21-05-2013, 03:37 PM
Mobile Ad-Hoc Networks Extensions to Zone Routing Protocol
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Abstract
Secure communication, an important aspect of any networking
environment, is an especiallysignicant challenge in ad hoc
networks. The MANET paradism seeks to enable communication
across networks whose topology and membership can change
frequently. Its distinctive feature is that network nodes need to
collaborate with their peers in supporting the network functionality.
In such an environment, malicious or selfish nodes can disrupt
or even deny the communications of potentially any node within
the ad hoc networking domain. This is so, exactly because every
node in the network is not only entitled, but is in fact required,
to assist in the network establishment, the network maintenance,
and the network operation. Ad-Hoc Networks consist of peer-topeer
communicating nodes that are highly mobile. As such, an
ad- hoc network lacks infrastructure and topology of the network
changes dynamically. The task of routing data from a source to
a destination in such a network is challenging. Several routing
protocols have been proposed for wireless ad-hoc networks.
Most of these protocols, however, presuppose the presence of
bi-directional links between the nodes in the network.
Introduction
What is Ad-Hoc Networks: A wireless network that transmits from
computer to computer. Instead of using a central base station
(access point) to which all computers must communicate. This
peer-to-peer mode of operation can greatly extend the distance
of the wireless network. To gain access to the Internet, one of the
computers can be connected via wire or wireless to an ISP routing
from one node to another on such a “mesh” network typically
uses an on-demand routing protocol, such as PROACTIVE and
REACTIVE, which generates routing Information only when a
station initiates a transmission. In the past, much research effort
has been devoted on Service Discovery in static networks, like
the Internet The emergence of wireless communications and small
mobile computing devices has created the need for developing
service discovery protocols and architectures targeted to mobile
environments. Especially, the proliferation of Mobile Ad Hoc
Networks (MANETs) has introduced new requirements to service
discovery due to the inherent characteristics of these networks. It is
a collection of mobile computing devices equipped with wireless
network interfaces which can connect together dynamically to
create a multi-hop wireless network, without the requirement for
any pre-existing infrastructure.
Zone Routing Protocol
The Zone Routing Protocol (ZRP) was introduced in 1997 by
Haas and Pearlman. It is either a proactive or reactive protocol.
It is a hybrid routing protocol. It combines the advantages
from proactive (for example AODV) and reactive routing
(OLSR). It takes the advantage of pro-active discovery within
a node’s local neighborhood (Interzone Routing Protocol
(IARP)), and using a reactive protocol for communication
between these neighborhoods (Interzone Routing Protocol
(IERP)). The Broadcast Resolution Protocol (BRP) is responsible
for the forwarding of a route request. ZRP divides its network
in different zones. That’s the nodes local neighborhood. Each
node may be within multiple overlapping zones, and each zone
may be of a different size. The size of a zone is not determined
by geographical measurement. It is given by a radius of length,
where the number of hops is the perimeter of the zone. Each node
has its own zone.
Intra Zone Routing Protocol (IARP)
The IARP is responsible for maintaining information about some
nearby links and nodes. Every node transmits information about
its in bound neighbors to nodes within a restricted neighborhood
defined by the parameter called the Zone Radius. This information
is used by each node to compute its outbound tree, which
is the shortest path tree rooted at node to nodes from which the
previously mentioned transmission restricted to Zone Radius. The
nodes reachable by the computed outbound tree, define the node’s
zone. The goal of the IARP is to maintain an outbound tree to
some nearby nodes. In case of networks with only bi-directional
links, ZRP defines the zone as consisting of nodes which are within
ZONE-RADIUS hops.
Conclusion
The mobile ad hoc networks have been a subject of quite a number
of investigations in recent years. Most of these investigations
have been motivated by the need to design an efficient routing
protocol for an ad hoc network. A good routing protocol needs
to provide reliability and energy efficiency with low control
overhead. To ensure reliability, load balancing and Quos, multipath
routing protocols have been proposed for MANET.