This document summarizes sensor networks, including their definition, components, applications, characteristics, architectures, challenges, and security approaches. Sensor networks consist of spatially distributed nodes that monitor environmental conditions and pass data to a central location. The nodes have sensors, microcontrollers, memory, and radios. Applications include area monitoring, healthcare, and environmental monitoring. Challenges include limited energy, computation, and transmission range. PEGASIS is an approach that forms nodes into chains to more efficiently pass data to the base station and minimize energy use. Security is provided using secret key encryption algorithms.

1. GOVT. COLLEGE OF ENGINEERING AND
TEXTILE TECHNOLOGY , BERHAMPORE
GROUP -- 7
PRADIP MONDAL(11100112025)
PROSENJIT DAS(11100112026)
RAJU KUMAR GIRI(11100112027)
RANVEER KUMAR DAS(11100112028)
STREAM : COMPUTER SCIENCE & ENGINEERING
SUBJECT : SEMINAR
YEAR : 3RD
(6SEMESTER)

2. SENSOR NETWORK

3. Contents
1. Definition
2. Components
3. Applications
4. Characteristics
5. Architecture
6. Network architecture
7. Challenges
8. PEGASIS
9. Security

4. Definition
Sensor network ( sometime called Wireless
Sensor Network and Actor Network (WSAN) ) are
spatially distributed autonomous sensor
to monitor physical or environmental conditions,
such as temperature, sound, pressure, etc. and to
cooperatively pass their data through the network
to a main location. The more modern networks
are bi-directional, also enabling control of sensor
activity.

5. Components
The WSN is built of "nodes" – from a few to
several hundreds or even thousands, where each
node is connected to one (or sometimes several)
sensors.
Each such sensor network node has typically
several parts:
Radio Transceiver
Internal Antenna
External Antenna
Microcontroller
Power source (battery)

6. Sensors
Enabled by recent
advances in MEMS
technology
Integrated Wireless
Transceiver
Limited in
Energy
Computation
Storage
Transmission range
Bandwidth
Battery
Memory
CPU
Sensing Hardware
Wireless
Transceiver

7. Cost :
The cost of sensor nodes is similarly variable, ranging
from a few to hundreds of dollars, depending on the
complexity of the individual sensor nodes.
Size:
It depends on sensor nodes resources such as energy,
memory, computational speed and communications
bandwidth.
Topology:
The topology of the WSNs can vary from a simple star
network to an advanced multi-hop wireless mesh network
 Routing and Flooding between the hopes of network is
used for propagation technique

9. Applications
 Area Monitoring : In area monitoring, the WSN is deployed over
a region where some phenomenon is to be monitored. A military
example is the use of sensors detect enemy intrusion.
 Health Care Monitoring : Body-area networks can collect
information about an individual's health, fitness, and energy
expenditure .
 Environmental/Earth Sensing :
I. Air pollution monitoring
II. Forest fire detection
III. Land slide detection
IV. Water quality monitoring
V. Natural disaster
VI. Chemical agent detection
 Industrial monitoring and some application in entertainment
industry

10. Characteristics
The main characteristics of a WSN include:
Power consumption constraints for nodes using
batteries or energy harvesting
Ability to cope with node failures (resilience)
Mobility of nodes
Heterogeneity of nodes
Scalability to large scale of deployment
Ability to withstand harsh environmental conditions
Ease of use
Cross-layer design

11. Architecture
Hardware : Low-power microscopic sensors with
wireless communication capability.
Miniaturization of computer hardware
 Intelligence
Micro Electro-Mechanical Structures (MEMS)
 Sensing
Low-cost CMOS-based RF Radios
Wireless Communications

12. Overall Architecture of a sensor node

13. Mica2 Wireless Sensors
CACM June 2004 pp. 43.
13
New MicaZ follows IEEE 802.15.4 Zigbee
standard with direct sequence sprad
spectrum radio and 256kbps data rate
MTS310 Sensor Boards
• Acceleration,
• Magnetic,
• Light,
• Temperature,
• Acoustic,
• Sounder

14. Software Architecture
WSNs may be deployed in large numbers in
various environments, including remote and
hostile regions, where ad hoc communications
are a key component. For this reason, algorithms
and protocols need to address the following
issues:
Increased lifespan
Robustness and fault tolerance
Self-configuration

15. Operating System : Operating systems for wireless
sensor network nodes are typically less complex than
general-purpose operating systems. It is possible to
use embedded operating systems such
as eCos or uC/OS for sensor networks because it
has low powered microcontroller available in nodes.
TinyOS is the first operating system
designed for wireless sensor networks. TinyOS is
based on an event-driven programming model
instead of multithreading .
ERIKA Enterprise is an open-source and
royalty-free OSEK/VDX Kernel offering BCC1,
BCC2, ECC1, ECC2, multicore, memory protection
and kernel fixed priority adopting C programming
language .

16. Online collaborative sensor data management
platforms are on-line database services that allow
sensor owners to register and connect their devices
to feed data into an online database for storage and
also allow developers to connect to the database
and build their own applications based on that data.
Simulation of WSN :
At present, agent-based modeling and
simulation is the only paradigm which allows the
simulation of complex behavior in the environments
of wireless sensors (such as flocking). Agent-based
simulation of wireless sensor and ad hoc networks
is a relatively new paradigm. Agent-based
modelling was originally based on social simulation.

17. Network Architectures
Layer 1
Layer 2
Layer 3
Layered
Architecture
Base
Statio
n
Clustered
Architecture
Base
Statio
n
Larger Nodes denote Cluster Heads

18. Cluster architecture (contd.)
Example - LEACH protocol
It uses two-tier hierarchy
clustering architecture.
It uses distributed
algorithm to organize the
sensor nodes into
clusters.
The cluster-head nodes
create TDMA schedules.
Nodes transmit data
during their assigned
slots.
The energy efficiency of
the LEACH is mainly due
to data fusion.

19. Layered Network Architecture
A few hundred sensor nodes
(half/full duplex)
A single powerful base-station
Network nodes are organized
into concentric Layers
Layer: Set of nodes that have
the same hop-count to the
base-station
Additional Mobile Nodes
traversing the network
Wireless Multi-Hop
Infrastructure Network
Architecture (MINA)
A 10 node sensor network depicting cluster of node 3;
there are 2 mobile nodes

20. Challenges
Cost and Size
Complexity
Energy management issue :
It is the main challenges regarding WSN
I. Actuation energy is the highest
II. Communication energy is the next important issue
III. Processor and sensor energy usually less important
Ultra low power sentinel nodes , energy aware data
communication and by software nodes minimization
technique we can minimize the consumption of
energy .

21. SOME TECHNIQUES ARE USED TO MINIMIZE
CHALLENGES
AND MOST USED IS PEGASIS :
Goals of PEGASIS (Power-Efficient GAthering for
Sensor Information Systems)
Minimize distance nodes must transmit
Minimize number of leaders that transmit to BS
Minimize broadcasting overhead
Minimize number or messages leader needs to
receive
Distribute work more equally among all nodes

22. PEGASIS
Greedy Chain Algorithm
Start with node furthest away from BS
Add to chain closest neighbor to this node that has
not been visited
Repeat until all nodes have been added to chain
Constructed before 1st round of communication
and then reconstructed when nodes di
Data fusion at each node (except end nodes)
Only one message is passed at every node
Delay calculation: N units for an N-node network
Sequential transmission is assumed

23. Start
End

24. Security
In WSN the security is achieved by A
secret key algorithm (sometimes called
a symmetric algorithm) is acryptographic algorithm
that uses the same key to encrypt and decrypt data.
Conclusion
In future it seen that mobile ad-hoc network
are use for larger project because it is more powerful
as basically WSN is the subtype of ad-hoc network
but WSN is also used with increasing probability as
based on requirement. Basically it is used for many
smart cities etc.

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