44778821 an Intelligent Routing Protocol for Vehicle Safety Communication in Highway Environments

JOURNAL OF COMPUTING, VOLUME 2, ISSUE 11, NOVEMBER 2010, ISSN 2151-9617 HTTPS://SITES.GOOGLE.COM/SITE/JOURNALOFCOMPUTING/ WWW.JOURNALOFCOMPUTING.ORG 65

An Intelligent Routing Protocol for Vehicle safety communication in Highway

Environments B. Ramakrishnan, Dr. R. S. Rajesh, R. S. Shaji

ABSTRACT - For rapidly changing topology and high speed mobility of the vehicles, Vehicular Adhoc Network emerges as a standard routing protocol. An efficient Adhoc routing protocol plays a very important role in VANET application to ensure the safety of drivers and passengers. In the earlier model routing protocols are applied to the802.11 technology based environment in which the vehicles are moving inside the city limit and the data communication is between vehicle to vehicle via. Road Side Unit. In this paper a new VANET model is designed for the vehicles moving outside the city without enough Road Side Units. Here the communication is purely based on vehicle to vehicle and not from vehicle to Road Side Unit. The standard VANET routing protocols are applied to the above mentioned VANET model and their characteristics are compared with the use of NS 2.34 version simulator and their results are presented. To increase the performance of routing protocol, a cluster method and VANET based IEEE 802.11P technology are included in this model. This simulation result shows the performance of reactive routing protocol and proactive routing protocol.

Index Terms – ITS, GPS, OBU, SHWM, DSDV,AODV,DSR.

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1. INTRODUCTION

HE Intelligent Transport System (ITS) has been developed by using Vehicular Ad-hoc Network to improve the safety of the passengers and drivers. It

provides the Emergency and Entertainment information to the vehicles which enables a new mobile application for the benefit of the travelers [1]. The inter-vehicular communication field includes: vehicle to vehicle communication and vehicle to Road Side Unit communication. Each VANET nodes includes a Global Positioning System (GPS) device, which is used to find the position of each vehicle in the vehicular network [2]. This information of the GPS is used by the VANET to identify the position of other vehicles and exchanges information which decreases the road accidents in the highways [2] [3]. This Vehicular Ad-hoc Network Communication requires a new type of routing protocols for efficient data transmission1.

This paper compares the main routing protocols and analyzes how these protocols behave in the given highway scenario with varying traffic density and speed of the vehicles.

F.A. Associate Professor,Department of Computer Science, S.T Hindu College, Nagercoil-02.

S.B. Associate Professor,Department of Computer Science and Engineering, Manonmaniam Sundaranar University, Tirunelveli-12.

T.C. Assistant Professor, Department of Computer Applications, St.Xaviers catholic College of Engineering, Nagercoil.

2. BACKGROUND OF VANET ENVIRONMENT

In the earlier research works, the area of vehicle to vehicle communication begins from the Adhoc network mode that further expands in to VANET in which the vehicles are assumed to be moving in the city limit only [4]. The present work considers the vehicles moving outside the city and exchanging information directly without using Road Side Unit. The range of 802.11 standards is nearly hundred meters, and the vehicles within this range behave as a router to propagate the information in a multi-hop communication [5]. To transfer the message from one vehicle to another vehicle, the network needs an efficient protocol. The main function of the routing protocol is to identify the position of each vehicle in a VANET. This information is used for identifying the source and destination vehicles in a vehicular network. The routing protocol can be classified according to the range of communication. By the use of routing algorithm, a route is established to link source and destination vehicles. The unicast protocol sends the information from one source vehicle to destination vehicle, but in multicast protocols the information is sent to a group of vehicles [6]. For reliable vehicular communication, the performance of the routing protocol used to communicate the message is important [3]. Different routing protocols are suited for different VANET characteristics and scenarios, but the main issue is how to select an efficient routing protocol among them. For this purpose reactive and proactive protocols are taken into

T


consideration and these protocols are applied to the proposed highway model scenario mentioned in this paper. The characteristics of these protocols are studied using of NS 2.34 version network simulator.

3. ROUTING PROTOCOLS IN VANETS

A routing protocol plays an essential role in vehicular network data communication. The VANET is a main component of MANET, so the operations of these two Adhoc networks are the same. Therefore most of the MANET routing protocols are applicable to vehicular networks. Due to the difference in high speed mobility of vehicles, VANET communication requires suitable modification in the predefined routing protocols and IEEE standards 802.11. This paper discusses the routing protocols for VANET implemented in NS2.34 version namely Destination Sequence Distance Vector (DSDV) protocol. It is a table driven protocol, while the other two, namely Dynamic Source Routing (DSR) and Ad-hoc On-demand Distance Vector (AODV) routings are on demand protocols [7][8]. DSDV is a modification of the Bellman-ford algorithm, which can solve routing problem in VANET environment. Each node maintains a routing table, which contains the shortest path information to other node in the vehicular network. The DSDV algorithm provides one route to the destination vehicle and chooses the shortest path according to the number of hops to reach the destination. The DSDV is well suitable for small scale ad-hoc network [6].

The DSR and AODV are on-demand Reactive routing, in which network routes are only updated when a source vehicle wants to send a message to the destination vehicle [9]. The DSR uses source routing in which the data packet contains the header field that includes the information about the hop-by-hop route to the destination. It also maintains multiple routes for each destination. The routing discovery in DSR sets up a route from the source vehicle to the destination vehicle by sending the Route request packet from the source vehicle. If any one of the vehicles breaks its wireless communication then this algorithm reconnects the route from the source to the destination vehicle by sending Route Error Packet to the adjacent node of the broken link. The DSR algorithm does not locally repair a broken wireless communication link. But it is done through Error Rectification procedure and it consumes much more time. Thus the connection setup time is higher than that of DSDV protocol. AODV is similar to DSR, in which a route setup from source to destination is done by sending a Route request message. AODV uses a destination sequence number to find the latest route to the destination vehicle [8].

4. RELATED WORK

Most of the previous works on routing protocols have been established for Mobile Ad-hoc Networks [8] [9] only a limited work has been done on vehicle to vehicle communication inside the city. But no major attempt has been made on vehicular communication outside the city area.

Algorithm1: Cluster Creation

Algorithm 2 : Service Discovery Algorithm

This paper makes an honest attempt to present a new simple highway model with a novel Cluster concept for improving the performance of the data communication [10]. Only a bird’s eye view of the Cluster creation, Cluster Head Election and


Cluster Head Switching procedure for this highway model is given in the present paper because these concepts were dealt elaborately by the author in paper [11]. The service discovery for the Cluster based highway model is presented in paper [12]. The results of the comparative study of the standard 802.11 and 802.11P are presented in paper [13]. The paper [14] presents the relative performance of the Cluster concept. The different routing protocols are analyzed with the information obtained from the above four studies and their characteristics are presented. The Algorithm 1 and Algorithm 2 describes the cluster creation method and service discovery procedure for the Simple Highway model [15].

5. SYSTEM MODEL

Instead of the random movement of nodes in MANETs, the nodes in VANET move in predefined road. The radio range of VANET is in between 250 and 350 meters. Within this range the vehicles can easily communicate with each other. The mobility of the vehicular node is dependent on parameters like speed, direction of the vehicles and the layout of roads. It is a fact that the speed of the moving vehicle on a highway is higher i.e. nearly 150 km/hr. Therefore the topology in VANET changes more frequently. For this reason the IEEE standard 802.11 is not well suited for vehicular environment. So the amendment made on 802.11 establishes a new standard for VANET model. It is known as the wireless access in vehicular environment (WAVE) . Another version of 802.11 is known as 802.11p [13]. The Figure 1 represents the VANET system architecture for Emergency situation.

Figure 1 : Emergency Broadcasting VANET Architecture

6. PROPOSED MODEL

The high speed vehicles moving in a highway are equipped with a communication device known as On-Board Unit (OBU). By using such devices, vehicle can communicate with each other as well as with Road Side Unit (RSU). As there is enough member of RSU in the city limit, the moving vehicles get good data communication among them. But when they move outside the city limit the communication is weak due to lack of RSU’s. In the present work each vehicle acts as a router to communicate with other vehicles. The routing protocols assume that each vehicle in the VANET knows its position. Therefore each vehicle is equipped with a Global Positioning System (GPS) device to identify the correct location of the destination node. Moreover it is assumed that each vehicle has an on-board navigation system and the preloaded digital maps through which it can determine the position of its neighboring junction. It is also assumed that each vehicle has the knowledge about its velocity and direction of movement of the vehicle.

The reliability of the Routing protocols is analyzed only on the basis of the above mentioned assumptions. It is observed that in the existing research work the IEEE standard used for data communication is 802.11. But due to the high speed vehicle movements the standard 802.11p is included in this model [13]. To increase the efficiency of the VANET communication, a clustering concept is introduced in this highway model. This new cluster algorithm splits the vehicular area into a number of clusters and each cluster has a cluster head. Generally the cluster head may be RSU’s in city environment but in the highways anyone of the vehicle with good data driven capability acts as a Cluster head [11]. All the Cluster heads are synchronized in a specific period of time and it is ensured that all the cluster heads have the latest service updates. If the vehicle crosses the Cluster boundary then the Cluster head algorithm selects a prominent vehicle as a new cluster head and the information of the old Cluster head is transferred to the current one.

Whenever a new service is included, then all the Cluster heads immediately update their database with the new information [11]. If a node wants to search a service, it immediately contacts its local Cluster head. If the specified service is available then it provides details to the requested node. If not, the discovery algorithm synchronizes all the Cluster heads and makes a search for the requested service [14].

7. SIMULATION

The simulation model is based on NS 2 simulation version 2.34. This simulation results are displayed in the NAM file and


the routing parameters are obtained from the trace file. To evaluate the performance of the routing protocols, some parameters have been used in the TCL file for measuring the efficiency of vehicle to vehicle communication. The study of these parameters is analyzed by the NS 2 Trace file. Therefore the Agent Trace ON and Route Trace ON in the TCL fie are activated.

8. EXPERIMENTAL ANALYSIS

The simulation scenario is designed according to the normal movement of the vehicles in highways. Let us assume the VANET area as 1400*1400 meters in highway with bidirectional movement of vehicles. The number of vehicles in this simulation is varying from 25 to 150. This proposed work defines a scenario for each set of nodes. The NS2.34 highway scenario is shown in Table 1 and the critical simulation parameters are shown in Table 2 and Table 3.

Table1: Simple Highway Mobility Model -NS2.34 NAM file output

Table 2: IEEE 802.11p Parameters in TCL file

In the first case, a simulation is done with 25 nodes where the communication takes place between the source vehicle 5 and the destination vehicle 20. This study has been repeated with the number of Clusters varying from 2 to 20 with multiples of two. Then the speed of the vehicle is assumed to be constant in each scenario and the communication has been tested by using the speed of the vehicle between 5 and 25m/sec.

Table3 : Critical parameters used in NS 2.34 VANET simulations

9. RESULTS AND ANALYSIS

9.1 Analysis of Packet receiving time for various protocols using 802.11 & 802.11p

This parameter defines the time it needs to establish the connection for each protocol. The Packet has been transmitted from the source vehicle 5 to the destination vehicle 20. This scenario contains 100 nodes with the number of Clusters varying from 2 to 20 in steps of two. The speed of each vehicle is assumed to be 10 m/sec and the IEEE standard 802.11 is used for this stimulation. The performance of Packet Receiving Time for routing protocol DSDV, AODV and DSR is shown in figure 2.


Figure 2 Number of cluster vs Packet receiving time (msec) using IEEE 802.11

Figure 3 Number of cluster vs Packet receiving time (msec) using IEEE 802.11p

Figure 4 Number of cluster vs Packet receiving time (msec) using IEEE 802.11p &802.11

It’s noticed that the DSDV protocol yields a low Packet Receiving Time than AODV and DSR. The same result is obtained when the VANET IEEE standard 802.11P is included in this network model which is shown in Figure 3. From

Figure 4 it is observed that the routing protocol DSDV with 802.11P yields a low Packet Receiving Time than the routing protocol DSDV with standard 802.11.

9.2 Comparison of broadcasting time for different routing protocols using802.11&802.11p

The broadcasting time for various protocols in the proposed simple highway model with 100 nodes is presented in figure 4. It is observed that, the presence of DSDV protocol with standard 802.11 is better than AODV and DSR. The DSR protocol has high broadcasting time which is shown in figure 4 and the simulation result is found in the broadcasting time for various protocols using 802.11P. From the Table 4 and Figure 5 and Figure 6, it is clear that DSDV yields lower broadcasting time than the other two. It is also noted that the DSR has high value than AODV protocol.

Figure 5 Number of cluster vs Broad casting time (msec) using IEEE 802.11

Figure 6 Number of cluster vs Broad casting time (msec) using IEEE 802.11p


Table 4. cluster vs Broad casting time (msec) using IEEE 802.11 &802.11p

9.3 Analytical study of packet delay time for different routing protocols using 802.11p

It indicates the propagation and transfer delay between first packet and second packet. The Packet delay times for various routing protocols are measured and the comparative delay time

Figure 7. cluster vs Packer delay time (msec)using 802.11p

Characteristic of standard 802.11 with speed 10 is noticed in Figure 7. With Cluster 4 and 8, the delay time of the packet for AODV is lower than other two protocols.

9.4 Performance analysis of normalized routing load for various Routing protocols

Figure 8 cluster vs Normalized routing load using IEEE 802.11p

The Figure 8 shows the analysis of normalized routing load for various routing protocol with speed 10. A low normalized load is observed when DSR protocol is used and better result is achieved for Clusters between 4 and 10.

9.5 Packet forward ratio for DSDV, DSR AND AODV protocols

Figure 9. Cluster vs Packet forward ratio using IEEE 802.11p

In Figure 9 it is observed that the Packet forward ratio is higher for AODV protocol and its performance is good if the


number of Cluster is below 8. When the number of Clusters increases, the packet forward ratio decreases in the AODV where as it increases in DSR protocol.

9.6 Packets delivery ratio and throughput analysis for reactive and proactive protocols

From Figure 10, it is observed that the packet delivery ratio is high for DSR protocol and low performance is received in AODV protocol. Figure 11 shows the throughput comparison of AODV, DSR and DSDV. The graph reveals that DSDV has higher throughput than AODV and DSR. The packet through put in a given highway scenario is low for DSR protocol.

Figure 10 Cluster vs Packet Delivery ratio using IEEE 802.11p

Figure 11 Cluster vs Throughput using IEEE 802.11p

10. CONCLUSION

This paper analyzes the routing protocols Destination Sequence Distance Vector (DSDV), Ah-hoc On-demand Distance Vector and Dynamic Source Routing in a VANET environment. It has been proved that a better performance is received in DSDV for both 802.11 and 802.11p standards in terms of the packet receiving time and Broadcasting time.

Normally DSDV protocol is well suited for small scale ad-hoc network [7]. Among three routing protocols the DSDV has the best packet receiving time and Broad casting time. It is also noted that the proactive routing protocol DSDV achieves better through put than the reactive protocols AODV and DSR. From this analytical work it has been proved that, when dealing with Packet delay time, Packet delivery ratio, Packet forward ratio and Normalized routing load the protocols that present better response are AODV and DSR. Future research can be done in this area to create a geographical routing procedure for VANET networks in order to increase their performance.

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44778821 an Intelligent Routing Protocol for Vehicle Safety Communication in Highway Environments