26-06-2012, 04:23 PM
PERFORMANCE ANALYSIS OF CLUSTER BASED ROUTING PROTOCOL IN MANETs
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Introduction
Wireless ad hoc network is a collection of mobile devices forming a network without
any supporting infrastructure or prior organization. Nodes in the network should be
able to sense and discover with nearby nodes .Due to the limited transmission range
of wireless network interfaces, multiple network “hops” may be needed for one node
to exchange data with another across the network. There are number of characteristics
in wireless ad-hoc networks, such as the dynamic network topology, limited
bandwidth and energy constraint in the network. Mobile ad hoc network is useful for
different purpose e.g. military operation to provide communication between squads,
emergency case in out-of-the-way places, medical control etc.
Routing protocol plays very important part in implementation of mobile ad hoc
networks. Due to the nature of mobile ad hoc networks it is non-trivial problem to
find path from source to the destination and perform the communication between
nodes for a long period of time.
Background
Computer networks are originally developed to operate by connecting computers
together with wires and transmitting data over these wires. Network sizes and
occurrences increased creating a requirement for inter network communication. This
led to development of the internet and suite of protocols. The use of the internet and
its applications became ubiquitous. A need for providing network access to entities
while not physically attached to the wired network arose. To enable this wireless
networking was developed, providing devices with methods to connect to a wired
network using radio wave technologies through wireless access points.
Simultaneously telephone networks were going a similar transformation. Cellular
network technologies[10] were developed to allow mobile phones to connect via base
stations and communicate in a circuit switched environment. In general , mobile
wireless networks can be classified into two types:
Infrastructure less mobile network (Ad-hoc networks)
Wireless nodes can dynamically form a network to exchange information without
using any pre-existing fixed network infrastructure(Figure2.2) This is a very
important part of communication technology that supports truly pervasive computing,
because in many contexts information exchange between mobile units cannot rely on
any fixed network infrastructure, but on rapid configuration of a wireless connections
on-the-fly.
Mobile Ad hoc networks
The area of mobile ad-hoc networking deals with devices equipped to perform
wireless communication and networking, but without any existing infrastructure such
as base stations or access points. Wireless devices form a network as they become
aware of each others presence. They communicate directly with devices inside their
radio range in a peer-to-peer nature. If they wish to communicate with a device
outside their range, they can use an intermediate device or devices within their radio
range to relay or forward communications to the device outside their range.
Multihop routing.
Basic types of ad hoc routing algorithms can be single-hop and multihop, based on
different link layer attributes and routing protocols. Single-hop MANET is simpler
than multihop in terms of structure and implementation, with the cost of lesser
functionality and applicability. When delivering data packets from a source to its
destination out of the direct wireless transmission range, the packets should be
forwarded via one or more
intermediate nodes
Dynamic network topology.
Since the nodes are mobile, the network topology may change rapidly and
unpredictably and the connectivity among the terminals may vary with
time. MANET should adapt to the traffic and propagation conditions as
well as the mobility patterns of the mobile network nodes. The mobile
nodes in the network dynamically establish routing among themselves as
they move about, forming their own network on the fly. Moreover, a user
in the MANET may not only operate within the ad hoc network, but may
require access to a public fixed network (e.g. Internet).