security requirements and quality of services (QoS)-sensitive (QS) users with real-time process requirements are paired to perform NOMA for increasing the network connectivity. In addition, the imperfect successive interference cancellation (SIC) is considered at both legitimate users and eavesdropper for providing a realistic analysis. The closed-form expressions for the connection outage probability (COP), the secrecy transmission probability (RSP), and effective secrecy throughput (EST) of the SR user are derived in the proposed lightweight but efficient randomized retransmission scheme (RRS). As benchmarks, the secrecy performances of the fixed retransmission scheme (FRS) and orthogonal multiple access (OMA) scheme are also investigated. Besides, the asymptotic secrecy analysis is given to gain a better insight into secrecy performance. The analytical results developed in the paper demonstrate that HARQ is beneficial to secrecy transmission and the RRS outperforms or equals to the FRS and OMA scheme when the transmit power and secrecy coding redundancy is sufficiently high.

中文翻译：

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具有不完善SIC的安全传输的HARQ辅助认知NOMA方案

本文采用混合自动重发请求（HARQ）辅助认知非正交多址访问（NOMA）方案，以在物联网网络中进行安全传输，在该网络中，对安全性要求很高的（SR）用户具有较高的安全性要求和服务质量（对具有实时过程要求的QoS（QS）敏感的用户进行配对以执行NOMA，以增加网络连接性。另外，合法用户和窃听者均会考虑使用不完善的连续干扰消除（SIC），以提供现实的分析。在建议的轻量级但有效的随机重传方案（RRS）中，得出了SR用户的连接中断概率（COP），保密传输概率（RSP）和有效保密吞吐量（EST）的闭式表达式。作为基准 还研究了固定重传方案（FRS）和正交多址访问（OMA）方案的保密性能。此外，还进行了渐近保密分析，以更好地了解保密性能。本文得出的分析结果表明，当发射功率和保密编码冗余度足够高时，HARQ有利于保密传输，RRS的性能优于或等于FRS和OMA方案。