Download Sensor Networks

Sensor Networks
© M Jamshidi
Definition of a Sensor
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Webster’s Definition: [Latin sentire to
perceive] (ca. 1928): a device that
responds to a physical stimulus, e.g. heat,
light, sound, pressure, magnetism, or a
particular motion and transmits a resulting
impulse (as for measurement or operating
a control).
Definition of Network
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A group or system of electric components and
connecting circuitry designed to function in a
specific manner.
Communication in a Network
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Headers
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Multiple Access protocols
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How to handle multiple
transmit requests
Header
Routing
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Handshaking protocols
Decision making for shared
resources
Path from source to
destination
Flow control
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Prevent Livelock/Deadlock
Maintain Quality of Service
Routing configurations
Sensor Network
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An array of sensors
networked to
communicate and
share information
about the data that
they are collecting
Sensor field
So what?
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What application does Computational
Intelligence have to Sensor Networks?
Problem: Randomly distributed sensor
network, low power nodes, remote
monitoring in a large scale environment
Power efficiency
Maximize Sensory function
Power Management
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Limited battery life
Transmission costs for sending data
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Low cost sensors
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Increases with distance
Often takes more resources than for acquiring data
Limited power resources
We can’t have every node “calling home” or we
will waste all our power on communication and
won’t have any left for monitoring the
environment
Clustering
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Goal: Create most efficient combination of
sensing and communication among nodes
Define some nodes as sensors
Define other key nodes as cluster heads whose
sole job is uplink, two examples:
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Predetermined cluster-heads whose sole task is uplink
Each node has full sensory and uplink capabilities
Clustering algorithm is run on the network for
nodes to determine which cluster arrangement is
the most efficient
Clustering Types
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K-means
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Fuzzy C means
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Degrees of membership
Hierarchical
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Simplest form, minimize error function
Fixed number of nodes
Clusters based on hierarchical distance relationships
Mixture of Gaussians
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Model based optimization
Fuzzy C Means
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Membership is a
function of similarity
to the average datum
in the cluster
Resulting Sensor Network
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Sample Cluster
Representation
Membership becomes a
function of power
efficiency
Nodes become members
of clusters that are the
most efficient for
communication and
sensing
Applications of Sensor Networks
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Counter Terrorism
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Monitor Disaster areas
Traffic Surveillance
Environmental Monitoring
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Earthquake Diagnostics
Tsunami Detection
Ecosystem Monitoring
Parking Lot
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Bio-agent detection, remote surveillance, border patrol
Identify usage and available spaces
Warfare and Surveillance
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Base surveillance
Advance scouting