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US 12,010,587 B2Granted
Base station synchronization in wireless location systems
AssigneeCenTrak, Inc.
InventorKaruppiah Annamalai
Life of this patent
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Abstract
A system and methods are disclosed for synchronizing two or more groups of base stations in a wireless location system. In one embodiment, a first wireless base station belonging to a first group of wireless base stations transmits a first RF beacon for synchronizing the first group of wireless base stations and a second RF beacon that is used to synchronize a second group of wireless base stations. Wireless base stations in the first and second groups transmit respective non-RF (e.g., infrared, ultrasound, etc.) beacons that can be used to locate a portable tag.
Claims19
An apparatus comprising:
- a first group of wireless base stations comprising a first wireless base station and a second wireless base station that is within RF communication range of the first wireless base station,
- the first wireless base station comprising a first RF transmitter to transmit a first RF beacon and a second RF beacon, and a first non-RF transmitter to transmit a first non-RF beacon that, when received by a portable tag, identifies a first location of the portable tag, and
- the second wireless base station comprising a first RF receiver to receive the first RF beacon, a first clock to synchronize using the first RF beacon, and a second non-RF transmitter to transmit a second non-RF beacon that, when received by the portable tag, identifies a second location of the portable tag;
- and
- a second group of wireless base stations comprising a third wireless base station that is within RF communication range of the first wireless base station and is out of RF communication range of the second wireless base station, and a fourth wireless base station that is within RF communication range of the third wireless base station and is out of RF communication range of the first wireless base station,
- the third wireless base station comprising an RF transceiver to receive the second RF beacon and transmit a third RF beacon, a second clock to synchronize using the second RF beacon, and a third non-RF transmitter to transmit a third non-RF beacon that, when received by the portable tag, identifies a third location of the portable tag, and
- the fourth wireless base station comprising a second RF receiver to receive the third RF beacon transmitted by the third wireless base station, a third clock to synchronize using the third RF beacon transmitted by the third wireless base station, and a fourth non-RF transmitter to transmit a fourth non-RF beacon that, when received by the portable tag, identifies a fourth location of the portable tag.
4 more elements
A method comprising:
- transmitting, by a first wireless base station belonging to a first group of wireless base stations:
- a first RF beacon to a second wireless base station belonging to the first group of wireless base stations, a second RF beacon to a third wireless base station belonging to a second group of wireless base stations, and a first non-RF beacon that, when received by the portable tag, identifies a first location of the portable tag, wherein the third wireless base station is out of RF communication range of the second wireless base station;
- synchronizing, by the second wireless base station, a clock of the second wireless base station using the first RF beacon;
- transmitting, by the second wireless base station, a second non-RF beacon that, when received by the portable tag, identifies a second location of the portable tag;
- receiving, by the third wireless base station, the second RF beacon;
- synchronizing, by the third wireless base station, a clock of the third wireless base station using the second RF beacon;
- transmitting, by the third wireless base station, a third non-RF beacon that, when received by the portable tag, identifies a third location of the portable tag;
- transmitting to a server, by the portable tag, an identifier of the portable tag and an identifier encoded in a non-RF beacon B received by the portable tag, wherein the non-RF beacon B is one of the first non-RF beacon, the second non-RF beacon, the third non-RF beacon, or a fourth non-RF beacon received by the portable tag, and where the fourth non-RF beacon received by the portable tag is transmitted by one of the first wireless base station, the second wireless base station, the third wireless base station, or a fourth wireless base station;
- and
- determining, by the server, a location of the portable tag based on the identifier encoded in the non-RF beacon B received by the portable tag.
7 more elements
Dependencies are inferred from the claim text.