Hybrid Bluetooth/RFID based real time location tracking

• US 20020126013A1
• Filed: 03/08/2001
• Published: 09/12/2002
• Est. Priority Date: 03/08/2001
• Status: Active Grant

• Current Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Bridgelall, Raj
• Granted Patent: US 6,717,516 B2
• Time in Patent Office: Days
• US Class Current: 340/572.1
• CPC Class Codes: G01S 11/02 using radio waves G01S19/00 takes precedence
• CPC Class Codes: G01S 13/765 with exchange of information between interrogator and responder
• CPC Class Codes: G01S 5/0009 Transmission of position information to remote stations involving assistance data G01S5/0236
• CPC Class Codes: G01S 5/12 by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial
• CPC Class Codes: G08B 13/2462 Asset location systems combined with EAS inventory, tracking, logistic G06Q10/00; entrance control systems G07C9/00
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks
• CPC Class Codes: H04W 84/20 Master-slave selection or change arrangements

Abstract

Devices having either wireless data communication capability or RFID tags can be located using dual function fixed devices which are distributed throughout a facility. The devices will identify those units with which they are communicating using a wireless radio data communications protocol and also identify items within the local area using RFID tags on the units.

Claims

1. A method for locating items, comprising:

providing a plurality of distributed fixed devices;

operating each said fixed device as a master units using first wireless data communications protocol, each said master unit controlling slave units within at least one area corresponding to the location of each said fixed device, said operating including identifying said slave units thereby to locate items corresponding to said slave units within said area; and

operating each said fixed device as an RFID reader to identify items having RFID tags within said area.

2. A method as specified in claim 1, further comprising providing items with slave units using said wireless data protocol and RFID tags.

3. A method as specified in claim 1, wherein said fixed device is operated as a master unit and as an RFID reader during alternating time periods.

4. A method as specified in claim 1, wherein said plurality of fixed devices are distributed at intervals corresponding to twice the range of said devices operating as RFID readers.

5. A method as specified in claim 1, wherein said operation to identify and locate items having RFID tags comprises transmitting RFID reader signals, receiving RFID response signals and determining the range of an RFID device from said fixed device using said response signals.

6. A method as specified in claim 5, wherein said range is determined from the phase of said response signals.

7. A method as specified in claim 6, wherein said phase is determined at a plurality of frequencies.

8. A method as specified in claim 1, wherein operating said device as an RFID reader includes transmitting and receiving RFID signals on a directional antenna beam to thereby determine the direction of an RFID device with respect to a fixed device.

9. A system for locating items comprising a plurality of fixed devices distributed over an area and subdividing said area into a plurality of cells, each fixed device corresponding to one or more of said cells, said fixed devices each comprising a transmitter, a receiver and a signal processor, each said fixed devices being arranged to operate as a master unit using a first wireless data communications protocol to communicate with slave units in said one or more cells corresponding to said fixed device to thereby locate items having said slave devices in said one or more cells, and said fixed devices being arranged to operate as RFID tag readers to identify and locate RFID tags on items in said one or more cells.

10. A system as specified in claim 9, wherein said fixed devices are arranged to communicate location data relating to said items having slave units and said items having RFID tags to a host processor.

11. A device comprising:

at least one transmitter;

at least one receiver;

and a processor coupled to provide signals for transmission by said transmitter and coupled to process signals received by said receiver;

said processor including a first program for sending and receiving digital data signals using a first wireless data communication protocol and thereby identifying remote units within range for communication therewith and a second program for sending and receiving RFID reading signals to thereby identify RFID tags within range for identification.

12. A device as specified in claim 11, wherein said second program further provides for determining range from said device to said RFID tags.

13. A device as specified in claim 11, wherein said device includes two transmitters and two receivers for respectively transmitting and receiving wireless data communications signals and RFID signals.

14. A device as specified in claim 13, wherein said two transmitters and two receivers are coupled to said processor by a common baseband signal processor.

15. A device a specified in claim 11, wherein said processor is arranged to cause said device to operate using said first and second program during alternating time intervals.

16. A device as specified in claim 11, wherein said processor is further programmed to provide data identifying said remote units within range and data identifying said RFID tags to a host processor.