【作者】 卢先领；

【导师】 孙亚民；

【作者基本信息】 南京理工大学 ， 计算机应用技术， 2008， 博士

【摘要】 无线Ad hoc网络是由众多的无线移动节点通过分布式算法自组织而成的一种网络,每个节点兼有终端和路由器的功能,这些节点不需要网络基础设施的支持,自发地以多跳的方式快速地建立通信联系,具有部署方便,灵活的特点。无线Ad hoc网络具有自我建立、自我组织及自我管理的能力,节点间能相互协作,采用分布式算法控制网络行为,共同完成任务,并可以在移动、不稳定连结的情况下有效地使用资源,因而在商业、军事等领域具有诱人的应用前景。无线Ad hoc网络是一个复杂系统,研究的内容非常广泛。由于其资源有限,信道的容量随着网络的控制参数、环境不断发生变化,造成网络拓扑多变,原有的网络分层结构无法适应无线Ad hoc网络的需要。本文针对无线Ad hoc网络独有的特点,应用网络跨层设计技术,在无线Ad hoc网络的广播路由、多径路由、拥塞控制等方面进行了探索和研究。主要的工作如下:1、对现有无线Ad hoc跨层设计技术进行了全面的研究,给出了无线Ad hoc网络跨层设计的定义,分析了跨层设计的原因、优势和主要技术;对跨层设计的方法进行了分类,主要包括四种方法:层间传递相关信息,联合优化网络相关层,融合相邻层,分层作为网络最优化分解,并对他们进行了分析比较和评价;最后探讨了无线Ad hoc网络跨层设计面临的挑战和今后的研究方向。2、研究了一种跨层协助的广播策略。在无线Ad hoc网络中,对全网进行广播有着重要的应用。然而,网络节点资源、网络资源严重受限,广播引起的广播风暴问题加剧了资源的消耗。文中提出一种跨层协助的广播策略,该策略利用一跳邻节点的信息和物理层、数据链路层的信息统一在MAC层设置退避时间,并根据发送节点密度自适应调整退避的时间,减少转播冗余、冲突发生的概率和延迟,确保了广播的可达性。3、研究了一种能量高效的广播算法。无线Ad hoc网络节点的能量有限,广播消耗了较多的网络能量,平衡节点的能量消费,延长网络的寿命非常重要。提出了一种能量高效的无冲突的广播策略,该策略利用所有两跳邻节点的剩余能量和度等信息选择前向转播节点,并将前向转播节点分为相互不干扰的独立子集,统一为独立子集设置退避时间,避免冲突的发生。该策略平衡了网络中节点的能量消费、延长了网络寿命,同时也减少了广播延迟和转播冗余。4、研究了能量均衡的跨层多径路由算法。提出了一种无线Ad hoc网络能量均衡的跨层多路径路由选择算法EBCLMRA。算法EBCLMRA利用网络节点的跨层信息:节点的剩余能量参数、发射接收节点之间的距离、缓存队列的长度以及数据包的平均处理延迟等,决策多条路由的选择,从而构建多条不相交的多径路由。并在实际的数据传输过程中,根据发射接收节点间的距离,自适应调整发射功率,减少节点间的干扰,提高能量效率。该算法能均衡网络节点的能量消费,减轻节点的拥塞,延长无线Ad hoc网络的生存时间,减少网络延迟。5、研究了流量自适应平衡的跨层多径路由算法。提出了一种无线Ad hoc网络流量自适应平衡的多径路由选择算法LACLMRA。算法LACLMRA利用网络的跨层信息:传输层提供的数据端到端传输延迟、节点MAC层提供的最近一次传输成功前重传次数、网络层的缓存队列长度等信息选择路由,构建多条不相交的多径路由。并根据路由的质量,在多条路径中自适应分配流量,缓解节点的拥塞,减少了网络延迟,延长无线Ad hoc网络的生存时间。6、研究了跨层的拥塞控制算法。尝试将分层作为跨层优化的分解,提出了一种无线Ad hoc网络拥塞控制算法,该算法将整个无线Ad hoc网络建模成网络端到端会话的效用最大化函数,将网络的拥塞控制问题分解为传输层和链路层的控制问题。传输层与数据链路层通过链路的拥塞价格协调网络传输层与数据链路层的数据传输,无需修改原有TCP协议,也不需要对网络进行额外的信息探测,能有效地调节网络资源的消费,网络能根据本地的信息,控制网络数据的传输,从而有效地控制拥塞。更多还原

【Abstract】 Wireless Ad hoc networks consist of wireless mobile devices which form temporary networks without of the aid of established infrastructure or central administration. Nodes can not only as a host but also as routers when two nodes can not directly link each other. They assemble the network themselves, adaptively allocate resource to performance degradation, manage technology variations of nodes and respond to network requirements and task diversifications. The wireless, distributed and self-configuring natures of Ad hoc networks make them suitable for a wide variety of applications such as military and business.Wireless Ad hoc networks are a complex system, in which the contents of the research are very extensive. The original network layering structure can’t adapt the demand of wireless Ad hoc networks, Because of its limited resources, the dynamic topology of network and the changeable capacity of wireless channel along with the control parameter and environment of the network. This text aims at a special characteristics of wireless Ad hoc network and mainly studies Cross layer design of wireless network. Include of cross layer design of broadcast, multi-path route protocol congestion control and simulates them. The details are as follows:In order to accelerate the development of various applications and high-performances in Ad hoc wireless networks, cross layer design has been discussed and is becoming an important and difficult research problem for wireless Ad hoc network. First cross layer design is defined, the motivations and the advantages of cross layer design are analyzed in the paper. Secondly, all important approaches of cross layer design are depicted and discussed according to different categories: passing information across layers、joint design cooperated layers、merging adjacent layers and layering as optimization decomposition. At the same time the paper evaluates and compares them with performance and complexity. At last the challenges of cross layer design are discussed and the future research work is proposed.Broadcasting is a common operation in Ad hoc wireless networks with severe resource constraints. The problem of broadcasting storm aggravated the resource consumption in Ad hoc networks. We propose a cross layer assisted broadcasting strategy for Ad hoc networks which is made use of 1-hop neighbor knowledge to decide to rebroadcast, and information of physical layer and MAC layer to differentiate time of rebroadcast at MAC layer. The different time of rebroadcast is adjusted adaptively by the density of transmitter node. We propose energy efficient broadcasting strategy without collision for Ad hoc networks which is made use of 2-hop neighbor knowledge, the surplus energy of a node and the degree of node to decide to rebroadcast. The nodes in forward node list are divided into several independent subsets which can rebroadcast simultaneously without collision. The different time of rebroadcast is set adaptively by the density of independent subset node.This paper presents an energy-balanced cross-layer multi-path routing algorithm (EBCLMRA) for Ad hoc wireless networks. In order to improve energy efficiency of Ad hoc networks, EBCLMRA combines the cross-layer information of networks such as the remained energy of nodes, the distance of neighbor node, the length of packets in sending buffer and the delay of the packets in node to find multiple node-disjoint paths in Ad hoc wireless networks. The sending nodes in the path selected power adaptively to reach the next hop according the distance of the sending and receiving to reduce interference and improve energy efficiency. The algorithm can balance the energy of node in the networks, reduce congestion in nodes, prolong the life time of networks and reduce the average delay of the network.This paper presents a load adaptive cross-layer multi-path routing algorithm (LACLMRA) for Ad hoc wireless networks. In order to improve performance of Ad hoc networks, LACLMRA combines the cross-layer information of networks such as the end to end delay of network, the number of re-transmission before success, the length of packets in sending buffer in nodes to find multiple node-disjoint paths in Ad hoc wireless networks. The sending node allocated rate for each path adaptively according the quality of routing path to improve performance. The algorithm can reduce congestion in nodes, reduce the average delay of the network and prolong the life time of networks. The results show that LACLMRA is able to reduce average delay, improve the throughput and prolong the life time of networks compared with SMR and AOMDV.This paper present a distributed congest control algorithm that couples with existing transmission control protocols (TCPs) and MAC protocols to increase end-to-end throughput and energy efficiency of the network. Under the rigorous framework of nonlinearly constrained, this paper presents a step toward a systematic understanding of "layering" as "optimization decomposition," where the overall communication network is modeled by a generalized network utility maximization problem, each layer corresponds to a decomposed subproblem, and the interfaces among layers are quantified as the optimization variables coordinating the subproblems. In the case of the transport and link layers, link congestion prices turn out to be the optimal "layering prices" to cooperate transport layer and link layer. There no modifies in tcps and no probes in networks. Congestion can be controlled by local information.更多还原