This paper delves into the performance evaluation of a non-orthogonal multiple access (NOMA) enabled vehicle-to-vehicle (V2V) communication system empowered by simultaneously transmitting and reflecting reconfigurable intelligent surfaces (STAR-RIS). Herein, we consider that a moving access point (AP) transmits superimposed signals to nearby and distant NOMA vehicles simultaneously via reflection and transmission through a STAR-RIS equipped vehicle with 2N reconfigurable elements, respectively. Specifically, by characterizing all V2V channels as double-Rayleigh fading distributed, we derive the outage probability (OP) and ergodic capacity (EC) expressions for each NOMA vehicle, by employing both perfect and imperfect successive interference cancellation (SIC) at nearby vehicle user. Furthermore, we present the asymptotic OP behavior at high signal-to-noise ratio (SNR) regime to gain deeper insights into the diversity order of NOMA vehicles. The findings reveal that the nearby vehicle under perfect SIC and far vehicle experience a diversity order of Nπ4256−π2, which is the function of number of reconfigurable elements (N) in the STAR-RIS. Whereas, a zero diversity order is obtained for nearby user under imperfect SIC case. Moreover, we analytically discuss the high SNR slopes of EC for both user vehicles. Furthermore, Monte-Carlo simulations are conducted to validate our analytical results under various channel and system parameter configurations. We also provide a comparison between the proposed scheme and STAR-RIS based orthogonal multiple access and cooperative relaying systems.

中文翻译：

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STAR-RIS-NOMA 赋能的车对车通信：中断和遍历容量分析


本文深入探讨了通过同时传输和反射可重构智能表面 （STAR-RIS） 实现的非正交多址多址 （NOMA） 车对车 （V2V） 通信系统的性能评估。在此，我们认为移动接入点 （AP） 通过反射和传输分别通过配备 2N 个可重构元件的 STAR-RIS 车辆同时将叠加信号传输到附近和远处的 NOMA 车辆。具体来说，通过将所有 V2V 信道描述为双瑞利衰落分布，我们通过在附近的车辆用户处采用完美和不完美连续干扰消除 （SIC） 来推导出每个 NOMA 车辆的中断概率 （OP） 和遍历容量 （EC） 表达式。此外，我们提出了高信噪比 （SNR） 情况下的渐近 OP 行为，以更深入地了解 NOMA 车辆的分集顺序。研究结果表明，完美 SIC 和远距离飞行器下的附近飞行器经历 Nπ4256−π2 的多样性阶数，这是 STAR-RIS 中可重构元件数量 （N） 的函数。然而，在不完美 SIC 情况下，附近用户获得零分度顺序。此外，我们分析讨论了两种用户车辆的 EC 的高 SNR 斜率。此外，还进行了蒙特卡洛模拟，以验证我们在各种通道和系统参数配置下的分析结果。我们还提供了所提出的方案与基于 STAR-RIS 的正交多址和协作中继系统之间的比较。