自组网中一种可靠的层次路由协议

针对自组网中基于多层有中心分级结构(MCHS)的分级状态路由(HSR)协议存在结构稳定性差、结构维护开销大、可靠性不高和丢包问题严重等问题,提出一种可靠的层次路由协议(RHRP)。它基于一种新的多层无中心分级结构(MCLHS),该结构采用无中心策略,有利于提高结构稳定性和降低结构维护开销,并能进一步提高可靠性和降低路由开销。RHRP采用"高层虚拟链路以群为构成元素"的策略,使高层虚拟链路更稳定,有利于提高可靠性。更稳定的结构和高层虚拟链路可以减少丢包数目和重路由次数,从而降低传输时延和路由开销。通过分析路由可靠度,从理论上证明了RHRP的可靠性较高。通过仿真评价RHRP和HSR的性能,结果表明,RHRP在投递率、平均端到端时延和路由开销等指标上都优于HSR。     

一种基于跨层设计的UWB无线Ad hoc网络MAC层协议

运用跨层设计思想和方法研究了超宽带（UWB）无线自组织（Ad hoc）网络媒体访问控制（MAC）层协议的设计,提出了一种可利用UWB技术定位性好的优势和实现跨层协作的MAC层协议。该协议通过物理层、MAC层和网络层之间的跨层协作来解决自组织网络单信道无线传输过程中的隐藏终端和暴露终端问题以及网络能量节约问题,以提高网络的性能。仿真实验表明,该协议在平均吞吐量、平均端到端时延以及能量开销等性能指标上,均优于已有的IEEE802．11和MACA—BIMAC协议。该协议的设计思想和方法为下一步的UWB无线Ad hoc网络研究奠定了理论和实验基础。     

基于节能的无线传感器网络跨层优化设计研究

无线传感器网络的特点决定了解决能量问题是WSN优化的关键。传统分层协议优化模式下层与层间信息难于共享,增加了通信开销以及信息冗余,没有充分利用网络资源。考虑到链路质量、剩余能量会在很大程度上影响路由方式,拓扑结构会影响信道的使用方式,本文在LEACH-L协议的基础上进行设计优化,提出一种基于跨层优化思想的分簇路由协议Leach-CLO。     

一种基于改进蚁群优化算法的WSNs路由协议

面对无线传感网络(wireless sensor network,WSN)路由问题,提出新颖生物激励-自我组织的安全自适应路由协议(biological inspired self-organized secure autonomous routing protocol,BIOSARP)。BIOSARP采用改进蚁群优化算法(improved ant colony optimization,IACO),利用端到端传输时延、剩余电量和链路质量计算信息素,并据此信息决策最优转发节点,从而减小广播次数和数据包负担,降低时延、数据包丢失率和功率消耗。仿真结果表明:提出的BIOSARP在数据包传递率、能量消耗优于安全实时负荷分配协议(secure real-time load distribution,SRTLD),数据包传递率提高24.75%,能量消耗降低31.8%。     

基于区域分组的城市VANETs的安全信息广播协议

为提高城市车辆自组织网络(VANETs)安全信息广播的有效性,提出了一种基于区域分组的安全信息广播协议(AGBP)。该协议采用正三角形法或正六边形法给中继节点每跳覆盖的区域平均分割,节点按照所在的区域分组。正三角形和正六边形顶点为中继节点的最佳位置,每一组内所有的节点根据自己和中继节点最佳位置的距离计算等待时延,由等待时延决定每一组内的中继节点并转发信息,因此信息可以同时沿着多个方向多条路转发。与传统的沿着一条道路转发信息的广播协议相比,该协议能够避免因分组不当造成信息冗余和碰撞,致使信息的传输效率下降,从而能够降低网络开销、链路时延和转发节点率,提高覆盖率。     

基于路径到达率和动态广播时延的汇聚树协议

汇聚树路由协议(CTP)是目前无线传感器网络(WSN)中常用的数据采集路由协议。它是基于期望传输次数(ETX)的树型路由协议。但对多跳路径的衡量,简单的ETX相加往往无法良好刻画实际路径质量,致使该协议很难选出最优路径。本文提出了基于端到端的数据到达率(PDR)的CTP改进协议,能更好地衡量多跳路径的网络质量。据此选出的最优路径能构建更优的汇聚树,提高端到端数据传递的成功率,减少平均传递次数和平均传递时间,这样可以节省能耗,提高网络生存时间。同时,本文提出在建树过程中采取动态时延广播策略,可以有效减少建路由树时的广播次数,节省开销。     

一种新的基于移动预测的MANET路由协议

移动自组网是一种由一系列可以自由移动的节点主机聚集而成的一个临时性动态网络。它没有固定基站，也没有作为控制管理中心的节点主机，由于其拓扑的动态性，其路由协议与其他传统网络有很大的区别。为了能更有效地移动自组网中实现数据的传送，本文提出了一种基于移动预测下的MANET路由协议，该协议综合考虑了传输路径的延时和稳定性，选择在延时限制下平均拥有最稳特性的传输路径，模拟结果表明，这种方法比基于移动预测量稳路径路由协议的传输时延要短，传送成功概率要高，而控制开销却相关不大。     

Ad Hoc网中的OLSR路由协议研究

本文主要描述了优化链路状态路由算法(Optimized Link State Routing Protocol：“OLSR”)的特点，并且对OLSR路由算法的性能进行仿真分析。主要评估的参数有：数据分组成功接收率，数据分组投递的平均端到端时延，点到点数据传输平均速率。在此基础上研究了OLSR在传统的链路状态路由算法上引入的优化策略多点中继站(multipoint relay，MPR)：采用选择一部分邻居节点来转发控制信息。     

基于广播树的移动自组织网络合作路由协议

为了激励自组网中的自私节点使其参与网络合作,提出了一种基于VCG机制计算转发节点支付的BEC协议,此协议对LDTTO协议的支付方案进行了改进,使源节点失去作弊动机.在路由发现阶段,创建以目的节点为根的广播树,将节点拓扑信息沿广播树以单播方式发送到根节点,降低了网络控制负载开销和路由发现延迟.BEC协议引入了容错机制,通过在混杂模式下对父节点的监听来确保数据的正确传输.在BEC协议中,高度为O(lgn)的广播树,路由发现过程的消息负载为O(nlogn),低于LOTID协议的O(n2).仿真实验结果表明,与现有的几种重要协议相比,BEC协议具有更低的消息负载和网络延迟.     

蚁群算法在智能LED路灯控制中的应用研究

为了优化LED路灯控制并达到有效监控,减少节点能量消耗,提升LED路灯控制中网络节点处理和传播数据的效率,本文使用蚁群算法研发一种可用在LED路灯低压配电网寻址法,能改善最优路径搜索的力度.针对计算精度低和能耗高现象,设计了蚁群算法的一种改进措施更好地免除算法陷进局部最优.算法根据PLC管理路灯性能特点构建网络拓扑结构模型,给出与此研究匹配的优化目标函数和状态转移定律并更新信息素,最后围绕函数目标与状态转移定律和搜寻等对要素订正和改善,设计自动路灯路由模型,拟定路由自动协议框架.凭借低压配电网,模型信道质量可达到动态识别,信道质量变化时,电力线网络通信载波能完成动态路由维护,使通信网络可靠实现.该方法能降低网络能耗,有效避免网络拥塞,提高平均路灯路由命中率,减少路由执行时间.此法在仿真验证中证明了其可靠性和有效性.     

On physical layer-oriented routing with power control in ad hoc wireless networks

Routing in ad hoc wireless networks does not simply consist in finding a route with shortest length (as in wired networks with virtually error-free communication links), but it requires the creation of a stable and good quality communication route to avoid any unnecessary packet loss. In this paper,we discuss physical layer-oriented routing in ad hoc wireless networks, and we analyse the potential advantages of combining the use of power control (PC) with the chosen routing strategy. More precisely, we propose a modified ad hoc on-demand distance vector (MAODV) routing protocol, with and without PC, derived from the AODV-routing protocol by considering the bit error rate at the end of a multi-hop path as the metric to be minimised for route selection. In other words, we consider routing with a physical layer-oriented quality of service criterion, and we analyse the system performance in scenarios with either strong line-of-sight (LOS) or shadowed communications. Although in a scenario with strong LOS communications there are a few cases where the MAODV-PC protocol offers the best performance, in the presence of shadowed communications the proposed physical layer-oriented strategy is not attractive.     

Sea trials of an underwater, ad hoc, acoustic network with stationary assets

The diverse roles of deployable underwater assets have increased the need for ad hoc networking capability. This capability is defined as the ability to form acoustic communication links by deploying assets in a non-deterministic manner, without depending on a priori route and positioning information. Each asset represents a node in the network, and can act as a data source, sink or router, and initiates, stores or relays data, respectively. Data packets may be hopped over a few nodes before arriving at the designated destination. This ad hoc network consists of two main layers: the medium access control (MAC) layer to resolve node contention, and the ad hoc routing layer to manage routing information. In the MAC layer, both random access and timedivision protocols are applied. The protocol in the routing layer is responsible for route setup and route maintenance. This concept of multiple-hop, ad hoc networking was implemented during sea trials conducted in Portland Harbour, UK, involving up to six nodes. The trial was designed with the aim of gaining application experience in ad hoc network deployment and in assessing the performance of the protocols in a real operating environment. The emphasis was on modem integration, and the stability and reliability of packet transport. The trial results and their subsequent analysis demonstrated the robustness of the network in performing ad hoc routing and resolving node contention in a realistic and acoustically challenging environment.     

Compatibility of TCP Reno and TCP Vegas in wireless ad hoc networks

Previous work has shown that TCP (transmission control protocol) Vegas outperforms the more widely deployed TCP Reno in both wired and wireless networks. It was also shown that when both TCP variants coexist on the same wired links, Reno dominates because of its more aggressive behaviour. This paper examines for the first time the compatibility between Reno and Vegas in wireless IEEE 802.11 ad hoc networks. It is shown that Vegas generally dominates in the heterogeneous Reno/Vegas network scenario; a startling result that is inconsistent with what is seen in wired networks. It is shown that the wireless ad hoc network environment does not reward the aggressive behaviour of Reno. On the other hand, Vegas, with its more accurate yet more conservative mechanisms, is able to capture most of the bandwidth. This is found to be true when using the on-demand routing protocols of dynamic source routing (DSR) or ad hoc on-demand distance vector (AODV): the failure of a node to reach a next-hop node because of media access control (MAC)-sublayer repeated collisions is reported to the routing protocol, which then declares a route error that impacts Reno in a more serious way than Vegas. When the table-driven routing protocol destination-sequenced distance vector (DSDV) is used, Reno and Vegas share the network bandwidth in a fairer manner. Generally, fairness in this environment can be improved by reducing the TCP maximum window size.     

Link stability and mobility in ad hoc wireless networks

The fact that ad hoc networks are required to support mobility of individual network nodes results in problems arising when routing data. These problems include route loss, poor longevity of established routes and asymmetric communications links. Mobility of nodes also increases the control traffic overhead and affects the performance of the protocol. Mobility can, however, be exploited to improve route longevity when establishing the route. In some situations, the source of information is not available (e.g. GPS information in the underground), hence protocols relying on this information will fail to operate correctly. In such situations, alternative `self-content' information should be available to perform the needed task of routing. Three novel schemes that make use of such information, the heading direction angle, to provide a mechanism for establishing and maintaining robust and long-lived routes are presented. The results show that these schemes reduce the overhead and increase the route longevity when compared with the AODV protocol. The schemes described can operate as a standalone mechanism or can be adopted by other routing protocols in order to improve their performance.     

An Energy Based Dynamic AODV Routing Protocol in Wireless Ad Hoc Networks

In recent years, with the rapid development of the Internet and wireless communication technology, wireless Ad hoc networks have received more attention. Due to the limited transmission range and energy of nodes in Ad hoc networks, it is important to establish a reliable and energy-balanced transmission path in Ad hoc networks. This paper proposes an energy-based dynamic routing protocol based on the existing AODV routing protocol, which has the following two aspects of improvement: (1) In the route discovery process, a node selects a suitable route from the minimum energy consumption route and the energy-balanced route designed in this paper according to a “Mark” bit that representing remaining energy of a node. (2) Based on (1), a route interruption update strategy was proposed to restart the route discovery process when node energy was used excessively. Simulation results demonstrate that compared with AODV and other existing routing protocols, proposed algorithm can reduce network energy consumption and balance node energy, thus extending the network lifetime.     

Directional routing protocols for ad-hoc networks

A directional routing approach for multihop ad-hoc networks, is presented which has been applied to two on-demand routing protocols: namely dynamic source routing (DSR) and ad-hoc on-demand distance vector routing (AODV). Both DSR-based and AODV-based directional routing protocols are designed to balance the tradeoff between co-channel interferences from nodes hops away and the total power consumed by all the nodes. In order to select the best route, three metrics are considered in the route discovery process. They consist of hop count, power budget and overlaps between adjacent beams. By exploiting the direction of directional antennas, both routing protocols are capable of reducing overlaps between beams of the nodes along the route, thus eliminating interference. Arbitrary networks and random networks are considered in the simulations. The results show considerable performance gains for transmission of real-time traffic over ad hoc networks.     

间断连通移动有组织网络中延时有界的概率路由策略

针对间断连通移动自组织网络(ICMAN)实际应用中对消息的送达率、发送延时及开销三项重要指标的要求,本文借助于发送延时的概率模型,分析了这三项指标的相互关系,进而提出了一种综合考虑这三种指标的延时有界的概率路由策略(BDPBR),其特点是重视精确的延时指标,而非现有算法关注的消息的平均传输延时,能以给定概率保证消息的端到端发送延时.仿真结果表明,该策略能够通过调整必需发送概率(RDP)和必需传输延时(RDD)来控制消息的实际发送率和发送延时,同时可根据RDP和RDD来调整系统开销,可按用户设定的送达率与延时指标以相应的代价发送消息,适应不同的服务要求.     

A load-balanced routing method for large-scale mesh multiprocessors

Research on message routing in large-scale mesh multiprocessors usually focuses on routing in light traffic. Studies employ simple routing methods that are not load-balanced but do not need route initiation before message transmission. In non-light and/or non-uniform input traffic situations, maximum bandwidth utilization and average latency of such routing methods can be poor due to congestion caused by unbalanced load in global mesh regions. Existing load-balanced routing methods applied in mobile ad hoc mesh networks require route initiation before message transmission, which is not acceptable in mesh multiprocessors. In this research, we designed a load-balanced hierarchical mesh-routing method without route initiation. We organize a large-scale mesh into a virtually structured hierarchical mesh structure. Global mesh routing can thus be transformed into a number of load-balanced routing subtasks at levels of hierarchical submesh regions. In such a structure, we designed periodical hierarchical traffic state polling and distribution with very low overhead. We developed two congestion-avoidance routing methods for load-balanced routing at levels of submesh regions with polled traffic states. Experimental results show that maximum bandwidth utilization and average latency in non-light and/or non-uniform input traffic situations can be improved significantly in comparison with ordinary mesh multiprocessor routing methods.     

A comparative QoS survey of mobile ad hoc network routing protocols

A mobile ad hoc network (MANET) is a wireless, dynamic, infrastructure-less, self-organized, multi-hop, and decentralized network. Each node in MANET can act as a router as well as a work station. Many routing protocols have been developed to increase the efficiency of MANET. The primary objective of this paper is a detailed QoS comparison of reactive (AODV), proactive (DSDV), and hybrid (ZRP) routing protocols of MANET in order to find which routing protocol works best in a particular network scenario. The analysis was made for TCP-based traffic patterns. The performance differentials were analyzed on the basis of normalized routing overhead, packet loss, packet delivery ratio, control packets, end-to-end delay, packet received, and packet sent with a variation of nodes density and mobility. The results were obtained using the NS-2 simulator.