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S.P. Setty et. al. / International Journal of Engineering Science and Technology Vol. 2(7), 2010, 2976-2981

PERFORMANCE EVALUATION OF AODV IN DIFFERENT ENVIRONMENTS Prof.S.P.SETTY, NARASIMHA RAJU K, NARESH KUMAR K CS&SE Dept Andhra University College of Engineering Visakhapatnam, Andhra Pradesh India – 530 003. [email protected], [email protected], [email protected]

  Abstract Routing is the task of directing data packets from a source node to a given destination. This task is particularly hard in Mobile Ad Hoc Networks due to the mobility of the network elements and the lack of central administration. The main method for evaluating the performance of MANETs is simulation. This paper is subjected to the on demand routing protocol AODV and evaluated its performance in three different environments namely Random, Grid and Uniform. We investigated the QOS metrics namely Average jitter, Average end-to-end delay , Packet delivery ratio and Throughput in various simulation scenarios by varying network size and maximum speed of the nodes. From the simulation results and analysis, a suitable protocol can be chosen for a specified environment. The results shows that the performance of AODV is better in Grid Environment comparative to other environments. Keywords: AODV, MANETs, Environments I.

Introduction

In recent years, the progress of communication Technology has made wireless devices smaller, less expensive and more powerful. Such rapid technology advance has provoked great growth in mobile devices connected to the Internet. There are two variations of wireless network, which are infrastructure networks and ad-hoc networks [1 2]. In an infrastructure network, a mobile station must find the nearest base station within its communication range before it communicates with another. In an ad hoc network where there is no base station, each mobile node acts as a router. The mobile nodes in an ad hoc network moves randomly resulting in a dynamic topology. The rest of the paper is organized as follows. The Protocol Description is summarized in section II and the operation of on-demand Distance vector (AODV) [3 4] for MANET is summarized in section III. The simulation environment is described in section IV. We present results in section V and conclude with section VI. II. Protocol Description Reactive routing techniques, also called on-demand routing, take a very different approach to routing than proactive protocols. on-demand routing approaches take a departure from traditional Internet routing approaches by not continuously maintaining a route between all pairs of network nodes. Instead, routes are only discovered when they are actually needed. When a source node needs to send data packets to some destination, it checks its route table to determine whether it has a valid route. If no route exists, it performs a route discovery procedure to find a path to the destination. Hence, route discovery becomes on-demand. These routing approaches are well known as Reactive routing. The route discovery typically consists of the network-wide flooding of a request message. Once a route has been established, it is maintained by some form of route maintenance procedure until either the destination becomes inaccessible along every path or until the route is no longer desired Reactive routing protocol includes Dynamic Source Routing (DSR)[5 6] protocol, Ad hoc On-demand Distance Vector (AODV) protocol.

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S.P. Setty et. al. / International Journal of Engineering Science and Technology Vol. 2(7), 2010, 2976-2981 III. Ad hoc On Demand Distance Vector Routing Protocol (AODV) Ad-hoc On-demand distance vector (AODV) discovers routes whenever it is needed by route discovery process using traditional routing tables; one entry per destination. AODV uses a broadcast route discovery algorithm and then the unicast route reply massage for finding the route. The following sections explain these mechanisms in more detail.

A. Route Discovery When a node wants to send a packet to some destination node and does not have a valid route in its routing table for that destination, it initiates a route discovery process. Source node broadcasts a route request (RREQ) packet to its Neighbours, which then forwards the request to their neighbours and so on. Nodes generates a Route Request with destination address, Sequence number and Broadcast ID and sent it to his neighbour nodes. . Each node receiving the route request sends a route back (Forward Path) to the node as shown in the figure 1.

Figure 1: Route Requests in AODV When the RREQ is received by a node that is either the destination node or an intermediate node with a fresh enough route to the destination, it replies by unicasting the route reply (RREP) towards the source node. As the RREP is routed back along the reverse path, intermediate nodes along this path set up forward path entries to the destination in its route table and when the RREP reaches the source node, a route from source to the destination established. Figure 2 indicates the path of the RREP from the destination node to the source node.

Figure 2: RREP in AODV

B. Route Maintenance A route established between source and destination pair is maintained as long as needed by the source. when a link break in an active route is detected, the broken link is invalid and a RERR message is sent to other nodes. These nodes in turn propagate the RERR to their precursor nodes, and so on until the source node is reached. The affected source node may then choose to either stop sending data or reinitiate route discovery for that destination by sending out a new RREQ message.

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S.P. Setty et. al. / International Journal of Engineering Science and Technology Vol. 2(7), 2010, 2976-2981 IV. Simulation Environment

The overall goal of this simulation study is to evaluate the performance of existing wireless routing protocol AODV in various nodes placement models like Grid, Random and Uniform i.e. the nodes are placed in various arrangements and moves arbitrarily. The simulations have been performed using QualNet version 5.0 [7 8], a software that provides scalable simulations of Wireless Networks. For this, the simulation is carried out in two scenarios. The two Scenario Simulation Models are given below. A.

Simulation Model

We consider a network of nodes placing in various arrangements (one source and one destination) within a 1000m X1000m area. The performance of AODV is evaluated by keeping the network speed and pause time constant and varying the network size (number of mobile nodes).Table 1 shows the simulation parameters used in the evaluation. Table 1 : Simulation parameters for Model A Simulation Environment Area

1000m x 1000m

Simulation Time

200 Sec

Nodes

10,20,30,40,50,100

Nodes Placement

Grid, Random, Uniform

Path loss Model

Two Ray

Mobility Model

Random Way Point

Pause Time

30

Maximum Speed

10mps

Traffic

CBR

Packet Size

512 bytes

MAC layer

802.11

B. Simulation Model We consider a network of nodes placing in various arrangements (one source and one destination) within a 1000m X1000m area. The performance of AODV is evaluated by keeping the network size(number of mobile nodes) constant and varying the maximum speed of the nodes. Table2 shows the simulation parameter used in the evaluation.

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S.P. Setty et. al. / International Journal of Engineering Science and Technology Vol. 2(7), 2010, 2976-2981 Table 2 : Simulation Parameters for Model B Simulation Environment Area

1000m x 1000m

Simulation Time

200 Sec

Nodes

50

Nodes Placement

Grid, Random, Uniform

Path loss Model

Two Ray

Mobility Model

Random Way Point

Pause Time

30

Maximum Speed

10,20,40,60,80,100 (mps)

Traffic

CBR

Packet Size

512 bytes

MAC layer

802.11

V. Results To evaluate the performance of routing protocol, the following metrics are considered.  1) Average End-to-End Delay: End-to-End Delay indicates how long it took for a packet to travel from the source to the application layer of the destination. The variation of Average End-to-End Delay with varying the number of mobile nodes and maximum speed of the nodes is shown in the Figure 3 and Figure 7 respectively. 2) Packet Delivery Ratio: The fraction of packets sent by the application that are received by the receivers. The variation of Packet Delivery Ratio with varying the number of mobile nodes and maximum speed of the nodes is shown in the Figure 4 and Figure 8 respectively. 3) Average Jitter: The delay variation between each received data packet. It measures the stability of the algorithm's response to topological changes. The variation of Average Jitter with varying the number of mobile nodes and maximum speed of the nodes is shown in the Figure 5 and Figure 9 respectively. 4) Throughput: The total amount of data a receiver R actually receives from the sender divided by the time it takes for R to get the last packet. The variation of Throughput with varying the number of mobile nodes and maximum speed of the nodes is shown in the Figure 6 and Figure 10 respectively.

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S.P. Setty et. al. / International Journal of Engineering Science and Technology Vol. 2(7), 2010, 2976-2981

   

 

Figure 3: Average End – to – End delay jitter with Varying

Figure 5: Average Jitter with Varying Number of Mobile nodes

Number of Number of mobile nodes

 

          

 

 

Figure 4 : Packet Delivery Ratio with varying Number of Mobile Nodes

Figure 6 : Throughput with varying number of Mobile nodes

Grid Random Uniform 120

P a ck et D eliv ery R a tio

100

80

60

40

20

0

10

        Figure 7 : Average End-to-End Delay with Varying Maximum speed of node

20

40

60

80

100

Maximum Speed of the Node

 

Figure 8 : Packet Delivery Ratio with varying Maximum speed of Node

 

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S.P. Setty et. al. / International Journal of Engineering Science and Technology Vol. 2(7), 2010, 2976-2981

     Figure 9: Average Jitter with Varying Maximum speed of the Node

Figure 10 : Throughput with varying Maximum speed of the Node

VI. Conclusion and Future Scope The performance of AODV is studied by placing the nodes in various arrangements. The simulation results shows that AODV achieves better performance in Grid Environment. One of our future research studies is the study of the behaviour of AODV by placing the mobile nodes in circular position which then moves arbitrarily. References [1] [2] [3] [4] [5] [6] [7] [8]

Perkins C., Ad Hoc Networking, Addison Wesley, 2001. Royer, E.M., 1999. A review of current routing protocols for ad hoc mobile wireless networks.IEEE Personal Communications, pp: 46-55. Perkins C., “Ad Hoc on Demand Distance Vector(AODV)Routing,”availablet:http://draft-ietf-manet-aodv-00.txt,November 1997. Perkins C. and Royer E.M., “Ad-Hoc on-Demand Distance Vector Routing,” in proceedings of the 2nd IEEE Workshop on Mobile Computing Systems and Applications, New Orleans, LA,pp.90-100,February 1999. D .Johnson and D. Maltz . Dynamic Source Routing in ad-hoc Wireless Networks in Computer Communication Review – Proceedings of SIGCOMM 96 Aug-1996 D.Johnson, D.Maltz, and J .Broch. Dsr the dynamic source routing protocol for multihop wireless ad-hoc network ,2001 QualNet Network Simulator; Available: http://www.scalable-networks.com. QualNet documentation, “QualNet 4.0 Model Library: Advanced Wireless”; Available: http://www.scalablenetworks.com/products/qualnet/download.php#docs

 

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