1. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN
0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 3, April (2013), © IAEME
226
DYNAMIC CLUSTER BASED ADAPTIVE GATEWAY
DISCOVERY MECHANISMS IN AN INTEGRATED INTERNET
MANET
Md Misbahuddin Mahabubul Haq Atif Rafi-U-Zaman
CSED,MJCET CSED,RITS CSED,MJCET
Hyderabad,AP,India Hyderabad,AP,India Hyderabad,AP,India
ABSTRACT
The interconnection of the wired Internet with mobile ad hoc networks is called Integrated-
Internet MANET. In this interconnection, various issues arise. Primary among them is the routing of
packets between mobile nodes in the ad hoc network and fixed nodes in the wired network. The
rationale behind using dynamic cluster based mobile gateways is to increase the reliability of the
Internet access and enhance the performance of the hybrid, wireless network in terms of high data
delivery ratio and low average delay. The results of the simulations show the impact of the number of
MANET nodes connected to the Internet, and the mobility of dynamic cluster based mobile gateways.
This is consistent with the design and functionality of dynamic cluster based mobile gateways, which
are moving around the border of access points’ coverage area in order to provide MANET nodes with
Internet connectivity. Existing system of hybrid gateway discovery mechanism by allocating statically
adjust value to TTL. The conclusion of this paper is to develop hybrid gateway discovery mechanism
by allocating dynamic value to TTL by using clusters with mobile gateways.
Keywords: MANET, Routing, Integration Strategy, Gateway Discovery.
1.INTRODUCTION
The Integration of the MANETs and infrastructure networks such as Internet extends the
network coverage and increases the application domain of ad hoc networks.
The difference in the network architectures of the MANET and the Internet imposed various
sorts of assumptions on the structure, topology of the underlying networks and on the communication
patterns of mobile nodes in both networks. Integrating these two networks into a hybrid network is a
challenging problem due to these differences. This inter connection is achieved by using gateways,
which act as bridges between a MANET and the Internet. Communication of the mobile devices in an
ad hoc network and a fixed device in the Internet requires the modification of the ad hoc routing
protocol. Before a mobile node can communicate with the Internet host it needs to find a route to a
INTERNATIONAL JOURNAL OF ADVANCED RESEARCH IN
ENGINEERING AND TECHNOLOGY (IJARET)
ISSN 0976 - 6480 (Print)
ISSN 0976 - 6499 (Online)
Volume 4, Issue 3, April 2013, pp. 226-232
© IAEME: www.iaeme.com/ijaret.asp
Journal Impact Factor (2013): 5.8376 (Calculated by GISI)
www.jifactor.com
IJARET
© I A E M E

2. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN
0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 3, April (2013), © IAEME
227
gateway. Most of the previous approaches use the shortest path for the selection of gateway for
onward transmission of data from MANET nodes to the wired hosts. In the proposed approach of
Kumar et. al., the length of the routing queue in addition to minimum hop count metric is used for the
selection of gateway by the mobile node. This approach has been extended by updating the path to the
gateway on the request of mobile node which facilitates efficient handoff from one gateway to
another, and thus maintaining continuous connectivity to the fixed host. Another extension is that
routing queue length and min hop count metric is not only used to discover the routes to the gateway
but also for the routing in the local ad hoc domain among the ad hoc host. Further, the occupancy
level of each of the nodes is updated every short interval of time. This updated occupancy is sent to all
the neighbors within the radio transmission range within the hello packet. This reduces the delay
along the path traversal.
The primary challenge in the design of Hybrid Gateway Discovery is how to determine an
optimal proactive area. If the proactive area is large (i.e. a large TTL value) more overhead is incurred
in maintaining routes in a wider area. On the other hand, if proactive area is small, then less
maintenance overhead is incurred but more delay in Gateway Discovery is experienced. In traditional
Hybrid Gateway Discovery approach, the TTL is set statically and never changed. This leads to a
rigid implementation of the proactive area. Existing integration strategies which use the hybrid
approach set the proactive area statically and do not dynamically adjust it, which may not turn out to
be a proper range anymore for changing network conditions.
A second issue is determining the periodicity of the GW_ADV messages. The periodicity of the
GW_ADV message determines the number of GW_ADV messages that will be flooded into the
MANET per second. A high periodicity leads to more control messages in a sparse MANET whereas
low periodicity may result in starvation of Internet connectivity to mobile nodes in a dense MANET.
A modified Hybrid Gateway Discovery mechanism which dynamically adjusts value of TTL and
periodicity of TTL depending on the MANET characteristics in order to achieve a good trade-off
between performance and network overhead is called an Adaptive Gateway Discovery Mechanism.
A mobile node which number of hops away from the gateway i.e. which is not a part of proactive
zone, even these types of mobile nodes can also registered with this gateway and this is called
adaptive gateway discovery in which we overcome the problem which is present in hybrid gateway
discovery i.e. the TTL value is fixed.
2. RELATED WORK
2.1 Existing Architecture
The proposed architecture shown in Figure 2.1 consists of the Mobile ad hoc Network
(MANET), with Clusters either overlapped or non-overlapped. Each Cluster has a Cluster Head and
the overlapping Clusters have a Cluster Gateway . At least one Cluster Head shall be in the
transmission range of the Foreign Agent (FA) in the Internet backbone. The Correspondent Node
(CN) is assumed to be present in the wired Internet. The Integrated Protocol uses the basic
functionalities of the Mobile IP as well as CGSR. We assume that the CHs are close to FA in order to
provide the Internet connectivity to the MANET nodes. The CHs are assumed to be registered with
some FA at any time.The Agent advertisements issued by the FA are meant only for the CHs. They
are ignored by the ad hoc hosts and CGs. So, we use proactive approach of registration of the CH with
the FA. If any CH receives advertisements from multiple FAs, then it selects that FA which is lightly
loaded. All the communication from the MANET nodes towards the Internet side is through the CH.
Therefore the CHs acts like a Mobile IP proxy for the MANET mobile nodes and the visiting mobile
nodes.

3. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN
0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 3, April (2013), © IAEME
228
Figure 2.1. Existing Architecture
3. INTEGRATED PROTOCOL DESIGN
3.1. Proposed Architecture
In the envisioned integrated MANET network, mobiles are distinguished as either mobile
nodes or mobile gateway. Based on their geographical locations, directions of movement, and other
metrics, mobile nodes are grouped into different clusters. Clustering enhances effective broadcasting
and relaying of messages, such as GWADV messages and reduces the overhead associated with
signaling, as links among mobile nodes within the same cluster tend to be more stable. The main
challenge in clustering lies in the dynamic topology changes in MANET and hence, an efficient
clustering should be based on adequate metrics and should take into account the frequent topology
changes.
A modified Hybrid Gateway Discovery mechanism which dynamically adjusts value of TTL
and periodicity of TTL depending on the MANET characteristics in order to achieve a good trade-off
between performance and network overhead is called an Adaptive Gateway Discovery Mechanism.
Several novel strategies have been proposed recently which implement adaptive gateway discovery
mechanisms in different ways. The purpose of this survey is to review these adaptive gateway
discovery mechanisms.
Figure3.1: Dynamic cluster based adaptive gateway Discovery mechanism in IIM

4. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN
0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 3, April (2013), © IAEME
229
4. IMPLEMENTATION ISSUES
4.1 Network Simulator (NS)
Network Simulator (NS) is an object-oriented, discrete event simulator for networking
research. NS provides substantial support for simulation of TCP, routing and multicast protocols over
wired and wireless networks. The simulator is a result of an on-going effort of research and
development. Even though there is a considerable confidence in NS, it is not a polished and finished
product yet and bugs are being discovered and corrected continuously. NS is written in C++, with an
OTcl1
interpreter as a command and configuration interface. The C++ part, which is fast to run but
slower to change, is used for detailed protocol implementation. The OTcl part, on the other hand,
which runs much slower but can be changed very quickly, is used for simulation configuration. One
of the advantages of this split-language programming approach is that it allows for fast generation of
large scenarios. To simply use the simulator, it is sufficient to know OTcl. On the other hand, one
disadvantage is that modifying and extending the simulator requires programming and debugging in
both languages simultaneously.
4.2 Network Animator (NAM)
Network Animator (NAM) is an animation tool for viewing network simulation traces and real world
packet traces [17]. It supports topology layout, packet level animation and various data inspection
tools.Before starting to use NAM, a trace file need to be created. This trace file is usually generated
by NS. It contains topology information, e.g. nodes and links, as well as packet traces.
5. SIMULATION RESULTS
5.1. Simulation Environment
The effectiveness of the proposed adaptive gateway discovery approach is demonstrated by
carrying out extensive experiments in NS-2 simulator. Different sizes of ad hoc networks are tested.
The size of ad hoc network with 20 mobile nodes are tested. These varying size MANETs were
integrated with Internet using Mobile Gateways as well as Fixed Gateways. Different mobility models
for MANET nodes have been utilized to explore the performance of proposed protocol. We also took
into account the different placements of mobile nodes in topographic area. In that, the density of
mobile nodes near the gateway nodes is varied. Few mobility models used number of mobile nodes
that are within the close proximity of gateway nodes, and apparently this produced good results as
indicated below. Whereas placement of nodes far away from the gateway nodes caused significant
increase in the number of packets dropped.
The topology used is a rectangular area 800 meter length and 500 meter width. The wired
nodes have the bandwidth capacity of 10Mbps. Wireless Transmission range of mobile node is set to
250m. Simulations for all scenarios were carried out for the duration of 900 seconds. Out of the
mobile nodes used in simulation 5 were designated as either Constant Bit Rate of File Transfer
Protocol based traffic generating agents.
5.2. Simulation Results
Packet Delivery Fraction (PDF): The ratio of the number of packets originated by the
“application layer” to the number of packets received by the destination is PDF. Figure 5.1 illustrates
the PDF as a function of changing mobile node speeds. The speeds of mobile nodes used ranged from
5, 10, 15, 20, and 25. Since increase in speed causes the route maintenance overhead, there is
degradation in PDF as the speed increases. Therefore it is mandatory for mobile nodes to move with a
moderate speed as high speed would cause route breakages. And this would have an impact on the
control overhead too.

5. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN
0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 3, April (2013), © IAEME
230
Figure 5.1 Packet Delivery Fraction Vs Node Speed
End-End Delay: As it can be observed from Figure 5.2, the end-end delay in the protocol increases as
the speed of the mobile node increases.
Figure 5.2 End-End Delay Vs Node Speed
Routing Overhead: As it is evident from the figure 5.3, the routing overhead of the proposed
protocol is proportional to the speed of the mobile nodes. If mobile nodes move with less speed, the
routes tend to be stable and do not cause frequent route breakage induced route maintenance. On the
other hand if nodes are moving with high speeds, this causes the topology to be very volatile and
routes are stable enough, and hence a large number of control packets need to be exchanged. However
if the nodes speeds are moderate, then our protocol registers minimal overhead as the routes are
stable. Moreover, because of the provision for multiple routes to exists between source node and
gateway node, a large many number of broadcasts of route requests and advertisements are avoided.
However, the size of the route request and route reply packets have slightly increased due to addition
of few fields to accommodate trust and residual route load capacities in them.

6. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN
0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 3, April (2013), © IAEME
231
Figure 5.3 Routing Overhead vs. Node Speed
5.3. Summary
In this chapter we presented the simulation related issues and performance analysis of the
proposed protocol. The implementation of protocol is carried out in different architectures of
integration such as three tier and hybrid. These simulations have been carried out varying different
parameters such as number of nodes, speeds of the mobile nodes etc. This is consistent with the
design and functionality of dynamic cluster based mobile gateways, which are moving around the
border of access points coverage area in order to provide MANET nodes with Internet connectivity.
6. CONCLUSION
The rationale behind using dynamic cluster based mobile gateways is to increase the
reliability of the Internet access and enhance the performance of the hybrid, wireless network in terms
of high data delivery ratio and low average delay. The results of the simulations show the impact of
the number of MANET nodes connected to the Internet, and the mobility of dynamic cluster based
mobile gateways.
Although many solutions have been suggested to the integration problem, we believe that
other issues have not yet been addressed. One research avenue is to design an efficient discovery
protocol of fixed and Dynamic mobile gateways by using adaptive approach. This discovery protocol
should be application oriented in order to find and locate these fixed and mobile servers. One of the
advantages of this discovery protocol is to minimize the overhead that would be introduced if existing
proactive or reactive routing protocol were used. Another research avenue we are interested in is the
investigation of different selection schemes of fixed and Dynamic mobile gateways in order to assure
a desirable QOS of wireless Internet access to mobile nodes.
7. REFERENCES
[1] A Three-Tier Architecture for Integrating Mobile Ad Hoc Network and the Internet using a
Hierarchical Integrated Routing Protocol-rafi u zaman(2008)
[2]Maximal Source Coverage Adaptive Gateway Discovery for Hybrid Ad Hoc Networks – Pedro H.
Ruiz et al (2007)
[3]Using Fuzzy Logic in Hybrid Multi-hop Wireless Networks – A.J. Yuste et al (2010)
[4]Adaptive Distributed Gateway Discovery in Hybrid Wireless Networks – Usman Javaid et al
(2008)
[5] Adaptive Gateway Management in Heterogeneous Wireless Networks – R. Manoharan et al
(2011)
[6] Study on the Need for Adaptive Gateway Discovery in MANETs – A. Trivino (2009)

7. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN
0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 3, April (2013), © IAEME
232
[7] QoS aware Internet Access Schemes for Mobile Ad Hoc Networks – Park et al (2007)
[8] Multiple End-to-End QoS Metrics Gateway Selection Scheme in Mobile Ad Hoc Networks –
Safdar H. Bouk et al (2009)
[9] An Effective Gateway Discovery Mechanism in an Integrated Internet-MANET (IIM)-rafi u
zaman(2010)
[10] Alex Ali Hamidian ”A Study of Internet Connectivity for Mobile Ad Hoc Networks in NS 2”
Department of Communication System s Lund Institute of Technology, Lund University Box 118 S-
221 00 Lund Sweden, January 2003. 5.J. D. Solomon, “Mobile IP: The Internet Unplugged,”
Prentice-Hall PTR, 1998 6. A Study of Internet Connectivity for Mobile Ad Hoc Networks in NS 2
[11] Ing. Bernardo Leal "Modeling and Perform ance Evaluation of MANET Handover" Advisor:
Dott. Ing. Luigi ATZORI Curriculum: ING-INF/03 - Ph.D. in Electronic and Computer Engineering,
March 2012.
[12] Rakesh Kumar, Anil K. Sarje and Manoj Misra "Review Strategies and Analysis of Mobile Ad
Hoc Network-Internet Integration Solutions", IJCSI International Journal of Computer Science
Issues, Vol. 7, Issue 4, No 6, July 2010.
[13] Johnson D.B.; Maltz D.A.; Hu Y.; Jetcheva J.G. The Dynamic Source Routing Protocol for
Mobile Ad Hoc Networks (DSR), IETF Internet Draft, Feb 2002. Work in progress.
[14] Antonios Argyriou and Vijay K. Madisetti. Performance evaluation and optimization of sctp in
wireless ad-hoc networks. In LCN, pages 317–318, 2003.
[15] Perkins C.; Belding-Royer E.M.; Das S. Ad hoc On-Demand Distance Vector (AODV)
Routing, IETF Internet Draft, Jan 2002.Work in progress.
[16] Lei H, Perkins C. Ad hoc networking with mobile IP. Proceedings of the Second European
Personal Mobile Communications Conference (EPMCC’1997), Bonn, Germany, 30 September–2
October 1997.
[17] McCanne S.; Floyd S. ns Network Simulator. http://www.isi.edu/nsnam/ns/. Fall K; Varadhan
K., and the VINT project. The ns manual.
[18] Belding-Royer E.M., Sun Y.; Perkins C. Global Connectivity for IPv4 Mobile Ad soc
Networks, IETF Internet Draft, Nov. 2001 .Work in progress.
[19] Bernard M. Gateway Detection and Selection for Wireless Multihop Internet Access,Master's
thesis, (Olching, Germany), 2002.
[20] Clausen T.; Jacquet P.; Laouiti A.; Minet P.; Muhlethaler P.; Qayyum A.; Viennot L Optimized
Link State Routing Protocol, IETF Internet Draft, July 2002. Work a progress.Comer D E.
Internetworking With TCP/IP Volume I: Principles, Protocols, and -Lrchitectures, fourth edition,
2000.
[21] Prerna Malhotra, “A Survey of Energy Efficient AODV Routing Algorithms in Manet”,
International journal of Computer Engineering & Technology (IJCET), Volume 4, Issue 2,
2013, pp. 213 - 220, ISSN Print: 0976 – 6367, ISSN Online: 0976 – 6375.
[22] Venkatesh Kumar .P, Vallikannu A.L and Kavitha B.C, “Effective Broadcasting
in Mobile Ad Hoc Networks Using Grid Based Mechanism”, International journal of
Computer Engineering & Technology (IJCET), Volume 2, Issue 1, 2011, pp. 39 - 46,
ISSN Print: 0976 – 6367, ISSN Online: 0976 – 6375.