1. INTRODUCTION:

Traditional routing protocols were developed to support user communication in networks with a fixed infrastructure with reliable, high-capacity links. However, in the mobile ad hoc network, the network infrastructure is dynamically changing, and the links are wireless with less capacity and more prone to errors.

A MANET is a collection of wireless nodes that can dynamically form a network to exchange information without using any pre-existing fixed network infrastructure. The special features of MANET bring these technology great opportunities together with severe challenges.

A Mobile Ad Hoc Network (MANET) is defined as a collection of mobile platforms or nodes where each node is free to move about arbitrarily [1]. Nodes in these networks utilize the same random access wireless channel, cooperating in a friendly manner to engaging themselves in multi hop forwarding. The node in the network not only acts as hosts but also as routers that route data to/from other nodes in network [3].

In this paper, we are studying about MANET’s routing protocol and overview of AODV, DSDV, DSR protocols. We analysing the effect of Network size and Pause time in these routing protocols. For analysis, we are using parameters i.e. End-to-End Delay, routing Overhead and PDF.

In this section, we give general introduction of MANET, briefly discussion about routing protocols i.e. AODV, DSDV and DSR. Section 2 discusses about the parameter metrics. Section 3 gives description of Experimental setup. Section 4 presents simulation results and analysis part. Section 5 is conclusion part, which concludes this paper.

1.1 ROUTING PROTOCOLS OF MANET:

MANET can be further classified as reactive (ondemand) and proactive (table-driven) routing protocols based on the method of acquiring information from the other nodes. In addition to these two main groups, there are hybrids routing protocols that combine the merits of both reactive and proactive routing protocols.[8]

Mobile Ad-hoc Network

DSDV WRP OLSR AODV DSR TORA ZRP OORP

Figure 1: Mobile Ad-Hoc routing protocols

Routing protocols are classified into two main categories: Table-driven routing protocols and source initiated on-demand driven routing protocols. The table driven routing protocols maintain consistent and up-to-date routing information from each node to the rest of the nodes in the network in one or more routing tables regardless of the need of such routes. It’s also called Proactive routing protocol. DSDV is a Table driven (proactive) protocol .The source initiated on-demand routing protocols are developed and employed in ad-hoc networks and initiates routing activities only when needed. So it is not needed to maintain routing table containing all the nodes as entries does not have to be maintained in each node. DSR and AODV are typical reactive protocols. Based on combination of both table and demand driven routing protocols, some hybrid routing protocols are proposed to combine advantage of both proactive and reactive protocols. The most typical hybrid one is zone routing protocol (ZRP) [4]. This paper presents three routing protocol i.e. DSDV, AODV and DSR.

1.1.1 DESTINATION SEQUENCE DISTANCE VECTOR (DSDV):

The DSDV is typically a pro-active routing protocol which maintains a table to store the routing information. Each node maintains a routing table in which all of the possible destinations within the network and the number of hops to each destination are recorded.

DSDV is a loop free routing protocol in which the shortest path calculation is based on the Bellman-Ford algorithm. Data packets are transmitted between the nodes using routing tables stored at each node. Each routing table contains all the possible destinations from a node to any other node in the network and also the number of hops to each destination [9, 10]. DSDV has limitation that it doesn’t support Multi path Routing. And also there is wastage of bandwidth due to unnecessary advertising of routing information even if there is no change in the network topology [11].

For larger network this would lead to overhead, which consumes more bandwidth. SO the Network size affects the overhead performance of DSDV.

1.1.2 AD-HOC ON DEMAND DISTANCE VECTOR (AODV):

AODV is a source initiated on-demand (Reactive) routing protocol with small delay that determines the route when it’s needed. When a source wants to initiate transmission with another node as destination in the network, AODV use control messages to find a route to the destination node in the network.

AODV is capable of operating on both wired and wireless media, although it has been designed specifically for wireless domain. Route tables used by AODV store the destination and next hop IP addresses as well as the destination sequence number [14]. AODV builds routes by using a route request (RREQ)/ rout reply (RREP) query cycle. When a source node requires a destination route for which it does not have a route already, it broadcasts RREQ packet across the network [12, 13]. Each entry contains the information of Destination, Next hop, Number of hops, Destination sequence number, and Active neighbours for this route and Expiration time for the route table entry .

1.1.3 DYNAMICSOURCE ROUTING (DSR):

The Dynamic Source Routing (DSR) protocol is an on-demand routing protocol based on source routing. The Dynamic Source Routing protocol is composed of two main mechanisms to allow the discovery and maintenance of source routes in the ad hoc networks.

In DSR, every mobile node in the network needs to maintain a route cache where it caches source routes that it has learned. When a host wants to send a packet to some other host, it first checks its route cache for a source route to the destination. In the case a route is found, the sender uses this route to propagate the packet. Otherwise the source node initiates the route discovery process [8].The DSR protocol has been mainly designed for mobile ad-hoc networks of up to about two hundred nodes, and is designed to work well even at very high rates of mobility.[15]

2. PERFORMANCE METRICS:

In this paper, for experiment three metrics are used, i.e.:

1. Routing Overhead:

In wireless ad hoc networks, nodes often change their location within network. So, some stale routes are generated in the routing table which leads to unnecessary routing overhead [17].

2. Avg. End-to-End delay:

Average End to End Delay signifies the average time taken by packets to reach one end to another end (Source to Destination).

It includes the average delay data packets that happened during transmission time from source to destination. So it consist of route discovery latency, the queuing delays at a node, retransmission delays at the MAC layer and the propagation and transfer time of wireless channel [17] .3.

Packet Delivery Fraction (PDF):

This is the ratio of total number of packets successfully received by the destination nodes to the number of packets sent by the source nodes throughout the simulation.

It specifies the packet loss rate, which limits the maximum throughput of the network. The better the delivery ratio, the more complete and correct is the routing protocol [16].

3. EXPERIMENTAL SETUP:

All the simulation work is perform in Network Simulator NS-2.Initially number of nodes are 50, Simulation time was taken 100 seconds and seed as 1.0.In this paper two scenarios are taken into considerations for performance analysis: 1) Varying of Pause-Time and 2) Varying of Network Size. 1) Pause-Time: Pause time is a time in which all nodes in network are motionless but transmission is continued. For simulation, environmental surrounding selected is Pause time. Pause time is varying between the ranges of 2-6 (2, 4 and 6) sec. All the simulation works were carried out using AODV, DSDV, DSR routing protocols. 2) Network Size: Here network size is used for network area, which is used for simulation. We experimenting with different network sizes i.e. (200*200),(500*500) and (1200*1200) for above three routing protocols AODV,DSDV,DSR.

4. SIMULATION RESULTS and ANALYSIS:

The simulation for proactive and reactive routing protocols is based on simulation time, number of node, area of network, pause time, routing protocol. In experimental methodologies performance matrix can be measured with variation in pause time and area of network while rest of all other parameters like simulation time, and no. of node kept constant. Effects of different parameter on performance of on-demand protocols are publicized below.

From simulation results in figure 2-10, it is observed that the overall performance of AODV protocol is better than other routing protocols (DSR, DSDV), because of the. But due to simulation results of End to End Delay with variation in pause time and Network Size performance also varies. For small network size with 2 pause time DSDV is good of end-to-end delay. But with increasing pause time

(6) DSDV going down. The average End-to-End Delay for all scenarios is best on AODV and DSR routing protocol. Shown in figure 2, 5 and 8.For Packet Delivery Fraction, DSDV gives worst performance. For increasing pause time DSR is best and AODV performance is good. Shown in figure 4,7 and 10. DSDV performs well for Routing Overhead with minimum pause time (2) by increasing network size. By increasing pause time AODV and DSR perform well. Shown in figure 3,6 and 9.

5. CONCLUSION:

This paper provides explanation and simulation analysis of proactive and reactive routing protocols i.e. DSR, AODV and DSDV for mobile ad-hoc networks .It has also presented a comparison of these routing protocols under the variation of Pause Time and Network Size, simultaneously measured performances under various performance metrics including routing overhead, packet delivery fraction and average end-to-end delay. From different analysis of graphs and simulations it can be concluded that DSR and AODV performs well than DSDV with variation in pause time and network area. DSDV is good for small size network. For overall scenarios, AODV performance is best.

6. REFERENCES:

[1] Charles. E. Perkins, “Ad Hoc networking”, Pearson Education, Dorling Kindersley (India) Pvt. Ltd. ISBN 978-81-317-2096-7, 2008.

[2] Xiaoyan Hong, Kaixin Xu, and Mario Gerla. “Scalable routing protocols for mobile ad hoc networks”, IEEE Network, Volume: 16, Issue: 4, July/August 2002.

[3] Mehran Abolhasan, Tadeusz Wysocki, and Eryk Dutkiewicz, “A review of routing protocols for mobile ad hoc networks”, Technical report, Telecommunication and Information Research, NSW 2522.

[4] Zygmunt J. Haas, Cornell University, Marc R. Pearlman, Cornell University, “The Zone Routing Protocol (ZRP) for Ad Hoc Networks”, draft-ietf-manet-zone-zrp-02.txt, 2001.

[5] Elizabeth M. Royer and Chai-Keong Toh, “ A review of current routing protocols for adhoc mobile wireless networks”, Technical report, USA, 1999.

[6] Jaya Kumar Geetha and Gopinath G., “Ad Hoc Mobile Wireless Networks Routing Protocols – A Review”, Journal of Computer Science, Vol. 3(8), pp. 574-582,2007.

[7] Kapang Lego, Pranav Kumar Singh , Dipankar Sutradhar, “Comparative Study of Adhoc Routing Protocol AODV, DSR and DSDV in Mobile Adhoc NETwork”, Indian Journal of Computer Science and Engineering, ISSN : 0976-5166, Vol. 1 No. 4 364-371.

[8] David Oliver Jörg, “Performance Comparison Of MANET Routing Protocols In Different Network Sizes”, Institute of Computer Science and Applied Mathematics Computer Networks and Distributed Systems (RVS) University of Berne, Switzerland, 2003.

[9] Charles EP, Royer EM, Das SR, Marina MK, “Performance Comparison of Two On-Demand Routing Protocols for Ad-hoc Networks”. IEEE Personal Communication, pp. 16-28, 2000.

[10] Charles E. Perkins, Pravin Bhagwat ,“Highly Dynamic Destination-Sequenced Distance-Vector Routing (DSDV) for Mobile Computers”, SIGCOMM 94 -8/94 London England UK, ACM 0-89791 -682-4/94/0008,1994.

[11] Guoyou He., Destination-sequenced distance vector (DSDV) protocol, Technical report, Helsinki University of Technology, Finland.

[12] E. M. Royer and C. K. Toh, “A Review of Current Routing Protocols Ad Hoc Mobile Wireless Networks”, IEEE Personal Communications, Volume 6, Number 2, pp: 46-55, April 1999.

[13] C. E. Perkins and E. M. Royer, “Ad-hoc On-Demand Distance Vector Routing”, proceedings of the second IEEE Workshop on Mobile Computing Systems and Applications, New Orleans, L.A., pp: 90-100,1999.

[14] S.S. Tyagi, R.K. Chauhan,” Performance Analysis of Proactive and Reactive Routing Protocols for Ad hoc Networks” , International Journal of Computer Applications (0975 – 8887) Volume 1 – No. 14, 2010.

[15] Marco Fotino, Antonio Gozzi, Juan-Carlos Cano, “Evaluating Energy Consumption of Proactive and Reactive Routing Protocols in a MANET”, ifip (International Federation for Information Processing) Grant TIN2005-07705-C02-01, 2005.

[16] Amandeep Verma, “A Study of Performance Comparisons of Simulated Ad-hoc Network Routing Protocols”, IJCTA (International Journal of Computer Technology and Application), Volume 2 Issue 3, 565569, ISSN:2229-6093, May-June 2011.

[17] V.P. PATIL, “Impact of Mobility and Network load on the Performance of Reactive and Proactive Routing Protocol in Manet”, IJCES(International Journal of Computer Engineering and Science), Volume 2, ISSN: 2231–6590, Issue 1, pp. 8-16,Sept 2012.

Received on 01.03.2013 Accepted on 25.03.2013

Research J. Science and Tech 5(3): July- Sept., 2013 page 335-339

KEY WORDS: MANET, AODV, DSDV, DSR, NS2 Simulator.