Wireless Sensor Network-A Survey

Wireless Sensor
Networks:
A Survey
I. F. Akyildiz, W. Su, Y.
Sankarasubramaniam and E.
Cayirci
Presented by Yuyan Xue
11-30-2005

Outline
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Introduction
Applications of sensor networks
Factors influencing sensor network
design
Communication architecture of
sensor networks
Conclusion
2

Introduction
A sensor network is composed of a
large number of sensor nodes, which
are densely deployed either inside
the phenomenon or very close to it.
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Random deployment
Cooperative capabilities
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Introduction
Sensor networks VS ad hoc networks:
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The number of nodes in a sensor network can be
several orders of magnitude higher than the nodes
in an ad hoc network.
Sensor nodes are densely deployed.
Sensor nodes are limited in power, computational
capacities and memory.
Sensor nodes are prone to failures.
The topology of a sensor network changes
frequently.
Sensor nodes mainly use broadcast, most ad hoc
networks are based on p2p.
Sensor nodes may not have global ID.
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Applications of
Sensor networks

5

Applications of sensor
networks
Military applications
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Monitoring friendly forces, equipment
and ammunition
Reconnaissance of opposing forces and
terrain
Battlefield surveillance
Battle damage assessment
Nuclear, biological and chemical attack
detection
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Applications of sensor
networks
Environmental applications
 Forest fire detection
 Biocomplexity mapping of the
environment
 Flood detection
 Precision agriculture
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Applications of sensor
networks
Health applications
 Tele-monitoring of human
physiological data
 Tracking and monitoring patients
and doctors inside a hospital
 Drug administration in hospitals

8

Applications of sensor
networks
Home and other commercial
applications
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Home automation and Smart environment
Interactive museums
Managing inventory control
Vehicle tracking and detection
Detecting and monitoring car thefts
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Factors Influencing
Sensor Network Design

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Factors influencing sensor
network design

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Factors influencing sensor
network design
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Fault Tolerance
Scalability
Hardware Constrains
Sensor Network Topology
Environment
Transmission Media
Power Consumption
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Factors influencing sensor
network design
Fault tolerance
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Fault tolerance is the ability to sustain
sensor network functionalities without any
interruption due to sensor node failures.

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The fault tolerance level depends on the
application of the sensor networks.
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Factors influencing sensor
network design
Scalability
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Scalability measures the density of
the sensor nodes.
Density = (R) =(N
 R2)/A
R – Radio Transmission Range

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Factors influencing sensor
network design
Production costs
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The cost of a single node is very important
to justify the overall cost of the networks.

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The cost of a sensor node is a very
challenging issue given the amount of
functionalities with a price of much less
than a dollar.
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Factors influencing sensor
network design
Hardware constraints

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Factors influencing sensor
network design
Sensor network topology
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Pre-deployment and deployment phase

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Post-deployment phase

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Re-deployment of additional nodes
phase

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Factors influencing sensor
network design
Environment
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Busy intersections
Interior of a large machinery
Bottom of an ocean
Surface of an ocean during a tornado
Biologically or chemically contaminated field
Battlefield beyond the enemy lines
Home or a large building
Large warehouse
Animals
Fast moving vehicles
Drain or river moving with current.

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Factors influencing sensor
network design
Transmission media

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In a multihop sensor network,
communicating nodes are linked by a
wireless medium. To enable global
operation, the chosen transmission
medium must be available worldwide.
Radio
infrared
optical media
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Factors influencing sensor
network design
Power Consumption
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Sensing
Communication
Data processing

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Communication
architecture of sensor
networks

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Communication
architecture of sensor
networks
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Combine power and
routing awareness
Integrates date with
networking protocols
Communicates power
efficiently through the
wireless medium
Promotes cooperative
efforts among sensor
nodes.

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Communication
architecture of sensor
networks

Physical layer:

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Address the needs of simple but robust
modulation, transmission, and
receiving techniques.
frequency selection
carrier frequency generation
signal detection and propagation
signal modulation and data encryption.
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Communication
architecture of sensor
networks
Propagation Effects
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Minimum output power
(dn 2=<n<4)
Ground reflect – Multihop in dense
sensor net work
Power Efficiency Modulation Scheme
M-ary Modulation scheme
Ultra wideband(impulse radio)
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Communication
architecture of sensor
networks

Open research issues
 Modulation schemes
 Strategies to overcome signal
propagation effects
 Hardware design: transceiver

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Communication
architecture of sensor
networks

Data link layer:

The data link layer is responsible for the
multiplexing of data stream, data frame
detection, the medium access and error
control.
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Medium Access Control
Power Saving Modes of Operation
Error Control

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Communication
architecture of sensor
networks
Medium access control
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Creation of the network infrastructure
Fairly and efficiently share
communication resources between
sensor nodes
Existing MAC protocols (Cellular System,
Bluetooth and mobile ad hoc network)
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Communication
architecture of sensor
MACnetworks
for Sensor Networks
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Self-organizing medium access control for sensor
networks and Eaves-drop-and-register Algorithm
CSMA-Based Medium Access
Hybrid TDMA/FDMA-Based

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Communication
architecture of sensor
networks

Power Saving Modes of Operation
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Sensor nodes communicate using short
data packets

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The shorter the packets, the more
dominance of startup energy

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Operation in a power saving mode is energy
efficient only if the time spent in that mode
is greater than a certain threshold.
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Communication
architecture of sensor
networks

Error Control
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Error control modes in Communication Networks
(additional retransmission energy cost)
Forward Error Correction (FEC)
Automatic repeat request (ARQ)

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Simple error control codes with low-complexity
encoding and decoding might present the best
solutions for sensor networks.
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Communication
architecture of sensor
networks

Open research issues
 MAC for mobile sensor networks
 Determination of lower bounds on
the energy required for sensor
network self-organization
 Error control coding schemes.
 Power saving modes of operation
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Communication
architecture of sensor
networks

Network layer:
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Power efficiency is always an important
consideration.
Sensor networks are mostly data centric.
Data aggregation is useful only when it does
not hinder the collaborative effort of the
sensor nodes.
An ideal sensor network has attribute-based
addressing and location awareness.
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Communication
architecture of sensor
networks

Energy Efficient
Routes

•Maximum available power (PA)
route: Route 2
•Minimum energy (ME) route: Route
1
•Minimum hop (MH) route: Route 3
•Maximum minimum PA node route:
Route 3
•Minimum longest edge route:
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Route 1

Communication
architecture of sensor
networks
Interest Dissemination
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Sinks broadcast the interest

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Sensor nodes broadcast the advertisements

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Attribute-based naming
“The areas where the temperature is over 70oF ”
“The temperature read by a certain node ”

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Communication
architecture of sensor
networks

Data aggregation

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Solve implosion and overlap
Problem
Aggregation based on same
attribute of phenomenon
Specifics (the locations of
reporting sensor nodes)
should not be left out
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Communication
architecture of sensor
networks
Several Network Layer Schemes for Sensor
Networks

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Communication
architecture of sensor
networks

Open research issues
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New protocols need to be developed to
address higher topology changes and higher
scalability.

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New internetworking schemes should be
developed to allow easy communication
between the sensor networks and external
networks.
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Communication
architecture of sensor
networks
Transport layer:
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This layer is especially needed when the
system is planned to be accessed through
Internet or other external networks.
TCP/UDP type protocols meet most
requirements (not based on global
addressing).
Little attempt thus far to propose a scheme or
to discuss the issues related to the transport
layer of a sensor network in literature.
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Communication
architecture of sensor
networks
Open research issues
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Because acknowledgments are too
costly, new schemes that split the
end-to-end communication probably
at the sinks may be needed.

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Communication
architecture of sensor
networks

Application layer:

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Management protocol makes the hardware
and software of the lower layers
transparent to the sensor network
management applications.
Sensor management protocol (SMP)
Task assignment and data advertisement
protocol (TADAP)
Sensor query and data dissemination
protocol (SQDDP)
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Communication
architecture of sensor
networks

Sensor management protocol (SMP)
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Introducing the rules related to data aggregation, attribute-based
naming, and clustering to the sensor nodes
Exchanging data related to the location
finding algorithms
Time synchronization of the sensor nodes
Moving sensor nodes
Turning sensor nodes on and off
Querying the sensor network configuration and the status of
nodes, and reconfiguring the sensor network
Authentication, key distribution, and security in data
communications
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42

Some Other Interesting
Applications
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MIT d'Arbeloff Lab – The ring
sensor
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Monitors the physiological status
of the wearer and transmits the
information to the medical
professional over the Internet

Oak Ridge National
Laboratory
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Nose-on-a-chip is a MEMS-based
sensor
It can detect 400 species of
gases and transmit a signal
indicating the level to a central
control station

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iButton
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A 16mm computer chip armored in a
stainless steel can
Up-to-date information can travel with a
person or object
Types of i-Button
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Memory Button
Java Powered Cryptographic iButton
Thermochron iButton
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iButton Applications
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Caregivers Assistance
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Do not need to keep a bunch of keys. Only
one iButton will do the work

Elder Assistance
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They do not need to enter all their
personal information again and again.
Only one touch of iButton is sufficient
They can enter their ATM card information
and PIN with iButton
Vending Machine Operation Assistance
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iBadge - UCLA
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Investigate behavior of
children/patient
Features:
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Speech recording / replaying
Position detection
Direction detection /
estimation(compass)
Weather data: Temperature, Humidity,
Pressure, Light

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iBadge - UCLA

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Conclusion
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Applications of sensor networks
Factors influencing sensor network
design
Communication architecture of
sensor networks

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