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.
drspsetty@yahoo.com, bcoolmind@gmail.com, Chakri.naresh@gmail.com
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
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 DiscoveryWhen 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
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
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.
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
0 20 40 60 80 100 120
10 20 40 60 80 100
Maximum Speed of the Node
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Grid Random Uniform
Figure 7 : Average End-to-End Delay with Varying Figure 8 : Packet Delivery Ratio with varying
Maximum speed of node Maximum speed of Node
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] Perkins C., Ad Hoc Networking, Addison Wesley, 2001.
[2] Royer, E.M., 1999. A review of current routing protocols for ad hoc mobile wireless networks.IEEE Personal Communications, pp: 46-55.
[3] Perkins C., “Ad Hoc on Demand Distance Vector(AODV)Routing,”availablet:http://draft-ietf-manet-aodv-00.txt,November 1997. [4] 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.
[5] D .Johnson and D. Maltz . Dynamic Source Routing in ad-hoc Wireless Networks in Computer Communication Review – Proceedings of SIGCOMM 96 Aug-1996
[6] D.Johnson, D.Maltz, and J .Broch. Dsr the dynamic source routing protocol for multihop wireless ad-hoc network ,2001 [7] QualNet Network Simulator; Available: http://www.scalable-networks.com.
[8] QualNet documentation, “QualNet 4.0 Model Library: Advanced Wireless”; Available: http://www.scalable-networks.com/products/qualnet/download.php#docs
