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