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.
4.Related Problem and Method
Collision of RF transmissions from different beacons
Wrong correlation of the RF data of one beacon with the ultrasonic signal of another
------ System parameters
------ Listener Inference Algorithms
5.use a relatively sluggish RF data transmission rate.
System Parameters Selection
Align the beacons
Using RF signal with long range
Ensure less than 5 beacons within range of each other
7.Listener Inference Algorithm
Picks the beacon with highest frequency of occurrence
Selects the beacon with the minimum mean value
Compute the per-beacon statistical mode over the past n samples.
8.Implementation :Beacon Positioning and Configuration
9.Implementation :Ultrasound Deployment
10.Experiment: Boundary Performance
11.Experiment: Static Performance
12.Experiment: Static Performance (Cont)
13.Experiment: Mobile Performance
Concerns when apply to sensor network
Calibration On the Transmitter.
Kalman Filter for the Mobile Algorithm