Review of Routing Protocols Routing Protocols ...

IJRIT International Journal of Research in Information Technology, Volume 2, Issue 4, April 2014, Pg: 625- 632

International Journal of Research in Information Technology (IJRIT) www.ijrit.com

ISSN 2001-5569

Review of Routing Protocols for VANET Namita Chandel1, Mr. Vishal Gupta2 1

M.tech Student Department of Computer Science & Engineering M. M. Engineering College, Maharishi Markandeshwar University, Mullana, Ambala, Haryana, India [email protected] 2

Assistant Professor Department of Computer Science & Engineering M. M. Engineering College, Maharishi Markandeshwar University, Mullana, Ambala, Haryana, India [email protected]

Abstract Vehicular Ad Hoc Network (VANET) is an emerging new technology integrating ad hoc network, wireless LAN (WLAN) and cellular technology to achieve intelligent inter-vehicle communications and improve road traffic safety and efficiency. VANETs are distinguished from other kinds of ad hoc networks by their hybrid network architectures, node movement characteristics, and new application scenarios. Therefore, VANETs pose many unique networking research challenges, and the design of an efficient routing protocol for VANETs is very crucial. In VANET, two kinds of communication can be done i.e. Vehicle to vehicle and vehicle to roadside communication. Since the performance of such communication between vehicles depends on various protocols. We have a tendency to survey a number of the recent analysis leads to routing space. In the following sections we present existing routing protocols with their pros and cons.

Keyword: VANET, Routing protocol, communication.

1. INTRODUCTION VANET is a new technology in recent years; researchers have taken huge attention on it. It is a special type of mobile ad hoc networks; where vehicles are simulated as mobile nodes. VANET consist 2 entities: access points and vehicles, the access points are fixed and usually connected to the net, and they could participate as a distribution point for vehicles [1]. VANET addresses the wireless communication between vehicles (V2V), and between vehicles and infrastructure access point (V2I). Vehicle to vehicle communication (V2V) has two types of communication: one hop communication (direct vehicle to vehicle communication), and multi hop communication (vehicle relies on other vehicles to retransmit). Due to new technology it has taken huge attention from government, academy & business. There are many research projects around the world which are related with VANET such as COMCAR [2], DRIVE [3], Fleet Net [4] and Now (Network on Wheels) [5], CarTALK 2000 [6], CarNet [7]. There are several VANET applications such as Vehicle collision warning, Security distance warning, Driver help, Cooperative driving, and Cooperative cruise management, Dissemination of road info, Net access, Map location, Automatic parking, and Driverless vehicles. The feature of VANET mostly resembles the operation technology of MANET in the sense that the method of self-organization, self-management, low bandwidth and shared radio transmission criteria remain same. But the key hindrance in operation of VANET comes from the high speed and uncertain mobility [in contrast to MANET] of the mobile nodes (vehicles) along the paths. This suggested that the design of efficient routing protocol demands up gradation of MANET architecture to accommodate the fast mobility of the VANET nodes in an efficient manner. For the building of the routes Namita Chandel, IJRIT

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and in order to build the network, the mechanism of routing protocols in the VANET networks introduced. The main functionality of routing protocols is to build the dynamic routes in the network in between any source and destination nodes in the network. Network topology for the VANET networks is not fixed because of the frequent nodes movement in the network. According to the movements of the nodes is resulted into the frequent topology changes. This warranted various research challenges to design appropriate routing protocol. It is therefore important at this stage to reiterate the key characteristics of VANET that may be accounted for the design of various routing protocols.

Fig 1: Vehicular ad hoc networks and some possible applications. The paper is divided into four sections. Section 2 explains the various characteristics of the VANET. Section 3 briefly describes the various routing protocols of VANET along with their pros and cons. Section 4 a comparison table of all stated routing protocols. Finally this paper is concluded in section 5.

2 CHARACTERISTICS OF VANET There are some unique characteristics of VANET which make it different from MANET as well as challenging for designing VANET applications. Some characteristics are given as following:

2.1 High dynamic topology The speed and choice of path defines the dynamic topology of VANET. Suppose that if two vehicles moving away from each other with a speed of 60 mph (25m/sec) and if the transmission range is about 250m, then the link between these two vehicles will last for only 5 seconds (250m/ 50ms-1). This defines its highly dynamic topology.

2.2 Frequent disconnected network Frequent disconnection occurs between two vehicles when they are exchanging information due to the above feature i.e. high dynamic topology. This disconnection will occur most in sparse network.

2.3 Mobility Modeling The mobility pattern of vehicles depends on various factors such as roads structure, traffic environment, the speed of vehicles, driver’s driving behavior and so on.

2.4 Communication environment The mobility model highly varies from highways to that of city environment. The node prediction design and routing algorithm also therefore need to adapt for these changes. The communication environment between vehicles is different in network. i.e. in dense network building, trees & other objects behave as obstacles where as in sparse network like high-way these things are absent. So the routing approach of sparse & dense network will be different.

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2.5 Hard Delay Constraints The safety aspect (such as accidents, brake event) of VANET application warrants on time delivery of message to relevant nodes. It simply cannot compromise with any hard data delay in this regard. Therefore high data rates are not as important an issue for VANET as overcoming the issues of hard delay constraints.

2.6 Interaction with onboard sensors This sensors helps in providing node location and their movement nature that are used for effective communication link and routing purposes.

2.7 Battery power and storage capacity It is the most important feature of the VANET In the modern vehicles battery power and storage is unlimited. It is helpful for effective communication & making routing decisions. Thus it has enough computing power which is unavailable in MANET.

3. ROUTING IN VANET A routing protocol provide a way that two communication entities exchange information it includes the procedure in establishing a route, decision in forwarding, and action in maintaining the route or recovering from routing failure. VANETs are a class of ad hoc networks, the main difference between MANET and VANET is the special mobility pattern and rapidly changing topology. The unremarkably used ad hoc routing protocols at first enforced for MANETs are tested and then evaluated to be used in a VANET environment. .There are some specific VANET-related issues such as network topology, mobility patterns, demographics, density of vehicles at different times of the day, rapid changes in vehicles arriving and leaving the VANET and the fact that the width of the road is often smaller than the transmission range all make the use of these conventional ad hoc routing protocols inadequate[8]. The routing protocols of VANETs classified into five major categories such as • Topology based Routing Protocol • Position based Routing Protocol • Cluster based Routing Protocol • Geocast based Routing Protocol • Broadcast based Routing Protocol. The characteristic of highly dynamic topology makes the design of efficient routing protocols for VANET challenging.

VANET ROUTING PROTOCOLS Position Based

GPS R

DRE AM

Broadcast Based

Topology Based

Proactive

DSD V

OLS R

TBR PF

Hyb rid

Reactive

DSR

AO DV

TOR A

DVDE CAS CA T

POC A

Cluster Based

COI N

LOR A_C BF

Geo Cast Based

IVG

DGCAS TOR

ZRP

Fig. 2- Routing protocol hierarchy Namita Chandel, IJRIT

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3.1 Position based routing protocol Position-based routing protocols [9] require that information about the physical position of the participating nodes be available. This position is made available to the direct neighbors in the form of periodically transmitted beacons. A sender can request the position of a receiver by means of a location service. The routing decision at each node is then based on the destination’s position contained in the packet and the position of the forwarding node’s neighbors. Consequently, position-based routing does not require the establishment or maintenance of routes. Examples of position-based routing algorithms include Greedy Perimeter Stateless Routing (GPSR) [10] and Distance Routing Effect Algorithm for Mobility (DREAM) [11]. Karp et al. [12] describe a position-based routing protocol based on a greedy forwarding mechanism in which packets are forwarded through nodes geographically closer to the destination than the previous node. Thus the position of the next hop will always be closer to the destination node than that of the current hop. The “perimeter routing” mode of GPSR (greedy perimeter stateless routing) that searches for alternate routes that may not be geographically closer is not considered since in a highway scenario the width of the road is often smaller than the range of transmission. Thus in this scenario there is no way for a route to move away from the destination and still find its way back.

Pros

• • • • •

Suitable for high node mobility pattern. Route discovery & management is not required. More stable in high mobility environment. Lowest overhead. More scalable.

Cons • • •

It needs position determining services. GPS device doesn’t work in tunnel because satellite signal is absent there. Obstacles in highway scenario.

3.2 Topology based routing protocol The topology based routing protocols use links information that exists in the network to perform packet forwarding from source to destination.

Pros

• • • •

No Route Discovery is required. Support unicast, multicast & broadcast message. Beaconless Low Latency for real time applications.

Cons • • •

Frequent network changes. Unused paths occupy a significant part of the available bandwidth. More control overhead.

The topology based routing protocols are further divided into Proactive, Reactive & Hybrid Protocols.

3.2.1 Proactive routing protocol The proactive protocol is also known as table driven routing protocol. So they keep information of all connected nodes in form of tables. Furthermore, these tables are also shared with their neighbors. Whenever any change occurs in network topology, every node updates its routing table. In the proactive routing protocols, distance-vector routing protocol (e.g., Destination-Sequenced Distance- Vector (DSDV) Namita Chandel, IJRIT

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routing) [13] or link-state routing methods (e.g., Optimized Link State Routing protocol (OLSR) [14] and Topology Broadcast-based on Reverse-Path Forwarding (TBRPF)) [15], which usually depends on shortest path algorithm to determine the route will be chosen.

Pros

• •

No route discovery is required. It have consist low latency for real time applications.

Cons • •

Unused paths occupy a significant part of the available bandwidth. As the size of the network is increases, the storage complexity and overhead of processing the routing table will also increase.

3.2.2 Reactive routing protocols The reactive routing protocols is also known as on- demand routing protocols because it starts route discovery when a node needs to communicate with another node thus it reduces network traffic. Many reactive routing protocols have been developed like Dynamic supply Routing (DSR) [16], Ad hoc Ondemand Distance Vector (AODV) [17] routing and Temporally Ordered Routing Protocol (TORA) [18].

Pros

• • •

To update routing table not require periodic flooding the network. Flooding requires when it is demanded. It is beaconless so it saves the bandwidth. Less memory is required.

Cons • •

For route finding latency is high. Excessive flooding of the network causes disruption of nodes communication.

3.2.3 Hybrid ad hoc routing protocols Hybrid protocol is a combination of both proactive and reactive protocols. The hybrid routing protocol is introduced to minimize the proactive routing protocol control overhead and reduce the delay of the route discovery process within on-demand routing protocols. In the hybrid routing protocol, it divides the network into two regions: local and global Zone routing protocol ZRP [19] combine local proactive routing and global reactive routing to minimize the routing overhead and delay due to route discovery process in order to achieve a higher level of efficiency and scalability. The combination of both strategies still needs to maintain at least those network paths that are currently in use, limiting the amount of topological changes that can be tolerated within a given amount of time.

Pros

• •

Higher efficiency. Scalability.

Cons •

High latency for finding new routes.

3.3 Broadcast Based Routing Protocol The broadcast based routing protocol is most frequently used routing protocol in VANET especially to communicate the safety related messages. Simplest of broadcast method is carried by flooding in which each node rebroadcast the message to other nodes. Since the broadcast routing protocol is flooding based routing protocol i.e. used in VANET for sharing information among vehicles such as when an accident or Namita Chandel, IJRIT

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an event occurs then it helps to t transmit the information to possible maximum nodes . Therefore broadcast send a packet to all nodes in the network which causes exponential increase in message transmission leading to collisions, higher bandwidth consumption and drop in overall performance. Although this protocol performs better when small numbers of nodes are involved. There are various broadcast routing protocols are developed such as Density aware reliable broadcasting protocol (DECA) and Position aware reliable broadcasting protocol (POCA) Distributed vehicular broadcast protocol (DV-CAST), Edge-Aware Epidemic Protocol (EAEP)

Pros

• • •

It helps to minimize overhead by occurrence of broadcast storms. Since packet is delivered via many nodes so the packet transmission is reliable Outperforms better for simple highway structure which contains smaller number of nodes.

Cons • • •

The large amount of network bandwidth. Many replicated packets reached to the node. High delay of data transmission.

3.4 Cluster Based Routing Protocol In Cluster-based routing protocols, all nodes refer as vehicles and all the vehicles near to each other form a cluster. For intra and inter-cluster management functions each cluster has consist one cluster head and perform specific task. Since, intra-cluster nodes communicate each other using direct links, whereas intercluster communication is performed via cluster headers. . If the packet to be sent in the same cluster then it is done by using the direct path, but when a node wants to communicate with other is who is outside the cluster then it is done with the help of cluster head by creating a virtual network infrastructure which provide scalability. In cluster based routing protocols the formation of clusters and the selection of the cluster-head is an important issue. In VANET due to high mobility dynamic cluster formation is a towering process. Clustering for open inter vehicular communication network (COIN) and LORA_CBF are main examples of this routing techniques.

Pros • •

For large network it has consist good scalability. Need not discover route so routing overhead is less.

Cons •

•

The cluster based routing protocol doesn’t consider velocity and direction which is important parameter for VANET. Delays in highly dynamic networks.

3.4 Geo Cast Routing Protocol Geo cast routing is a location based multicast routing protocol and it uses mobicast messages to communicate with the vehicles [20] .It is used to send a message to all vehicles in a pre-defined geographical region. The selected area for transmission is called Zone of Relevance or ZOR. If the source wants to send the packet to the other ZORs then it is done by using the zone of forwarding (ZOF). The vehicle comes inside the ZOF has the responsibilities to forward the data packet to the other ZORs. The main idea is that sender node need not to packet to nodes beyond the ZOR. Direct flooding strategy is used to reduce the amount of overhead and network congestion when packets are flooded. The various Geo cast routing protocols are IVG, DG-CASTOR, DRG.

Pros

• •

Reduced congestion. Reduced network overhead.


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•

Reliable packet delivery in highly dynamic topology.

Cons •

Due to network disconnection packet transmission delay is occurring.

4. COMPARISONS The comparisons of the various routing protocols are given as below: Table1. Comparison of Various Routing Protocols Protocols

Position Based

Proactive

Reactive

Cluster Based

Broadcast

Geo Cast

Forwarding Method

Heuristic Method

Virtual Infrastructure Requirement Realistic Traffic Flow

No

Wireless Multihop Forwarding No


Wireless Multihop Forwarding Yes



Yes

Yes

Yes

No

No

Yes

Environment

Urban

Urban

Urban

Urban

Highway

Highway

Digital Map Requirement Recovery Strategy Examples

No

No

No

Yes

No

No

Carry & Forward

Multihop Forwarding DSDV, OLSR, TBRPF

Carry & Forward DSR, AODV, TORA

Carry & Forward COIN, LORA_CBF

Carry & Forward DV-CAST, DECA, POCA

Flooding

GPSR, DREAM

IVG, DGCASTOR

5. CONCLUSION In this paper, we have discussed about the different routing protocols that are applicable in VANET. We also discuss about the pros and cons of different routing protocols that are applicable in vehicular communications for the development. Also discuss about the some important features of the VANET. Since by studying the different routing protocol in VANET we have seen that more performance analysis is needed to verify performance of a routing protocol with different routing protocols supported numerous traffic environments. The last table shows the comparative analysis of all the above stated routing protocols. The comparison of different VANET protocols features is essential to design a new proposal for VANET.

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[3] Online, http://www.ist-drive.org/index2.html. [4] W. Franz, H. Hartenstein, and M. Mauve, Eds., Inter-Vehicle-Communications Based on Ad Hoc Networking Principles-The Fleet Net Project Karlshue, Germany: Universitatverlag Karlsuhe, November 2005. [5] A. Festag, et. al., “NoW-Network on Wheels: Project Objectives,Technology and Achievements”, Proceedings International Journal of Computer Applications (0975 – 8887) Volume 20– No.3, April 2011 34 of 6th International Workshop on Intelligent Transportations (WIT), Hamburg, Germany,March 2008. [6] Reichardt D., Miglietta M., Moretti L., Morsink P., and Schulz W.,“CarTALK 2000 – safe and comfortable driving based upon inter-vehicle-communication,” in Proc. IEEE IV’02. [7] Morris R., Jannotti J., Kaashoek F., Li J., Decouto D., “CarNet: A scalable ad hoc wireless network system,” 9th ACM SIGOPS European Workshop, Kolding, Denmark, Sept. 2000. [8] S. Zeadally, R. Hunt, Y.S. Chen, A. Irwin & A. Hassan, “Vehicular ad hoc networks (VANETS): status, results and challenges,” © Springer Science+ Business Media , LLC 2010. [9]F u b l e r , H . , M a u v e , M . , H a r t e n s t e i n , H . , K ä s e m a n n , M . , & Vollmer. “A comparison of routing strategies for vehicular ad hoc networks” (Technical report, TR-02-003). Department of Computer Science, University of Mannheim, July 2002. [10] Karp, B., & Kung, H. (2000). Greedy perimeter stateless routing for wireless networks. In Proceedings of ACM international conference on mobile computing and networking (MobiCom 2000) (pp. 243–254), Boston, MA, August 2000. [11] Basagni, S., Chlamtac, I., Syrotiuk, V., & Woodward, B. (1998). A distance routing effect algorithm for mobility (DREAM). In Proceedings of ACM international conference on mobile computing and networking (pp. 76–84), Dallas, TX, October 1998. [12]. Naumov, V., & Gross, T. (2007). Connectivity-aware routing (CAR) in vehicular ad-hoc networks. In proceedings of 26th.IEEE international conference on computer communications, Infocom 2007, Anchorage, Alaska, 2007. [13 C. Perkins and P. Bhagwat, “Highly Dynamic Destination Sequenced Distance vector Routing (dsdv) for Mobile Computers,” Comp. Commun. Rev., pp. 234–44, Oct. 1994. [14] P. Jacquet et al., “Optimized Link State Routing Protocol. Internet draft, draftietf- manet-olsr-04.txt, work in progress, Sept. 2001. [15]B. Bellur, R.Ogier, and F. Templin, “Topology Broadcast Based on Reverse- Path Forwarding (tbrpf),” Internet draft, draft-ietf-manet-tbrpf-01.txt, work in progress, Mar. 2001. [16] D. Johnson and D. Maltz, Mobile Computing, Chap. 5 - Dynamic Source Routing, Kluwer Academic Publishers, pp. 153–81,1996. [17] C. Perkins and E. Royer, “Ad-hoc on-demand Distance Vector Routing,” Proc. 2nd IEEE Wksp. Mobile Comp. Sys. App., Feb. 1999, pp. 90–100. [18] ] V. Park and M. Corson, “A Highly Adaptive Distributed Routing Algorithm for Mobile Wireless Networks,” Proc. INFOCOM ’97. [19 Z. Haas and M. Pearlman, “The Performance of Query Control Schemes for the Zone Routing Protocol,” ACM/IEEE Trans. Net., vol. 9, no. 4, Aug. 2001, pp. 427–38. [20] J. C. Navas and T. Imielinski, “Geographic Addressing and Routing,” Proc. 3rd ACM/IEEE Int. Conf. Mobile Comp. Net., MobiCom’97, Sept. 1997.


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