The Cricket Location-Support System
By: Min Chen10/28/03
Goal
User PrivacyDecentralized administrationNetwork heterogeneityLow costRoom-sized granularity
System ArchitectureBeacon:
Disseminate the string of space information about a geographic space to listeners.Listener: Infer its current location from the set of beacons .
Use combination of RF and ultrasound to provide a location-support service to users.
Approach
Related Problem and Method
Collision of RF transmissions from different beacons
------------Randomization Wrong correlation of the RF data of one beacon with the ultrasonic signal of another
------ System parameters ------ Listener Inference Algorithms
use a relatively sluggish RF data transmission rate.
System Parameters Selection
Interference ScenariosRF-A:US-RA Align the beacons
RF-A:US-I Using RF signal
with long range
RF-A:US-RI Ensure less than 5
beacons within range of each other
Listener Inference Algorithm
Majority Picks the beacon with highest
frequency of occurrenceMinMean Selects the beacon with the minimum
mean valueMinMode Compute the per-beacon statistical
mode over the past n samples.
Implementation :Beacon Positioning and Configuration
Implementation :Ultrasound Deployment
Experiment: Boundary Performance
Experiment: Static Performance
Experiment: Static Performance (Cont)
Experiment: Mobile Performance
Comments
Concerns when apply to sensor network
2D Constrain
Power Consideration
Calibration On the Transmitter.
Kalman Filter for the Mobile Algorithm
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