Patent ID: 8139945
Filing Date: 2012-03-20
Classification: G01S,H04B,H04W

Abstract:
1. A system for determining a location and an identity of a portable device, the system comprising: a plurality of stationary infrared (IR) base stations, the plurality of IR base stations being configured to receive timing synchronization information and to concurrently transmit corresponding IR location codes in a common time period based on the received timing synchronization information, each IR location code representative of a location of the corresponding IR base station; a plurality of portable devices, at least one portable device configured to 1) receive the timing synchronization information, 2) enter a sleep mode, 3) enter a wake-up mode in the common time period to detect the IR location codes concurrently transmitted by the IR base stations and 4) if one of the IR location codes is detected, transmit an output signal including a portable device ID representative of the portable device and the detected IR location code; and at least one RF transceiver configured to periodically transmit beacons in predetermined time slots to the plurality of IR base stations and the plurality of portable devices, the beacons including the timing synchronization information and respective time delay information relative to a unified time of origin.