IX.   Vanet Routing Protocols.Now coming to different routing protocols,Vanetrouting protocols can be classified into 5 broader categories which also havetheir subdivisions. The classification is mainly on the basis of the routeupdate methods and the positions.                                                 Figure7:Routing protocol hierarchy 10  a. Position basedrouting :- The communicationbetween source and destination node uses the geographical location rather thanthe network address. The exact position of the nodes which took part in thecommunication can be accessed via periodically transmitted beacons 11. GPS isthe necessity of the protocol to determine the location of different vehicularterminals.

They can work easily without establishing or maintaining routes.They can be further classified into 2 parts:   1.  Greedy Parameterstateless routing(GPSR):- GPSR makes use of the geographical location. Each node has the knowledgeof the corresponding neighbour and it chooses the next hop which is nearest tothe respective destination. This procedure is known as greedy forwarding.

Theconcept of HELLO messages comes into the picture in this procedure, if theHELLO message is not captured from the corresponding node then it assumes thatthe neighbour is out of the respected area 122. Distance RoutingEffect Algorithm for Mobility(DREAM):- This Protocol is basically used in unformedarchitectures. Each terminal maintains a Position table which has the locationof all the nodes present in the network and thus a position Packet is updatedon a regular time interval .The packet delivery rate is dependent on the speedof the respective source node 13.                                                                                               Figure 8 a) mobility scenario  13                   b) the structure of each intersection 13 PROS:1.Position basedrouting protocol is suitable in highway because of high mobility of thevehicles and less obstacles 102.

There is no need tomaintain the routing table and thus overhead is low.3. The latency is lowin this protocol. Cons :1.Gps is the necessityof the protocol, if GPS is not working than this protocol might not work.2.This protocol isnon-responsive in the case of link failure.

3.As the network sizeincreases, the complexity of the storage also increases so overhead increasesin that case 104.Also bandwidthconsumption is high because of the routing paths which are not used 10. b.  Topology Based Routing Protocol :-  There is unique address assignment to all theterminals in this protocol. This protocol can be further classified into threeparts:                                          I.  Proactive RoutingProtocol :- Also known asTable driven protocol, Shortest path algorithms forms the basis of theseprotocols .

Whenever there is change in the network, all of the participatingterminals updates their routing tables .DSDV(Destination SequencedDistance-Vector) is  widely used which isa distance vector routing protocol. In this protocol,each record in therouting table consists of a sequence number, the sequence number is even if thelinks are present otherwise they are odd if link is inactive 14. DSDV Mechanism :- 1.

Update technique :- Each terminal transfersthe updates in regular time instances which consists of their sequences numberand the respective updates of their routing tables.When two consecutiveroutes to a final point are received from two corresponding neighbour terminalsthen it selects the one which has higher sequence number, however in case ifthe sequence numbers are exactly same then the decision is based on the hopcount. Thus it provides loop free routes 14. 2.Two way mechanism :-In this mechanism whole dump that is full routing table can be transferred tothe neighbor terminal. It is optimal in case when the network update is morecontinual and also when there are less distortions in the network. Next hopwill be assigned as the first terminal going forward towards the final positionof hops thus the exact number of the terminals available between the source andthe destination terminal14.                                            Figure 9 DSDV Routing  14       II.

   Reactive RoutingProtocol :- They areon demand routing protocols, thus the routing path is selected whenever it isrequired hence only used routing paths are taken into the consideration. Thistype of protocols is best suited to the dynamic network where there arerestricted pattern of the available routes 10.It can be further classifiedinto 3 categories: 1.AODV :- Ad HocOn-Demand Distance vector routing:In AODV the network isconstant till the time a proper association is required. The source terminaltransmits a appeal message whenever it needs a particular path.

When the finallocation collects the appeal then it retransmit the reply message via ashort-term route to the source terminal. Thesource terminal then starts the interconnection utilizing the path which hasminimum number of hops, thus the entries which are not used are deleted aftercertain interval 14.Each path request has a certain sequence number assignedwhich are different from other respective paths. Thus it helps in bypassingrepeated path requests.

                                       Figure 10 AODV Routing 14 2.  DSR (Dynamic Source Routing) :- It is also anon-demand reactive routing protocol in which the source terminal controls thewhole path for every routing procedure 15.This protocol follows a 2 phasemechanism as follows:i. Route Discovery Phase :- Whenever thereis requirement for the route it transmits the route appeal and the terminals which collects the packets retransmitthem  consequently.ii. Route Maintenance Phase : If there arepresence of errors in the transmitted messages then there will be the deletionof the particular path from the route cache maintained and thus another routeto the destination is used.

With the use of DSRredundancy can be maintained as whenever the main route crashes ,thealternative route comes into the picture without calling the route deliveryprocedure 15.To every route request there is a route reply and It has a RREQformat which has an initiator id, initiator sequence, Target ID and Partialroute.RREQFORMAT:         Figure 11 Thequery/reply phase in the route discovery procedure 15 3. TORA (TemporallyOrdered Routing Algorithm):- TORA is another on-demand routing protocol which makes use of multi-hoproutes. This protocol is not based on shortest path algorithm, therefore therouting architecture does not constitute distance 16.It creates a directedacyclic graph(DAG) which contains the various terminals between the source andthe destination and the source node is the main route.

It has a 3 phasemechanism:1.Route Creation: Formation of DAG2.Route Maintenance: It comes into picture in the case of linkfailure.3.Route Erase: To erase the invalid routes .

 III.  Hybrid Routing Protocol :This type of topology based protocol carriesfeatures of both proactive and reactive protocols, thus the main goal is toreduce the proactive routing protocol overhead and minimize the latency of theroute discovery procedure16. It divides the network to multiple areas knownas Zones in order to get the optimal route discovery and maintenance procedures16.

It is further divided into 2 categories: 1.  ZRP : In this type of protocol, the terminals in the network are furtherdistributed into special areas known as zones according to many such as powerof broadcasting, moving speed of the nodes and several other factors. ZRP worksas a Proactive protocol for large sized zones and it worked as a reactiveprotocol for small sized zones 16.2.   Zone-Based Hierarchicallink state(ZHLS) : It distributes the network into non-intersecting zones and everyterminal in the network consists of a zone ID and a node id by making use ofthe GPS. Thus they have two topologies at zone and network level 16.Advantages of ZHLS OverZRP : 1.  there are no intersecting Zonesin ZHLS as compared to ZRP2.

The traffic isreduced in ZHLS and it also prevents failure for the one point 17.                      Figure 12 Routing Zone of A 17  Figure 13 ZHLS Protocol Topology 17C.  CLUSTER BASED ROUTING PROTOCOLSCluster based Routingprotocol is another category of VANET routing protocol in which differentvehicles forms a cluster depending upon Several characteristics like thedirection and the velocity 10.A virtual Network infrastructure is beingcreated via grouping of several terminals so as to increase the scalability,also this  infrastructure is  important for scalability of media access ,routingprotocols and the network infrastructure18.There are two main techniques forthis protocol namely COIN(Clustering for Open inter vehicular communicationnetwork ) and LORA_CBF 10.1.

COIN :- In Coin a structurehead is selected based on the dynamics of the vehicles as well as the driving calculationsrather than the relative mobility 18.This also carries the revolving natureof the distance in between the vehicles, and Thus it can be concluded that COINproduces much more stable architectures and overall lower overhead 18. 2. LORA_CBF :- In this protocol, eachterminal can be the cluster head, gateway or the respective group member.Gateway can be described as a node connected to multiple clusters. If the finallocation is not there then the source terminal will send the LREQ Packet i.e.the location request packet.

This part is same as that of the AOD but the maindifference lies in the LREQ and LREP packets are dispensed only by the clusterheads and the gateways 18. Figure 14 Vehicles form multiple clustersin cluster-based routing 18.Pros:1.

The scalability isgood in a huge group of networks2. Overhead is less .Cons:1.Higher latency in largedynamic networks.D.  Broadcast based Routing: – As the name indicates,this type of routing method broadcast the packets in the network.

There is aspecified broadcast domain and the packets are available to all the vehicleswithin the range of the specified domain. It is mainly used in the emergencysituations such as blockage of roads, sharing weather conditions, in case of roadaccidents and for conveying announcements and advertisements 18.Flooding isthe most acceptable way to carry out a broadcast service in which each terminalre-transmits message to all of its corresponding neighbors besides the one fromwhich it has received the message concerned 18.Several broadcast basedrouting protocols are there such as DVCAST(Distributed Vehicular broadcastprotocol),Position aware reliable broadcasting protocol(POCA) and Density Awarereliable broadcasting protocol(DECA ) 10. BROADCOMM Protocol: – For highway environment, broadcomm emergency protocol has beendeveloped in which the architecture of highway is distributed into virtualcells which show movement according to the vehicular movement 18.

Further, Theterminals are divided into two levels  inwhich first consists of all the terminals in a respective cell and the secondlevel contains the cell reflectors which are located in proximity to the centerof the cell 18.  Figure 15 Broadcast routing 18Pros:1. It is a reliable transmission protocol.2.Overall overhead is low due to the broadcastingphenomenonCons:1. Duplicate packetscan be reached to the terminal.2.

Bandwidth requirementis more in this case.E . GEOCAST ROUTING :-Multicast packetforwarding forms the basis of these protocols. A single source can send packetsto a cluster of nodes which act as a destination.

ZOR(Zone of Relevance):- It is defined as a particular geographical area which consists of a group ofnodes to which all the packets are transferred from a particular starting point18.Wheneverthe Final destination terminal belongs to a different ZOR then communication isdone via Zone of forwarding (ZOF),thus all the vehicles which falls into theZOF  will transmit the data packet to thealternate ZOR’S 10.IVG (Inter-Vehicles Geocast protocol) is the most renownedgeocast protocol whose main function is to transmit the announcement to the allthe vehicles in a particular risk prone area on delay time algorithm in ahighway architecture 18.  Figure 16 Geocastrouting 18. PROS:1. Overall network congestionis reduced.2.

Overhead is also reduced.3.Reliable in case ofcomplex network topology.

 CONS:1. Packet broadcastdelay will be there in case of network disconnection 10.X.  CONCLUSION AND FUTURE WORKThe confluence ofInformation and communication technology, computing and Telecommunication aswell as rise in the vehicular industry are encouraging the optimal utilizationof Vanet technologies.

In the past years,Several VANETS projects are deployed and several standards have been made inorder to improvise the inter-vehicular or vehicle-to-infrastructurecommunications 11.The main area where research is going on includes Vanet security,QOS and to enhance the various broadcasting techniques.The different protocols withhigh priority are still in investigation phase when focussing on the securitymeasures 11.Also, Future work willfocus on the development of prevalent applications and context aware driverapplication systems where cooperative driving techniques can be used forcontrolling the traffic 19. Also research is ongoing on emergency basedProtocol in order to prevent the road blockages and road accidents in case of restrictedareas. XI.  References10.

Proceedings of 2014RAECS UIET Panjab University Chandigarh, 06 – 08 March, 2014 VANET RoutingProtocols: Issues andChallenges UIET, Panjab University Chandigarh, India11. Vehicular ad hocnetworks (VANETS): status, results,and challenges Sherali Zeadally · Ray Hunt ·Yuh-Shyan Chen ·Angela Irwin · Aamir Hassan© Springer Science+Business Media,LLC 201012. GPSR-L: Greedy Perimeter Stateless Routing with Lifetime for VANETS SunderAditya Rao1Manohara, Pai M.

M1Mounir Boussed,jra2Joseph Mouzna2 ManipalInstitute of Technology, Manipal, IndiaIRSEEM-ESIGELEC, Technopole duMadrillet, 76800 Saint Etienne du Rouvray – France13. PerformanceEvaluation of DREAM Protocol for inter-vehicle Communication M. Bakhouya, J.

Gaber, M. WackGSEM/SeT Laboratory, UTBM90010 Belfort, [email protected],{gaber, maxime.wack}@utbm.fr 14.

Analysis of TopologyBased Routing Protocols for Vehicular Ad-Hoc Network (VANET) InternationalJournal of Computer Applications (0975 – 8887)Volume *– No.*, __2014 15. Proceedings of the35th Hawaii International Conference on System Sciences – 2002An ExtendedDynamic Source Routing Scheme in Ad Hoc Wireless Networks Jie WuDepartment of ComputerScience and Engineering Florida Atlantic University16. International Journalof Innovation and Applied Studies and ISSN 2028-9324 Vol. 3 No. 3 July 2013,pp. 829-846© 2013 Innovative Space of Scientific ResearchJournalshttp://www.

issr-journals.org/ijias/ Survey of Vehicular Ad hoc Networks Routing Protocols Marwa Altayeb1 andImad Mahgoub2Department of Computer Information & Networks, College ofComputer Science & Information Technology, Sudan University of Science& Technology, Khartoum, Sudan Department of Computer & ElectricalEngineering and Computer Science,  Collegeof Engineering & Computer Science, Florida Atlantic University ,Florida,USA17. Kanishka Raheja et al,/ (IJCSIT) International Journal of Computer Science and InformationTechnologies, Vol.

5 (4) , 2014, 5512-5516A Survey on DifferentHybrid Routing Protocols of MANET Kanishka Raheja , Sunil Kr Maakar Departmentof CSE,BRCM-CET (Bahal),India18. R18. Routing in VehicularAd HocNetworks: A Survey Fan Li and Yu Wang, University of North Carolina atCharlotte19. Performance Evaluationof DREAM Protocol for Inter-vehicle Communication M.

Bakhouya, J. Gaber, M.WackGSEM/SeT Laboratory, UTBM90010 Belfort, [email protected], {gaber,maxime.wack}@utbm.fr


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