Mobile Adhoc Wireless Networks: An overview on its

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Indian Journal of Information Science and Applications (IJISA)

Volume 2, Number 1­ January­June 2012

- 43 -
Mobile Adhoc Wireless Networks: An overview on its
Routing Protocols and Applications

Ranjit Panigrahi

Department of Computer Science & Engineering
Sikkim Manipal Institute of Technology, Majhitar, Sikkim, India
Email- ranjit@smitcse.in, ranjit.panigrahi@gmail.com



Abstract An adhoc wireless network is a collection of nodes
which are connected wirelessly with each other in order to form a
network without using any centralized infrastructures. The
architecture of adhoc wireless network can be used for a variety
of areas such as emergency rescue operations, military activities,
air traffic control, disaster management etc. As the architecture
itself is wireless and most of the nodes in the systems are mobile
in nature, therefore the protocols used for the wired network is
no more feasible in a wireless medium. That is why an adhoc
wireless network requires specialized protocols that can handle
common network issues such as traffic, bandwidth constraint,
congestion, mobility and hidden and exposed node problems. The
current paper mainly focuses on the characteristics of an efficient
routing protocol, common protocols used for routing, and the
application areas of adhoc wireless network.

Keywords- Adhoc Wireless Network (AWN), Quality of Service
(QoS), Local Area Network (LAN), Routing Information Protocol
(RIP), Interior Gateway Routing Protocol (IGRP), Destination-
Sequenced Distance-Vector Routing (DSDV), Open Shortest Path
First (OSPF), Border Gateway Protocol (BGP), Exterior Gateway
Protocol (EGP), A mobile ad-hoc network(MANET), Wireless mesh
network (WMN).

1. I
NTRODUCTION
:-

In current world a computer network can be classified as
Infrastructure based network and Infrastructure less network. In
general the infrastructure less network is called adhoc
network[7]. In the former type of network the nodes are
connected with each other physically through cabl es where as
in the later case the nodes are connected wirelessly through
radio signals. An adhoc network as the name suggests is a
temporary network which is formed when wireless nodes are
come across the transmission range of each other. As there is
no centralized device or nodes[2] to coordinate the entire
system, therefore each node in this type of network acts both as
router as well as a host. All the nodes in an adhoc wireless
network are mobile in nature, i.e. the nodes always change their
position. Therefore when a node leaves the transmit ting zone of
other nodes then the node is said to be separated from the
network and when the same node entered into the transmitting
zone of any other node then the node forms a network with the
nodes in the same zone. Due to this dynamic nature of this type
of network the protocols used for packet transmission in the
network layer need to be robust and dynamic for handling such
a scenario. In this paper common protocols used for routing are
mentioned along with their characteristics and the application
areas of adhoc wireless network. The rest of the paper is as
follows: Section 2 describes the common application areas of
adhoc wireless netwotk and section 3 addresses the
characteristics of a good routing protocol, followed by section
4 which describes the common routing protocols used in adhoc
wireless network by the conclusion in section 5.
2.

APPLICATION

OF

AWN:-

The field of wireless networking [16] is nothing but the
integration of personal computing, cellular technology, and the
Internet. The increasing use of adhoc wireless network
enhances the information access from "anytime anywhere" into
"all the time, everywhere."

Ad-hoc networks are best suited for the situations where an
infrastructure is unavailable or to deploy.One of many possible
uses of mobile ad-hoc networks is Military applications,
Collaborative and distributed computing, emergency rescue
operations, crisis management and in wireless mess networks.

There is a broad area of application of AWN in military
applications. One of such application is the tactical planning
among a group of soldiers in the war field. In such a case
specifically in the enemy terrain the AWN is t he best and
secure way of communication medium among soldiers.
Another application area of AWN in the war field is the target
specific attack. Using GPS along with AWN high speed short
distance missiles can be lunched accurately.

Indian Journal of Information Science and Applications (IJISA)

Volume 2, Number 1­ January­June 2012

- 44 -
When a business meeting is schedule outside the office then
the need for collaborative computing becomes the interest area.
In such a case the AWN can be used to address such issue.
Using an AWN an instant infrastructure can be created to
manage such meetings.

A mobile ad-hoc network can also be used to provide crisis
management, such as in disaster recovery in a land slide prone
area, where the restoration of communication process is vital.
By using a mobile ad-hoc network, an infrastructure could be
set up in hours. Similarly a search and rescue operation can be
carried out through the AWN.

The AWN can be implemented along with the mess
architecture. Wireless mesh network (WMN) [8][9]is made up
of radio nodes arranged in mesh topology. The mess
architecture of wireless mess network provides many
alternative paths for data transfer where the bandwidth is very
less. So in case of a path failure an alternate path can be easily
identified for transmission.

An adhoc wireless network can be implemented as
Wireless Sensor Network[6] where a set of sensors are
deployed along with the AWN. Due to deployment of sensors
the user can control the network and its surroundings
wirelessly. The applications include remote diagnostics in the
healthcare sectors where a doctor can diagnose his patients
remotely from his own premises.
3.CHARACTERISTICS

OF

A

GOOD

ROUTING

PROTOCOL
Adhoc wireless networks are generally characterize by the
fact that it is mobile in nature. The mobility issue of an adhoc
wireless network demands a routing protocol to be more robust
and sensitive to the dynamic nature of the network. Therefore a
good routing protocol must have the following characteristics.
� Routing Scalability
� Scalability defines how large a network can become
based on the routing protocol that is systematically
distributed. The larger the network is, the more
scalable the routing protocol needs to be for better
performance.
� Decentralized Routing
� A good routing protocol need to be decentralized in
nature. It is because a decentralize routing is more
efficient and fault tolerant than that of a centralized
routing.
� Mobility of nodes
� The major issue of an adhoc wireless network is the
mobility of nodes. Therefore a good routing protocol in
MANET must be flexible enough to handle such issue.
� Route Computation
� The prime responsibility of a routing protocol is the
route computation. A routing protocol must be capable
of identifying the shortest/best path during route
discovery/maintenance.
� Collision of routing packets
� A good routing protocol in MANET must encourage
less packet collision during route
discovery/transmission and route maintenance process.
� Quick Convergence
� Another characteristic is the time taken by routers to
converge i.e. how faster the routers in the network
topology shares the routing information and reach a
state of consistent knowledge. We can say Protocol is
directly proportional to converge, the faster the
convergence, it more preferable the protocol.
� Optimum resource utilization
� MANET has very limited resources such as battery
power, bandwidth, memory etc. Therefore a good
routing protocol must use these scarce resources
efficiently.
4. COMMON

ROUTING

PROTOCOLS

USED

IN

MANET
Network layer of the OSI Reference Model carries
information between devices which are not attached in the
same LAN. Routers or network layer Switches are particular
device at the network and offer the routing services in an inter-
network. The routing protocols are generally responsible for
management of these devices.

Basically Routing protocols which are used in network
layer are divided into two general groups: interior and exterior
protocols [1][3]

The routing protocols that run within an autonomous
system are called interior gateway routing protocol. Similarly
Routing protocols that route between autonomous systems or
routing domains are referred to as Exterior Gateway Protocols.
The higher-level areas are added to hierarchy to the
internetwork architecture called autonomous systems in the IP
world and routing domains in the ISO world. An autonomous
system was once defined as a group of routers under a common
administrative domain running a common routing protocol.

4.1. Interior Gateway Protocols
Networks within an autonomous system communicate with
each other using an Interior Gateway Protocol (IGP). IGP's fall
into two categories:
Indian Journal of Information Science and Applications (IJISA)

Volume 2, Number 1­ January­June 2012

- 45 -

4.1.1. Distance Vector Protocols:
The distance vector routing protocol[1][12] states the
principle  a node sends its updates to neighboring modes and
depends entirely on them to pass the update information along
to their neighbors.

In distance vector protocols, each router over the
internetwork sends the information about destination to the
neighboring routers. In this process each router transmits two
pieces of information first, the router convey, how far the
destination is and secondly, in which direction (vector) the
destination resides. When the router receives the information
from the neighbors, it maintains a table of destination addresses
and distances associated with it, and from this table it select the
shortest route to the destination. The best example for this is
the routing information protocol (RIP), Destination Sequenced
Distance Vector Routing (DSDV) Protocol and Interior
Gateway Routing Protocol (IGRP).

Destination-Sequenced Distance-Vector Routing (DSDV)
[4] is an adoption of a conventional routing protocol to ad hoc
networks. It is based on the Routing Information Protocol
(RIP) [5], used in parts of the Internet. Consequently, DSDV
only makes use of bidirectional links. DSDV is one of the
earlier ad hoc routing protocols developed. In DSDV, packets
are routed between nodes of an ad hoc network using routing
tables stored at each node. DSDV routing table is used and
each routing table, at each node, contains a list of the addresses
of every other node in t he network. Along with each nodes
address, the table contains the address of the next hop for a
packet to take in order to reach the node.

4.1.2. Link State Protocols
In link state protocols [1] [14][15], a router doesnt provide
the information about the destination instead it provides the
information about the topology of the network. This usually
consist of the network segments and links that are attached to
that particular router along with the state of the link i.e.,
whether the link is in active state or the inactive state. This
information is flooded throughout the network and then every
router in the network then builds its own picture of the current
state of all the links in the network. The common Link state
protocols is Open Shortest Path First (OSPF).

4.2. Exterior Gateway Protocols
Exterior Gateway Protocol is used to get from outside
network i.e. on internet. Exterior Gateway Protocols handle
routing outside an Autonomous System and get from our
network, through our Internet provider's network and onto any
other network. The example of exterior gateway protocol is
Border Gateway Protocol (BGP)

The basic routing protocols used in MANETs can be
classified depending on routing strategy [10, 11] and network
structure [14, 15]. As per the routing strategy t he common
routing protocols can be categorized as Proactive (Table
driven) and Reactive (Demand driven).

4.3. Table-driven routing protocol (Proactive)
A table driven routing protocol [14, 15] maintains a set of
routing tables. It tries to maintain, up-to-date routing
information from each node to every other node in the network
in terms of these tables. As soon as a network change occurs
(i.e. a link is up or goes down or a node changes its place) each
node on the network updates their routing table with the fresh
information. Some of existing table-driven protocols are
The Wireless Routing Protocol
Destination-Sequenced Distance-Vector Routing
Cluster head Gateway Switch Routing

4.4. Demand-driven routing protocol (Reactive)
These protocols are also called source initiate protocols
[13], it is because, these protocols never maintains any routing
table rather the path from source to destination is initiated by
the source node only and is supported by the intermediate
nodes during route discovery. Normally, the route discovery
occurs by flooding the route request packets throughout the
network. Some examples this routing protocol is:
Ad Hoc On-Demand Distance Vector Routing
Dynamic Source Routing
Associativity-Based Routing
Signal Stability Routing

Each of these routing strategies have their own advantages
and disadvantages to the network however the table-driven and
demand driven protocols are differ from each other based on
communication complexity and Time complexit y, multicast
capability, frequency of update transmission, route
reconfiguration methodology, Quality of service support etc.

5.

CONCLUSION
In this paper we provide the description of adhoc network,
how it works, what are the routing protocols how they
communicates, characteristics of routing protocols, different
routing protocols used in layer three, applications of adhoc
network considering todays scenario.

The area of ad hoc networks is rapidly growing and changing,
many unlimited applications are developing and while there are
Indian Journal of Information Science and Applications (IJISA)

Volume 2, Number 1­ January­June 2012

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still many challenges that need to be come, it is likely such
networks which will have widespread use in coming future.
And it will be the first choice for the researchers to work on.

6.

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