ABSTRACT
A mobile ad hoc network (MANET), sometimes called a mobile
mesh network, is a self-configuring network of mobile devices
connected by wireless links. The Ad hoc networks are a new
wireless networking paradigm for mobile hosts. Unlike traditional
mobile wireless networks, ad hoc networks do not rely on any
fixed infrastructure. Instead, hosts rely on each other to keep the
network connected. It represent complex distributed systems that
comprise wireless mobile nodes that can freely and dynamically
self-organize into arbitrary and temporary, ‘‘ad-hoc’’ network
topologies, allowing people and devices to seamlessly internetwork
in areas with no pre-existing communication infrastructure.
Ad hoc networking concept is not a new one, having been around
in various forms for over 20 years. Traditionally, tactical networks
have been the only communication networking application that
followed the adhoc paradigm. Recently, the introduction of new
technologies such as the Bluetooth, IEEE 802.11 and Hyperlan are
helping enable eventual commercial MANET deployments outside
the military domain. These recent evolutions have been generating
a renewed and growing interest in the research and development of
MANET.
This paper attempts to provide a comprehensive overview of this
dynamic field. It first explains the important role that mobile ad
hoc networks play in the evolution of future wireless technologies.
Then, it reviews the latest research activities in these areas of
MANET_s characteristics, capabilities and applications.
KEYWORDS :
Adhoc Network, Bluetooth, 4G, Routing, Security, Performance
evaluation
1. INTRODUCTION
Wireless cellular systems have been in use since 1980s. We have
seen their evolutions to first, second and third generation's wireless
systems. Wireless systems operate with the aid of a centralized
supporting structure such as an access point. These access points
assist the wireless users to keep connected with the wireless
system, when they roam from one place to the other.
The presence of a fixed supporting structure limits the adaptability
of wireless systems. In other words, the technology cannot work
effectively in places where there is no fixed infrastructure. Future
generation wireless systems will require easy and quick
deployment of wireless networks. This quick network deployment
is not possible with the existing structure of current wireless
systems.
Recent advancements such as Bluetooth introduced a new type of
wireless systems known as mobile ad-hoc networks. Mobile adhoc
networks or "short live" networks operate in the absence of
fixed infrastructure. They offer quick and easy network
deployment in situations where it is not possible otherwise. Ad-hoc
is a Latin word, which means "for this or for this only." Mobile adhoc
network is an autonomous system of mobile nodes connected
by wireless links; each node operates as an end system and a router
for all other nodes in the network.
An Ad-hoc network is a collection of wireless mobile nodes which
dynamically forming a temporary mobile nodes which dynamically
forming a temporary network without the aid of any established
infrastructure or centralized administration..
The proliferation of mobile computing and communication devices
(e.g., cell phones, laptops, handheld digital devices, personal
digital assistants, or wearable computers) is driving a revolutionary
change in our information society. We are moving from the
Personal Computer age (i.e., a one computing device per person) to
the Ubiquitous Computing age in which a user utilizes several
electronic platforms at a single instance through which he can
access all the required information whenever and wherever needed.
Mobile users can use their cellular phone to check e-mail, browse
internet; travelers with portable computers can surf the internet
from airports, railway stations, Starbucks and other public
locations; tourists can use Global Positioning System (GPS)
terminals installed inside rental cars to locate driving maps and
tourist attractions, researchers can exchange files and other
information by connecting portable computers via wireless LANs
while attending conferences; at home, users can synchronize data
and transfer files between portable devices and desktops. Not only
are mobile devices getting smaller, cheaper, more convenient, and
more powerful, they also run more applications and network
services, commonly fueling the explosive growth of mobile
computing equipment market. The exploding number of Internet
and laptop users driving this growth further. Projections show that
in the next two years the number of mobile connections and the
number of shipments of mobile and Internet terminals will grow
yet by another 20–50%. With this trend, we can expect the total
number of mobile Internet users soon to exceed that of the fixedline
Internet users. Among all the applications and services run by
mobile devices, network connections and corresponding data
services are without doubt the most demanded service by the
mobile users. According to a study, the number of subscribers to
wireless data services will grow rapidly from 2.6 billion worldwide
in 2009 to more than 3.3 billion in 2010, and the number of
wireless messages sent per month will rise continuously. Currently,
most of the connections among these wireless devices are achieved
via fixed infrastructure-based service provider, or private
networks.

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