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1.
从继成  张韧志 《电视技术》2015,39(23):58-62
车联网 VANETs(Vehicular ad hoc networks)是传统自组织网络派生的一个子类,具有鲜明的特性。传统的地域性多播协议不能有效地适用于车联网。为此,提出了基于单播和无比率编码的地域性多播路由URC-GR( unicast and rateless coding based geocast routing)协议。URC-GR协议引用两个策略解决传统地域性多播路由协议在开销和数据包传递率方面的不足。首先,利用单播机制向目标区域传输数据,然后,在目标区域内再泛洪。其次,利用无比率编码提高数据传输率。最后,将提出的URC-GR协议与IVG(Inter Vehicle Geocast)、DRG(Distributed Robust Geocast)协议进行比较,仿真结果表明URC-GR协议能够有效地降低开销和提高数据包传输率。  相似文献   

2.
The message delivery .ratio and transmission delay is affected deeply by road traffic flow in vehicular ad hoc networks (VANETs). An opportunistic routing based on geography and road traffic flow for VANETs (ORRIS) was proposed. ORRIS leverages the knowledge of geography positions, motion vectors and road traffic flows. In order to estimate the traffic flow density, the history of encounter number of the vehicles in the opposite direction is considered in ORRIS. The forwarding decisions are made by distributed vehicles based on the geography topology and the road traffic flow. The real map based simulation results show that ORRIS has a better performance than other algorithms, especially when the road traffic is busy or the traffic flow rates have great differences between roads.  相似文献   

3.
Routing in cooperative vehicular networks is a challenging task because of high mobility of vehicles and difficulty of localization. In this paper, we study the geocast routing problem in Vehicular Ad‐hoc NETworks (VANETs), which aims at delivering data to a specific group of mobile vehicles identified by their geographical location. Although many geocast routing protocols have been proposed, only partial inherent constraints of VANETs (such as mobility, internal network fragmentation problem, external network fragmentation problem, and overload) are taken into account. Therefore, we propose two novel and robust geocast routing protocols: the first one, called Robust Geocast Routing Protocol for Safety Applications (RGRP‐SA), is dedicated to road safety applications, while the second, namely, Robust Geocast Routing Protocol for Comfort Applications (RGRP‐CA), is designed for comfort applications. Simulations conducted in NS‐2 demonstrate that our safety‐oriented RGRP‐SA protocol outperforms Inter‐Vehicle Geocast protocol and Mobicast Routing Protocol in VANETs by sending up to 25% more packets, cutting the end‐to‐end delay in half, and solving the internal network fragmentation problem. Besides, it is also shown that our comfort‐oriented RGRP‐CA protocol serves well comfort applications with only light overhead by solving internal and external network fragmentation problems and providing more reliable data delivery (with a 25% higher packet delivery ratio) and higher network throughput utilization in comparison with Mobicast with Carry‐and‐Forward protocol. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

4.
《现代电子技术》2016,(7):19-23
针对车载自组网VANETs的车间通信的连接问题进行分析。首先,假定车辆进入高速公路的时间间隔服从泊松分布,进而分析车辆间的通信连接性能。然后,推导了由n个车辆组成的通信连接概率的闭合表达式,同时,分析了在维持一定的连接概率时簇大小CLS和簇长度CLL的期望值,并讨论了车辆传输范围和密度对连接的影响,推导了满足一定连接概率时的车辆传输范围的临界值。最后,提出基于连接概率的路由协议CPRP,选择连接概率大的路径作为数据传输通道。仿真结果表明,提出的CPRP改善了数据包传递率、端到端传输时延以及吞吐量性能。  相似文献   

5.
Over the last few years, wireless sensor networks have become a great field of interest for the scientific community. This novel kind of network provides an array of applications for different aspects of human life. To give a satisfying performance to the final user, the wireless sensor networks must ensure the quality of service. The use of multipath technique was widely applied in the literature. Nevertheless, there might be a problem if the interference issues are not taken into account by the multipath routing design. In this paper, we propose a novel multipath routing protocol called Carrier Sense Aware Multipath Geographic Routing protocol (CSA‐MGR). This protocol creates multiple paths while avoiding any shared carrier sense range by using a distributed and dynamic process. In addition, the CSA‐MGR employs a new metrics named the Number of Common Neighbors to guarantee a faster and an efficient path construction. Simulations conducted over the NS‐2 simulator show promising results in terms of delay, Packet Delivery Ratio and routing overhead. The performance gain of CSA‐MGR in terms of delay is up to 275% compared with the Two‐Phase geographical Greedy Forwarding and up to 565% compared with the ad hoc on‐demand multipath distance vector. For the Packet Delivery Ratio, the performance gain of CSA‐MGR is up to 16% compared with the Two‐Phase geographic Greedy Forwarding and up to 28% compared with the ad hoc on‐demand multipath distance vector. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

6.
When it comes to keeping the data routing robust and effective in vehicular ad hoc networks (VANETs), stable and durable connectivity constitutes the keystone to ensure successful point‐to‐point communication. Since VANETs can comprise all kinds of mobile vehicles moving and changing direction frequently, this may result in frequent link failures and network partitions. Moreover, when VANETs are deployed in a city environment, another problem arises, that is, the existing obstructions (eg, buildings, trees, and hoppers) preventing the line‐of‐sight between vehicles, thus degrading wireless transmissions. Therefore, it is more complicated to design a routing technique that adapts to frequent changes in the topology. In order to settle all these problems, in this work, we design a flooding scheme that automatically reacts at each topology variation while overcoming the present obstacles while exchanging data in ad hoc mode with drones that are commonly called unmanned aerial vehicles (UAVs). Also, the aim of this work is to explore well‐regulated routing paths providing a long lifetime connectivity based on the amount of traffic and the expiration time of each discovered path. A set of experiments is carried out using a simulation, and the outcomes are confronted with similar protocols based on a couple of metrics. The results clearly show that the assistance of UAVs to vehicles is capable of providing high delivery ratios and low delivery delays while efficiently extending the network connectivity.  相似文献   

7.
The highly mobility of vehicles, intermit-tent communication between the vehicles and the requirements of real time applications are some of the main challenges of multi-hop message delivery in Vehicular Ad Hoc Networks(VANETs).There are also additional challenges, especially when the des-tination for the message delivery is a moving vehi-cle. In this paper, we propose a novel multi-hop message delivery method, called the Coverage Area-based oPportunistic message forwarding algorithm (CAP). The main idea of CAP is to cover the poten-tial area of a moving target vehicle as much as pos-sible with the reachable area of the required deliver-y messages, so that the message can be delivered successfully. Because the success ratio and overhead of the multi-hop message delivery are two important but incompatible parameters in CAP, two tunings are discussed in the algorithm in order to maintain the balance of the two parameters. The simulation results show that compared with other reference ap-proaches, CAP provides an efficient message deliv-ery with a higher success ratio and a shorter mes-sage delay.  相似文献   

8.
在AdHoc网络技术的工程实现中,路由协议的选择以及硬件无线通信系统设计是要解决的两个关键环节。本文针对节点之间无等级结构的AdHoc网络,基于一种泛搜索路由协议进行AdHoc网络系统设计和实现。硬件通信设备采用单片机C8051F920控制无线数传模块的方案进行设计,按照搜索路由协议对单片机编写程序,继而组建AdHoc网络系统。通过对网络测试所得的数据结果进行分析,表明该路由协议能适应网路拓扑结构变化,准确地找到一条适合传输的路由,所设计通信系统满足AdHoc网络的基本特征。  相似文献   

9.
广域网和以太网是两种不同的网络技术,而小型局域网因为其业务多样性和分布离散性,使得其需要兼容不同协议的网络。提出一种基于以太网RIP路由协议和广域网的帧中继协议的网络设计,满足不同协议互通,为不同核心路由器和交换机之间配置RIP路由、静态默认路由和帧中继子接口,最终完成了该网络的布置。  相似文献   

10.
魏然  李貌 《数字通信》2013,(6):33-36
为了延长无线传感网络的生存时间,需要设计满足高效率、低功耗的路由算法。一种CMRA(intercluster head multi-hop routing algorithm)算法被提出来,这种算法通过节点通信能量消耗模型建立最小能量路径树,但CMRA对于簇头选择的能量分配不均衡,造成簇头结点负载过重。提出一种新的路由算法CMRA-EE(CMRA-energy efficient),在簇头选举阶段引入节点能量参数,同时将簇头节点能量与距离作为代价参数,从而平衡了网络节点能耗。通过仿真对CMRA-EE算法进行性能分析与评价,结果显示,CMRA-EE算法在延长无线传感网有效生存时间方面比CMRA算法有了明显的改善。  相似文献   

11.
The authentication protocol is vital for the security of the wireless sensor network to resist the known threats, such as eavesdropping, replay attack, man‐in‐the‐middle attack, etc. In this paper, a lightweight authentication protocol for vehicular ad hoc networks is proposed using the symmetric encryption, the group communication method, and the proactive authentication technique, which not only achieves the desired security goals but also guarantees the practical anonymity and the accountability. The analysis demonstrates that the proposed protocol works properly in the high‐density and the low‐density traffic environment.  相似文献   

12.
This paper presents a novel trust model based on multiple decision factor theory (MDFT) and a trust routing algorithm based on MDFT to exactly evaluate routing node trust and establish a trustworthy routing path. MDFT integrates four dimensional trust decision factors including behavior, state, recommend and node liveness to realize an exactly finer-grained trust evaluation. On the basis of MDFT, a trust routing algorithm is presented and validated in open shortest path first (OSPF) protocol. Simulation resuRs show that the algorithm can reflect the routing node trust accurately and has better dynamic response ability. Under the circumstance of existing deceptive nodes, the algorithm has better anti-deception performance and higher attack node detection rate than conventional algorithm.  相似文献   

13.
Vehicular ad hoc networks is an integral component of intelligent transportation systems and it is an important requisite for smarter cities. Network formation and deformation among the vehicles are very frequent because of the variation in speed. Furthermore, for safety applications, messages should not face any kind of delay or collision. Therefore, establishing communication between the vehicles becomes even more challenging. Position‐based routing protocols work productively in vehicular ad hoc networks. Only finding an efficient routing protocol does not solve our purport. We need to carefully examine the effect of media access control layer parameters additionally. In the event of collisions, a large number of nodes would be re‐transmitting rather than sending fresh packets. A node busy in sending the retransmitted packet is called a backlog node. With an increase in the number of collisions, number of backlog nodes also increases, which affects the delay and throughput. In this article, we present the mathematical modeling of delay and throughput with IEEE 802.11 distributed coordination function (at media access control layer) for directional‐location aided routing (D‐LAR) position based routing protocol. For performance evaluation, simulation has been done in realistic environment created with SUMO (traffic simulator) and NS‐2 (network simulator). Simulation results show the comparison between D‐LAR and location aided routing (LAR) on various metrics in terms of delay, packet delivery ratio, routing overhead, throughput, and collision probability. To validate the mathematical model, analytical results has been compared with simulation results. The results confirm that performance of D‐LAR is better than LAR in terms of increasing the throughput and reduction in routing overhead and delay.  相似文献   

14.
The nodes in a wireless ad hoc network act as routers in a self‐configuring network without infrastructure. An application running on the nodes in the ad hoc network may require that intermediate nodes act as routers, receiving and forwarding data packets to other nodes to overcome the limitations of noise, router congestion and limited transmission power. In existing routing protocols, the ‘self‐configuring’ aspects of network construction have generally been limited to the construction of routes that minimize the number of intermediate nodes on a route while ignoring the effects that the resulting traffic has on the overall communication capacity of the network. This paper presents a context‐aware routing metric that factors the effects of environmental noise and router congestion into a single time‐based metric, and further presents a new cross‐layer routing protocol, called Warp‐5 (Wireless Adaptive Routing Protocol, Version 5), that uses the new metric to make better routing decisions in heterogeneous network systems. Simulation results for Warp‐5 are presented and compared to the existing, well‐known AODV (Ad hoc On‐Demand Distance Vector) routing protocol and the reinforcement‐learning based routing protocol, Q‐routing. The results show Warp‐5 to be superior to shortest path routing protocols and Q‐routing for preventing router congestion and packet loss due to noise. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

15.
Mobile ad-hoc networks (MANETs) are failure-prone environments; it is common for mobile wireless nodes to intermittently disconnect from the network, e.g., due to signal blockage. This paper focuses on withstanding such failures in large MANETs: we present Octopus, a fault-tolerant and efficient position-based routing protocol. Fault-tolerance is achieved by employing redundancy, i.e., storing the location of each node at many other nodes, and by keeping frequently refreshed soft state. At the same time, Octopus achieves a low location update overhead by employing a novel aggregation technique, whereby a single packet updates the location of many nodes at many other nodes. Octopus is highly scalable: for a fixed node density, the number of location update packets sent does not grow with the network size. And when the density increases, the overhead drops. Thorough empirical evaluation using the ns2 simulator with up to 675 mobile nodes shows that Octopus achieves excellent fault-tolerance at a modest overhead: when all nodes intermittently disconnect and reconnect, Octopus achieves the same high reliability as when all nodes are constantly up. A preliminary version of this paper appears in Proceedings of the 24th IEEE Symposium on Reliable Distributed Systems (SRDS 2005) October 26–28, 2005, Orlando, Florida. Idit Keidar is a faculty member at the department of Electrical Engineering at the Technion Israel Institute of Technology, and a recipient of the national Alon Fellowship for new faculty members. She holds Ph.D., M.Sc. (summa cum laude), and B.Sc (summa cum laude) degrees from the Hebrew University of Jerusalem. She was a postdoctoral research associate at MIT’s laboratory for Computer Science, where she held post-doctoral fellowships from Rothschild Yad-Hanadiv and NSF CISE. Dr. Keidar has consulted for BBN Technologies (a Verizon Company) in the area of fault-tolerance and intrusion tolerance, and for Microsoft Research in the area of fault-tolerant storage systems. Dr. Keidar’s research focuses on reliability in distributed algorithms and system. She is the academic head of Software Systems Laboratory at the Technion. Dr. Keidar served as a member of the Steering Committee of the ACM Symposium on Principles of Distributed Computing (PODC), has served on numerous program committees of leading conferences in the area of distributed and parallel computing, has twice served as a vice-chair for the IEEE International Conference on Distributed Computing Systems (ICDCS), and once served as a vice-chair for Euro-Par. Yoav Barel is a Senior Business Line Manager at Sun Microsystems. He holds a B.Sc from the Technion—Israel Institute of Technology. Mr. Barel works with wireless carriers world wide and assists them in deploying innovative services based on cutting edge Java technologies. Roie Melamed is a research staff member at IBM Haifa Research Laboratory. He holds Ph.D. and B.A. (cum laude) degrees from the Technion—Israel Institute of Technology. Dr. Melamed’s research focuses on reliability in distributed systems.  相似文献   

16.
为了降低无线传感器网络(WSN)能量消耗,延长网络生存周期,提出了一种基于混沌粒子群(CPSO)和蚁群算法相结合的路由协议。该协议针对典型的分簇协议LEACH(Low-Energy Adaptive Clustering Hierarchy)协议的簇头选择进行了优化,考虑了节点剩余能量和簇内密集性等因素,采用新的混沌粒子群算法对簇头选择进行优化。然后,针对LEACH协议簇头到基站采用单跳通信,容易使簇头早亡的问题,采用蚁群算法优化簇头到基站的路由路径,减少通信消耗的能量。仿真结果表明,与传统的LEACH协议相比,新的协议能有效减少能量消耗,延长网络生命周期。  相似文献   

17.
Vehicular ad hoc networks (VANETs) have attracted much research attentions in the recent years. Although there are many outstanding solutions of geographic routing designed for the VANETs, only one or two features of the VANETs have been specifically utilized in each of the proposed solutions. In this paper, we propose a novel adaptive fuzzy multiple attribute decision routing (AFMADR) scheme, by which a packet carrier is supposed to be a decision maker in the selection of a target for the next hop transmission with more factors to be considered. The AFMADR scheme consists of four steps. Firstly, the candidate vehicles are characterized by four attributes including the distance, the direction, the road density, and the location to obtain a fuzzy attribute score of each attribute. Secondly, according to the real‐time conditions of the candidates' attributes, weights of attributes will be calculated by the proposed adaptive weight algorithm, which makes the AFMADR scheme more scalable and robust in different VANET scenarios. Then, a fuzzy performance score will be produced for each candidate based on the fuzzy attribute score and their real‐time weights. Lastly, a route decision is made by choosing a candidate with the highest performance score as the target for the next hop transmission. We carry out simulation experiments to compare the performance of the AFMADR scheme with the existing well‐known geographic routing protocols for the VANETs. The simulation results demonstrate that the proposed AFMADR scheme can achieve the best performance in terms of the highest delivery ratio and the lowest delivery delay with a reasonable number of hops among all protocols in all the simulation scenarios. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

18.
Power-aware single- and multipath geographic routing in sensor networks   总被引:1,自引:0,他引:1  
Shibo  K. Seluk 《Ad hoc Networks》2007,5(7):974-997
Nodes in a sensor network, operating on power limited batteries, must save power to minimize the need for battery replacement. We note that the range of transmission has a significant effect on the power consumption of both the transmitting node and listeners. This paper first presents a Geographical Power Efficient Routing (GPER) protocol for sensor networks. Each sensor node makes local decisions as to how far to transmit: therefore, the protocol is power efficient, localized, highly distributed, and scalable. In GPER, given a final destination, each node first establishes a subdestination within its maximum radio range. The node, however, may decide to relay the packet to this subdestination through an intermediary node or alter the subdestination if this will preserve power. Traditional deterministic geographic routing algorithms aim at achieving close to the shortest weighted paths. However, they normally stick to the same paths for the same source/destination pairs. This may conversely drain the nodes on these paths and result in short network life when the communication in the network is unevenly distributed. Thus, we further investigate a set of probabilistic multipath routing algorithms, which generate braided multipaths based only on local information. The algorithms have less communication and storage overhead than conventional on-demand multipath routing algorithms, while providing greater resilience to node failures. Simulations on NS2 show that GPER almost halves the power consumption in the network relative to alternative geographic routing algorithms. Furthermore, in situations where the communication tasks are non-uniformly distributed, probabilistic multipath routing contributes up to an additional 30% to network lifetime.  相似文献   

19.
基于假名认证机制是保护车与路边设施间通信(V2I)隐私的有效方法,传统的基于证书撤销清单(CRL)方法存在通信和计算开销大的问题。为此,提出基于布谷鸟(Cuckoo)过滤器的轻量V2I认证算法(CFLA)。CFLA算法通过局部信任中心(LTA)给其覆盖内的车辆分配假名,并利用Merkle散列树(MHT)存储车辆假名,每辆车维持一棵独立MHT。同时,采用布谷鸟过滤器(CF)数据结构,降低存储、计算和通信开销。安全性能分析表明,提出的CFLA算法能够具有防御中间攻击、重放攻击的能力。相比于相关的同类算法,CFLA算法降低了认证开销。  相似文献   

20.
In a vehicular ad‐hoc network (VANET), vehicles can play an essential role in monitoring areas of a smart city by transmitting data or multimedia content of environmental circumstances like disasters or road conditions. Multimedia content communication with quality of experience (QoE) guarantees is a challenging undertaking in an environment such as that of a VANET. Indeed, a VANET is characterized by numerous varying conditions, significantly impacting its topology, quality of communication channels, and paths with respect to bandwidth, loss, and delay. This paper introduces a link efficiency and quality of experience aware routing protocol (LEQRV) to improve video streaming provisioning in urban vehicular ad‐hoc networks. LEQRV uses an enhanced greedy forwarding‐based approach to create and maintain stable high quality routes for video streaming delivery. It improves the performance of the quality of experience by increasing the achieved QoE scores and reducing the forwarding end‐to‐end delay and frame loss.  相似文献   

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