What is Wireless Sensor
Networks?
WSN combines sensing, computation,
and communication into single tiny
device called sensor node.
Group of sensors linked by wireless
media to perform distributed sensing
task

What is Sensor Node?
Sensor is a device, which senses
information and passes it to the mote.
Figure : Wireless sensor network device

Progression of Sensor
Technology
Figure : Progression of sensor technology
(motes) over time

Architecture of a Sensor
Node
 A Power unit (Battery)
 Computational logic & Storage
 Sensor Transducer
 Communication
 Components of Sensor Node
1. HARDWARE

Architecture of a Sensor
Node
Figure : The architecture of a sensor node.
Contd..

2. SOFTWARE
Operating System Microcode
Sensor Drivers
Communication Processors
Communication Drivers
Data Processing Mini-Apps

Specific Sensor Node
Sensor Node:
Processor: 4Mhz
Memory: 128KB Flash & 4KB RAM
Radio: 916Mhz and 40Kbits/second.
Transmission Range: 100 Feet
TinyOS:
Operating System(small)
Open Source
Energy Efficient

Available Wireless Technologies

Available Wireless Technologies
Standard Data Rate Range Power
Consumption
ZigBee
(802.15.4)
20 kbps to
250 kbps
Up to 10 m Ultralow
Bluetooth
(802.15.1)
Up to 3 mbps 1m to 100 m low
Wi-Fi
(802.11)
54 mbps 45 m to 90
m
Medium
Contd…

Need of Security
 WSNs are becoming a cost effective,
practical way to go about deploying
sensor networks.
 Protecting confidentiality, integrity
and availability of communications.
 Large range of applications from
civilian to military purposes.

Need of Security
• Obstacles:
 Very-Limited Resources
 Unreliable Communication
 Unattended Operations
• Attacks:
 Sybil Attack
 Traffic Analysis Attacks

Need of Security
• Attacks:
1) Sybil Attack:
Introduced by “Brain Zill” in 2002
Subverted by Foreign identities in
peer-to peer Network
2) Traffic Analysis
Intercepting & Examine messages to
deduce info. from patterns in
Communications.
Able to detect Encrypted messages but
Not able to Decrypt it.

Security for Sensor Network
 SMACS :
Self organizing medium access
control for sensor networks.
 Encryption:
Encoding info. in such a way that
hackers can’t read it, but authorized
one can.
 Cryptography & Steganography:
Techniques for Secure
Communication in presence of Third
parties.

Application of WSN
 Home and Office Applications
 Environmental Applications
 Medical & Health Applications
 Military Applications

Advantages
 Implementation cost is cheaper
than wired network
Ideal for non-reachable places
 It avoids hell lot of wiring
It can accommodate new devices
at any time

Disadvantages
 Less secure because hacker's laptop
can act as Access Point.
 Lower speed as compare to wired
networks.
 Affected by surrounding. E.g.: walls
(blocking), microwave oven , far distance

Conclusion
 The low cost, flexibility, fault tolerance,
high sensing fidelity and rapid deployment
makes way for new applications on remote
sensing.
 Realization needs to satisfy the constraints
such as scalability, topology changes,
power consumption, environment etc.
 New wireless ad hoc networking
techniques are required to overcome this
constraints.

References
 Wireless Sensor Network (KAZEM
SOHRABY, DANIEL MINOLI,
TAIEB ZNATI)
 System Architecture for Wireless
Sensor Networks (Jason Lester Hill)
 http://today.cs.berkeley.edu/800dem
o/.s
 http://www.powerstream.com
 http://www.wikipedia.com

WIRELESS SENSOR NETWORK

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