基于位置信息的移动P2P路由发现策略

由于EDSR路由协议在路由选择时采取向邻居节点全部转发路由信息的策略,在路由请求时,容易引起转发次数过多而导致网络瘫痪。提出了借助LAR协议利用目的节点的位置信息设置路由的期望域,从而构建路由选择区域,提高发起路由请求时预知目的节点位置的几率。提出了增强性LAR路由协议。当位置辅助路由协议发现路由失败时避免采用全网洪泛机制,采用基于距离的位置路由改进算法,设置距离更新门限来达到节点位置信息实时性与更新负载的平衡,通过路由选择权重值Qpath使路由选择达到最优。     

基于位置信息的移动P2P路由发现策略

由于EDSR路由协议在路由选择是采取向邻居节点全部转发路由信息的策略,在路由请求时,容易引起转发次数过多而导致网络瘫痪。本文提出借助LAR协议利用目的节点的位置信息设置路由的期望域,从而构建路由选择区域,提高发起路由请求时预知目的节点位置的几率,提出增强性LAR路由协议。当位置辅助路由协议发现路由失败时避免采用全网洪泛机制,采用基于距离的位置路由改进算法,设置距离更新门限来达到节点位置信息实时性与更新负载的平衡,通过路由选择权重值Qpath使路由选择达到最优。     

P2P网络两级混合路由算法

为了提高纯分布式P2P网络的路由效率,减少因为节点频繁的加入和退出而产生的网络不稳定性,提出一种两级混合路由算法,该算法结合了非结构化Flooding路由算法和结构化的Pastry路由算法的优点,将整个网络分为两级,即虚节点网络和子节点网络,分别采用不同的路由算法,实验证明该路由算法能减少路由过程的中心热点效应和不稳定性,有效提高路由效率.     

结构化P2P网络模型的改进

文章通过对现有P2P网络[1,2]模型的分析,指出了现有网络模型的缺陷,并建立了一种节点分级网络模型(HNN)。HNN在继承了DHT算法路由的所有优点(如很强的鲁棒性)的同时,通过对网络节点带宽和位置信息的引入,解决了原有网络模型因哈希(HASHING)而引起的对实际网络拓扑结构的破坏问题,使虚拟网络模型更好地与实际网络的小世界特性相匹配。     

无线传感器与执行器网络地理路由算法研究

在无线传感器与执行器网络中,源节点不断向目标节点传输测量报告,这需要建立一条从源节点指向目标节点的路由。路由算法的设计涉及到节点的地理位置信息,每个节点需要根据邻居节点和目标节点的位置信息做出路由决策,以尽可能地节省通信开销。文章介绍了基于记忆的保证传输地理路由算法、基于成本进度比的地理路由算法、基于自适应定位的地理路由算法和基于虚拟坐标、树坐标的地理路由算法的工作原理,分析了这些地理路由的实现方式。     

适应城市交通环境的改进型车载路由优化方法设计

为了优化城市交通环境中车载自组织网络中路由协议的链路存活时间、吞吐量等性能指标,在拓扑反应式路由协议的基础上,引入车载网络节点的位置信息,设计基于动态实时位置信息变化的车载路由协议优化模型。该模型按照十字路口车辆优先和相对位置为同方向节点优先转发的原则,根据路由信息表中位置信息区分转发控制包,并给出该路由算法的面向C++语言的UML建模图及其算法流程图。通过NS2仿真平台仿真表明,与传统的路由模型相比,该模型优化了VANETs网络中链路存活时间、时延、吞吐量等性能指标。     

MANET中基于位置路由算法综述

基于位置路由算法的基本思想是基于节点的位置信息来选择下一跳,将包向目的节点的方向上进行转发。由于不必维护明确的路由,基于位置的路由协议即使在网络高度动态的情况下也具有很好的扩展性。这是在拓扑经常变化的MANET网络中的一个主要优点。文章对基于包的目的节点的地理位置做出路由决定的算法进行了总结,并对这这些方法进行了定性的比较。     

一种基于两跳邻居信息的贪婪地理路由算法

 基于地理信息的路由算法由于其高效、低路由开销和良好的可扩展性等特点,在无线传感器网络中得到比较广泛的应用.许多采用贪婪策略作为其基本数据转发机制的地理路由算法都不可避免会遇到路由空洞现象.针对这个问题,本文提出了一种基于掌握两跳邻居节点位置信息的贪婪地理路由算法——Greedy-2算法.该算法能够使节点提前意识到路由空洞的存在,从而尽可能使数据包及时绕开空洞边界节点,减少路由空洞发生的概率,提高分组到达率.对于Greedy-2算法仍然遭遇路由空洞现象的情况,文章提出了一种基于两跳邻居信息的平面化算法PATN,该算法不需要增加额外的平面化开销,即可将网络平面化以采取边缘恢复机制,在UDG网络中保证数据可靠传输.仿真结果表明,与基于一跳邻居节点位置信息的贪婪算法相比,Greedy-2算法可以明显减少路由空洞现象发生的次数,在分组到达率和数据传送的路由跳数方面都有着更好的性能.Greedy-2算法与PATN规则结合后的GPSR-2算法也比GPSR算法有着更优化的路由跳数.     

基于中断概率的多跳混合协作地理路由算法

为了减小无线传感器网络中路由的路径长度,该文提出基于中断概率的多跳混合协作地理路由(MHCGR)算法。首先对不同协作机制的链路进行分析,理论分析表明,在一定中断概率要求下,采用译码放大转发混合协作机制可以进一步扩大传输距离,并推导了每跳协作链路的理想最大协作传输距离和理想中继的位置。在无信标地理路由(BLGR)算法的基础上,MHCGR算法结合节点位置信息为每跳选择最佳的中继节点和转发节点,建立从源节点到目的节点的多跳协作路由。仿真表明,与ENBGCR算法和基于DF协作机制的MPCR算法两种协作地理路由算法相比,MHCGR算法可明显减少路由的跳数,改善路由的整体发射功率。     

水下传感器网络路由协议研究

现有水下传感器网络路由协议都属于地理路由协议,需要知道各个节点的水下三维位置信息,从而导致大量水下通信,难以有效延长网络生存时间。本文深入分析了现有研究的不足,提出一种基于深度信息与能量均衡的水下路由协议,只需要节点深度信息,节点间通信量极少;设计了协议的算法,并提出了空洞处理对策。     

Improved ant colony-based multi-constrained QoS energy-saving routing and throughput optimization in wireless Ad-hoc networks简

In order to establish a route supporting multi-constrained quality of service（QoS）, increase network throughput and reduce network energy consumption, an improved ant colony-based multi-constrained QoS energy-saving routing algorithm（IAMQER） is proposed. The ant colony algorithm, as one of the available heuristic algorithms, is used to find the optimal route from source node to destination node. The proposed IAMQER algorithm, which is based on the analysis of local node information such as node queue length, node forwarding number of data packets and node residual energy, balances the relationship between the network throughput and the energy consumption, thus improving the performance of network in multi-constrained QoS routing. Simulation results show that this IAMQER algorithm can find the QoS route that reduce average energy consumption and improves network packet delivery ratio under the end-to-end delay and packet loss ratio constraints.     

基于改进的混合P2P的Chord算法

Chord是一种数值逐步逼近的P2P路由算法,它能够快速地定位资源。在Chord环上由于结点的随机性,资源定位时产生了逻辑路径和物理路径不一致及绕环问题,致使网络延迟增大。混合P2P具有很强的网络局部性,但查询效率低。提出了基于改进的混合P2P的Chord算法（Chord Algorithm Based on Enhanced Hybrid P2P,CBEH）,该算法利用增强的混合P2P中超级结点的网络信息,在路由过程中优先选取物理距离近的结点。实验表明CBEH能够有效地减少路由查找时延,提高路由性能。     

基于缓存旁路和本地修复的多跳网络路由重建机制

该文针对多跳网络中现有AODV和AODV-BR按需路由算法的弊端,提出了基于缓存旁路和本地修复的AODV-CL路由重建机制。该机制利用空闲时间监听无线信道中传输的所有数据包和路由控制信令,用于维护有效的邻居节点列表及本地路由缓存,有效降低了周期性HELLO消息带来的信令负担,并增加了可用路由信息。中间节点在发现断链时,尝试采用局部修复,尽量避免由源节点广播RREQ消息发现路由。根据本地路由缓存及邻居节点的路由信息,实现了快速的路由发现及修复,能有效降低路由控制信令开销及丢包率。     

RPSF: A Routing Protocol with Selective Forwarding for Mobile Ad-Hoc Networks

Many existing reactive routing algorithms for mobile ad-hoc networks use a simple broadcasting mechanism for route discovery which can lead to a high redundancy of route-request messages, contention, and collision. Position-based routing algorithms address this problem but require every node to know the position and velocity of every other node at some point in time so that route requests can be propagated towards the destination without flooding the entire network. In a general ad-hoc network, each node maintaining the position information of every other node is expensive or impossible. In this paper, we propose a routing algorithm that addresses these drawbacks. Our algorithm, based on one-hop neighborhood information, allows each node to select a subset of its neighbors to forward route requests. This algorithm greatly reduces the number of route-request packets transmitted in the route-discovery process. We compare the performance of our algorithm with the well known Ad-hoc On-demand Distance Vector (AODV) routing algorithm. On average, our algorithm needs less than 12.6% of the routing-control packets needed by AODV. Simulation results also show that our algorithm has a higher packet-delivery ratio and lower average end-to-end delay than AODV.     

A hop‐by‐hop delay‐constrained routing algorithm with explicit loop avoidance and backup routing information

QoS Routing is crucial for QoS provisioning in high‐speed networks. In general, QoS routing can be classified into two paradigms: source routing and hop‐by‐hop routing. In source routing, the entire path to the destination node of a communication request is locally computed at the source node based on the global state that it maintains, which does not scale well to large networks. In hop‐by‐hop routing, a path‐selecting process is shared among intermediate nodes between the source node and the destination node, which can largely improve the protocol scalability. In this paper, we present the design of hop‐by‐hop routing with backup route information such that each intermediate node can recursively update the best known feasible path, if possible, by collectively utilizing the routing information gathered thus far and the information that it locally stores. Such a route is kept as a backup route and its path cost is used as a reference to guide the subsequent routing process to search for a lower‐cost constrained path and avoid performance degradation. In this way, the information gathered is maximally utilized for improved performance. We prove the correctness of our presented algorithm and deduce its worst message complexity to be O(∣V∣²), where ∣V∣ is the number of network nodes. Simulation results indicate that, however, the designed algorithm requires much fewer messages on average. Therefore it scales well with respect to the network size. Moreover, simulation results demonstrate that the cost performance of our algorithm is near‐optimal. Copyright © 2004 John Wiley & Sons, Ltd.     

AO2P: ad hoc on-demand position-based private routing protocol

Privacy is needed in ad hoc networks. An ad hoc on-demand position-based private routing algorithm, called AO2P, is proposed for communication anonymity. Only the position of the destination is exposed in the network for route discovery. To discover routes with the limited routing information, a receiver contention scheme is designed for determining the next hop. Pseudo identifiers are used for data packet delivery after a route is established. Real identities (IDs) for the source nodes, the destination nodes, and the forwarding nodes in the end-to-end connections are kept private. Anonymity for a destination relies on the difficulty of matching a geographic position to a real node ID. This can be enforced by the use of secure position service systems. Node mobility enhances destination anonymity by making the match of a node ID with a position momentary. To further improve destination privacy, R-AO2P is proposed. In this protocol, the position of a reference point, instead of the position of the destination, is used for route discovery. Analytical models are developed for evaluating the delay in route discovery and the probability of route discovery failure. A simulator based on ns-2 is developed for evaluating network throughput. Analysis and simulation results show that, while AO2P preserves communication privacy in ad hoc networks, its routing performance is comparable with other position-based routing algorithms.     

Distributed cache updating for the dynamic source routing protocol

On-demand routing protocols use route caches to make routing decisions. Due to mobility, cached routes easily become stale. To address the cache staleness issue, prior work in DSR used heuristics with ad hoc parameters to predict the lifetime of a link or a route. However, heuristics cannot accurately estimate timeouts because topology changes are unpredictable. In this paper, we propose proactively disseminating the broken link information to the nodes that have that link in their caches. We define a new cache structure called a cache table and present a distributed cache update algorithm. Each node maintains in its cache table the information necessary for cache updates. When a link failure is detected, the algorithm notifies all reachable nodes that have cached the link in a distributed manner. The algorithm does not use any ad hoc parameters, thus making route caches fully adaptive to topology changes. We show that the algorithm outperforms DSR with path caches and with Link-MaxLife, an adaptive timeout mechanism for link caches. We conclude that proactive cache updating is key to the adaptation of on-demand routing protocols to mobility.     

一种安全的Ad Hoc On-demand路由协议

由于Ad Hoc网络固有的弱点,设计安全、有效的Ad Hoc路由协议是困难的.本文从新的角度设计了一个简单、安全的On-demand路由协议.在路径请求和响应阶段,源节点和目的节点的身份分别被隐藏,只有那些位于目的节点选择的最优路径上的节点可以获得完整的路由信息,从而产生有效的前向和反向路径.同时,一个公开的单向Hash函数可以利用隐藏的路由信息构建单向Hash链用于路由信息的认证,从而不需要预先的共享密钥.在一次路由计算中,只有源节点和目的节点需要进行一次非对称密码运算.     

A new Ad Hoc routing algorithm based on minimizing the channel handoff

How to improve the performance of the wireless Ad Hoc network by utilizing the spectrum resources efficiently has become a hot research topic in recent years. In this paper we propose a reactive routing algorithm that supports multiple channels to improve the performance of the Ad Hoc network based on the minimizing of the channel handoff. Our approach allocates the communication channel during the route discovery, and notifies the allocated channel information to the corresponding node in the route reply packets. Each node in the route tries its best to choose the same channel with the upstream node without interference. The simulation results show that our algorithm performs better than the K-hop distinct protocols in both average delays and network throughputs obviously     

基于用户节点相似度的局部社团挖掘

随着Web2.0的迅速发展,社交网络规模变得越来越庞大,包含的信息量也越来越多。传统的从全局角度出发进行社团挖掘的算法由于较高的复杂度以及获取全网信息的困难度,不适用于大型复杂网络的社团挖掘。文中提出了一种基于节点相似度和局部中心点的社团挖掘算法,实验结果表明,该算法在保证较高准确度的同时具有线性时间复杂度。