基于频分复用的无线移动自组网路由优化

无线移动自组网路由协议是提高网络吞吐量及减小时延的关键,也是目前研究的热点。该文提出了基于频分复用技术的路由优化方法;论述了使用碰撞机制解决路由无效通知的方法;分析了优化方法在提高系统吞吐量中的突出表现和时延问题,结果表明优化方法在充分利用频率资源及提高系统容量方面具有优越的性能。     

一种支持单向链路的QoS路由协议

设计了一种支持单向链路并能保证实时业务服务质量的路由协议QUR(QoS-supportUnidirectional-linkRout-ing),提出了一种新的带宽计算方法。QUR在路由选择时综合考虑路径的带宽因素和跳数因素,并为实时业务预约资源,提高了网络的整体效率。仿真结果表明:QUR协议保证了实时业务的服务质量,在网络吞吐量和相对控制开销方面优于DSDV协议。     

An adaptive approach for information dissemination in Vehicular Ad hoc Networks

Vehicular Ad hoc Networks (VANETs) appeared as a subclass of MANETs for inter-vehicle communication. However, VANETs have a relatively more dynamic nature as compared to MANETs concerning the network topology. The design and implementation of an efficient and scalable algorithm for information dissemination in VANETs constitutes a major issue that should be tackled. Indeed, in this dynamic environment, an increasing number of redundant broadcast messages will increase resource utilization, which would indirectly affect the network performance. In the past few years, several statistical-based broadcasting schemes, such as counter-based protocol, for information dissemination have been proposed in the context of MANETs. These schemes are based on various threshold parameters to help nodes to decide whether to rebroadcast or discard received messages. However, in dynamic networks, such as in VANETs, it is difficult even impossible to determine a priori these threshold values. Dynamically changing these values, to minimize the number of redundantly received messages while maintaining good latency and reachability, is a complex issue in the absence of centralized controllers or constant threshold parameters. This paper presents a decentralized and adaptive approach for information dissemination (AID) in VANETs. Simulations are conducted and results are presented to show that adaptive approaches have a better performance over statistical-based approaches.     

Prevention of selective black hole attacks on mobile ad hoc networks through intrusion detection systems

A black hole attack on a MANET refers to an attack by a malicious node, which forcibly acquires the route from a source to a destination by the falsification of sequence number and hop count of the routing message. A selective black hole is a node that can optionally and alternately perform a black hole attack or perform as a normal node. In this paper, several IDS (intrusion detection system) nodes are deployed in MANETs in order to detect and prevent selective black hole attacks. The IDS nodes must be set in sniff mode in order to perform the so-called ABM (Anti-Blackhole Mechanism) function, which is mainly used to estimate a suspicious value of a node according to the abnormal difference between the routing messages transmitted from the node. When a suspicious value exceeds a threshold, an IDS nearby will broadcast a block message, informing all nodes on the network, asking them to cooperatively isolate the malicious node. This study employs ns2 to validate the effect of the proposed IDS deployment, as IDS nodes can rapidly block a malicious node, without false positives, if a proper threshold is set.     

基于可靠稳定性评价的MANET多路径路由优化算法

针对移动Ad hoc网络动态拓扑特性,该文提出一种以可靠路径稳定度估计为基础的多路径路由优化算法。该算法从路径剩余生存期统计特性出发,充分考虑相邻链路生存期相关性,从而消除已有算法在路径稳定度估计中存在的理论误差,并利用优化后的稳定度准则实现路由发现进程的多路径选取和基于备用路径支持的快速路由修复。仿真对比结果表明,该算法具有较快的收敛速度,能够有效提高网络吞吐量,缩短数据传输时延并降低路由开销,更好地保证较高节点移动度下的数据传输稳定性。     

不同Mac接入机制的AODV路由协议性能分析

为了提高网络的综合性能,充分考虑了数据链路层和网络层的影响因素。对比分析了不同Mac接入协议的切换方法,为无线自组网络选择了一个合适的路由和接入协议。通过在NS-2中仿真Mac层的802.11a和802.11Ext路由场景,对AODV协议的归一化路由开销、路由发现频率、端到端平均时延以及数据分组投递率进行了全面的分析比较。结果表明,802.11Ext接入协议具有明显的优势特点,更加稳定、更适合移动网络。     

移动自组网中一种新的混合认证协议

在现有的面向移动自组网环境的认证方案中,分布式认证的安全性高,但其认证成功率低,尤其是在大规模移动自组网中。针对这一问题,该文提出一种将分布式认证和链式认证有机结合的混合认证方案,前者用于证书管理,后者用于身份认证。理论分析表明,在保证安全性的前提下,该方案提高了协议的可扩展性和认证成功率。     

Triangle-based routing for mobile ad hoc networks

Routing protocols for Mobile ad hoc networks (MANETs) have been studied extensively in the past decade. Routing protocols for MANETs can be broadly classified as reactive (on-demand), proactive, hybrid and position-based. Reactive routing protocols are attractive because a route between a source and a destination is established only when it is needed. Such protocols, unlike proactive protocols, do not have high overhead for route maintenance and are especially suitable for networks in which not all nodes communicate frequently. One problem with existing reactive routing protocols is the propagation of redundant route request messages during route discovery. In this paper, we present a low-overhead reactive routing protocol which reduces propagation of redundant route request messages. We also compare its performance with the well-known reactive routing protocol AODV.     

An evolutionary computation approach for designing mobile ad hoc networks

This paper presents the topological design of ad hoc networks in terms of distances among static nodes and speeds of mobiles nodes. Due to the complexity of the problem and the number of parameters to be considered, a genetic algorithm combined with the simulation environment NS-2 is proposed to find the optimum solution. More specifically, NS-2 provides the fitness function guiding the genetic search. The proposed framework has been tested using a railway scenario in which several static and mobile nodes are interacting. Results show the feasibility of the proposed framework and illustrate the possibility of genetic approach for solving similar application scenarios.     

Energy Based Random Repeat Trust Computation in Delay Tolerant Network

As the use of mobile devices continues to rise, trust administration will significantly improve security in routing the guaranteed quality of service (QoS) supply in Mobile Ad Hoc Networks (MANET) due to the mobility of the nodes. There is no continuance of network communication between nodes in a delay-tolerant network (DTN). DTN is designed to complete recurring connections between nodes. This approach proposes a dynamic source routing protocol (DSR) based on a feed-forward neural network (FFNN) and energy-based random repetition trust calculation in DTN. If another node is looking for a node that swerved off of its path in this situation, routing will fail since it won’t recognize it. However, in the suggested strategy, nodes do not stray from their pathways for routing. It is only likely that the message will reach the destination node if the nodes encounter their destination or an appropriate transitional node on their default mobility route, based on their pattern of mobility. The EBRRTC-DTN algorithm (Energy based random repeat trust computation) is based on the time that has passed since nodes last encountered the destination node. Compared to other existing techniques, simulation results show that this process makes the best decision and expertly determines the best and most appropriate route to send messages to the destination node, which improves routing performance, increases the number of delivered messages, and decreases delivery delay. Therefore, the suggested method is better at providing better QoS (Quality of Service) and increasing network lifetime, tolerating network system latency.