无线Mesh网络多信道MAC协议研究

【作者】 李鹤松；

【导师】 冷甦鹏；

【作者基本信息】 电子科技大学 ， 通信与信息系统， 2010， 硕士

【摘要】 随着WMN的不断普及个人数据通信的日益发展,人们对无线网络带宽的需求更高,对覆盖范围的要求更广也更可靠。使得MAP接入的终端用户越来越多,业务量也越来越大,如何解决接入点MAP的瓶颈问题并为多种业务提供不同服务质量的保证成为学术界与技术届的研究热点。使用多信道技术,并改进MAC协议的性能是一种有效的方式来解决不同业务QoS需求问题。IEEE 802.11s是对IEEE802.11标准针对Mesh网络的增补,它改进了IEEE 802.11的MAC协议,并使用IEEE 802.11e标准提供的MAC级QoS增强对不同业务进行服务区分。本文在IEEE 802.11s无线Mesh网络结构下,围绕网络重负载时MAP节点的瓶颈问题以及多介质业务的QoS保证问题展开了讨论。本文分析比较了现有多信道MAC协议,在网络轻负载或者中度负载时,这些协议能很好的协调各节点接入信道,增加网络吞吐量,减少时延。但是现有的多信道MAC协议都无法很好的解决重负载下节点通信问题,不能合理的协商各节点接入信道,冲突率较高,降低了信道利用率。本文提出了NPBM-MAC协议,采用全局节点通信状况表协商信道分配,从而减小了竞争信道的冲突概率。同时,综合考虑节点优先级和业务优先级来区分不同业务,在满足不同业务QoS需求的同时,保证了音视频业务的优先传输。NPBM-MAC协议保证了MPP一跳邻居节点通信时进行合理的分配信道,但不能解决各MAP所辖BSS之间的信道干扰问题,为此,本文提出了一种新的基于地理位置信息和网络负载的频率分配方案LLBFA,该方案对MAP所辖网络负载和其干扰范围进行综合权衡,根据网络拓扑结构,从全局上进行频率分配,减小各BSS间的频率干扰,增加了整个网络的吞吐量。OPNET仿真表明,NPBM-MAC协议和LLBFA频率分配方案,可以有效降低各节点通信时的信道干扰,明显改善端到端时延和网络吞吐量,有效解决重负载下MAP节点的瓶颈问题,最大限度的满足了音视频等大业务流的QoS需求。更多还原

【Abstract】 With the development of WMN and the ever-growing popularity of personal data communication, people want to have a higher demand on wireless network’s bandwidth and coverage. More and more users have opportunity to access MAP, the network traffic becomes bigger and bigger. A lot of researchers want to found a solution for the bottleneck problem at MAPs and provide different services for different business. The use of multi-channel technology, and improve the performance of MAC protocol is an effective way to solve the QoS needs of different businesses.IEEE 802.11s is an amendment of IEEE802.11 standard for Mesh Networks. It improves the IEEE 802.11’s MAC protocol, and provides different services for different businesses by using IEEE 802.11e standard’s QoS enhancements. The background of research is IEEE 802.11s Wireless Mesh network. This paper discusses the bottleneck problem at MAPs and QoS assurance for different business under heavy load network,This paper has analyzed some existing multi-channel MAC protocols. In light-load or moderate-load network, they can do well in coordinating nodes accessing channel for data communications and have some good performance on network throughput, delay and so on. But they don’t have a proper solution to assign channel for every nodes when the network becomes heavy load. This paper designs a new multi-channel MAC protocol (NPBM-MAC), it uses a global node communication state table for channel assignment. Thereby the channel conflict probability has been reduced. At the same time, this protocol distinguishes different services by node priorities and business priorities. It can meet the different businesses’QoS requirements and ensure the traffic of audio/video businesses can be prioritized.NPBM-MAC protocol can not solve the frequency interference problem between BSS, which belongs to different MAP. This paper provides a new frequency assignment scheme—LLBFA, it is based on nodes’location information and network load. This scheme can assign frequency from the overall situation according to network topology. So, it can resolve the problems pointed above. At last, this paper does some simulations by OPNET. The results shows that NPBM-MAC protocol and LLBFA can effectively reduce frequency interference problems, improve the transmission delay and network throughput. It is an effective solution to solve the bottleneck problem at MAPs/MPPs in the heavy load network, so that it can ensure the QoS requirements by video streams and other applications with large bandwidth demand.更多还原