1. Sensor Networks
© M Jamshidi

2. Definition of a Sensor
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).

3. Definition of Network
A group or system of electric components and connecting circuitry designed to function in a specific manner.

4. Communication in a Network
Headers
Handshaking protocols
Multiple Access protocols
How to handle multiple transmit requests
Routing
Decision making for shared resources
Path from source to destination
Flow control
Prevent Livelock/Deadlock
Maintain Quality of Service
Header
Routing configurations

5. Sensor Network
An array of sensors networked to communicate and share information about the data that they are collecting
Sensor field

6. So what?
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

7. Power Management Limited battery life
Transmission costs for sending data
Increases with distance
Often takes more resources than for acquiring data
Low cost sensors
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

8. Clustering
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:
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

9. Clustering Types K-means Fuzzy C means Hierarchical
Simplest form, minimize error function
Fixed number of nodes
Fuzzy C means
Degrees of membership
Hierarchical
Clusters based on hierarchical distance relationships
Mixture of Gaussians
Model based optimization

10. Fuzzy C Means
Membership is a function of similarity to the average datum in the cluster

11. Resulting Sensor Network
Sample Cluster Representation
Membership becomes a function of power efficiency
Nodes become members of clusters that are the most efficient for communication and sensing

12. Applications of Sensor Networks
Counter Terrorism
Bio-agent detection, remote surveillance, border patrol
Monitor Disaster areas
Traffic Surveillance
Environmental Monitoring
Earthquake Diagnostics
Tsunami Detection
Ecosystem Monitoring
Parking Lot
Identify usage and available spaces
Warfare and Surveillance
Base surveillance
Advance scouting