无线Mesh网络多媒体传输QoS路由与MAC层策略研究

发布时间：2018-01-10 09:41

本文关键词：无线Mesh网络多媒体传输QoS路由与MAC层策略研究　出处：《中南大学》2014年博士论文　论文类型：学位论文

【摘要】：摘要：随着无线设备制造成本的下降以及各种无线通信技术的成熟应用,作为下一代宽带接入的重要技术之一的无线Mesh网络已被广泛应用于无线宽带城市、无线校园(企业)和抗灾抢险等领域。与此同时,基于无线Mesh网络的各种音频、视频和高实时性数据业务(如VOIP、视频会议等)在商业应用上的迅速发展,使得人们对无线Mesh网络数据传输的各项QoS指标(如平均延迟、延迟抖动、带宽分配等)提出了更高的要求。然而,无线Mesh网络MAC层的分布式自由竞争模式、节点对全网信息掌握的不完全性等固有特性,都使得现有无线(有线)网络所采用的QoS保障技术很难直接应用于无线Mesh网络及其上的多媒体业务传输,因此,QoS保障问题是仍然是目前无线Mesh网络研究的热点和难点问题。本文从无线Mesh网络的MAC层、网络层和跨层设计的不同角度,对QoS保障策略进行了相关的分析研究,并提出了相应的解决方案。主要的研究工作包括以下几个部分： (1)针对802.11e的EDCA机制和单路径路由协议在QoS保障方面的不足,从跨层优化的角度,提出了一种优先级自适应的QoS路由策略。该策略通过在网络上层设定各类数据流传输的QoS阈值,并在网络层对MAC层AC队列的状态信息进行实时监控,来动态调整不同业务数据包的优先级别,同时在MAC对不同业务数据包的传输时延进行估算,以获取数据成功发送后不同AC队列的平均时延,并对队列的平均冲突概率进行统计,以自适应地调整各队列的信道竞争参数,从而更好地平衡不同类型业务流占用信道机会,以保证不同业务流之间的传输公平性,提升网络的整体传输效率。 (2)针对多路径相邻链路之间的干扰对数据传输质量带来的相关问题,在现有802.11e标准EDCA机制和多路径路由相关问题分析的基础上,利用跨层优化的设计思想,定义了适应于多业务多路径传输的联合路由判据,使网络层的路由选择策略能够根据多媒体数据的业务类型和联合路由判据估算出的当前可用路径的状态与质量信息,合理地选择能满足不同业务类型QoS要求的数据传输路径,同时对EDCA静态的信道竞争参数分配方案进行了自适应改进,使其能适应于无线多跳的数据传输环境,减少了网络中数据包传输的冲突,有效地提高和满足了各类媒体业务数据的传输质量,以及网络传输的公平性。 (3)针对802.11e的EDCA机制在业务区分时未能提供良好的QoS保证的问题,提出了一种基于剩余时延界限的CFB数据包转发机制,该机制在现有802.11e EDCA机制的基础上,针对由于具有较大时延界限的数据流长期占用传输信道,而导致具有较低时延界限数据流出现大量丢包、重传,从而影响整个网络的吞吐量及多数据流传输的公平性问题,通过估算数据包的剩余时延,以及动态调整TXOP的时长及CFB突发数据块的大小,来自适应网络中多优先级业务流量的变化,有效地提高了网络中各类业务数据流的吞吐量。
[Abstract]:Abstract: with the mature application of wireless equipment decreased manufacturing costs and a variety of wireless communication technology, as one of the most important technologies in the next generation broadband access Mesh wireless network has been widely applied in wireless broadband wireless city, campus (enterprise) and disaster rescue and other fields. At the same time, a variety of audio and video based on wireless Mesh network, and high real-time data services (such as VOIP, video conferencing, etc.) in the rapid development of the commercial application, the QoS index of Mesh wireless network data transmission makes people (such as average delay, delay jitter, bandwidth allocation etc.) put forward higher requirements. However, distributed free competition mode in wireless Mesh network MAC layer the node of the inherent information of the whole network of incomplete features, makes the existing wireless (wired) QoS security technology network used is difficult to directly apply to Mesh network and its on line As a result, the problem of QoS guarantee is still a hot and difficult problem in the research of wireless Mesh network.
From the perspective of MAC layer, network layer and cross layer design of wireless Mesh network, this paper analyzes and studies QoS guarantee strategy and proposes corresponding solutions. The main research work includes the following parts.
(1) according to the EDCA mechanism of 802.11e and single path routing protocol in QoS security problems, from the angle of cross layer optimization, proposed a priority adaptive QoS routing strategy. This strategy by setting the QoS thresholds of the various data stream transmission in the network layer, and real-time monitoring in the network layer of the MAC layer AC the queue state information to dynamically adjust the priority level of different business data packets, and packet transmission delay of business data in MAC were estimated, the average delay for data delivery after different AC queue, and the queue average collision probability statistics, to adaptively adjust the parameters of the queue channel competition thus, a better balance of different traffic flow channel opportunities, in order to guarantee the transmission fairness between different business flow, improve the overall efficiency of the transmission network.
(2) for issues related to multipath interference between adjacent links for data transmission quality, analyzing the related problems in the existing 802.11e standard EDCA mechanism and multi path routing, the design idea of cross layer optimization, combined with routing criterion adapted to multi service multi path transmission is defined, the network layer routing according to the state selection strategy and quality of information currently available path of business types and combined routing of multimedia data to estimate the reasonable selection of data transmission path QoS to meet the requirements of different business types, channel competition parameter allocation scheme for static EDCA at the same time to improve the adaptive, so that it can adapt to the data transmission environment wireless multi hop, reduce the packet collision in transmission network, effectively improve the transmission quality and meet all kinds of media business data, and network transmission Fairness.
(3) provide a good QoS guarantee to solve the problem of EDCA mechanism of 802.11e failed to distinguish between business and CFB data is proposed based on residual delay limits packet forwarding mechanism, this mechanism based on the existing 802.11e EDCA mechanism, according to the limit of time delay due to their large data stream transmission channel has long occupied. The emergence of a large number of flow loss, the lower limit of time delay caused data retransmission, thus affecting the fairness of the throughput of the whole network and multi data stream transmission, the remaining delay by estimating the data packets, and dynamically adjust the TXOP time and CFB burst data block size, adapt to changes in the network from multi priority traffic. To effectively improve the various types of business data flow in the network throughput.

【学位授予单位】：中南大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TN929.5

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