一种节点自分布最优Ad Hoc多播树及其应用

为无线单播模式设计的RTS/CTS信道握手机制不适用于多播模式,导致Ad hoc多播树节点易与隐藏终端发生冲突.通过提出m阶冲突域、节点在冲突域中的分布指标,结合无线网多播数据通信机制分析树节点所在m阶冲突域的冲突概率,进而得到节点自分布最优树的概念,并将它融入多播树的适应函数的设计中,淘汰不良树,优化树节点在m阶冲突域中的分布,在网络层形成一种预防机制,可降低隐藏终端冲突概率;应用于MAODV协议中,提高了MAODV的端到端数据分组平均投递率,这也能够为基于网的和混合式的其他类型MANETs多播路由协议的路由节点分布优化提供有价值的参考.     

基于MAODV无线Mesh网多播路由协议的优化

针对无线Mesh网(WMNs)现有的路由协议不能很好地解决多播视频业务对时延的要求,以Ad hoc网络中多播路由协议MAODV为基础,结合无线网络拓扑的动态变化,在WMN下提出一种基于路径优化的ROMAODV(Routing Optimization-MAODV)路由算法.此算法以很小的优化开销获得延时的大幅度减小,仿...     

Ad hoc网络按需路由协议DSR性能研究

该文对无线自组网Ad hoc的基于源驱动的按需路由选择协议DSR进行了系统研究,并利用通信网络仿真建模软件OPNET对全部采用固定节点的Ad hoc网络利用DSR作为其路由协议,分设场景进行仿真,并对DSR协议随着节点数增多所表现出来的性能进行了较为详尽的比较和分析。     

Ad hoc网络按需路由协议DSR性能研究

该文对无线自组网Ad hoc的基于源驱动的按需路由选择协议DSR进行了系统研究,并利用通信网络仿真建模软件OPNET对全部采用固定节点的Ad hoc网络利用DSR作为其路由协议,分设场景进行仿真,并对DSR协议随着节点数增多所表现出来的性能进行了较为详尽的比较和分析.     

MANET环境下基于能量保护的路由策略及其研究进展

移动Ad hoc网络是由一组带有无线收发装置的移动节点组成的一个支持多跳的临时性的网络自治系统。由于移动自组网的大多数节点是由有限寿命的电池来提供能量,因此节能策略正逐步成为设计和评价路由协议的一个重要依据。通过分析现有移动自组网的节能路由策略,给出了未来该领域的若干研究方向。     

基于博弈论的无线自组网路由协议研究

Ad hoc网络,是无线自组织网络的简称.它没有固定的基础设施,网路中的每个节点具有双重身份,即通信终端和路由器.路由协议是Ad hoc网络的关键技术,但传统的协议在设计时并未考虑效率因素.本文基于博弈论提出一种平均场均衡的方法,能有效的减少信息泛洪,以满足节点移动性对自组网的性能要求.     

无线Ad hoc网络中的多播路由技术

该文对目前无线Ad hoc网络的多播路由协议研究结果进行了归纳和分类,并阐述了它们的工作机制,分析了它们的特色与优劣,定性地比较了它们的性能指标,指出了它们的使用范围。最后总结了无线Ad hoc网络多播路由协议应具有的特性,并指出了目前的多播路由机制所存在的问题和进一步研究的方向。     

复杂网络环境下的DSR路由协议性能仿真

DSR是用于多跳无线Ad hoc网络的一个简单高效的路由协议,DSR协议由路由发现和路由维持两部分组成,允许节点在Ad hoc网络中发现、维持到任意节点的源路由.文章详细介绍了DSR协议的特点并利用Opnet Modeler 10.5构建了小规模(50节点)和大规模(100节点)复杂的(所有节点同时移动、所有节点既是源节点又是目的节点)移动自组网模型,通过改变节点移动速度及发送分组大小,对DSR路由算法的平均路由发现时间、平均路由长度、吞吐量、数据分组平均端到端的时延、及分组交付率在两种场景下进行了仿真分析和性能比较.     

基于Mesh网的MAODV路由协议在Linux下的实现

详细叙述了无线Mesh网中MAODV(Multicast Ad hoc On-Demand Distance Vector)组播路由协议的基本原理和工作流程。分析了在Linux操作系统的路由体系中实现MAODV路由协议的关键技术和难点。针对该协议的技术难点,结合Linux操作系统中的网络数据包过滤和控制模块Netfilter技术,提出了具体的解决方案及实现流程,并在Linux操作系统上对MAODV路由协议的实现方案进行了验证。     

基于OPNET的MAODV仿真技术分析

移动Ad Hoc网络是指由一组带有无线收发装置的移动节点组成的一个多跳的、不需要固定中心接入点或者基站支持的自治系统。对移动Ad Hoc网络多播路由中的MAODV协议进行理论分析,采用OPNET软件对该协议在AdHoc网络中的分组投递速率和延迟等关键参数进行仿真统计,并分析了节点移动速率对路由协议性能的影响。     

移动自组织网络中基于树结构的优化组播路由算法(英)

Mobile Ad hoc Networks(MANETs) play an important role in emergency communications where network needs to be constructed temporarily and quickly.Since the nodes move randomly,routing protocols must be highly effective and reliable to guarantee successful packet delivery.Based on the data delivery structure,most of the existing multicast routing protocols can be classified into two folders:tree-based and mesh-based.We observe that tree-based ones have high forwarding efficiency and low consumptions of bandwidth,and they may have poor robustness because only one link exists between two nodes.As a treebased multicast routing protocol,MAODV(Multicast Ad hoc On-demand Vector) shows an excellent performance in lightweight ad hoc networks.As the load of network increases,QoS(Quality of Service) is degraded obviously.In this paper,we analyze the impact of network load on MAODV protocol,and propose an optimized protocol MAODV-BB(Multicast Ad hoc On-demand Vector with Backup Branches),which improves robustness of the MAODV protocol by combining advantages of the tree structure and the mesh structure.It not only can update shorter tree branches but also construct a multicast tree with backup branches.Mathematical analysis and simulation results both demonstrate that the MAODV-BB protocol improves the network performance over conventional MAODV in heavy load ad hoc networks.     

Cross-Layer-based Local Repair for Maximizing Goodput and Minimizing Control Messages in Multicasting MANET

The Multicast Ad hoc On-Demand Distance Vector (MAODV) protocol achieves multicast routing in self-organizing wireless mobile on-demand networks, e.g., Mobile Ad-hoc Networks (MANETs). However, unreliable wireless links degrade network reliability and network goodput, and the unreliable link problem becomes worse in multicasting because a multicast tree consists of more number of wireless links. MAODV adopts a broadcast-type local repair, and thus yields a large number of broadcast-type repair messages, increases extensive control overhead, and involves largely power consumption. Thus, a cross-layer unicast-type multihop local repair approach is proposed to recover broken links in multicasting MANETs. Additionally, the cross-layer mechanism provides mobile nodes to send a cross-layer message to the TCP sender to keep current congestion window (cwnd) and slow start threshold (ssthresh) when downstream links are temporarily broken, and then increases network goodput. Finally, the optimal number of neighbor-tiers is analyzed and the optimal substitute node is identified. Numerical results demonstrate that the proposed approach outperforms other approaches in successful repair rate, control message overhead, packet delivery ratio, and network goodput.     

Transmission Range Effects on AODV Multicast Communication

As laptop computers begin to dominate the marketplace, wireless adapters with varying bandwidth and range capabilities are being developed by hardware vendors. To provide multihop communication between these computers, ad hoc mobile networking is receiving increasing research interest. While increasing a node's transmission range allows fewer hops between a source and destination and enhances overall network connectivity, it also increases the probability of collisions and reduces the effective bandwidth seen at individual nodes. To enable formation of multihop ad hoc networks, a routing protocol is needed to provide the communication and route finding capability in these networks. The Ad hoc On-Demand Distance Vector Routing protocol (AODV) has been designed to provide both unicast and multicast communication in ad hoc mobile networks. Because AODV uses broadcast to transmit multicast data packets between nodes, the transmission range plays a key role in determining the performance of AODV. This paper studies the effects of transmission range on AODV's multicast performance by examining the results achieved at varying transmission ranges and network configurations.     

一种提高Ad hoc网络中多播可靠性的算法和模型

在Ad hoc网络中,低可靠性的无线链路使多播应用网络扩展性较差,然而有线网络多播应用中FEC(Forward Error Correction)技术和NACK(Negative ACKnowledgement)重传机制不适于Ad hoc网络。该文旨在提高Ad hoc网络中多播可靠性,提出由PDA(Packet Dispersal Algorithm)算法和ARM(Active Retransmission Model)重传模型相结合的可靠多播传输方案(RMTS)。理论分析和仿真结果都表明该方案具有效率高、复杂度低、资源占用少和开销小等优点。     

Ad Hoc网络中基于粒子群优化的QoS多播路由研究

针对Ad Hoc网络中带QoS约束的多播路由问题，提出了一种新的结合MAODV多播路由发现方法和粒．子群优化算法的QoS多播路由发现算法。仿真试验显示该算法较好地改进了端到端传输的代价、延时和带宽利用率，能够找到一棵消耗趋于最小、状态稳定的多播路由树。     

无线Ad hoc网络中QoS路由协议的研究

QoS保证体系在Ad hoc网络中扮演着重要的角色.在引入Ad hoc网络中QoS保证体系的基本组件和面临的新挑战之后,对其中的QoS路由协议进行了讨论,按照先应式、反应式、基于群集、利用地理位置信息、组播、多径等类别,对近几年来的各种研究成果进行了阐述和分析,并对未来的发展趋势进行了展望.     

Flooding for Reliable Multicast in Multi-Hop Ad Hoc Networks

Ad hoc networks are gaining popularity as a result of advances in smaller, more versatile and powerful mobile computing devices. The distinguishing feature of these networks is the universal mobility of all hosts. This requires re-engineering of basic network services including reliable multicast communication. This paper considers the special case of highly mobile fast-moving ad hoc networks and argues that, for such networks, traditional multicast approaches are not appropriate. Flooding is suggested as a possible alternative for reliable multicast and simulation results are used to illustrate its effects. The experimental results also demonstrate a rather interesting outcome that even flooding is insufficient for reliable multicast in ad hoc networks when mobility is very high. Some alternative, more persistent variations of flooding are sketched out.     

NS2的Ad hoc网络AODV协议的仿真

无线Ad hoc网络作为一种典型的自组织网络,其路由协议一直是研究的重点。以仿真AODV（Adhocon．demand distancevector）协议为例介绍了NS2仿真路由协议的详细步骤,给出了仿真结果图和一些性能分析。结果表明,对路由协议性能影响最大的是数据源的发送频率。