This paper investigates the performance of physical layer security (PLS) in a vehicle-to-vehicle (V2V) communication system, where a transmitter vehicle exploits a dual reconfigurable intelligent surface (RIS) to send confidential information to legitimate receiver vehicles under the non-orthogonal multiple access (NOMA) scheme in the presence of an eavesdropper vehicle. In particular, it is assumed that an RIS is near the transmitter vehicle and another RIS is close to the receiver vehicles to provide a wider smart radio environment. Besides, we suppose that the channels between two RISs suffer from the Fisher-Snedecor F fading model. Under this scenario, we first provide the marginal distributions of equivalent channels at the legitimate receiver vehicles by exploiting the central limit theorem (CLT). Then, in order to evaluate the PLS performance of the considered secure communication system, we derive analytical expressions of the average secrecy capacity (ASC), secrecy outage probability (SOP), and secrecy energy efficiency (SEE) by using the Gauss-Laguerre quadrature and the Gaussian quadrature techniques. Moreover, to gain more insights into the secrecy performance, the asymptotic expression of the ASC is obtained. The numerical results indicate that incorporating the dual RIS in the secure V2V communication under the NOMA scheme can significantly provide ultra-reliable transmission and guarantee more secure communication for intelligent transportation systems (ITS).

翻译：本文研究了车辆间(V2V)通信系统中物理层安全(PLS)的性能，其中发射车辆利用双可重构智能表面(RIS)，在非正交多址接入(NOMA)方案下向合法接收车辆发送机密信息，且存在窃听车辆。具体而言，假设一个RIS靠近发射车辆，另一个RIS靠近接收车辆，以提供更广阔的智能无线电环境。此外，我们假设两个RIS之间的信道服从Fisher-Snedecor F衰落模型。在此场景下，我们首先利用中心极限定理(CLT)给出合法接收车辆处等效信道的边缘分布。然后，为评估该安全通信系统的PLS性能，我们采用Gauss-Laguerre求积和高斯求积技术，推导了平均保密容量(ASC)、保密中断概率(SOP)和保密能效(SEE)的解析表达式。此外，为更深入地洞察保密性能，还获得了ASC的渐近表达式。数值结果表明，在NOMA方案下的安全V2V通信中引入双RIS能够显著实现超可靠传输，并为智能交通系统(ITS)保障更安全的通信。