基于MF协议的协作NOMA系统物理层安全性能研究

针对协作非正交多址(NOMA)系统中信息安全传输问题，该文提出一种基于修改转发(MF)中继的物理层安全(PLS)传输方案。该方案利用MF中继将解码信息修改后再转发，避免了合法信息泄露到窃听节点。首先对NOMA-MF系统进行建模，然后推导了系统安全中断概率(SOP)、严格正保密容量(SPSC)和窃听概率(IP)来衡量系统的保密性和安全性，以及中断概率(OP)以衡量其可靠性。此外，推导了系统的渐近性能，对比分析了解码转发(DF)协议下NOMA-DF系统与NOMA-MF系统的性能。推导及仿真结果表明：NOMA-MF系统的保密性能和安全性能比NOMA-DF系统更具有优势；NOMA-MF系统的OP和IP之间存在最优信噪比(SNR)以实现系统安全及可靠性的平衡；存在最佳功率分配参数以实现最低的SOP和OP。

Research on Physical Layer Security of Cooperative NOMA System Based on MF Protocol

For evaluating the problem of information security transmission in cooperative Non-Orthogonal Multiple Access (NOMA) system, a Physical Layer Secure (PLS) transmission scheme based on Modify-and-Forward (MF) relay is proposed. The scheme uses MF relay to modify the decoded information and then forward it, to avoid disclosing the legitimate information to the eavesdropping node. Firstly, the NOMA-MF system is modeled, and then Secrecy Outage Probability (SOP), Strictly Positive Security Capacity (SPSC) and Intercept Probability (IP) are deduced to measure the confidentiality and security of the system and Outage Probability (OP) to measure its reliability. In addition, the asymptotic performance of the system is derived, and the performance of NOMA-DF system and NOMA-MF system under Decode-and-Forward (DF) protocol is compared. The derivation and the simulation results show that: The confidentiality and security performance of NOMA-MF system has more advantages than that of NOMA-DF system; There is an optimal Signal-to-Noise Ratio (SNR) between OP and IP of NOMA-MF system to achieve the balance of system safety and reliability; There is an optimal power allocation parameter to achieve the lowest SOP and OP.