Wireless Sensor Networks
Content
WIRELESS SENSOR
NETWORK
INTRODUCTION TO
WIRELESS SENSOR
NETWORKS
Wireless network consisting
of
spatially distributed autonomous
devices using sensors to monitor
physical or environmental conditions.
A WSN system incorporates a
gateway that provides wireless
connectivity back to the wired world
and distributed nodes.
The wireless protocol you select
depends on your application
requirements.
Some of the available standards
include 2.4 GHz radios based on
either IEEE 802.15.4 or IEEE 802.11
(Wi-Fi) standards or proprietary
radios, which are usually 900 MHz.
BACKGROUND DETAILS OF
WSN
WSN’s have existed for decades and used for applications as
diverse as earthquake measurements to warfare.
The modern development of small sensor nodes dates back to
the 1998 Smartdust project and the NASA Sensor Webs Project.
One of the objectives of the Smartdust project was to create
autonomous sensing and communication within a cubic
millimetre of space. They include major research centres in
Berkeley NEST and CENS. The researchers involved in these
projects coined the term mote to refer to a sensor node.
The equivalent term in the NASA Sensor Webs Project for a
physical sensor node is pod, although the sensor node in a
Sensor Web can be another Sensor Web itself.
Physical sensor nodes have been able to increase their capability
in conjunction with Moore’s Law. The chip footprint contains more
complex and lower powered microcontrollers.
THE MAIN CHARACTERISTICS OF
WSN
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
WIRELESS SENSOR NETWORK
ARCHITECTURE
Wireless technology offers several advantages for
those who can build wired and wireless systems and
take advantage of the best technology for the
application. To do this, you need a flexible software
architecture.
Each wireless network can scale from tens to
hundreds of nodes and seamlessly integrate with
existing wired measurement and control systems.
UNDERSTANDING THE WSN
ARCHITECTURE
A wireless sensor network architecture consists of three
main components:Nodes
Gateways
Software
The spatially distributed measurement nodes interface
with sensors to monitor assets or their environment. The
acquired data wirelessly transmits to the gateway, which
can operate independently or connect to a host system
where you can collect, process, analyze, and present
your measurement data using software. Routers are a
special type of measurement node that you can use to
extend WSN distance and reliability.
WSN
ARCHITECTURE
GATEWAYS
SOFTWARE
NODES
•Feature direct
sensor connectivity.
•Devices are
battery-powered.
•Long-term outdoor
deployment.
•acts as network
coordinator in
charge of node
authentication.
• collects
measurement data
from distributed
nodes. enterprise
network, where
you can collect,
process, analyze.
•Provide graphical
development
environment.
•Powerful
programming
capabilities.
•Analysis and
control applications
with professional
user interface.
WSN NETWORK
TOPOLOGIES
WSN nodes are typically organized in one of three types of
network topologies.
STAR TOPOLOGY :- In a star topology, each node
connects directly to a gateway.
CLUSTER TREE TOPOLOGY:- In a cluster tree network,
each node connects to a node higher in the tree and then
to the gateway, and data is routed from the lowest node on
the tree to the gateway.
MESH TOPOLOGY:- Mesh networks feature nodes that can
connect to multiple nodes in the system and pass data
through the most reliable path available. This mesh link is
often referred to as a router.
Common WSN Network Topologies
RADIO
•must efficiently
transmit a signal
• must make
important trade-offs
ANALOG
CIRCUIT
COMPONENTS
OF WSN NODE
BATTERY
MICROCONTROLLER
SENSOR
INTERFACE
•In addition to long
life requirements,
size and weight must
be considered
•international
standards
•ZigBee due to its
low-power
•reducing power
consumption
consumption
• maintaining or
increasing
processor speed
•power
consumption and
processing speed
trade-off is major
WSN Sensor Node Components
WIRELESS SENSOR NETWORK
APPLICATIONS
Health Applications
Environmental
Applications
Forest fire detection
Bio-complexity
mapping of
environment
Flood detection
Precision Agriculture
Air and water pollution
•Telemonitoring of human
physiological data
•Tracking and monitoring
doctors and patients inside a
hospital
•Drug administration in
Commercial
hospitals
Applications
•Environmental control in
office buildings (estimated
energy savings $55 billion per
year!)
•Interactive museums
•Detecting and monitoring car
Automotive
Applications
Reduces wiring effects
Measurements in
chambers and rotating
parts
Remote technical
inspections
Conditions monitoring
e.g. at a bearing
Pictures of applications
of wireless sensor
networks
FACTORS INFLUENCING WSN
DESIGN
Scalability
Hardware constraints
Environment
Power Consumption
◦ Sensing
◦ Communication
◦ Data processing
•Fault tolerance
•Production costs
•Sensor network
topology
•Transmission media
FEW WSN PROTOCOLS
Sensor management protocol
◦ Provides software operations needed to perform
administrative tasks e.g. moving sensor nodes, turning
them on an off
Sensor query and data dissemination protocol
◦ Provides user applications with interfaces to issue queries
and respond to queries
◦ Sensor query and tasking language (SQTL)
Directed diffusion
Sensor MAC (S-MAC)
IEEE 802.15.4
WSN OPERATING SYTEMS
o
o
o
o
o
o
o
o
OS for wireless sensor network nodes are typically less complex
than general-purpose OS
strongly resemble embedded systems, for two reasons
wireless sensor networks are typically deployed with a particular
application in mind, rather than as a general platform
need for low costs and low power leads most wireless sensor nodes
It is therefore possible to use embedded operating systems such as
:TinyOS
Contiki
MANTIS
Btnut
SOS
Nano-RK
TinyOS
Event-driven programming model instead of
multithreading
TinyOS and its programs written in nesC
TinyOS CHARACTERISTICS
Small memory footprint
◦ non-preemptable FIFO task scheduling
Power Efficient
◦ Puts microcontroller to sleep
◦ Puts radio to sleep
Concurrency-Intensive Operations
◦ Event-driven architecture
◦ Efficient Interrupts and event handling
No Real-time guarantees
WSN DEVELOPMENT
PLATFORMS
Crossbow
Worldsens Inc. Sensor
Node
Dust
Networks
Sensoria Corporation
Ember Corporation
Worldsens
Crossbow Sensor
WSN SIMULATORS
NS-2
GloMoSim
OPNET
SensorSim
J-Sim
OMNeT++
Sidh
SENS
FUTURE ASPECTS
WSNs possible today due to technological
advancement in various domains
Envisioned to become an essential part of our
lives
Design Constraints need to be satisfied for
realization of sensor networks
Tremendous research efforts being made in
different layers of WSNs protocol stack
BIBLIOGRAPHY
www.google.co.in
www.wikipedia.com
www.natgeo.in
THANK
YOU
NETWORK
INTRODUCTION TO
WIRELESS SENSOR
NETWORKS
Wireless network consisting
of
spatially distributed autonomous
devices using sensors to monitor
physical or environmental conditions.
A WSN system incorporates a
gateway that provides wireless
connectivity back to the wired world
and distributed nodes.
The wireless protocol you select
depends on your application
requirements.
Some of the available standards
include 2.4 GHz radios based on
either IEEE 802.15.4 or IEEE 802.11
(Wi-Fi) standards or proprietary
radios, which are usually 900 MHz.
BACKGROUND DETAILS OF
WSN
WSN’s have existed for decades and used for applications as
diverse as earthquake measurements to warfare.
The modern development of small sensor nodes dates back to
the 1998 Smartdust project and the NASA Sensor Webs Project.
One of the objectives of the Smartdust project was to create
autonomous sensing and communication within a cubic
millimetre of space. They include major research centres in
Berkeley NEST and CENS. The researchers involved in these
projects coined the term mote to refer to a sensor node.
The equivalent term in the NASA Sensor Webs Project for a
physical sensor node is pod, although the sensor node in a
Sensor Web can be another Sensor Web itself.
Physical sensor nodes have been able to increase their capability
in conjunction with Moore’s Law. The chip footprint contains more
complex and lower powered microcontrollers.
THE MAIN CHARACTERISTICS OF
WSN
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
WIRELESS SENSOR NETWORK
ARCHITECTURE
Wireless technology offers several advantages for
those who can build wired and wireless systems and
take advantage of the best technology for the
application. To do this, you need a flexible software
architecture.
Each wireless network can scale from tens to
hundreds of nodes and seamlessly integrate with
existing wired measurement and control systems.
UNDERSTANDING THE WSN
ARCHITECTURE
A wireless sensor network architecture consists of three
main components:Nodes
Gateways
Software
The spatially distributed measurement nodes interface
with sensors to monitor assets or their environment. The
acquired data wirelessly transmits to the gateway, which
can operate independently or connect to a host system
where you can collect, process, analyze, and present
your measurement data using software. Routers are a
special type of measurement node that you can use to
extend WSN distance and reliability.
WSN
ARCHITECTURE
GATEWAYS
SOFTWARE
NODES
•Feature direct
sensor connectivity.
•Devices are
battery-powered.
•Long-term outdoor
deployment.
•acts as network
coordinator in
charge of node
authentication.
• collects
measurement data
from distributed
nodes. enterprise
network, where
you can collect,
process, analyze.
•Provide graphical
development
environment.
•Powerful
programming
capabilities.
•Analysis and
control applications
with professional
user interface.
WSN NETWORK
TOPOLOGIES
WSN nodes are typically organized in one of three types of
network topologies.
STAR TOPOLOGY :- In a star topology, each node
connects directly to a gateway.
CLUSTER TREE TOPOLOGY:- In a cluster tree network,
each node connects to a node higher in the tree and then
to the gateway, and data is routed from the lowest node on
the tree to the gateway.
MESH TOPOLOGY:- Mesh networks feature nodes that can
connect to multiple nodes in the system and pass data
through the most reliable path available. This mesh link is
often referred to as a router.
Common WSN Network Topologies
RADIO
•must efficiently
transmit a signal
• must make
important trade-offs
ANALOG
CIRCUIT
COMPONENTS
OF WSN NODE
BATTERY
MICROCONTROLLER
SENSOR
INTERFACE
•In addition to long
life requirements,
size and weight must
be considered
•international
standards
•ZigBee due to its
low-power
•reducing power
consumption
consumption
• maintaining or
increasing
processor speed
•power
consumption and
processing speed
trade-off is major
WSN Sensor Node Components
WIRELESS SENSOR NETWORK
APPLICATIONS
Health Applications
Environmental
Applications
Forest fire detection
Bio-complexity
mapping of
environment
Flood detection
Precision Agriculture
Air and water pollution
•Telemonitoring of human
physiological data
•Tracking and monitoring
doctors and patients inside a
hospital
•Drug administration in
Commercial
hospitals
Applications
•Environmental control in
office buildings (estimated
energy savings $55 billion per
year!)
•Interactive museums
•Detecting and monitoring car
Automotive
Applications
Reduces wiring effects
Measurements in
chambers and rotating
parts
Remote technical
inspections
Conditions monitoring
e.g. at a bearing
Pictures of applications
of wireless sensor
networks
FACTORS INFLUENCING WSN
DESIGN
Scalability
Hardware constraints
Environment
Power Consumption
◦ Sensing
◦ Communication
◦ Data processing
•Fault tolerance
•Production costs
•Sensor network
topology
•Transmission media
FEW WSN PROTOCOLS
Sensor management protocol
◦ Provides software operations needed to perform
administrative tasks e.g. moving sensor nodes, turning
them on an off
Sensor query and data dissemination protocol
◦ Provides user applications with interfaces to issue queries
and respond to queries
◦ Sensor query and tasking language (SQTL)
Directed diffusion
Sensor MAC (S-MAC)
IEEE 802.15.4
WSN OPERATING SYTEMS
o
o
o
o
o
o
o
o
OS for wireless sensor network nodes are typically less complex
than general-purpose OS
strongly resemble embedded systems, for two reasons
wireless sensor networks are typically deployed with a particular
application in mind, rather than as a general platform
need for low costs and low power leads most wireless sensor nodes
It is therefore possible to use embedded operating systems such as
:TinyOS
Contiki
MANTIS
Btnut
SOS
Nano-RK
TinyOS
Event-driven programming model instead of
multithreading
TinyOS and its programs written in nesC
TinyOS CHARACTERISTICS
Small memory footprint
◦ non-preemptable FIFO task scheduling
Power Efficient
◦ Puts microcontroller to sleep
◦ Puts radio to sleep
Concurrency-Intensive Operations
◦ Event-driven architecture
◦ Efficient Interrupts and event handling
No Real-time guarantees
WSN DEVELOPMENT
PLATFORMS
Crossbow
Worldsens Inc. Sensor
Node
Dust
Networks
Sensoria Corporation
Ember Corporation
Worldsens
Crossbow Sensor
WSN SIMULATORS
NS-2
GloMoSim
OPNET
SensorSim
J-Sim
OMNeT++
Sidh
SENS
FUTURE ASPECTS
WSNs possible today due to technological
advancement in various domains
Envisioned to become an essential part of our
lives
Design Constraints need to be satisfied for
realization of sensor networks
Tremendous research efforts being made in
different layers of WSNs protocol stack
BIBLIOGRAPHY
www.google.co.in
www.wikipedia.com
www.natgeo.in
THANK
YOU
