【作者】 秦丹阳；

【导师】 沙学军；

【作者基本信息】 哈尔滨工业大学 ， 信息与通信工程， 2011， 博士

【摘要】 随着社会信息化进程的不断加快,无线移动通信网络已经成为人们生产生活中不可替代的重要组成部分,其相关技术研究的不断深入和发展促使人类朝着“信息化世界和数字化地球”的目标大踏步前行。作为无线移动通信网络的重要分支,移动Ad Hoc网络无需依赖预先架设的基础设施以及能够快速组网和灵活开展等优点,使得其具有良好的环境适应性和结构健壮性,可以被广泛的应用到战场部署、临时会议召开、野外科考、矿区作业以及灾后救援等有着特殊需求的通信环境中。然而,正是这些极具优势和应用潜力的特点却为移动Ad Hoc网络相关技术的研究带来了新的问题和挑战。除了需要面对与传统无线移动网络一样带宽资源和供电能力受限、无线链路连接脆弱、安全性较低以及传输质量无法保证等问题以外,拓扑结构的频繁变化、业务分组的多跳转发以及缺少中心控制机构的调度协调等固有本质也极大的制约了移动Ad Hoc网络的发展。没有中心控制机构以及拓扑结构频繁变化的特征使得路由问题成为移动Ad Hoc网络最具特色也最难解决的技术环节之一。前者意味着需要采用多跳转发的形式实现业务传输,而后者则意味着路由上的每一条链路都是不稳定、不可靠的。因此,如何在复杂多变的环境下通过多跳方式建立端到端的路径便成为路由技术需要面对的重要问题。作为开展最早、所得成果最为丰富的研究领域,路由算法的设计仍然还有很多有待解决的问题。本课题的研究内容将主要针对移动Ad Hoc网络路由算法对网络环境适应性的不足,从节点邻域状态的更新维护、网络业务集中时的传输均衡以及链路失效后的本地修复三个方面展开,通过环路反馈控制算法和最优搜索理论算法建立环境变量与路由因素间的映射关系,使得路由算法能够根据网络环境的动态变化及时做出反应并进行调整,从而提高业务分组在网络中的传输效率和网络整体的服务质量。首先,围绕移动Ad Hoc网络路由技术,分别从节点邻域状态的维护问题、网络业务集中的均衡问题以及链路失效的修复问题三个方面入手,对问题产生的原因及其对网络性能产生的影响进行了阐述和分析。总结了目前针对上述问题从不用角度提出的具有代表性的解决方案,深入研究了这些方案所取得的成果及仍有待解决的问题。对面向动态环境的典型路由算法设计思想进行剖析,分析并给出移动Ad Hoc网络路由问题的本质以及网络环境与路由算法设计间的关系,并据此确定文本的研究思想路线。其次,研究了移动Ad Hoc网络路由技术中节点对邻域状态的维护与更新问题。分析了动态网络环境中采用固定更新周期进行邻域状态维护将产生大量的控制开销从而影响网络性能的本质。基于节点链路连接的变化情况,设计了本地拓扑振荡度,用于衡量其邻域网络环境的稳定程度。采用环路控制理论构造了状态更新周期的控制模型,并据此建立了本地拓扑振荡度与状态更新周期间的映射关系。结合本地拓扑振荡度及所得控制模型,提出了由HELLO分组自适应广播、邻居超时值自适应调整以及反应式HELLO信息重调度三种机制构成的邻域状态自适应更新算法,以保证状态更新周期能够根据网络环境的需要而进行动态设置和调整,从而实现降低网络控制开销并提高业务分组传输效率的研究目的。再次,研究了移动Ad Hoc网络中当业务集中在某些链路或节点处时分组传输的路径均衡问题。分析了在拓扑结构动态性较弱的网络环境中,由于采用反应式路由协议而较长时间利用某些路径进行业务传输对网络生存期及业务分组传输效率产生的影响。基于节点缓存业务转发后剩余功率的情况,设计了业务负载度的度量用于衡量节点业务的繁忙程度,并据此提出了一种包括主动均衡和被动均衡两种机制的自适应业务均衡路由算法,以实现节点根据自身业务负载度的不同而分别采用业务路径转移和放弃转发的方式实现业务均衡传输的目标。此外,针对均衡过程中可能出现的个别节点为了保存自身能量而拒绝转发其它节点的业务分组从而导致均衡受阻的现象,提出了一种自适应业务均衡公平性辅助算法,旨在快速、准确的检测出自私节点并迫使其参与到均衡过程中,以实现提高业务均衡效果并延长网络生存期的目标。最后,研究了移动Ad Hoc网络由于节点相对运动或无线环境变化所引起的链路失效的修复问题。分析了传统的本地修复方式采用全网泛洪所产生的大量控制开销对业务传输时延及分组成功交付率等方面产生的影响。基于最优搜索理论建立了链路失效时本地节点对下一跳节点的搜索模型并构造相应的状态方程,从而将最优搜索的数学问题转化为链路失效时本地节点对当前链路的修复问题。根据业务分组接收功率的情况,设计了路由质量检测方法用以缓解传统方式在链路失效后才发起修复过程对业务传输效率产生的影响,并建立网络环境与路由修复间的映射关系。结合路由质量检测结果和最优搜索模型的射线解,提出了控制修复信息传输范围的本地路由自适应修复算法,以较小代价和较高概率实现业务传输路径的修复。此外,针对最优搜索方程扩展后可能引起解的不唯一性,提出了路由修复后的优化算法,用以确保修复路径在稳定的前提下最短。更多还原

【Abstract】 With the accelerating of social informationization, wireless mobile communication networks have become an irreplaceable component of daily life, and the development of relative researches has promoted the process towards“information world and the digital earth”. As an important branch, the strong points of infrastructureless, rapid networking and flexible to carry out of mobile Ad Hoc network make it adaptable and survivable, and it can meet special needs such as battlefield deployment and disaster relief. It is these advantages, however, that brings new challenges for mobile Ad Hoc network research. Besides the bandwidth and energy limit, weak wireless connection and so on, mobile Ad Hoc network has to meet more than topology frequent changes, multihop forwarding and lack of central scheduling, which restrict the development greatly.The characteristics of centerless control and topology frequent changes, make routing problem one of the most important technical keys. The former means multihop style needs to be adopted, and the latter indicates each link of the route is unstable and unreliable. As a field that carried out earliest and achieved most, routing design has many issues to be addressed. This dissertation will mainly focus on the deficiency of network adaptability from routing algorithm of mobile Ad Hoc network, and carry out from node neighborhood state update, transmission balancing and local repair after link invalidation to make the routing algorithm be able to react with dynamic environment through setting up mapping relationship between environment variables and routing factors by the loop control algorithm and optimal exploration theory, so as to improve traffic transmission efficiency and service quality.Firstly, this dissertation will analyze and expatiate on the causes and impacts of the neighborhood maintenance, the traffic balancing and the link repair around routing technology in mobile Ad Hoc network. With an introduction on representative solutions from different points of view, the achievements and problems remained will go into details. The design of dynamic environment-oriented typical routing algorithms has been taken apart, and the essence of routing issues as well as relationship between network environment and algorithms devising will be presented, based on which the ideological line of this dissertation will be mapped out. Secondly, the neighborhood state maintenance and update problems in routing issues will be addressed. The impacts of fixed updating cycle in neighborhood state maintenance will be analyzed. Local topology flapping measurement will be devised to judge the stability of neighborhood state. The control model of state updating cycle and its relationship with LTFM will be established based on loop control theory. The neighborhood state self-adaptive updating algorithm will be proposed to ensure that the updating cycle will be set and adjusted dynamically according to network environment so as to reduce the control overhead and improve traffic transmitting efficiency.Moreover, the issue of transmission balancing when the traffic concentrates on some links or nodes will be studied. Impacts of long time usage about some certain paths according to reactive routing protocol on the network life time and transmission efficiency will be analyzed in detail. The traffic load measurement will be devised to judge the busy degree. The self-adaptive traffic balancing routing algorithm will be proposed to make nodes balance the transmission according to the value of load measurement. Besides, considering some individual nodes may refuse to forward to save energy in balancing process, a self-adaptive traffic balancing fairness auxiliary algorithm will be proposed to detect the selfish nodes quickly and exactly to compel them to join in balancing process in order to prolong the network life time.Finally, the local link repair problem caused by relative motion or environment changing will be presented. The exploring model and corresponding state functions from the local node to the next hop will be established by the optimal exploration theory, so as to convert the optimal exploration problem into the local repair one. A route quality inspection approach based on traffic packets received power will be adopted to alleviate the delay cause by repair process initialed after the link invalid and establish the relationship between network and route repair. Combining route inspection result and radial solution from the optimal exploring model, a local link self-adaptive repair algorithm will be proposed by restricting the flooding region to repair the route with less cost and higher probability. Furthermore, an optimizing algorithm will be supplemented to solve the problem of more than one solution obtained so as to ensure the shortest route with stability.更多还原