【作者】 李阳辉；

【导师】 曾志文； 陈志刚；

【作者基本信息】 中南大学 ， 计算机科学与技术， 2010， 硕士

【摘要】 多跳无线网络(Multi-hop wireless networks),如移动自组网(Mobile Ad hoc network, MANET),无线传感器网络(Wireless Sensor Network, WSN),无线Mesh网络(wireless mesh network, WMN),在监测,通信,控制等方面有着广泛的应用前景。在多跳无线网络中由于网络节点的移动性、链路的不稳定性、无线传输的不可靠性,导致寻找高效的路由算法存在很大的挑战。传统的路由策略在传输数据之前必须寻找一条有效的传输路径,再传输数据。由于网络中节点的移动,环境的影响,节点自身的故障等,导致传输路径寿命很短,严重降低了传输的效率。机会路由(Opportunistic Routing, OR)则无须寻找一条完整的传输路径,每通过一跳传输,数据包就越“接近”目标节点,每一跳的传输通过无线传输的广播性来提高传输的成功率。机会路由有效地提高了传输稳定性,非常适合于多跳高丢包率的无线网络。针对机会路由本文主要进行了如下的研究工作：提出了一种自组织的节点间断性故障监测方法。基于分段连续监测的思想,本文采用累计信任度来判断节点间断性故障的监测方法SCMCT(Self-configurable Monitoring by Cumulative Trust)。在单次监测中利用信息熵记录节点响应频率,通过信息熵的共享,基于伪空间距离联合诊断节点的间断性。试验结果对比表明,此单次监测方法比已有方法效率明显的提高。为提高节点高速运动时监测的准确性,通过分段连续监测,把单次监测结果作为分类器,计算节点的累计信任度,通过累计信任度衡量节点的间断性。试验仿真表明此方法显著了当节点高速运动时的监测准确性。提出了在多信道多跳无线网络中的机会路由策略MC-OR。首先分析了多跳无线网络中信道冲突的严重性和信道分配的复杂性,给出了一种新颖的基于网络节点路径负载的启发式多信道分配算法,极大地减少了网络的信道冲突。然后分析了考虑信道冲突时,链路的有效带宽,提出了基于EOTT指标的转发候选集的选择策略,并证明了EOTT满足最优化原则。结合背压式调度在高负载网络上的优势和机会路由传输质量上的特性,兼顾优势路径和负载平衡,提出了基于背压式调度的机会路由策略(BPS-OR)。在背压式调度中,利用EODB来描述网络节点与下一跳节点的期望积压差。在机会路由中,设计了EODT指标描述数据包传输到目地节点的期望延迟时间,并证明了EODT指标满足最优化原则,给出了基于EODT的转发候选集产生算法。仿真实验表明,在网络负载轻时,BPS-OR相比DiffQ吞吐量提高了28%,在网络负载较重时,吞吐量提高了52%,能够保证在不同的网络负载上传输效率的稳定。更多还原

【Abstract】 Multihop wireless networks, such as mobile ad hoc networks (MANETs), wireless sensor networks (WSNs), and wireless mesh networks (WMNs), have broad application prospects in monitoring, communication, control, etc. Routing in multi-hop wireless networks presents a great challenge mainly due to the following facts:the mobility of network node, the instability of network link, and the unreliability of wireless transmission. The traditional routing strategy must look for an effective transmission path, and then transfer data. Because of the network of mobile nodes, environmental impacts, the node own failures, and so on, the life span of transmission path is very short, and they seriously reduce the transmission efficiency. On the contrary, opportunistic routing (OR) is not need to find a complete transmission path. Data packets are closer the destination node by each hop transmission through, and the broadcast nature of wireless transmission to improve the success rate of transmission in each hop transmission through. Opportunistic routing effectively improve the transmission route stability, is very suitable for multihop packet loss wireless networks. In this paper, the main research work about Opportunistic routing is carried out as follows:Firstly, this paper proposes an approach which uses cumulative trust to measure intermittent failure (SCMCT) in MANET. In the one-time monitoring, the information entropy is used for taking down the intermittent of nodes response, and a new distributed monitoring scheme with several collaborative detection methods based on pseudo-space distance is defined in this paper. The simulation result shows this approach is much better than the old. In order to improve on the veracity of detection when nodes with high mobility, by the series of subsection monitoring, the monitoring results are seen as classifiers, and the intermittent failure is measured by the cumulative trust. The simulation result shows this approach is wonderful when nodes with high mobility.Secondly, we first present a new routing strategy that generalizes opportunistic routing in multi-channel multi-hop wireless networks. Firstly, after analyzing the seriousness of channel interference and the complexity of channel assignment in Multi-hop Wireless Networks, the novel heuristic channel assignment approach based on the load of network nodes is proposed, which greatly reduces the channel interference of networks. Secondly, we analyze the effective bandwidth of link, in considering the channel Interference, propose the strategy for selecting forwarding candidates set based on EOTT, and prove that EOTT meets the optimization principle.Thirdly, Considering the factors of both advantage path and load balance, this paper takes advantage of back-pressure scheduling in the high-load network and makes use of characteristics of Qos in opportunistic routing transmission, and proposes an opportunistic routing strategy(BPS-OR), which based on back-pressure scheduling. In this strategy, EODB is used to describe the expected differential backlog between current node and the next. In opportunistic routing, EODT is designed to depict the expected delay of transmitting the packet to the destination and it is proved that EODT meets the optimization principle, and then the algorithm of forming forwarding candidates set is given out. Experimental results also show that BPS-OR’s throughput is 28% higher than DiffQ in low-load network, and the gains rise to 52% in high-load network, which potentially improves the stabilization of transmission efficiency of the wireless networks.更多还原