Patent ID: 7499376
Filing Date: 2009-03-03
Classification: G01S

Abstract:
1. A method for position awareness, comprising the steps of: (a) calculating initial position coordinates using beacon information received from adjacent beacons in response to a broadcast beacon solicitation signal, sending a synchronization signal to the beacons, and synchronizing the beacons; (b1) periodically broadcasting a start message, which is an ultrasonic signal, and activating the adjacent beacons; (b2) receiving the ultrasonic waves generated in time frames assigned in order of numbered identifications (IDs) of beacons after the activated beacons are synchronized by time compensation; (b3) updating information on a distance between a receiver and a beacon using the received ultrasonic waves, transmitting the distance information to a user device and a context awareness server, and calculating the position coordinates; and (c) when the calculated position coordinates correspond to a predetermined hand-off threshold position, transmitting a hand-off process message to a newly activated beacon, and executing a hand-off process routine.