RIS辅助FSO/RF混构系统性能研究

Performance Study of RIS-Assisted FSO/RF Hybrid System

为了研究可重构智能表面(RIS)辅助自由空间光(FSO)/射频(RF)混构系统的性能,在RF链路中考虑同信道干扰问题的影响。RIS能够解决RF链路无法完成视距通信的问题,从而提升通信系统性能。FSO链路服从双广义伽马分布,并考虑指向误差的影响,RF链路服从瑞利分布,在中继节点处采用译码转发协议,减少噪声对传输信号的干扰。推导了系统端到端瞬时信噪比的累积分布函数,在此基础上,进一步推导了该系统的中断概率和平均误码率的闭合公式。仿真结果表明,该系统方案在弱湍流和中湍流强度下性能提升较为明显。在弱湍流强度下,RIS可以有效抵抗干扰对RF链路的影响,从而提升系统性能。

This paper presents an investigation of the performance of a reconfigurable intelligent surface(RIS)-assisted freespace optical(FSO)/radio frequency(RF)hybrid system by considering the effect of the cochannel interference problem in the RF link.An RIS is used to address the inability of the RF link to complete line-of-sight communication and thus improve the communication system performance.The FSO link adheres to a double generalized gamma distribution and considers the pointing error effect,while the RF link obeys a Rayleigh distribution.Further,a decode-and-forward protocol is used at the relay node to mitigate noise interference in the transmitted signal.The cumulative distribution function of the end-to-end instantaneous signal-to-noise ratio of the system is then derived;on this basis,the closed formulas for the outage probability and average bit error rate(BER)of the system are derived.The simulation results show that the performance improvement of this system scheme is relatively evident under weak and medium turbulence intensity.Under weak turbulence intensity,the RIS can effectively resist the influence of interference on the RF link,thus improving the system performance.