This paper presents and analyzes a novel multiuser network based on hybrid free-space optical (FSO)/radio-frequency (RF) transmission system, where every user is serviced by a primary FSO link. When more than one FSO link fail, the central node services these corresponding users of non-equal priority by using a common backup RF link according to a $p$ persistence servicing protocol. A novel discrete-time Markov chain model is developed for the proposed network, where different transmission rates over RF and FSO links are assumed. We investigate the throughput from central node to the user, the average size of the transmit buffer allocated for every user, the frame queuing delay in the transmit buffer, the efficiency of the queuing system, the frame loss probability, and the RF link utilization. Numerical examples show that transmitting a data frame with probability $p$ when using the common backup RF link achieves considerable network performance improvement while ensuring high-priority users enjoy better performance. Meanwhile, the performance of low-priority users approaches the performance when using equal priority protocol to serve all the remote users.

中文翻译：

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基于P-Persistence协议的非等优先级多用户FSO/RF网络性能分析

本文介绍并分析了一种基于混合自由空间光 (FSO)/射频 (RF) 传输系统的新型多用户网络，其中每个用户都由主 FSO 链路提供服务。当多个 FSO 链路发生故障时，中心节点根据一个共同的备份 RF 链路为这些不等优先级的对应用户提供服务。 $p$ 持久化服务协议。为提议的网络开发了一种新颖的离散时间马尔可夫链模型，其中假设 RF 和 FSO 链路上的传输速率不同。我们调查了从中心节点到用户的吞吐量、为每个用户分配的发送缓冲区的平均大小、发送缓冲区中的帧排队延迟、排队系统的效率、帧丢失概率和 RF 链路利用率。数值例子表明，以概率传输数据帧 $p$ 当使用普通备份射频链路时，可显着提高网络性能，同时确保高优先级用户享受更好的性能。同时，低优先级用户的性能接近使用等优先级协议为所有远程用户服务时的性能。