AbstractMobile Ad-hoc network (MANET) is a wireless network with no prior infrastructure; all nodes in the network are allowed to move freely which in turns make routing very difficult. The purpose of this paper is to analyze the performance of two on-demand routing protocols, Temporary ordered Routing Protocols (TORA) and Ad hoc on-demand Distance Vector (AODV) with Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) based applications and variable number of nodes. OPNET is used to implement the scenario and parameters like delay, through put and congestion are used to evaluate the performance. Evaluation of simulation results will show that AODV will perform better than TORA.
Index TermsMANET, TORA, AODV
New routing protocol have been developed for MANET to provide solution for the routing problems which mainly arises due to its dynamic nature and node mobility. Each routing protocol has its own characteristics and yield different results under different circumstances. Therefore it is necessary to compare these routing protocols and check that which routing protocol can perform better under given scenario. As the number of nodes can easily vary in MANET as there is no bound on nodes entering or leaving the network, which is why we are using the scenario of increasing number of nodes in order to cover this problem. Traffic can also be of great importance as different applications are used now a day's which can require different arrangements and setups.
Review of the State of Art
Different methods are used to perform the performance evaluation of MANET Routing protocols. Most of the evaluation work includes simulation on NS-2 or Qual Net as OPENT has recently included its MANET model. Performance evaluation with TCP traffic in  shows that AODV outperforms TORA as the number of nodes increase. Simulation results from  show that TORA produces lesser through put due to extra overhead used for link establishment and path up gradation. Performance evaluation on NS-2 in  shows that AODV out performs TORA in end to end delay as the network size, and hence the congestion in the network increases.  Suggests that the use of UDP in ad hoc networks will result in higher packet delivery ratios and hence reduce the end to end delay as compared to that of TCP.
Problem Statement and Main Contribution
MANET is dynamic in nature and there is no restriction on the nodes entering or leaving the network. What makes it different from other wireless networks is the fact that is does not have and prior infrastructure or Base Station to support communication in between the nodes. So each node in the network has to perform as a router as well as a host to support communication in between the nodes. As routing of packets is dependent on the nodes so it becomes really difficult for such networks to handle the routing with high node mobility and large scale of nodes entering or leaving the network.
That is why various routing protocols have been developed to solve the problems in MANET. But these routing protocols have different characteristics and yield different results under different situations and applications. So the question arises that which protocol can be used for a particular scenario. One solution is by doing the performance evaluation of the selected protocols. We have used AODV and TORA for our comparison over TCP and UDP traffic and under the scenario of increasing number of nodes. Observation and Evaluation of the performance metrics like Delay and throughput will show that AODV is performing better than TORA when we increase the number of nodes.
The approach that we have used for the performance evaluation of TORA and AODV is a simulation based approach. OPENT Modeler 14.5 is used to perform the performance evaluation of AODV and TORA over TCP and UDP based applications. We have implemented a campus network having a size of 1000 * 1000 meters.
Two OPENT projects are implemented; each having two scenarios. Task manager in OPENT is used for the deployment and setting of UDP traffic in OPENT. In the first project we have compared performance of AODV and TORA over TCP traffic with 3, 6 and 12 ad hoc nodes respectively, and in the second project we have used UDP based application for the performance evaluation. We have used the packet size of 1024 bytes for both TCP and UDP based Applications. Random Way Point Mobility Model is used to ensure that the node mobility is independent. Random Way Point Mobility makes sure that the nodes are mobile and they move independently of one another. Performance metrics like delay and through put are used for the behaviour analysis of these routing protocols.
The results obtained are compared and evaluated to decide that which protocol and perform better when we increase the number of nodes.
A. End to End Delay:
The average end to end delay across the Wireless Network for packet delivery is higher in TORA as compared to that of AODV as shown in the Fig.2. This observation is made while changing the number of nodes and transmission protocols between TCP and UDP. As we increase the number of nodes, delay in TORA also increases as more time is spent in delivery of the packets.
Fig.3 shows that AODV is giving sufficiently higher through put as compared to that of TORA as we increase the number of nodes, as "a small delay in the network will produce a higher throughput" . This increase in through put is subject to the network load and Bandwidth utilization which increases with the size of the network. So there is a prominent increase in the through put across WLAN as the network size increases.
C. Comparison over TCP and UDP:
Fig.2 shows that UDP is better than TCP in terms of end to end delay for AODV, because TCP is a connection oriented protocol which introduces delay while transmission of the packets.
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- Anipakala Suresh, "Performance Analysis of Ad hoc On-demand Distance Vector Routing" (AODV) using OPENT Simulator, Communication Networks, University of Bremen, Bermen,11th April 2005.
- Ioannis Broustis,GentianJ akllari,Thomas Repantis, MartMolle, "A Comprehensive comparison of Routing Protocols for Large-Scale Wireless MANETS", Department of Computer Science and Engineering, University of California, Riverside, CA 92521.
- Md. Golam Kaosar, Hafiz M. Asif, Tarek R. Sheltami, Ashraf S. Hasan Mahmoud, "Simulation-Based Comparative Study of On Demand Routing Protocols for MANET", Department of Computer Engineering, King Fahd Univrsity of Petroleum & Minerals, Dhahran 31261, KSA.