PowerPoint Department of Computer Science
National Tsing Hua University

1
Outline
Introduction
Goal
Guiding navigation is one of the major applications in WSNs.
Destination
Destination
Goals
Less congested paths to minimize
The escape time
The congestion time
Each sensor knows the distances to each exit
Each road section is equipped with one sensor and indicator
Responsible for sensing dangerous events
Detecting the number of moving objects
We assume each sensor knows the area of its own road and the distances to each exit.
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The indicator is used for showing the guiding information
Fluent degree
Initialization phase
Computation phase
Maintenance phase
No people and emergency event
Each exit sensor on an exit has a constant maximal potential value
It starts broadcasting an initial packet
A maximum moving speed of an object
The distance from sensori to an exite
The exit capacity
Flow-Based Guiding Protocol
d =The number of people/square meters
Flow-Based Guiding Protocol
The dangerous area will spread among adjacent roads
If the objects are too close to the dangerous area, they probably enter the dangerous area
The average of all of neighbor
potential value
Flow-Based Guiding Protocol
If φ is high, the escaping paths will be further away from dangerous areas.
If φ is low, the escaping paths go along the side of dangerous areas.
Flow-Based Guiding Protocol
Ping-pong effect
The standard deviation of ptlneighbors
A weighted constant and 0 << 1
sensorsensor
~
The events flow velocity
Simulation
Guide moving objects to exits safely and quickly
Decrease the escaping time and congestion time
Balance the traffic load on paths and exits
Thank You