Manet

1. MANET
(Mobile Ad-Hoc Network)
and
Routing Techniques and Protocols
How To Drop Unwanted Weight Super Fast! (MGID)
AUTHORS: Saptarshi Bhadra
Soumyadeep Ghosh
IntroductionRecent trends in wireless communications have expanded possible applications from simple voice
services in early cellular networks (firstand second generation,1Gand 2G) to new integrated data applications.4G
technologyis now new promising application ofmobile technology.It is basicallynew generation ofmobile devices.
Fig 1. Mobile ad-hoc network
In a MANET, the router connectivity may change frequently, leading to the multi-hop communication paradigm that
can allow communication withoutthe use of BS/AP, and provide alternative connections inside hotspotcells.A dual-
mode MS can operate in both the infrastructure (communicating directlyto a BS or AP) and MANET modes using the
WLAN interface. A MANET is a type of ad hoc network that can change locations and configure itselfon the fly. All
nodes in this network are mobile and they use wireless connections to communicate with various networks
Routing is one of the core problems ofnetworking for delivering data from one node to the other. Wireless ad-hoc
networks are also called Mobile ad-hoc multihop networks withoutpredetermined topologyor central control. This is
because MANETs can be characterized as having a dynamic,multihop,potentiallyrapid changing topology. The aim
of such networks is to provide communication capabilities to areas with limited or no existing communication

2. infrastructures.A MANET is usuallyformed by mobile nodes using wireless communications.It uses a peer-to-peer
multihop routing instead ofa static network infrastructure to provide network connectivity.
Some salientcharacteristics ofMANETs are:-
1. Dynamic topologies, 2.)Bandwidth constrained,variable capacitylinks,
3.) Energy constrained operation,and 4.) Limited physical security.
MANET has been a popular topic of research in recentyears with the advent and growth of wireless technology.Two
popular types of MANET are (i) VANET (Vehicular Ad-hoc network) and (ii) iMANET (Internet based ad-hoc
networks).
Several routing protocols have been suggested and used for MANET. Dynamic Source Routing (DSR), Ad Hoc On -
Demand DistanceVector Routing (AODV) and Destination Sequenced Distance-Vector (DSDV) have been
implemented.
There are several ways to study MANETs. One solution is the use of simulation tools like OPNET,NetSim and NS2.
Ns is a discrete event simulator targeted atnetworking research.Ns provides substantial supportfor simulation of
TCP, routing,and multicastprotocols over wired and wireless (local and satellite) networks.The core of ns-2 is also
written in C++, but the C++ simulation objects are linked to shadow objects in OTcl and variables can be linked
between both language realms.Simulation scripts are written in the OTcl language,an extension of the Tcl scripting
language.This structure permits simulations to be written and modified in an interpreted environmentwithouthaving
to resortto recompiling the simulator each time a structural change is made.
The general process ofcreating a simulation can be divided into several steps:-
1. Topology definition:- To ease the creation of basic facilities and define their interrelationships,ns -3 has a system of
containers and helpers thatfacilitates this process.
2. Model usage:- Models are added to simulation (for example,UDP,IPv4, point-to-pointdevices and links,
applications);mostofthe time this is done using helpers.
3. Node and link configuration:- Models settheir default values (for example,the size of packets sentby an application
or MTU of a point-to-pointlink);mostof the time this is done using the attribute system.
4. Execution:- Simulation facilities generate events,data requested by the user is logged.
5. Performance analysis:- After the simulation is finished and data is available as a time-stamped eventtrace. This
data can then be statisticallyanalysed with tools like R to draw conclusions.
6. Graphical Visualization:- Raw or processed data collected in a simulation can be graphed using tools
like Gnuplot, matplotlib or Xgraph. Xgraph is the plotting tool bundled with manyof the installation packages.
Comparative Study

3. Routing protocols for MANETs can be broadly classified[3]into three main categories:-
1.) Proactive routing protocols:- Every node in the network has one or more routes to any possible destination in its
routing table at any given time.
2.) Reactive routing protocols:-Every node in the network obtains a route to a destination on a demand fashion.
Reactive protocols do not maintain up-to-date routes to any destination in the network and do not generallyexchange
any periodic control messages.
3.) Hybrid routing protocols:-Every node acts reactively in the region close to its proximity and proactively outside of
that region,or zone.
Fig 1. Classification of routing protocols in mobile ad-hoc network.
Some Routing Algorithms in MANETS [7] :-
1. Ad Hoc On-Demand Distance Vector Routing (AODV) – uses traditional routing tables,one entry per
destination.This is in contrastto DSR, which can maintain multiple route cache entries for each destination.
Without source routing,AODV relies on routing table entries to propagate an RREP back to the source and,
subsequently,to route data packets to the destination.AODV uses sequence numbers maintained ateach
destination to determine freshness ofrouting information and to prevent routing loops.All routing packets carry
these sequence numbers.
2. Destination-Sequenced Distance Vector (DSDV)- The firstMANET algorithm thatwe implemented as partof this
work is called the Destination-Sequenced Distance Vector (DSDV) routing algorithm.It is a proactive routing
algorithm.The DSDV algorithm is a Distance Vector (DV) based routing algorithm designed for use in MANETs,
which are defined as the cooperative engagementofa collection ofMobile Hosts withoutthe required intervention
of any centralised Access Point(AP).
It operates each node as a specialised router which periodicallyadvertises its knowledge ofthe network with the
other nodes in the network. It makes modifications to the basic Bellman-Ford routing algorithms,therebydoing away
with the count-to-infinityproblem.The algorithm is designed for portable computing devices such as laptops who

4. have energy and processing capabilities far beyond that of a typical WSN node.
1. Dynamic Source Routing (DSR)- It is a routing protocol for wireless mesh networks.It is similar to AODV in that it
forms a route on-demand when a transmitting computer requests one.However,it uses source routing instead of
relying on the routing table at each intermediate device.This protocol is truly based on source routing wherebyall
the routing information is maintained (continuallyupdated) atmobile nodes.It has only two major phases,which are
Route Discovery and Route Maintenance. Route Reply would only be generated ifthe message has reached the
intended destination node (route record which is initiallycontained in Route Requestwould be inserted into the
Route Reply). Therefore,it is an on-demand protocol designed to restrictthe bandwidth consumed bycontrol
packets in ad hoc wireless networks byeliminating the periodic table-update messages required in the table-driven
approach.The major difference between this and the other on-demand routing protocols is thatit is beacon-less
and hence does not require periodic hello packet(beacon) transmissions,which are used by a node to inform its
neighbors ofits presence.The basic approach ofthis protocol (and all other on-demand routing protocols) during
the route construction phase is to establish a route by flooding RouteRequestpackets in the network.The
destination node,on receiving a RouteRequestpacket,responds bysending a RouteReplypacketback to the
source,which carries the route traversed by the RouteRequestpacketreceived.
Related Work
Survey of applications of MANET [5]- We shall now get an overview of different types of MANET and their uses.
1. Pure general purpose MANET
The mostlydiscussed application scenario for pure general-purpose MANET is Battlefield or disaster-recovery
networks.However, these kinds ofnetworks have not yet achieved the envisaged impactin terms ofreal world
implementation and industrial deployment.
1. Mesh networks
Mesh networks are builtupon a mix of fixed and mobile nodes interconnected via wireless links to form a multihop ad
hoc network.Unlike pure MANETs, a mesh network introduces a hierarchyin the network architecture by adding
dedicated nodes (called mesh routers) thatcommunicate wirelesslyto constructa wireless backbone.An example is
MIT Roofnetproviding the city of Boston,with broadband access with an 802.11b-based wireless network backbone
infrastructure.
1. Opportunistic Networking (Delay Tolerant Networking)
(i)PocketSwitched Networks in the Haggle Project
It targets solutions for communication in autonomic/opportunistic networks.In this framework,researchers are
studying the properties ofPocket Switched Networks (PSNs),i.e., opportunistic networks thatcan exploit any

5. possible encountered device (e.g., cell phones and PDAs that users carry in their pockets) to forward messages.
(ii)Wildlife monitoring
Wildlife monitoring is an interesting application field for opportunistic networks.Itfocuses on tracking wild species to
deeply investigate their behavior and understand the interactions and influences on each other,as well as their
reaction to the ecosystem changes caused byhuman activities.
1. Vehicular ad hoc networks
VANETs use ad hoc communications for performing efficientdriver assistance and car safety. The communications
include data from the roadside and from other cars. VANET research aims to supplydrivers with information
regarding obstacles on the road and emergencyevents,mainlydue to line-of-sightlimitations and large processing
delays.VANET can be used to communicate premonitions,notification ofemergencies,and warnings abouttraffic
conditions.
1. Wireless sensor networks (WSN)
WSN benefit from the advances in computing technology,which led to the production ofsmall,wireless,battery
powered,smartsensor nodes.These nodes are active devices with computing and communication capabilities that
not only sample real world phenomena butalso can filter,share,combine,and operate on the data they sense.
Conclusion
This paper discusses the various aspects ofmobile ad-hoc networking,the differentrouting protocols used for
wireless sensor networks and the NS-2 network simulator.Also,we compared DSDVand AODV routing protocols
for ad hoc networks using ns-2 simulations.DSDVuses the proactive table-driven routing strategy while AODV uses
the reactive On-demand routing strategy. AODV performs better under high mobilitysimulations than DSDV. High
mobilityresults in frequentlink failures and the overhead involved in updating all the nodes with the new routing
information as in DSDV is much more than that involved AODV, where the routes are created as and when required.
AODV uses on -demand route discovery, but with different routing mechanics. AODV uses routing tables,one route
per destination,and destination sequence numbers,a mechanism to preventloops and to determine freshness of
routes.There are still many challenges facing wireless ad hoc networks.However because ofthese advantages,
wireless ad hoc networks are becoming more and more prevalentin the world.
References
[1] www.wikipedia.com
[2]www.ucmss.com
[3] Routing techniques for Mobile Ad Hoc Networks Classification and Qualitative/Quantitative Analysis, by Mr.
Ankur Khetrapal,Delhi University.
[4] Characterisation and Applications ofMANET,Routing Algorithms in Wireless Sensor Networks ,bySiddhu Warrier.

6. [5] A Survey on the Applications of MANET, by Jiazi YI,Polytech’Nantes .
[6] An Overview of Mobile Ad Hoc Networks:Applications and Challenges,by Jeroen Hoebeke,Ingrid Moerman,Bart
Dhoedtand Piet Demeester
[7] Performance Evaluation ofAd Hoc Routing Protocols Using NS2 Simulation, by Samyak Shah, Amit Khandre,
Mahesh Shirole and Girish Bhole
[8] Routing Protocols in Mobile Ad-hoc Networks,by Krishna Gorantala.
[9] An Efficient Scheme for MANET Domain Formation (ESMDF) by Adwan AbdelFattah.
[10] An Improved Approach for Working outside the MANET by Extending MANET Routing Protocol,by Rashween
Kaur Saluja.