光载无线网络的MAC层优化控制及性能分析

同播光载无线分布式天线系统(Radio-over-Fiber based Distributed Antenna Systems,RoF-DAS)中,基站在下行链路采用同播方式向多个远程天线单元(Remote Antenna Units,RAUs)传输无线信号,而不同RAUs覆盖的用户站点在上行方向通过不同长度的光纤链路接入位于基站的无线网络接入点。文中提出一种并行调度门限服务方式下的IEEE 802.11 PCF接入控制策略,通过捎带技术实现数据传输和数据请求过程的并行处理,同时利用门限服务方式进行数据传输,以提高信道资源利用率,减小光纤引入时延对网络性能的影响；建立数学模型,分析得出系统平均排队队长和吞吐量的闭式解析式,弥补了在研究光载无线网络性能时仅依靠实验进行性能分析的不足。通过仿真实验和理论分析验证了 所提策略对提高网络吞吐量和缩短数据排队等待长度的有效性。

Improved MAC Protocol in Radio-over-fiber Networks and Its Performance Analysis

In simulcast radio-over-fiber based distributed antenna systems (RoF-DAS),a single set of base stations simu-ltaneously broadcast wireless signals to multiple remote antenna units (RAUs) in the downlink,and in the uplink,user stations covered by different RAUs are connected to a wireless local-area network access point with different-length fiber links.To provide a contented-free media access control,this paper presented a parallel gated service IEEE 802.11 point coordination function (PGPCF) with gated service scheme and piggyback technology,improving the throughput of channel resources and reducing the delay deriving from the fiber.This paper also established a Markov chain analysis model to achieve the closed form expression of the mean queue length and the throughput,which overcomes the shortcoming of only employing experiments to analyze the access mechanism of RoF networks.Both the theory analysis and simulation results suggest the validity of improving the network throughput and shortening the mean queue length.