AD HOC NETWORKS

waralligatorMobile - Wireless

Nov 21, 2013 (3 years and 10 months ago)

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AD HOC NETWORKS

BY:


Bhagyashree Fulzele 03


Sneha Ghosh 23


Yamini Kothe 27


Namrata Nitnawre 12

Wireless AD HOC network




A

wireless

ad

hoc

network

is

a

decentralized

wireless

network




The

network

is

ad

hoc

because

it

does

not

rely

on

a

preexisting

infrastructure,

such

as

routers

in

wired

networks

or

access

points

in

managed

(infrastructure)

wireless

networks
.




Instead,

each

node

participates

in

routing

by

forwarding

data

for

other

nodes,

and

so

the

determination

of

which

nodes

forward

data

is

made

dynamically

based

on

the

network

connectivity
.


Application of Wireless AD HOC Networks


The decentralized nature of wireless ad hoc networks
makes them suitable for a variety of applications
where central nodes can't be relied on, and may
improve the scalability of wireless ad hoc networks
compared to wireless managed networks, though
theoretical


and practical

limits to the overall capacity
of such networks have been identified.


Minimal configuration and quick deployment make ad
hoc networks suitable for emergency situations like
natural disasters or military conflicts. The presence of
a dynamic and adaptive routing protocol will enable ad
hoc networks to be formed quickly.


Technical

requirements



An adhoc network is made up of multiple “nodes”
connected by “links”.


Links are influenced by the node's resources (e.g.
available energy supply, transmitter power, computing
power and memory) and by behavioral properties
(reliability, and trustworthiness), as well as by link
properties (e.g. line
-
of
-
sight interference, length
-
of
-
link
and signal loss, interference and noise).


Since new and old links can be connected or
disconnected at any time, a functioning network must
be able to cope with this dynamic restructuring,
preferably in a way that is timely, efficient, reliable,
robust and scalable.


Technical

requirements

conti
….


The network must allow any two nodes to
communicate, often via other nodes that relay the
information. A “path” is a series of links that
connects two nodes.



Often there are multiple paths between any two
nodes. Nodes are often limited by transmitter
power (transmission range) and available energy
resources. Transmitter power often consumes the
most energy in the node.



Wireless ad hoc networks can be further classified
by their application:


Mobile AD HOC Networks

(MANETs)


Wireless Mesh Networks


Wireless Sensor Networks


1.Mobile AD HOC Networks



A
mobile ad hoc network (MANET), sometimes
called a mobile mesh network, is a self
-
configuring
network of
mobile devices connected by
wireless links.





Each
device in a MANET is free to move
independently in any direction, and will therefore
change its links to other devices frequently.




Each
must forward traffic unrelated to its own use,
and therefore be a router.




The
primary challenge in building a MANET is
equipping each device to continuously maintain the
information required to properly route traffic.





Such networks may operate by themselves or may
be connected to the larger
Internet

.




MANETs are a kind of wireless ad hoc networks
that usually has a routable networking environment on
top of a Link Layer ad hoc network.


Types of MANET



Vehicular Ad Hoc Networks (VANETs)



Intelligent vehicular ad hoc networks (InVANETs)



Internet Based Mobile Ad hoc Networks
(iMANET)









Intelligent

vehicular

ad

hoc

Networks
:

Intelligent

vehicular

ad

hoc

networks

(InVANETs)

are

a

kind

of

artificial

intelligence

that

helps

vehicles

to

behave

in

intelligent

manners

during

vehicle
-
to
-
vehicle

collisions,

accidents,

drunken

driving

etc
.





Internet

Based

Mobile

Ad

hoc

Networks
:

Internet

Based

Mobile

Ad

hoc

Networks

(iMANET)

are

ad

hoc

networks

that

link

mobile

nodes

and

fixed

Internet
-
gateway

nodes
.

In

such

type

of

networks

normal

ad

hoc

routing

algorithms

don't

apply

directly
.






Vehicular Ad Hoc Networks
:Vehicular Ad Hoc Networks (VANETs)
are used for communication among vehicles and between vehicles and
roadside equipment.
















2.Wireless mesh network

o

A wireless mesh network
(WMN) is a communication
network made up of radio nodes
organized in a mesh topology.

o
Wireless mesh networks often
consist of mesh clients, mesh
routers and gateways.

o
The mesh clients are often
laptops, cell phones and other
wireless devices while the mesh
routers forward traffic to and
from the gateways which may
but need not connect to the
Internet.


Wireless mesh network
conti
….


o
The coverage area of the radio nodes working as a
single network is sometimes called a mesh cloud.

o
Access to this mesh cloud is dependent on the radio
nodes working in harmony with each other to create a
radio network.

o
A mesh network is reliable and offers redundancy.
When one node can no longer operate, the rest of the
nodes can still communicate with each other, directly or
through one or more intermediate nodes

Architecture

o

Wireless mesh architecture is a first step towards providing
cost effective and dynamic high
-
bandwidth networks over a
specific coverage area.


o

Wireless mesh architectures infrastructure is, in effect, a
router network minus the cabling between nodes. It's built of
peer radio devices that don't have to be cabled to a wired
port like traditional WLAN access points (AP) do.


o

Mesh architecture sustains signal strength by breaking long
distances into a series of shorter hops.


o

Intermediate nodes not only boost the signal, but
cooperatively make forwarding decisions based on their
knowledge of the network, i.e. perform routing.


o

Such an architecture may with careful design provide high
bandwidth, spectral efficiency, and economic advantage over
the coverage area.

Example of three types of wireless mesh network:


Infrastructure wireless mesh networks:

Mesh routers form an
infrastructure for clients.


Client wireless mesh networks:

Client nodes constitute the actual
network to perform routing and configuration functionalities.


Hybrid wireless mesh networks:

Mesh clients can perform mesh
functions with other mesh clients as well as accessing the
network.

Operation


o

The principle is similar to the way packets travel around
the wired Internet



data will hop from one device to
another until it reaches its destination.

o
Dynamic routing algorithms implemented in each device
allow this to happen.

o
To implement such dynamic routing protocols, each device
needs to communicate routing information to other
devices in the network.

o
Each device then determines what to do with the data it
receives



either pass it on to the next device or keep it,
depending on the protocol.

o
The routing algorithm used should attempt to always
ensure that the data takes the most appropriate (fastest)
route to its destination.

Applications



Some current applications:

o
U.S. military forces are now using wireless mesh
networking to connect their computers, mainly ruggedized
laptops, in field operations. It enables troops to know the
locations and status of every soldier or marine, and to
coordinate their activities without much direction from
central command.

o
Electric meters now being deployed on residences transfer
their readings from one to another and eventually to the
central office for billing without the need for human meter
readers or the need to connect the meters with cables.

o
The laptops in the one laptop per child program use
wireless mesh networking to enable students to exchange
files and get on the Internet even though they lack wired
or cell phone or other physical connections in their area.

o

Calls between two satellite phones are routed through
the mesh, from one satellite to another across the
constellation, without having to go through an earth
station.


3.Wireless sensor network




A Wireless Sensor Network (WSN) consists
of spatially distributed autonomous sensors to
monitor

physical or environmental conditions,
such as temperature, sound vibration,
pressure, motion or pollutants and to
cooperatively pass their data through the
network to a main location.


The more modern networks are bi
-
directional, enabling also to
control

the activity
of the sensors.


The development of wireless sensor networks
was motivated by military applications such as
battlefield surveillance; today such networks
are used in many industrial and civilian
application areas, including industrial process
monitoring and control, machine health
monitoring

, environment and habitat
monitoring, healthcare applications, home
automation, and traffic control.

Characteristics



Unique characteristics of a WSN include:


Limited power they can harvest or store


Ability to withstand harsh environmental conditions


Ability to cope with node failures


Coping with mobility of nodes


Dynamic network topology


Communication failures


Heterogeneity of nodes


Large scale of deployment


Unattended operation


Node capacity is scalable, only limited by bandwidth of
gateway node.


Applications



Area monitoring

Area monitoring is a common application of WSNs. In area monitoring, the
WSN is deployed over a region where some phenomenon is to be
monitored. For example, a large quantity of sensor nodes could be
deployed over a battlefield to detect enemy intrusion.
















Greenhouse monitoring

Wireless sensor networks are also used to control the temperature and
humidity levels inside commercial greenhouses.



Landslide detection

A landslide detection system, makes use of a wireless sensor network to
detect the slight movements of soil and changes in various parameters that
may occur before or during a landslide.



Landfill ground well level monitoring and pump counter

Wireless sensor networks can be used to measure and monitor the water
levels within all ground wells in the landfill site and monitor accumulation
and removal.

END