An improved distance‐based ant colony optimization routing for vehicular ad hoc networks

Vehicular ad hoc network (VANET) has earned tremendous attraction in the recent period due to its usage in a wireless intelligent transportation system. VANET is a unique form of mobile ad hoc network (MANET). Routing issues such as high mobility of nodes, frequent path breaks, the blind broadcasting of messages, and bandwidth constraints in VANET increase communication cost, frequent path failure, and overhead and decrease efficiency in routing, and shortest path in routing provides solutions to overcome all these problems. Finding the shortest path between source and destination in the VANET road scenario is a challenging task. Long path increases network overhead, communication cost, and frequent path failure and decreases routing efficiency. To increase efficiency in routing a novel, improved distance‐based ant colony optimization routing (IDBACOR) is proposed. The proposed IDBACOR determines intervehicular distance, and it is triggered by modified ant colony optimization (modified ACO). The modified ACO method is a metaheuristic approach, motivated by the natural behavior of ants. The simulation result indicates that the overall performance of our proposed scheme is better than ant colony optimization (ACO), opposition‐based ant colony optimization (OACO), and greedy routing with ant colony optimization (GRACO) in terms of throughput, average communication cost, average propagation delay, average routing overhead, and average packet delivery ratio.     

AODV路由协议性能的改进研究

路由问题一直是移动Ad Hoc网络（MANET）研究中的难点和重要问题。按需路由协议是当前移动Ad Hoc网络的主流路由协议。丈中通过对AODV和DSR两种典型的按需路由协议的分析与比较，提出了一种利用DSR的路径收集机制来改进和提高AODV路由协议性能的方法。通过NS2仿真实验表明，该方法能有效减少路由请求的数量，从而降低路由的开销，提高分组发送的成功率，减少端对端的延时。     

A Novel Robust Routing Scheme Against Rushing Attacks in Wireless Ad Hoc Networks

Standard on-demand routing protocols in wireless ad hoc networks were not originally designed to deal with security threats. Because of that, malicious users have been finding ways to attack networks. Rushing attacks represent one of such possibilities. In these attacks, malicious nodes forward the Route Request (RREQ) packets, asking for a route, to the destination node quicker than the legitimate nodes do. This is possible because the legitimate nodes only forward the first received RREQ packet for a given route discovery. Besides, the attackers can tamper with either the Medium Access Control or routing protocols to get faster processing. As a result, the path through the malicious nodes is chosen, which renders throughput degradation. We propose here a novel, robust routing scheme to defend ad hoc networks against rushing attacks. Our scheme utilizes the “neighbor map mechanism” to establish robust paths as far as rushing attacks are concerned. The proposed scheme also improves path recovery delay by using, whenever it is possible, route maintenance rather than route discovery. Yet, it is energy efficient. The simulation results show that our proposal is indeed viable.     

A secure and trust based on-demand multipath routing scheme for self-organized mobile ad-hoc networks

A mobile ad hoc network (MANET) is a self-configurable network connected by wireless links. This type of network is only suitable for provisional communication links as it is infrastructure-less and there is no centralized control. Providing QoS and security aware routing is a challenging task in this type of network due to dynamic topology and limited resources. The main purpose of secure and trust based on-demand multipath routing is to find trust based secure route from source to destination which will satisfy two or more end to end QoS constraints. In this paper, the standard ad hoc on-demand multi-path distance vector protocol is extended as the base routing protocol to evaluate this model. The proposed mesh based multipath routing scheme to discover all possible secure paths using secure adjacent position trust verification protocol and better link optimal path find by the Dolphin Echolocation Algorithm for efficient communication in MANET. The performance analysis and numerical results show that our proposed routing protocol produces better packet delivery ratio, reduced packet delay, reduced overheads and provide security against vulnerabilities and attacks.     

Mitigation and Performance Analysis of Routing Protocols Under Black-Hole Attack in Vehicular Ad-hoc Network (VANET)

Vehicular Ad-hoc network (VANET) is a self-organized ad hoc network. VANET becomes a most challenging research area as it has several issues related to routing protocols, quality of service, security, etc. Vehicular communication is critically unsafe to several kinds of active and passive routing attacks. This paper analyzes the impact of a compromised node (vehicle) on zone routing protocol and ad-hoc on-demand distance vector, and recommends a suitable solution called secure vehicular on demand routing to find out and mitigate the black hole attack. The given study analyses the effect of vehicle density on the average throughput, packet delivery ratio, end-to-end delay, normalized routing load and average path length.     

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。     

Road Oriented Traffic Information System for Vehicular Ad hoc Networks

Over the last few years, vehicular ad hoc networks (VANETs) have gained popularity for their interesting applications. To make efficient routing decisions, VANET routing protocols require road traffic density information for which they use density estimation schemes. This paper presents a distributed mechanism for road vehicular density estimation that considers multiple road factors, such as road length and junctions. Extensive simulations are carried out to analyze the effectiveness of the proposed technique. Simulation results suggested that, the proposed technique is more accurate compared to the existing technique. Moreover, it facilitate VANET routing protocols to increase packet delivery ratio and reduce end-to-end delay.     

ACAR: Adaptive Connectivity Aware Routing for Vehicular Ad Hoc Networks in City Scenarios

Multi-hop vehicle-to-vehicle communication is useful for supporting many vehicular applications that provide drivers with safety and convenience. Developing multi-hop communication in vehicular ad hoc networks (VANET) is a challenging problem due to the rapidly changing topology and frequent network disconnections, which cause failure or inefficiency in traditional ad hoc routing protocols. We propose an adaptive connectivity aware routing (ACAR) protocol that addresses these problems by adaptively selecting an optimal route with the best network transmission quality based on statistical and real-time density data that are gathered through an on-the-fly density collection process. The protocol consists of two parts: 1) select an optimal route, consisting of road segments, with the best estimated transmission quality, and 2) in each road segment of the chosen route, select the most efficient multi-hop path that will improve the delivery ratio and throughput. The optimal route is selected using our transmission quality model that takes into account vehicle densities and traffic light periods to estimate the probability of network connectivity and data delivery ratio for transmitting packets. Our simulation results show that the proposed ACAR protocol outperforms existing VANET routing protocols in terms of data delivery ratio, throughput and data packet delay. Since the proposed model is not constrained by network densities, the ACAR protocol is suitable for both daytime and nighttime city VANET scenarios.     

Modified Light Weight distributed QoS Algorithm for wide area ad hoc networks

The direction and velocity of a node are the most important parameters to create a valuable path in ad hoc networks. A valuable path is one that has a longer life time and more durability than others. As we know, the durability of a path is under the influence of the nodes' velocity. This paper proposes an algorithm to provide QoS in ad hoc networks. The proposed algorithm entitled Modified Light Weight distributed QoS Algorithm, considering the direction and relative velocity of the nodes and predicting the value of link durability, chooses a path with longer duration time, minimizes the link breaks, and improves QoSs. We implemented it in a simulation environment by using the Network Simulator Version 2 software and evaluated the effectiveness of it in packet delivery ratio, packet delivery latency, average end‐to‐end delay, routing overhead, and dropped packets. The simulation results demonstrate that Modified Light Weight distributed QoS Algorithm improves the QoS parameters in ad hoc networks.     

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.     

无线传感器网络路由协议的设计与实现

针对传统路由协议端到端时延长、丢包率过高的现实问题,提出了一种基于贪婪转发的能量感知多路径路由协议(Greedy Forward Energy-aware Multipath Routing Protocol,GFEMRP)。GFEMRP从传感器起始结点出发,如果遇到网络黑洞则选择周边转发方式,否则将选择吞吐量大、且更接近于目的结点的结点作为下一跳结点。利用了OMNET++5.0和INET框架对包括无线自组网按需平面距离向量路由协议(Ad hoc on-demand distance vector routing protocol,AODV),动态按需无线自组织网络(Dynamic MANET On-demand,DYMO),贪婪周边无状态路由无线网络(Greedy Perimeter Stateless Routing for Wireless Networks,GPSR)和GFEMRP协议在内的四种路由协议进行了仿真和比较,实验结果表明GFEMRP协议具有良好的端到端时延、丢包率等性能。     

Intersection-Based Routing Protocol for VANETs

Vehicular ad hoc network (VANET) is an emerging wireless communications technology that is capable of enhancing driving safety and velocity by exchanging real-time transportation information. In VANETs, the carry-and-forward strategy has been adopted to overcome uneven distribution of vehicles. If the next vehicle located is in transmission range, then the vehicle forwards the packets; if not, then it carries the packets until meeting. The carry mostly occurs on sparsely populated road segments, with long carry distances having long end-to-end packet delays. Similarly, the dense condition could have long delays, due to queuing delays. The proposed intersection-based routing protocol finds a minimum delay routing path in various vehicle densities. Moreover, vehicles reroute each packet according to real-time road conditions in each intersection, and the packet routing at the intersections is dependent on the moving direction of the next vehicle. Finally, the simulation results show that the proposed Intersection-Based Routing (IBR) protocol has less end-to-end delay compared to vehicle-assisted data delivery (VADD) and greedy traffic aware routing protocol (GyTAR) protcols.     

Study of MANET routing protocols by GloMoSim simulator

This paper compares ad hoc on‐demand distance vector (AODV), dynamic source routing (DSR) and wireless routing protocol (WRP) for MANETs to distance vector protocol to better understand the major characteristics of the three routing protocols, using a parallel discrete event‐driven simulator, GloMoSim. MANET (mobile ad hoc network) is a multi‐hop wireless network without a fixed infrastructure. Following are some of our key findings: (1) AODV is most sensitive to changes in traffic load in the messaging overhead for routing. The number of control packets generated by AODV became 36 times larger when the traffic load was increased. For distance vector, WRP and DSR, their increase was approximately 1.3 times, 1.1 times and 7.6 times, respectively. (2) Two advantages common in the three MANET routing protocols compared to classical distance vector protocol were identified to be scalability for node mobility in end‐to‐end delay and scalability for node density in messaging overhead. (3) WRP resulted in the shortest delay and highest packet delivery rate, implying that WRP will be the best for real‐time applications in the four protocols compared. WRP demonstrated the best traffic scalability; control overhead will not increase much when traffic load increases. Copyright © 2005 John Wiley & Sons, Ltd.     

A location-based routing method for mobile ad hoc networks

Using location information to help routing is often proposed as a means to achieve scalability in large mobile ad hoc networks. However, location-based routing is difficult when there are holes in the network topology and nodes are mobile or frequently disconnected to save battery. Terminode routing, presented here, addresses these issues. It uses a combination of location-based routing (terminode remote routing, TRR), used when the destination is far, and link state-routing (terminode local routing, TLR), used when the destination is close. TRR uses anchored paths, a list of geographic points (not nodes) used as loose source routing information. Anchored paths are discovered and managed by sources, using one of two low overhead protocols: friend assisted path discovery and geographical map-based path discovery. Our simulation results show that terminode routing performs well in networks of various sizes. In smaller networks; the performance is comparable to MANET routing protocols. In larger networks that are not uniformly populated with nodes, terminode routing outperforms, existing location-based or MANET routing protocols.     

RMRPTS: a reliable multi-level routing protocol with tabu search in VANET

Vehicular ad hoc network (VANET), a subclass of mobile ad hoc networks (MANETs), is a promising approach for the intelligent transportation system (ITS). One of the main challenges in VANETs is establishment of vehicular communication and stable routing. Another problem of VANETs is their tendency of being trapped in a local optimum. In this paper, a reliable multi-level routing protocol based on clustering, RMRPTS has been introduced in VANETs. Even if this topology constantly changes, clustering based multi-level routing will create the possibility of self-organization and route maintaining; moreover, it will solve the problem of developing a trap in the local optimum using tabu search. At the first level, the proposed protocol is an extension of AODV routing protocol that has been improved using fuzzy logic in order to create reliable routing between cluster members. Tabu search has been used at a higher level for routing between cluster heads and destination. Tabu search is a meta-heuristic improved learning method used for solving hybrid optimization problems, and it uses cost function to select a solution among a set of possible solutions. The effective parameters used in the proposed method to select the best path include nodes distance, the velocity of nodes, node’s angle, link stability, and link reliability. The proposed protocol was simulated using an NS-2 simulator, and the results of its performance showed increased average packet delivery rate and decreased average end to end delays, number of packet losses compared with earlier protocols.     

Route Stability Based QoS Routing in Mobile Ad Hoc Networks

To provide high quality communications service among mobile wireless devices is basically a challenging task in wireless ad hoc networks. In this paper, we propose a Route Stability based QoS Routing (RSQR) protocol in Mobile Ad Hoc Networks (MANETs) which is an extension of QoS routing with throughput and delay constraints. Ensuring a data path to be valid for sufficiently longer period of time is a very difficult problem in MANET due to its highly dynamic nature. We propose a simple model for computing link stability and route stability based on received signal strengths. By including some extra fields in route request/reply packets, the route stability information can be utilized to select a route with higher stability among all the feasible routes between a given source destination pair. Further, inclusion of a signal strength based admission control enhances the performance of the routing. Results of our experiments show performance improvements in terms of packet delivery ratio, control overhead and average end-to-end delay in comparison with a QoS routing protocol proposed by Q. Xue and A. Ganz.     

DEBH: detecting and eliminating black holes in mobile ad hoc network

Security in mobile ad hoc network (MANET) is one of the key challenges due to its special features e.g. hop-by-hop communications, dynamic topology, and open network boundary that received tremendous attention by scholars. Traditional security methods are not applicable in MANET due to its special properties. In this paper, a novel approach called detecting and eliminating black holes (DEBH) is proposed that uses a data control packet and an additional black hole check table for detecting and eliminating malicious nodes. Benefiting from trustable nodes, the processing overhead of the security method decreases by passing time. Ad hoc on-demand distance vector (AODV) routing protocol is used as the routing protocol in our design. After finding the freshest path using AODV, our design checks the safety of selected path. In case of detecting any malicious node, it is isolated from the entire network by broadcasting a packet that contains the ID of malicious nodes. Simulation results show that DEBH increases network throughput and decreases packet overhead and delay in comparison with other studied approaches. Moreover, DEBH is able to detect all active malicious nodes which generates fault routing information.     

On the reliability of ad hoc routing protocols for loss-and-delay sensitive applications

In this paper, we analyze the packet delivery reliability of ad hoc routing protocols for loss-and-delay sensitive applications. Since a typical flooding-based route discovery used in ad hoc routing protocols – DSR for instance – can only discover node-disjoint paths. In this context, we first show that the reliability function of such a multipath system is concave with respect to the total number of paths. Therefore, maximum steady-state reliability may be attained by routing each packet through a small set of node-disjoint paths. Subsequently, we prove that a partially-disjoint path is more reliable than a node-disjoint path. Hence, high reliability and significant energy savings may be achieved by routing a packet through fewer partially-disjoint paths. Based on these findings, we suggest modifications to flooding-based route discovery procedure to discover partially-disjoint paths. We complement our theoretical outcomes through extensive simulations. Finally, we analyze the reliability of beacon-based routing protocols and derive an upper bound on the number of hops at which a beacon should be placed to satisfy a given packet reliability constraint.     

An EDRI-based approach for detecting and eliminating cooperative black hole nodes in MANET

Mobile Ad hoc Network (MANET) is a self-configurable, self-maintenance network with wireless, mobile nodes. Special features of MANET like dynamic topology, hop-by-hop communications and open network boundary, made security highly challengeable in this network. From security aspect, routing protocols are highly vulnerable against a wide range of attacks like black hole. In black hole attack malicious node injects fault routing information to the network and leads all data packets toward it-self. In this paper, we proposed an approach to detect and eliminate cooperative malicious nodes in MANET with AODV routing protocol. A data control packet is used in order to check the nodes in selected path; also, by using an Extended Data Routing Information table, all malicious nodes in selected path are detected, then, eliminated from network. For evaluation, our approach and a previous work have been implemented using Opnet 14 in different scenarios. Referring to simulation results, the proposed approach decreases packet overhead and delay of security mechanism with no false positive detection. In addition, network throughput is improved by using the proposed approach.     

An Energy-Aware Routing Protocol for Mobile Ad Hoc Networks Based on Route Energy Comprehensive Index

The design of energy-aware routing protocols has always been an important issue for mobile ad hoc networks (MANETs), because reducing the network energy consumption and increasing the network lifetime are the two main objectives for MANETs. Hence, this paper proposes an energy-aware routing protocol that simultaneously meets above two objectives. It first presents Route Energy Comprehensive Index (RECI) as the new routing metric, then chooses the path with both minimum hops and maximum RECI value as the route in route discovery phase, and finally takes some measures to protect the source nodes and the sink nodes from being overused when their energies are low so as to prolong the life of the corresponding data flow. Simulation results show that the proposed protocol can significantly reduce the energy consumption and extend the network lifetime while improve the average end-to-end delay compared with other protocols.