Analysis of HARQ Performance Based on STAR-RIS Assisted RSMA in V2I Communication

为解决车辆与基站之间通信链路受阻和通信可靠性问题，本文研究同时传输和反射可重构智能表面(Simultaneous Transmitting and Reflecting Reconfigurable Intelligent Surfaces, STAR-RIS)辅助的车辆通信，考虑速率分割多址接入(Rate-Splitting Multiple Access, RSMA)，并结合混合自动重传(Hybrid Automatic Repeat reQuest, HARQ)技术，分析系统性能。通过信道近似分布推导HARQ传输协议下车辆用户的中断概率，根据中断概率表达式进一步分析吞吐量和能量效率，推导出吞吐量和能量效率的闭式表达式。最后，借助MATLAB平台进行数值模拟，验证了理论分析的正确性。结果表明，通过对比不同STAR-RIS元件个数、基站发射功率和HARQ最大重传次数下的系统性能，发现采用HARQ的系统性能优于不采用HARQ的系统，且分配更多功率的车辆用户性能更优。To solve the problems of communication link obstruction and communication reliability between vehicles and base stations, this paper studies vehicle communication assisted by Simultaneous Transmitting and Reflecting Reconfigurable Intelligent Surfaces (STAR-RIS), considers Rate Splitting Multiple Access (RSMA) and combines Hybrid Automatic Repeat reQuest (HARQ) technology to analyze system performance. The outage probability of vehicle users under the HARQ transmission protocol is deduced from channel approximation distribution, throughput and energy efficiency are further analyzed based on the outage probability expression, and closed-form expressions for throughput and energy efficiency are derived. Finally, numerical simulations are conducted using the MATLAB platform to verify the correctness of the theoretical analysis. The results show that by comparing the system performance under different numbers of STAR-RIS elements, base station transmission power, and maximum HARQ retransmission times, it is found that the system performance using HARQ is better than that without HARQ, and the performance of vehicle users who allocate more power is better.