This study presents an analysis for evaluating the physical layer (PHY) security performance of a two-hop amplify-and-forward cooperative relaying system employing Alamouti orthogonal space–time block coding (OSTBC) in the presence of an eavesdropper, where the transmit antennas for OSTBC are assumed to be spatially correlated. It is also assumed that the authorised main channels as well as the non-authorised eavesdropper channels follow Rayleigh fading distribution. Closed-form mathematical expressions are derived for three performance metrics for evaluating the PHY security, namely the probability of non-zero secrecy capacity, the secrecy outage probability, and the average secrecy capacity. Using the extensive numerical results obtained from the derived mathematical expressions, the impact of antennas correlation on the PHY secrecy performance of the system is studied and evaluated under different parameters. It is also shown that the antennas correlation corresponding to the main channels has more impact than the antennas correlation corresponding to the eavesdropper channels.

中文翻译：

---

天线相关性对OSTBC系统协同中继物理层安全性的影响

这项研究提出了一种分析，用于评估在存在窃听器的情况下采用Alamouti正交空时分组编码（OSTBC）的两跳放大转发协作中继系统的物理层（PHY）安全性能假定OSTBC的空间关系是空间相关的。还假定授权主信道以及未授权窃听者信道遵循瑞利衰落分布。为评估PHY安全性的三个性能指标导出了封闭形式的数学表达式，即非零保密容量的概率，保密中断概率和平均保密容量。使用从派生的数学表达式获得的广泛数值结果，研究并评估了不同参数下天线相关性对系统PHY保密性能的影响。还显示出，对应于主要信道的天线相关性比对应于窃听者信道的天线相关性具有更大的影响。