This paper introduces the hybrid-decode-amplify-forward (HDAF) cooperative relaying into a control jamming aided NOMA network under Rayleigh-flat-fading channel conditions. In HDAF, the relay switches between AF and DF modes based on SNR threshold to forward the information signal to the corresponding NOMA users in the existence of an eavesdropper. We first characterize the secrecy performance of the considered network in terms of secrecy rate at both NOMA users analytically under different jamming scenarios. Further, to improve the secrecy rate, Differential Evolution (DE) algorithm-based power allocation is adopted to optimize the powers of jammer, relay, and NOMA users for which maximization of secrecy rate is chosen as the cost function. Moreover, the impact of different numerical parameters such as signal-to-noise ratio (SNR), jammer-to-eavesdropper distance, and relay-to-eavesdropper distance on the secrecy rate is investigated at both NOMA users by employing different jamming schemes. The MATLAB based simulation results validate the efficacy of proposed power allocation over fixed power allocation, CJ over other jamming schemes, and application of HDAF relaying for physical layer security enhancement of NOMA enabled cooperative network.

本文在瑞利平坦衰落信道条件下将混合解码放大转发 (HDAF) 协作中继引入控制干扰辅助 NOMA 网络。在 HDAF 中，中继根据 SNR 阈值在 AF 和 DF 模式之间切换，以在存在窃听者的情况下将信息信号转发给相应的 NOMA 用户。我们首先根据两个 NOMA 用户在不同干扰场景下的保密率来分析所考虑网络的保密性能。此外，为了提高保密率，采用基于差分进化 (DE) 算法的功率分配来优化干扰机、中继和 NOMA 用户的功率，其中选择保密率最大化作为成本函数。此外，不同数值参数如信噪比 (SNR)、通过采用不同的干扰方案，在两个 NOMA 用户处研究了干扰者到窃听者距离和中继到窃听者距离对保密率的影响。基于 MATLAB 的仿真结果验证了提议的功率分配相对于固定功率分配、CJ 相对于其他干扰方案的有效性，以及 HDAF 中继在启用 NOMA 的协作网络的物理层安全增强中的应用。