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Second UKSIM European Symposium on Computer Modeling and Simulation

AnEfficient DSDV Routing Protocol for Wireless Mobile Ad Hoc Networks

and its Performance Comparison

Khaleel Ur Rahman KhanDept. of CSEM J College of Engg.Hyderabad, [email protected]

A Venugopal ReddyDept. of CSEUniv. College of Engg..Osmania Univ., [email protected]

Rafi U ZamanDept. of CSEM J College of EnggHyderabad, [email protected]

K. Aditya ReddyDept. of CSEM J College of EnggHyderabad, INDIA

T Sri HarshaDept. of ITM J College of EnggHyderabad, INDIA

[email protected] [email protected]

Abstract

One of the popular wireless network architectures

is mobile Ad Hoc Network (MANET) which can be

deployed easily in almost any environment, without any

underlying backbone and infrastructure support.

In this paper, an efficient DSDV (Eff-DSDV) Protocol is

proposed for Ad Hoc networks. Eff-DSDV overcomes the

problem of stale routes, and thereby improves the

performance of regular DSDV. The proposed protocol has

been implemented in the NCTUns Simulator and

performance comparison has been made with regular DSDV

and DSR protocols. The performance metrics considered are

packet-delivery ratio, end-end delay, dropped packets,routing overhead, route length. It has been found after

analysis that the performance of Eff-DSDV is superior to

regular DSDV and sometimes better than DSR in

certain cases.

1. Introduction

The idea of Ad Hoc Networking is gainingpopularity with the recent proliferation of mobilecomputers like laptops and palmtops. Minimalconfiguration, absence of infrastructure and quick deployment make Ad Hoc Networks convenient foremergency operations. Since host mobility causes

frequent and unpredictable topological changes, theformation and maintenance of Ad Hoc Network is notonly a challenging task and also it is different from thewired networks.Ad Hoc Routing Protocols are classified into Proactiveand Reactive type. Proactive routing protocols use theperiodic update of information to know about thecurrent topology while the reactive routing protocolscreate a route to a destination on demand basis. Few of

978-0-7695-3325-4/08 $25.00 © 2009 IEEE

DOI 10.1109/EMS.2008.11506

the proactive protocols are DSDV[1], WRP[2],DBF[3]etc. while DSR[4],AODV[5],ABR[6] are fewexamples of reactive protocols. Even though noprotocol is superior to the other, but the previousstudies indicate that in general reactive protocolsexhibit better performance than proactive protocols.

The remainder of this paper is organized as follows:Section 2 provides the previous work done in this area.Section 3 describes the design of the proposed protocolin an algorithmic approach. Section 4 gives theSimulation Results and Performance Comparison of the proposed protocol. Section 5 concludes the paper.

2. Previous Work

Numerous routing protocols have been proposed inthe recent past. A detailed review and classification of Routing protocols for Ad Hoc Networks has beengiven in [7] and [8]. In the recent years several routingalgorithms have been developed. Johnson and Maltz[4] point out that conventional routing protocol areinsufficient for ad hoc networks, since the amount of routing related traffic may waste a large portion of thewireless bandwidth, especially for protocols that useperiodic updates of routing tables. They proposedusing the Dynamic Source routing which is based on

on-demand route discovery. A number of protocoloptimizations are also proposed to reduce the routediscovery overhead. Perkins and Royer [5] presentedthe AODV which also uses a demand approach of route establishment. Temporally Ordered Routingalgorithm [9] is proposed to minimize reaction totopological changes by localizing routing –relatedmessages to a small set of nodes where the change is.Zone Routing Protocol (ZRP) by Hass et.al [10] has

mailto:[email protected]












507


NeighborNo.of

Hops

Via

Node

Update

Time

C 2 H 1765

E 2 F 1860

G 3 E 1050

I 3 A 805

been proposed which attempts to combine proactiveand reactive approaches, but limits the scope of theproactive procedure only to the initiator’s localneighborhood.

3. Proposed Efficient DSDV (Eff - DSDV)

Protocol

In DSDV the low packet delivery is due to the factthat, it uses stale routes in case of broken links. InDSDV the existence of stale route does not imply thatthere is no valid route to the destination. The packetscan be forwarded thru other neighbors who may haveroutes to the destination. When an immediate link fromthe host say ‘A’ to the destination say ‘T’ breaks, theproposed protocol creates a temporary link thru aneighbor which has a valid route to the desireddestination. The temporary link is created by sendingone-hop ROUTE-REQUEST and ROUTE-ACKmessages. The host ‘A’ upon finding the next hop

broken link broadcasts a one-hop ROUTE-REQUESTpacket to all its neighbors. In turn, the neighborsreturns the ROUTE-ACK if it has a valid route to thedestination and the host ‘A’ is not the next hop on theroute from the neighbor to the destination.Each entry in the routing table has an additional entryfor route update time. This update time is embedded inthe ROUTE-ACK packet and is used in selecting atemporary route. In case of receiving multipleROUTE-ACK with the same number of minimumhops , ad hoc host ‘S’ chooses that route which has thelatest update time.

The Figure 1 shows how host ‘A’ creates a

provisional route to the destination ‘T’, when theintermediate link from ‘A’ to ‘B’ breaks. Host ‘A’

suspends sending packets (Figure 1(a)). After which itbroadcasts ROUTE-REQUEST packets to itsimmediate one hop neighbors. The Ad Hoc hosts C,E,and G responds with ROUTE ACK packets along withhop count and the route update time to Ad Hoc host A(Figure 1 (b)). Table 1 shows the snapshot of therouting information received by Ad Hoc host A. Fromthe table it can be seen that, Ad Hoc Host C and Ehave the same value for hop count metric, but therouting update time for E is greater than that of C,meaning the path thru E is updated more recently.

Therefore Host A resumes sending packets to thedestination T (Figure 1(c)). Later on whenever any AdHoc host moves in the range of the host A then therouting table of host A gets updated by the regularDSDV routing process. Then the updated route will betaken for forwarding the packets from the host A to thedestination T.

The whole process is explained in the algorithmgiven below:

Figure 1: Creation of provisional route in Node“A”

Table 1: Route update at Host A

3.1 Algorithm of Eff-DSDV

The mechanism of Eff-DSDV is described by the

following algorithm.

Algorithm Eff-DSDV (Host A, Destination D,MAXBufferSize N, Packet X)

1. if (A. NextHopLink () == ACTIVE) thenUse Standard DSDV;

else if (A. BufferLength () == N) thenDiscard X;

elseplace X in A.Buffer;

2. A. Broadcasts (ROUTE-REQUEST, 1, D, A);3. if (A. NEXT_NEIGHBOR has route to ‘D’) then

A. RECIEVE (ROUTE_ACK)4. Min_Hops = ∞ ; Next_Hop = 0; Updated_Time=0;5. While (Host A has ROUTE_ACK Packets)

{if ( ROUTE_ACK.HOP_COUNT< =Min_Hops )

{if ( ROUTE_ACK.HOP_COUNT =Min_Hops )

{if ( ROUTE_ACK.UPDTD_TIME > Updated_Time )



508


{Host_ID = ROUTE_ACK.HOST_ID;

Updated_Time = ROUTE_ACK.UPDTTD_TIME;

}}else

{

Min_Hops = ROUTE-ACK.HOP_COUNT;Host_ID = ROUTE_ACK.HOST_ID;Updated_Time = ROUTE_ACK.UPDTTD_TIME;

}}

}6. Forward the incoming Packet ‘X’, via Host_ID;

4. Simulation Results and Performance

Comparison

The Simulations were carried out using NCTUnsNetwork Simulator [11] from Simreal Technologies.

NCTUns is a network simulator and emulator. It uses anovel kernel re-entering simulation methodology. Thepacket size is fixed to 1400 Bytes. Random Waypointmobility model is used. Initially the nodes were placedat certain specific locations, and then the nodes movetowards new locations. The simulations were carriedout by varying the number of nodes in multiples of 5,i.e 5,10,15,20,25,30 and 35.The Speed of the node isfixed. Seven Simulations were carried out for each of the three protocols. Thus a total of 21 Simulationswere carried out for varying number of nodes. Onsimilar lines, 21 Simulations were carried out byvarying the speed of the nodes in multiples of 10, i.e

10, 20,30,40,50 m/S. The numbers of nodes were fixedat 30.

In order to evaluate the performance of ad hocnetwork routing protocols, the following metrics wereconsidered.

4.1 Packet Delivery Ratio

The ratio of the number of packets originated by the“application layer” to the number of packets receivedby the destination. Figure 2 shows the graph for thethree protocols as a function of the number of nodesand Figure 3 shows the performance of the protocols

as a function of the node speed.It can be seen from the graphs that the performance

of Eff-DSDV is better than the other two protocolsespecially when the number of nodes are between 15and 30. The speed of node has less impact on the DSRprotocol.

Figure 2: Packet Delivery Ratio for DSDV,DSR , Eff- DSDV as a function of number of

nodes

Figure 3: Packet Delivery Ratio for DSDV,DSR , Eff- DSDV as a function of node speed

4.2 Packets Dropped

The number of data packets that are not successfullysent to the destination. Figure 4 shows the number of dropped packets for the three protocols as a function of the number of nodes and Figure 5 shows for varyingspeed. Here the performance of DSR is better than theother two protocols. Among DSDV and Eff-DSDV theperformance of the latter is better. It can be observedthat the node speed has relatively less impact on theperformance of the DSR. The dropped packets rateincreases with the number of nodes in the DSDV andEff-DSDV due to the increase in the number of routingdumps exchanged among the nodes. The dip at 25nodes is due to the barrier in the topology and theplacement of source and destination nodes.



509


Figure 4: Dropped Packets for DSDV, DSR ,Eff- DSDV as a function of number of nodes

Figure 5: Dropped Packets for DSDV, DSR ,Eff- DSDV as a function of node speed

4.3 End To End Delay

The delay experienced by a packet from the time itwas sent by a source till the time it was received at thedestination. Figure 6 shows the End-End Delay for thethree protocols as a function of the number of nodesand Figure 7 shows for varying speed. Theperformance of Eff-DSDV is better than the other twoprotocols for varying number of nodes especiallybetween 15 and 30 nodes. For varying speed theperformance of DSR is the best. But the performanceof Eff-DSDV is better than regular DSDV protocol.

Figure 6: End-End for DSDV, DSR , Eff- DSDVas a function of number of nodes

Figure 7: End-End Delay for DSDV, DSR , Eff-DSDV as a function of node speed

4.4 Routing OverheadThe number of control packets produced per mobile

node. Control packets include route requests, repliesand error messages. Figure 8 shows the performance of the three protocols for Routing overhead as a functionof the number of nodes and Figure 9 shows for varyingspeed. For varying number of nodes, the performanceof the three protocols is close. Relatively theperformance of DSR is better the other two. Amongregular DSDV and Eff-DSDV, the performance of thelatter is better. However for varying speed, theperformance of DSR is far superior. Regular DSDVand Eff-DSDV is almost close to each other for

varying speed. Eff-DSDV is slightly better than theregular DSDV as far as this metric is concerned.



510


Figure 8: Routing Overhead for DSDV, DSR ,Eff- DSDV as a function of number of nodes

Figure 9: Routing Overhead for DSDV, DSR,Eff- DSDV as a function of node speed

4.5 Route Length

The average route length (in terms of the number of hops) of all the packets that reach the destination fromthe source. Figure 10 shows the performance of thethree protocols as a function of the number of nodesand Figure 11 shows the performance as a function of the speed of the mobile node. The performance of theDSR protocol is better than the other two protocols inboth the cases. The performance of the Eff-DSDVprotocol is slightly better than the regular DSDVprotocol with regard to the number of nodes (Figure10). However it can be seen from the Figure 11, that

the performance of the Eff-DSDV is much superiorthan regular DSDV with regard to the speed of thenode. This is because the the Eff-DSDV finds betterroutes faster than the regular DSDV. It can as well beseen that the performance of the DSR protocol isalmost the same for the case of varying number of

nodes (Figure 11).

Figure 10: Route Length for DSDV, DSR , Eff-DSDV as a function of number of nodes

Figure 11: Route Length for DSDV, DSR , Eff-DSDV as a function of node speed

Figure 12: Percentage improvement of Eff-DSDV over DSDV (Varying no. of nodes), with

respect to performance metrics.



511

Figure 13: Percentage improvement of Eff-DSDV over DSDV (Varying speed of nodes),

with respect to performance metricsThe figure 12 and 13 shows the percentage

improvement of the Eff-DSDV protocol over theDSDV protocol as a function of number of nodes andthe node speed with respect to the performancemetrics.It can be seen from the graph that there is a significantimprovement with respect to the varying number of nodes than in comparison with speed of the nodeexcepting for the dropped packets.

5. Conclusion

In this paper we have implemented the proposed Eff-DSDV protocol in C++ and integrated the module in

the NCTUns Simulator. The performance of theproposed protocol was measured with respect tometrics like Packet delivery ratio, end – end delay etc.We have made the performance comparison of theproposed protocol with one of the Proactive routingprotocol (DSDV) and one of the reactive protocol(DSR). Simulations were carried out with identicaltopologies and running different protocols on themobile nodes.

The results of the simulation indicate thatperformance of the Eff-DSDV protocol is certainlysuperior to standard DSDV. It is also observed that theperformance is better especially when the number of

nodes in the network is in the range of 10 to 30. Whenthe number of nodes increases beyond 35 theperformance of both the proactive protocolsdegenerates due to the fact that a lot of control packetsare generated in the form of incremental or full dumpsof the routing updates/tables in the subnet. It is alsoobserved that the performance of Eff-DSDV is betterthan the regular DSDV in the case of varying speed of

the mobile nodes. In certain cases it is observed thatthe performance of the proposed protocol is even betterthan the DSR protocol like packet delivery ratio andend-end delay. The reason for the performance to getdrop at 25 nodes and in some cases for node speed isdue to varying source and destination nodes and theplacement of barrier in the network topology.In future, the performance comparison can be madebetween the proposed protocol and the other classes of the Ad Hoc Routing Protocols with differentsimulation parameters and metrics.

References

[1] C.E. Perkins & P. Bhagwat, “Highly DynamicDestination Sequence-Vector Routing (DSDV) for MobileComputers”, Computer Communication Review, 24(4), 1994,234-244.

[2] S. Murthy and J.J Garcia-Luna-Aceves, “An efficientrouting protocol for wireless networks”, ACM Mobile

Networks and Application Journal, Special issue on Routingin Mobile Communication Networks,1996.

[3] D. Bertsekas and Gallager, Data Network, pages 404-410,second ed. Prentice Hall, Inc., 1992.

[4] David B. Johnson and David A. Maltz. “Dynamic sourcerouting in ad hoc wireless networks”, Mobile Computing,Kluwer Academic Publishers, edited by Tomasz Imielinskiand Hank Korth, chapter 5, pages 153–181, 1996.

[5] C.E. Perkins and E.M. Royer, “Ad-Hoc on-DemandDistance Vector Routing,” Proc. Workshop Mobile

Computing Systems and Applications (WMCSA ’99), Feb.1999, pages 90-100.

[6] C.K Toh,”Long-lived ad hoc routing based onthe concept of associativity”, Internet draft, IETF, March1999.

[7] E.M. Royer, C-K. Toh, “A Review of Current RoutingProtocols for Ad Hoc Mobile Wireless Networks”, IEEEPersonal Communications Magazine, April 1999,pp 46-55.

[8] Mehran Abolhasan, Tadeusz A. Wysocki, Eryk Dutkiewicz: “A review of routing protocols for mobile adhoc networks”, Ad Hoc Networks 2(1): 1-22 (2004).

[9] V.D. Park and M.S. Corson, “Temporally-Orderedrouting alogorithm(TORA) version 1 functional

specification(Internet-Draft):, August 1998.

[10] Z.J. Hass and M.R. Pearlman, “The Zone RoutingProtocol for ad hoc networks(Internet-Draft),” August 1998.

[11] S.Y. Wang, C.L. Chou, C.H. Huang, C.C. Hwang, Z.M.Yang, C.C. Chiou, and C.C. Lin, "The Design andImplementation of the NCTUns 1.0 Network Simulator",

Computer Networks, Vol. 42, Issue 2, June 2003, pp.175-197.

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