Cluster‐based data dissemination,cluster head formation under sparse,and dense traffic conditions for vehicular ad hoc networks

Information and communication technologies have changed the way of operations in all fields. These technologies also have adopted for wireless communication and provide low cost and convenient solutions. Vehicular ad hoc networks are envisioned with their special and unique intercommunication systems to provide safety in intelligent transportation systems and support large‐size networks. Due to dense and sparse traffic conditions, routing is always a challenging task to establish reliable and effective communication among vehicle nodes in the highly transportable environment. Several types of routing protocols have been proposed to handle high mobility and dynamic topologies including topology‐based routing, position and geocast routing, and cluster‐based routing protocols. Cluster‐based routing is one of the feasible solutions for vehicular networks due to its manageable and more viable nature. In cluster‐based protocols, the network is divided into many clusters and each cluster selects a cluster head for data dissemination. In this study, we investigate the current routing challenges and trend of cluster‐based routing protocols. In addition, we also proposed a Cluster‐based Routing for Sparse and Dense Networks to handle dynamic topologies, the high‐mobility of vehicle nodes. Simulation results show a significant performance improvement of the proposed protocol.     

Stable routing protocol based on fuzzy logic system in vehicular ad hoc networks

Vehicular ad‐hoc networks have several roles in alert messages dissemination between vehicles in danger, the most important role is to provide helpful information for drivers (eg, road traffic state). But, some performance improvements are frequently needed in terms of routing. Hence, several clustering approaches have been proposed to optimize the network services. These approaches are based on increasing data delivery, reducing data congestion, and dividing the traffic into clusters. However, a stable clustering algorithm is always required in order to ensure the data dissemination in a dense, mobile, or a large‐scale environment. Therefore, in this paper, we have proposed a stable routing protocol based on the fuzzy logic system, which can deliver alert messages with minimum delay and improve the stability of clusters structure by generating only a small number of clusters in the network. In this work, the fuzzy logic system has been used to create the clusters and select a cluster head for each cluster. We have used the network simulator (NS2) to generate the results. As a result, we could reduce the cluster head changes and increase the cluster member lifetime compared with recent approaches.     

一种动态寻路中的机会转发模型

动态寻路（Dynamic Routing）是一项用以解决城市交通拥堵的智能交通技术.通过让一些车辆产生和转发路况拥堵消息,另一些车辆能够避开拥堵路段,从而缓解交通状况.以“存储-携带-转发”为通信模式的机会网络被广泛运用于动态寻路研究.文中提出了一种新型路况信息的机会转发算法,算法综合考虑车辆的位置和行驶方向.仿真实验表明,算法在保持信息散布效果的前提下,显著降低了网络负载,提升了效率.     

Efficient multi‐hop wireless broadcast protocol in vehicular networks using automated threshold function design

Vehicular networking applications often use multi‐hop wireless broadcasting as a primary data dissemination mechanism. Therefore, protocols that efficiently and thoroughly propagate application data while adapting to a wide range of network density, vehicle distribution pattern, channel quality, and other conditions are critical for vehicular communications. Here, we design the Statistical Vehicular Broadcast (SVB) protocol to efficiently distribute data via multi‐hop broadcast in vehicular networks. First, we present an automated optimization technique for the design of threshold functions in statistical broadcasting methods. Next, we compare and analyze known statistical techniques, including different fundamental methods, assessment delay algorithms, and failsafe mechanisms. All combinations of these techniques are given threshold functions optimized using the proposed automated procedure then are evaluated in a wide range of simulations. High‐level statistical design principles and recommendations are established based on analysis of these results. Finally, we apply those principles to design SVB. It is evaluated in JiST/SWANS and is shown to achieve a high target reachability level while consuming less bandwidth than similar protocols across urban and highway vehicular networking scenarios.Copyright © 2014 John Wiley & Sons, Ltd.     

A geographic routing protocol based on trunk line in VANETs

A Trunk Line Based Geographic Routing(TLBGR) protocol in Vehicular Ad-hoc Networks (VANETs) is proposed in this paper to solve the problem of data acquisition in the traditional trunk coordinated control system. Because of the characteristics of short communication time and high packet loss among vehicles, the vehicles entering the trunk lines can not transmit their information to the trunk coordinated control system stably. To resolve this problem, the proposed protocol uses the trunk lines’ traffic flow and the surrounding road network to provide a real-time data transmission routing scheme. It takes into account the data congestion problem caused by the large traffic flow of the main roads, which leads to the corresponding increase of the information flow of the section and the package loss, and the link partition problem caused by the insufficient traffic flow, which makes the vehicles have to carry and relay information thus increasing the transmission delay. The proposed TLBGR protocol can be divided into two stages: the next-intersection selection, and the next-hop selection in the chosen path between the current and next intersections. Simulation results show that, compared with other IoT routing protocols including Greedy Perimeter Stateless Routing (GPSR), Ad-hoc On Demand Vector (AODV), and Q-AODV, the TLBGR protocol has better performance in aspects of end-to-end delay, delivery rate, and routing cost under the scenario of urban traffic trunk lines. The TLBGR protocol can effectively avoid data congestion and local optimum problems, increase the delivery rate of data packets, and is therefore suitable for the routing requirements in this application scenario.     

V2V protocols for traffic congestion discovery along routes of interest in VANETs: a quantitative study

One of the most interesting and promising challenges for Intelligent Transportation Systems (ITSs) relates to the traffic congestion problem. Congestion is a relevant issue for transportation because it reduces the efficiency of infrastructure and increases travel time, air pollution, and fuel consumption. Nowadays, the most promising technology in support of ITSs is found in the domain of Vehicular Ad Hoc Networks (VANETs). In this paper, we propose three protocols that are able to transmit traffic information for routes of interest on VANETs without any Road Side Unit (RSU) support. The proposed protocols adopt strategies to improve the performance of packet routing based on the density and location of vehicles; moreover, they enable an interesting comparison of the performance achievable with either reactive or proactive approaches. The extensive performance results reported show how it is possible to limit the congestion monitoring overhead along Routes of Interest (ROIs), while maintaining a sufficiently high performance in terms of traffic reporting. This may be done by employing context‐aware data delivery techniques that autonomously adapt to runtime conditions. Copyright © 2016 John Wiley & Sons, Ltd.     

车载自组织网络中基于贪婪算法能地理位置路由

车载自组织网络（VANET）技术发展迅速,但由于其特殊的节点类型和信道特性,采用传统AdHoc网络路由协议无法取得满意的性能。实现高速可靠的数据传输速率,需要研究新兴的路由算法。基于贪婪算法的地理位置辅助路由是目前VANET路由的主流思路。文章认为基于这类思路的协议利用车载GPS装置、电子地图和下一代网络导航技术,能使路由发现和建立的时间大大缩短;结合已知的道路拓扑结构,选择多跳传输的最优路径,能避免路边建筑物的屏蔽效应,改善信道条件;动态评估道路上的车流密度,选择可靠性最高的传输路径,能很好地降低传输时延,提高网络吞吐能力。     

车载自组织网络路由协议研究进展与比较

车载自组织网络( VANET)是一种新型移动自组织网络。作为移动无线网络的热点研究领域,车载自组织网络的间歇连通性使路由设计充满挑战。首先阐述了车载自组织网络的主要特征和应用;在对车载网络路由协议进行分类的基础上,详细描述了一批有代表性的路由协议;对比和总结了各类路由协议的特点,并提出相关研究建议,可为车载网络路由协议研究提供一定的参考价值。     

车载自组织网络路由协议研究进展与比较

车载自组织网络（VANET）是一种新型移动自组织网络。作为移动无线网络的热点研究领域,车载自组织网络的间歇连通性使路由设计充满挑战。首先阐述了车载自组织网络的主要特征和应用;在对车载网络路由协议进行分类的基础上,详细描述了一批有代表性的路由协议;对比和总结了各类路由协议的特点,并提出相关研究建议,可为车载网络路由协议研究提供一定的参考价值。     

The importance of nature-inspired metaheuristic algorithms in the data routing and path finding problem in the internet of things

Over the last decade, the Internet of Things (IoT) has become ever more popular, as is evident from its role in changing the human lifestyle and conferring remarkable privileges for them. It has a significant presence in various crucial areas, including smart cities, smart factories, manufacturing, transportation, and healthcare. Massive amounts of data generated by IoT devices have the potential to endanger the lifetime of nodes in IoT-based networks due to increased communication power consumption. It has become crucial to propose solutions for network-based issues, such as quality of service, security, network heterogeneity, congestion avoidance, reliable routing, and energy conservation. To address the mentioned problems, routing protocols play a critical role in data transmission among heterogeneous items. In such environments, routing refers to constructing routes between mobile nodes. Since identifying optimal routes among IoT nodes and establishing an effective routing protocol in an IoT network are an NP-hard issue, employing metaheuristic algorithms may be a viable solution to overcome this problem. Various IoT routing protocols based on metaheuristic algorithms have been presented in recent years, but there is still a lack of systematic study for reviewing the existing works. The current study emphasizes the impact of metaheuristic algorithms in the IoT routing problem, discusses the optimization models, presents a comprehensive comparison of protocols based on critical parameters, and eventually suggests some hints for future studies.     

VANETs路由协议的研究进展

车辆自组织网络是传统自组织网络派生出的一个分支,其与应用场景高度相关.传统路由协议不能有效的适用于车辆自组织网络,因此,针对车辆自组织网络提出了许多新的路由协议.首先在总结车辆自组织网络的特性后,分别介绍了单播路由、广播路由和地域性多播路由的概念,然后着重分析和总结了近年来具有代表性的路由协议的核心路由机制及其优缺点,...     

城市环境VANETS下的基于beacon控制的路由方案

车载网络(Vehicular ad hoc networks,VANETs)是一种特殊形式的网络,具有节点高速移动、拓扑频繁的变化的特性。这些特性为消息的传播带来挑战。路由机制是实现消息传递的关键因素。地理位置路由被广泛地应用于VANETS,要求节点周期广播beacon消息。然而,节点周期地广播beacon消息,降低了路由性能,特别是在城市区域,由于节点密集,每个节点均广播beacon消息,恶化了路由性能。为此,针对城市环境,提出基于beacon控制的路由协议RPBC(Routing protocol with beacon control)。在RPBC中,并非每个节点广播beacon消息,而设置有效的机制选择部分节点广播,从而降低了beacon冗余,同时,采用最短路径算法,减少数据传输跳数。仿真结果表明,提出的RBPC在分组投递率、端到端传输时延以及路由开销方面均有较好的性能。     

面向可扩展的VANETs混合路由的研究与仿真

车载网VANETs(Vehicular ad hoc networks)属于高速移动的无线网络,可供车辆安全、交通监测以及其他的商业服务的应用。然而,为此,提出混合式的位VANETs中车辆的快速移动导致通信链路频繁地断裂,增加路由开销,降低了可扩展性。议地理位置路由的特点。HLAR(Hybrid location-based ad hoc routing)。HLAR结合了反应式路由、HLAR克服了反应式路由的扩展性问题,并改善了地理位置路由对位置误差的敏感性。同时,通过理论分析,量可扩展性,并推导了路由开销的表达式。通过分析、仿真表明,提出的路由协议具有很好的扩展性,并降低了路由开销。在仿真中引入位置误差因子,结果表明。同时,与同类的其他协议相比,输时延方面HLAR到对位置误差具有很强的鲁棒性HLAR在数据传输率、端到端传提升。     

缓存交换：间歇连通车载网络中的路到路的路由机制

Due to the road-constrained data delivery and highly dynamic topology of vehicle nodes in a Vehicular Ad Hoc Network (VANET), it is better to construct routing based on the road-to-road pattern than the traditional node-to-node routing pattern in MANETs. However, the challenging issue is the opportunistic forwarding at intersections. Therefore, we propose a novel routing scheme, called Buffer and Switch (BAS). In BAS, each road buffers the data packets with multiple duplicates propagation in order to provide more opportunities for packet switching at intersections. Different from conventional protocols in VANETs, the propagation of duplicates in BAS is bidirectional along the routing path. Moreover, BAS's cost is much lower than other flooding-based protocols due to its spatio-temporally controlled duplicates propagation. Different from recent researches, BAS can deliver packets not only to a stationary node, but also to the stationary or mobile nodes in a specified area. We conduct the extensive simulations to evaluate the performance of BAS based on the road map of a real city collected from Google Earth. The simulation results show that BAS can outperform the existing protocols, especially when the network resources are limited.     

FGWSO‐TAR: Fractional glowworm swarm optimization for traffic aware routing in urban VANET

In mobile distributed applications, such as traffic alert dissemination, dynamic route planning, file sharing, and so on, vehicular ad hoc network (VANET) has emerged as a feasible solution in recent years. However, the performance of the VANET depends on the routing protocol in accord with the delay and throughput requirements. Many of the routing protocols have been extensively studied in the literature. Although there are exemptions, they escalate research challenges in traffic aware routing (TAR) protocol of VANET. This paper introduces the fractional glowworm swarm optimization (FGWSO) for the TAR protocol of VANET in an urban scenario that can identify the optimal path for the vehicle with less traffic density and delay time. The proposed FGWSO searches the optimal routing path based on the fitness function formulated in this paper. Fractional glowworm swarm optimization is the combination of the GWSO and fractional theory. Moreover, exponential weighted moving average is utilized to predict the traffic density and the speed of the vehicle, which is utilized as the major constraints in the fitness function of the optimization algorithm to find the optimal traffic aware path. Simulation of FGWSO shows the significant improvement with a minimal end‐to‐end delay of 6.6395 seconds and distance of 17.3962 m, respectively, in comparison with the other existing routing approaches. The simulation also validates the optimality of the proposed TAR protocol.     

Mixing greedy and predictive approaches to improve geographic routing for VANET

In recent years, thanks to the development and popularization of wireless network technologies, the issue of vehicular ad hoc network (VANET) has received great attention, and more and more VANET‐related researches have been brought up. Generally speaking, the biggest difference between VANET and traditional ad hoc network is the velocity of carriers because in VANET, the velocity of vehicles, the carriers, is much higher than those in traditional ad hoc. Therefore, it would be a great challenge to forward data efficiently in VANETs and many researches proposed have focused on the development of routing protocols. The current proposed routing protocols are all assumed to simulate in a distributed and ideal environment. As for the complex geographic environments, such as urban scenarios, extra amendments must be needed to improve the efficiency of the routing protocols. Thus, the main purpose of this paper is to design a suitable routing protocol for urban scenarios with better performance and adaptability. For this reason, greedy on straight roads and predictive at the intersections (GSPI) routing protocol is proposed to use greedy mode on straight roads and to use predictive mode at the intersections. In greedy mode, we choose the next hop according to the weight value that combines the distances and multi‐rate. In predictive mode, we predict the directions of the vehicles to determine the next hop. The simulation results reveal that our proposed algorithm indeed proves its feasibility. Copyright © 2010 John Wiley & Sons, Ltd.     

Performance evaluation of ad hoc routing protocols for military communications

Mobile ad hoc networks (MANETs) are of much interest to both the research community and the military because of the potential to establish a communication network in any situation that involves emergencies. Examples are search‐and‐rescue operations, military deployment in hostile environments, and several types of police operations. One critical open issue is how to route messages considering the characteristics of these networks. The nodes act as routers in an environment without a fixed infrastructure, the nodes are mobile, the wireless medium has its own limitations compared to wired networks, and existing routing protocols cannot be employed, at least without modifications. Over the last few years, a number of routing protocols have been proposed and enhanced to address the issue of routing in MANETs. It is not clear how those different protocols perform under different environments. One protocol may be the best in one network configuration but the worst in another. This article provides an analysis and performance evaluation of those protocols that may be suitable for military communications. The evaluation is conducted in two phases. In the first phase, we compare the protocols based on qualitative metrics to locate those that may fit our evaluation criteria. In the second phase, we evaluate the selected protocols from the first phase based on quantitative metrics in a mobility scenario that reflects tactical military movements. The results disclose that there is no routing protocol in the current stage without modifications that can provide efficient routing to any size of network, regardless of the number of nodes and the network load and mobility. Copyright © 2011 John Wiley & Sons, Ltd.     

A novel hierarchical model for vehicular traffic regulation

The aim of the research is to regulate the vehicular traffic in the most effective and efficient way in Vehicular Adhoc Networks (VANET). The challenges faced by the existing networks are ripple effect of reclustering, communication complexity, mobility, throughput and delay in an urban environment. Moreover unpredictable topology changes in VANET, obstruct expected packet delivery ratio and leads to congestion by overheads for link maintenance. The existing routing techniques suffer from excessive loss of data, delay and need for continuous monitoring where group member’s loss their link in randomwaypoint mobility scenarios. In this paper, a novel hierarchical model combining the features of hierarchical clustering, hybrid mobility model and location based 2hop Multicast Flooding (L2MF) for data forwarding has been proposed. By comparing the proposed protocol with previous protocols, the enhanced performance in packet delivery ratio, control overhead, and end-to-end delay has been proved.     

自组网路由协议综述

自组网路由协议用于监控网络拓扑结构变化,交换路由信息,定位目的节点位置,产生、维护和选择路由,并根据选择的路由转发数据。本文综述了自组网路由协议研究方面的一些最新工作,描述了设计自组网路由协议所面临的问题,并着重对该研究开展以来所提出的各种主要协议进行了对比、分析和分类阐述,为进一步的研究提出了新的课题。     

Adaptive Inter Vehicle Communications

Inter Vehicle Communications (IVC) have the potential to significatively increase the safety in our highways. In such communications, the quality and reliability of service becomes a very critical issue. In particular, it is important that in case of emergencies, when the inter vehicle traffic increases exponentially, the message delay should be kept low. We present a reliable hierarchical routing protocol that uses load balancing to keep message delay low even in presence of high level of traffic. Our protocol is based on geographical routing. The protocol is designed for highway travelers but can be used in other mobile ad-hoc scenarios. The highway is divided in virtual cells, which moves as the vehicles moves. The cell members might choose one or more Cell_Leaders that will behave for a certain time interval as Base Stations. We assume that every node knows its geographical position, given by Global Positioning System (GPS) or some other method. Cell_Leaders form a virtual backbone that is used to forward messages among nodes on different cells. The traffic is distributed among Cell_Leaders in order to optimize the communication delay. We study the effect of load balancing in minimizing delay. Our simulation results show that our proposed protocol improves the delay and the network utilization compared to existing inter vehicles protocols.