This document discusses mobile ad-hoc networks (MANETs) and wireless sensor networks. It describes how MANETs are self-configuring networks formed by mobile nodes connected wirelessly without any fixed infrastructure. Each node acts as a router to forward packets. Wireless sensor networks are similar but use smart sensor nodes that can sense environmental data and disseminate it through the network. Examples of MANET and sensor network applications include content sharing between devices, industrial plant monitoring, and traffic monitoring. Security challenges in these networks are also discussed.

1. UNIT - VII
MOBILE AD-HOC
&
WIRELESS SENSOR NETWORKS

2. INTRODUCTION:
• A fixed infrastructure network is one, in
which incorporated access points, base
stations, and gate ways.
• The systems which are remotely located
are networked using switches, hubs and
routes, location of these are fixed.
• A mobile device moved in the vicinity
(connectivity range) of an access point,
that enables itself to connect to the access
point and access the network. Cellular
network is example for fixed infrastructure
network.

3. • An ad-hoc network is one, in which
locations of switches, hubs, and routers
can also be mobile.
• At an instant of time the availability of
routers can be increased or decreased and
routing paths may also changed.
• In ad-hoc networks, the mobile devices can
work as access points or routers and
routes between them are changed from
time to time, it depends on the presence,
locations and capacity of number of mobile
devices in the vicinity.

4. Fixed Infrastructure Architecture:
• In fixed infrastructure network, each
mobile device connects to an access-point,
base station, or gateway using a switch,
hub, or router.
• A switch is used to provides connectivity
between the two or more mobile devices,
and a hub functions as a central switching
exchange.
• A router provide two or more paths to
route a message or packet so all the
available paths can be used at an instant.

5. • The access point function as the node of
the network.
• A mobile device or sensor has to acquire
an access-point or node of the fixed
infrastructure network before being able to
connect to another, then only the
messages can be routed.
• For example, the connectivity between two
or more cellular phones are established
only through the GSM base stations in
which it has three sub systems. Each
mobile first connects to the RSS of GSM.

6. • The following diagram shows the fixed
infrastructure network architecture;

7. • The following are some drawbacks with
fixed infrastructure networks;
a) Disconnection from the network - thus
unable to communicate through the network
when a wireless sensor or mobile device
moves out of the range of access point,
base station, or gateway having the switch
or router, even though there may be
another wireless device in the vicinity
connected to the network.
b) Network not usable in operations like
disaster relief.

8. MANET Infrastructure Architecture:
• MANET is a self configured wireless ad-hoc
network of mobile nodes.
• Each node act as a router or a switch
connected by the wireless connection.
• The combination of all these connections
may form an arbitrary topology and the
network either function independently or
connect to internet.
• An important characteristic of ad-hoc
network architecture is, its organization
can change due to movement of a devices.

9. •A MANET organization depends upon the
location of the nodes, their connectivity,
their service discovery capability, and their
ability to search and route messages using
nearest node or nearby nodes.
• so in MANET The routes available to the
mobile devices or wireless sensors can thus
change at any time depend on presence and
locations of other wireless devices.
• The following diagram shows MANET
architecture;

10. • In the above diagram the ad-hoc network
is formed by the nodes A, B, C, D, E, F and
G.

11. • The diagram shows that each mobile
device functions as a node with a switch or
router.
• The following is an example describes how
MANET are established and organize them
selves.
1)Let us consider the above diagram,
suppose the nodes D and E move away
from each other then two new ad-hoc
networks will be formed one with A, C and
D and other with A, G, F and E. But all the
devices in connection to each other
through common node A.

12. 2) Let consider a Bluetooth enabled mobile
device, a Bluetooth enabled computer and
the computer has Wi-Fi internet
connection. Let us assume the computer
also connects through Jini client with
printer which is at office.
now the user by carrying the mobile device
moves from office to home, when he
reaches to home an ad-hoc network is
established between mobile device,
computer at home and printer at office.

13. MANET Properties & Spectrum Applications:
• MANET provides seamless way of
interaction and everywhere mobile
computing environment.
• Seamless connectivity maintained
between the devices when they move with
the nearby wireless nodes, sensor nodes,
and embedded devices in
Automobiles.
• Generally each MANET node have a
frequency spectrum that is smaller than
the spectrum frequency in fixed
infrastructure network.

14. • Another version of MANET is VANET-Vehicular
ad-hoc network which is used
for communication among vehicles and
between vehicles and road side equipment.
• The following are some properties of
MANET;
• One of the important property of MANET is
neighbour discovery, it enables data
reception and transmission using
discovered node.
• Data routing is another property of MANET
that is data routed from source node to a
neighbouring node.

15. 1) Flexibility:
• Enables fast establishment of networks.
• When a new network is to be established,
the only requirement is to provide a new
set of nodes with limited wireless
communication range.
• A node has limited capability, that is, it
can connect only to the nodes which are
nearby and thus consumes limited power.
2) Direct communication through nearby
node and neighbour discovery:
• A MANET node has a ability to discover a
neighbouring node and service.

16. • A node discovers the service of the
neighbouring node using service discover
protocol then it is able to communicate
with remote node.
3) Peer-to-Peer connectivity: MANET nodes
have peer-to-peer connectivity among
themselves.
4) Computations decentralizations: We know
that each MANET node has an
independent computational, switching and
communication capabilities.
5) Limited wireless connectivity range: In
MANETs a node should move in the

17. Coverage area of at least one near by node,
else the node should be provided with
access point of wired communication.
• we conclude that the wireless connectivity
range in MANETs only nearest node
connectivity.
6) Weak connectivity and remote server
latency: Unreliable links to base station or
gateway and failure of an intermediate
nodes may cause in greater latency in
communicating with the remote server.

18. 7) Resource constraints: Limited bandwidth
available between the nodes is the major
constraint in MANETs, and also limited
power capability needs may perform
energy efficient operations only.
8) No access point requirement: There is no
need of access points in MANETs, only
selected access points are provided for
connection to other networks or MANETs
9) Requirement to solve hidden/exposed
terminal problem: The MANET organization
should require a mechanism to solve hidden
and exposed terminal problem.

19. 10) Diversity in nodes: The MANET support
various kinds of nodes such as iPods,
handheld computers, smart phones, PCs,
Smart labels, Smart sensors, and
automobile embedded systems.
11) Protocol diversity: MANET nodes can use
different protocols, such as IrDA,
Bluetooth, ZigBee, 802.11, GSM, and
TCP/IP.
12) Data caching, Saving and Aggregation:
The MANET node can perform data
caching, saving it can also perform data
aggregation.

20. Spectrum: We know that a huge number of
devices are connected to the access point
based fixed infrastructure network. The
bandwidth required to service all these
devices within the vicinity is too large.
• Suppose N devices are connected to the
access point by using FDMA, then the
required bandwidth for these devices is:
N X fbw0
where fbw0 is bandwidth allotted for one
device.

21. • Suppose it is a full duplex transmission
then the need of bandwidth is doubled, i.e
2 X N X fbw0
• But we know that in fixed infrastructure
network the bandwidth requirement can
reduced by using some other techniques
like TDMA and SDMA.
• In each MANET node has much smaller
frequency spectrum requirements than
that for a node in a fixed infrastructure
network.
• Here a node itself a router for all the
packets coming from or going out to the
other nodes.

22. • In MANET the nodes are themselves
mobile so the bandwidth available to any
node at any instant is not constant.
• The MANETs allow reuse of spectrum and
each wireless link provide a limited
bandwidth.
• In MANET the communication is carried in
multi hop fashion, so each node has low
and adaptable transmission power which
is having signal strength just sufficient to
carry the data up to next hop.
• The hops can occur in MANET
simultaneously using same frequency band.

23. • It mean that there is a spatial reuse of
bandwidth, which depending on the
surrounding environment.
• Let us consider an example

24. • In the above diagram node D at a instant
get incoming packets from E, F, G and A
and can send packets C and A vice versa.
• When node D transmit data to G it happen
in three hops D-E, E-F and F-G
• In MANET which node need higher
bandwidth is depends number of next hop
neighbours from that node.
• The bandwidth requirement can also
reduced in MANET by scheduling the each
node path and hop direction at different
instants.

25. MANET Applications: The MANET supports
many applications the following are few
applications;
a)Content distribution & content
synchronization: Let us consider in an
enterprise, there are a number of
Bluetooth-enabled mobile handheld
devices, PCs, laptops, and Wi-Fi access
points, the MANET used for content-distribution,
by following PIM, information
dissemination,
information fusion, and file sharing
techniques.

26. b) Multicast network: MANET supports
multicasting by organizing the nodes in
multicast tree topology. Here we use CGSR
protocol for multicasting.
c) Mesh network: Mesh-based mobile
networks offer highly dynamic
autonomous topology segments for the
robust IP-compliant data services. The
mesh is inexpensive to infrastructure-based
cellular mobile networks.
• Mesh network is build by using PUMA
(Protocol for unified multicasting through
announcements) protocol. Mesh connects
MANET nodes each other.

27. • We know that the multicast tree is
different from mesh. Multicast tree
provides a single path between the sender
and receiver, but mesh supports multiple
paths between sender and receiver.
• But we know that the error rate is high on
wireless links so PUMA can send the
packets from sender to receiver through
various paths.
d) Image acquisition, processing and
distribution using MANET: Let us consider
number of imaging devices forming a
MANET.

28. •low cost digital still camera with a wireless
network interface, Wireless Webcam, mobile
device connected to a digital still camera,
mobile phones, and pocket PCs equipped
with an image acquisition sensor.
•The following are some applications where
MANETs to apply;
1.Remote view finder by security personal in
office.
2.Remote processing on a computer for a
video from wireless webcam or from other
devices.
3.Image file transfer

29. 4) Messaging and data transmission to
remote device using 802.11b.
5) Remote controlling.
e) IPv6 integration and wireless sensor
networks: IPv6 is a new generation
internet protocol used for internet radio
and real time video over the internet.
• Now we integrate IPv6 with MANET and
wireless sensor networks. This integration
leads to pervasive computing and other
innovative applications.

30. Security in Ad-hoc Networks:
security is important for maintaining
privacy in mobile ad-hoc networks, the
following are some of the security problems
in wireless computing systems;
1)Confidentiality: Only intended user only
able to read the data. Encryption of the
data before the transmission and
decryption at the user end is employed for
confidentiality.
2)Integrity: Here data integrity as well as the
system integrity to be maintained to avoid
manipulated messages and messages to
wrong nodes.

31. 3) Pre-Keying: A key should be exchanged
before the transmission of the data
between the sender and receiver for
decryption of the data at receiver side. The
key exchanging is through wireless link, it
increases the risk of key tapping.
4) Availability: There may be a denial of
service attack, a source may block the
availability of data at the user end due to
intermediate router misdirection.
5) Non-Repudiation: A sender is unable to
refuse send a message or information.

32. 6) Resource constraint: Resource constraint
of mobile systems have several points;
a) The service provider (server) runs slower
than a node.
b) Less memory availability.
c) Limited battery life.
d) Certain kinds of attacks.
7) Power of detection: A mobile device may
not detect the signals therefore unable to
get the data by jamming the signals.
8) Interception: Some times the signals may
intercepted.

33. 9) Replay: Some time the attacker replay the
same sequence of messages to the server
by hacking the authentication requests.
10) Stealing of subscriber service: Hijacking
of user name and password by an
attacker, results getting service of another
client.
11) Mobility risks: Frequent change in
locations may lead to changing of routing
path frequently.
12) Spoofing: A node can imitate the address
of another node in ad-hoc network.
Suppose spoofing at common node leads to

34. chocking of all routes.
13) Reconfiguration: Changing of network
parameters due to configuration attacks
may cause configure the network in
frequent intervals of time.
14) eavesdropping: Certain times unsolicited
messages from third party during a talk
between two nodes.
15) Traffic analysis: By extracting the
network traffic analysis some security
problems may occur.

35. Wireless Sensor Networks:
• Wireless sensor networks are a kind of
MANETs functions with smart sensors
having computational, communication and
networking capabilities.
• A sensor is consider as a smart one, if it
consists of computational and logical
capabilities.
• A wireless sensor is one which have
communication abilities by using a radio
frequency transceiver.

36. • The RF transceiver is able to receive the
data from nearby nodes and route these
packets to the next hop neighbouring
nodes.
• The RF transmission and reception can
use Wi-Fi, Access-point, or ZigBee
protocols.
• The following diagram shows wireless
sensor networks,

37. •

38. • The following are elements of wireless
sensor network;
1)Sensor.
2)An RF transceiver for communication.
3)A micro controller (CPU, ADC, Memory)
4)Energy source or power supply – A charge
pump in the sensor can catch the charge
from radiations and supply the power.
5)Alternative energy – An energy harvesting
module can used to catch the solar
radiations and store the energy.

39. • The following diagram shows wireless
sensor architecture;

40. • The wireless sensor node is able to
disseminate the data to the neighbouring
nodes in the network, central computer or
to a controller.
• The wireless node have sophisticated
hardware and software, each node has a
sensor, which senesces light, temperature,
physical, chemical and biological data.
• Software once embedded into the sensor
node is for lifetime should be robust, fault
tolerant, and should provide maximum
features.

41. •Software should have features of security,
self-healing, and self configuration.
•Finally we know that the sensors has
computational, communication and
networking capabilities, but are constrained
due to size, energy availability, and memory.
So the sensors operated at limited
computational speed and bandwidth.
Data dissemination in sensor networks:
Data dissemination in wireless sensor
networks is carried out in three ways;

42. 1) Aggregation: It refers to the process of
joining present and previously received
data packets after removing the duplicate
data.
2) Compacting: It is the process of making
information short without changing
meaning and context.

43. 3) Fusion: It mean formatting the
information received in parts through
various packets and several types of data,
in case when individual records not
required and/or not retrievable later.
Wireless Sensor Network Applications:
1)Street lights with local as well as remote
central control.
2)Industrial plant wireless sensor networks:
Industrial plants use large number of
sensors in instruments and Controllers
they proves powerful for industrial plants.

44. 3)Pervasive computing networks: Mobile
pervasive computing means a set of
computing devices, sensors, or systems or a
network having the characteristics of
transparency, application-aware adaptation,
and environment sensing.
4) Traffic monitoring using traffic density
wireless sensor networks: Traffic can be
monitored at different points in a city and
traffic density information can be aggregated
at central server. The server send the
information in the form of SMS to drivers to
select roads with least hurdles.

45. 5) Medical applications: Patients can be
monitored by sensors attached to them.
6) Military applications: The physical
characteristics of a person can be sensed
by a wireless sensor networks deployed in
borders. This monitors the army troops
and machines moments.
7) Smart labels and RFID applications:
These are used world wide for monitoring
movement of goods and supply chain
management system.

46. 8)Environmental applications:
Environmental parameters, such as
temperature, pressure, light, rainfall, and
seismic activities are sensed and
communicated over the wireless links.
9) Home automation: Various home
automation applications like security may
possible with sensor networks.
UNIT-VII
THE END