2009 International Conference on Signal Processing Systems
Performance Comparison of Reactive Routing Protocols of MANETs using Group Mobility Model S. R. Biradar1, Hiren H D Sarma2, Kalpana Sharma3, Subir Kumar Sarkar4 , Puttamadappa C5 1 ,2, 3
Sikkim Manipal Institute of Technology, Majitar -737 132, INDIA 4 Jadavpur University, Kolkata- 700 032, INDIA 5 S.J.B. Institute of Technology, Bangalore – 560 060, INDIA Email: [email protected]
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protocols. Section III, describes the simulation environment. Section IV presents the simulation and results followed by their interpretations in and conclusion in Section V.
Abstract—A Mobile Ad hoc Network (MANET) is a infrastructure less network comprising of mobile nodes which dynamically form a network without the help of any centralized administration. Frequently changing network topology needs efficient dynamic routing protocols. We compare the performance of two on-demand routing protocols for mobile ad hoc networks Dynamic Source Routing (DSR) and Ad Hoc On-Demand Distance Vector Routing (AODV). We demonstrate that even though DSR and AODV both are on-demand protocol, the differences in the protocol mechanics can lead to significant performance differentials. The performance differentials are analyzed using varying mobility
II. ROUTING PROTOCOLS FOR MANETS: Dynamic Source Routing (DSR): The main feature of DSR is the use of source routing. That is, the sender knows the complete route form source to destination including all intermediate hops. These routes are stored in a route cache. The data packets carry the source route in the packet header [4, 5]. When a node in the ad hoc network attempts to send a data packet to a destination for which it does not already know the route, it uses a route discovery process to dynamically determine such a route. Route discovery works by flooding the network with route request (RREQ) packets. Each node receiving a RREQ, rebroadcasts it, unless it is the destination or it has a route to the destination in its route cache. Such a node replies to the RREQ with a route reply (RREP) packet that is routed back to the original source. RREQ and RREP packets are also source routed. The RREQ builds up the path traversed so far. The RREP routes itself back to the source by traversing this path backwards. The route carried back by the RREP packet is cached at the source for future use. If any link on a source route is broken, the source node is notified using a route error (RERR) packet. The source removes any route using this link from its cache. A new route discovery process must be initiated by the source, if this route is still needed.
Keywords- Ad hoc networks, wireless networks, mobile networks, routing protocols, performance, Analysis .
An ad hoc network is a collection of mobile nodes, communicating with each other using multi-hop wireless links. MANET nodes are equipped with wireless transmitters and receivers. The term “ad hoc” tends to imply “can take different forms” and can be “stand-alone, mobile or networked”. Due to the infrastructure less, self configuring network property, MANET has wide application in industrial and commercial field involving cooperative mobile data exchange, inexpensive alternatives or enhancement to cellular-based mobile network infrastructures. MANET has potential applications in the locations where setting of infrastructured networks is not possible. Military ad hoc networks detect and gain as much information as possible about enemy movements, explosions, and other phenomena of interest. Such kind of networks also has applications in emergency disaster relied orations after natural hazards like hurricane or earthquake. Some of the wireless traffic sensor networks monitor vehicle traffic on highways or in congested parts of a city. Wireless surveillance sensor networks may deployed for providing security in shopping malls, parking garages, and many such other areas where direct or wired communication cannot be made. Our goal is to carry out a systematic performance study of two routing protocols for ad hoc networks: AODV and DSR. A briefly review of these protocol[3, 4] is presented below. The rest of the paper is organized as follows. In the following section II, we briefly review the DSR and AODV 978-0-7695-3654-5/09 $25.00 © 2009 IEEE DOI 10.1109/ICSPS.2009.56
DSR makes very aggressive use of source routing and route caching. No special mechanism to detect routing loops is needed. Also, any forwarding node caches the source route in a packet it forwards for possible future use. Promiscuous listening: When a node overhears a packet not addressed to itself, it checks whether the packet could be routed via itself to gain a shorter route. If so, the node sends a gratuitous RREP to the source of the route with this new, better route. Aside from this, promiscuous listening helps a node to learn different routes without directly participating in the routing process.
Ad-Hoc On-Demand Distance Vector Routing (AODV): AODV inherits the property of both DSR and DSDV protocols. It borrows the basic on-demand mechanisms of Route Discovery and Route Maintenance from DSR, plus the use of hop-by-hop routing, sequence numbers, and periodic principal of DSDV. It provides loop-free path, avoids Bellman-Ford count to infinity and the convergence is also fast when the topology changes. RRREQ, RREP, RERR are the message types defined by AODV [5, 6]. When a route to a new destination is needed, the node broadcasts a RREQ to find a route to the destination. In case of link break in an active route, a RERR message is used to notify other nodes that the link failure has occurred. AODV is a reactive protocol and it deals with route table management. It uses the following fields with each routing table entry:
Average End-to-End Delay: This includes all possible delay caused by buffering during route discovery latency, queuing at the interface queue, retransmission delay at the MAC, propagation and transfer time.
Packet delivery ratio is an important metric; it describes the loss rate that will be seen by the transport protocols. For all our simulations we have kept the number of data packets sent out as constant 4 packets/seconds, so the number of packets successfully received at their destinations will give us a comparison as to how efficient the underlying routing algorithm is under similar traffic load. Here we have used the number of routing packets as our metric for routing overhead. In MANET routing overhead and average delay increase as the number of groups and node movement increases.
We used Network Simulation (NS)-2 in our evaluation. The NS-2 is a discrete event driven simulator  developed at UC Berkeley. The current version of the simulator is NS2.33. The goal of ns2 is to support networking research and education. It is suitable for designing new protocols, comparing different protocols and traffic evaluations . It is an object oriented simulation written in C++, with an OTcl interpreter as a frontend. NS uses two languages because simulator got to deal with two things: i) detailed simulation of protocols which require a system programming language which can efficiently manipulate bytes, packet headers and implement algorithms, ii) research involving slightly varying parameters or quickly exploring a number of scenarios. The two protocols maintain a send buffer of 50 packets. To prevent buffering of packets indefinitely, packets are dropped if they wait in the send buffer for more than 30s. Traffic sources are Continuous Bit Rate (CBR) the sourcedestination pairs may be in same group or in different group. The size of the data packets are 512-byte. During the simulation we use group mobility model  which is developed by University of Southern California (USC). The node speed variations considered are 1, 5 10, 30, 60 m/s. Simulations are run for 900 seconds with offered network load as 20 sources.
TABLE 1 Value
Performance Metrics: We used the following metrics for evaluating the performance of various MANET routing protocols:
Normalized Routing Overhead: Number of routing packets transmitted per data packet delivered at destination. Each hop-wise transmission of a routing is counted as one transmission.
Simulation Parameter: Simulation parameters are shown in table 1. All the above metrics are calculated from the trace file generated when the simulation is done. After getting the above metrics, graphs are plotted using Matlab.
III. SIMULATIOM ENVIRONMENT
Packet delivery ratio: It is the ratio of data packets delivered to the destination to those generated by the CBR sources.
Number of nodes
Number of connection
IV. RESULT AND DISCUSSION In this experiment we analyze how the increasing node speed influences the performance of routing protocols. Figure 1 shows PDR with different mobility. Single group mobility model achieved a higher packet deliver ratio than four groups mobility model shown in Figure 1. Single mobility is not affecting the PDR. Therefore, mobility has no
Routing Overhead: It is the number of routing packets used during the simulation.
impact on it. In case of four groups scenario DSR performs better than AODV only in case of high mobility. Whenever mobility increases PDR reduces smoothly due to dynamic topology.
Figure 3. Comparison between the two protocols of the normalized control overhead packets as a function of number of nodes speed
In case of DSR with 4 group mobility the average packet delay increases, as the nodes move with higher speed, shown in Figure 4. This effect is due to route caching. Mobility has no impact on single group. Overall AODV and single group mobility has the better delay.
Figure 1. Comparison between the two protocols of the packet delivered as a function of nodes speed
Figure 2. Comparison between the two protocols of the number of routing packets as a function of number of nodes speed Figure 4. Comparison between the two protocols of the average end-to-end delay as a function of number of nodes speed
In case of single group mobility model routing overhead and normalized routing overhead are almost constant as shown in figure 2 and figure 3 respectively, the node's speed is not influencing the control overhead. For low mobility, DSR generated less control traffic than AODV in 4 groups mobility model. The routing protocol that generates less control traffic, uses less energy and scalable also.
V. CONCLUSION In this paper, we analyze the MANET popular routing protocols DSR and AODV. That DSR performs better in high mobility, and average delay is better in case of AODV for increased numbers of groups. DSR Protocol produces higher control traffic during high mobility, due to its aggressive caching.
J. Broch, D. A. Maltz, D. B. Johnson, Y-C. Hu, and J. Jetcheva. A performance comparison of multi-hop wireless ad hoc network routing protocols. In Proceedings of the 4th International Conference on Mobile Computing and Networking (ACM MOBICOM’98)  C. E. Perkins, E. M. Royer, S. R. Das, and M. K. Marina, "Performance Comparison of Two On-Demand Routing Protocols for Ad Hoc Networks," IEEE Personal Communications, February 2001, pp. 16-28.  C. E. Perkins and E. M. Royer, “Ad Hoc On-demand Distance Vector Routing,” Proc. 2nd IEEE Workshop. Mobile Comp. Sys. and Apps., Feb. 1999.  F. Bai, N Sadagopan, A. Helmy, “IMPORTANT: A framework to systematically analyze the Impact of Mobility on Performance of Routing Protocols for Adhoc Networks, ” IEEE INFOCOM, April 2003.
This work has been supported by All India Council for Technical Education (AICTE) under the grant numbered: 8023/BOR/RID/RPS-216/2007-08 Author promptly acknowledge this support of AICTE REFERENCES  “The network simulator - ns-2,” in, http://www.isi.edu/nsnam/ns.  The ns Manual (formerly ns Notes and Documentation) The VINT Project a Collaboration between researchers at UC Berkeley, LBL, USC/ISI, and Xerox PARC. Kevin Fall, Editor Kannan Varadhan  Elizabeth M. Royer, University of California, Santa Barbara C-K Toh, Georgia Institute of Technology, "A Review of Current Routing Protocols for Ad Hoc Mobile Wireless Networks," IEEE Personal Communications, April 1999