联合频谱切换调度和QoS重路由的性能优化算法

Joint Spectrum Handoff Scheduling and QoS Re-routing for Performance Optimization

频谱切换技术可以降低无线传输干扰、优化网络结构,成为无线网络研究的热点。现有频谱切换技术忽视了频谱切换执行顺序对网络性能的影响,无法保证网络在切换过程中的连通性和吞吐量。为了最大化网络吞吐量,提出一新的频谱切换调度问题(SHSTM:Spectrum Handoff Scheduling for Throughput Maximization),并证明SHSTM是NP难问题。为解决SHSTM问题,提出联合频谱切换调度和QoS重路由的跨层优化算法JSHSQ-R。在JSHSQ-R中,频谱切换分多轮执行。为了减少切换延时并保证网络连通性,该算法基于加权最小生成树来确定每轮需要切换的链路,并在切换过程中为数据流进行重路由来满足数据流的QoS需求。在NS2上进行了大量仿真实验,结果表明所提算法能够充分利用无线网状网多接口多信道资源,并能为多流提供较高的网络吞吐量保证。

Spectrum handoff has attracted the interest of many people as it can reduce interference among wireless transmissions and optimize the structure of wireless network. Current studies on spectrum handoff can＇t guarantee the connectivity and high throughput of wireless network when spectrum handoff happens because these studies ignore that spectrum handoff order among multiple links can impact performance. To maximize the throughput of wireless network, this paper proposed a novel spectrum handoff scheduling problem （SHSTM）, and proved that SHSTM is an NP-hard problem. To solve the SHSTM problem, we proposed a cross-layer optimization algorithm by jointly considering the spectrum handoff scheduling and QoS Re-routing （JSHSQ-R）. Spectrum handoff executes in several rounds in JSHSQ- tL To reduce the total delay of spectrum handoff and to guarantee the network cormectivity,JSHSQ-R computes links sets whose spectrum needs to handoff in every round based on weighted Minimum Spanning Tree. To satisfy the QoS requirement of every flow,JSHSQ-R computes a QoS routing for every flow in every round. We made lots of simula- tions in NS2. The simulation results demonstrate that the proposed algorithm can make full use of multi-radios and multi-channels in wireless mesh network and obtain high throughput for multiple flows.