RFID tag assisted GPS receiver system

• US 8,743,699 B1
• Filed: 11/24/2010
• Issued: 06/03/2014
• Est. Priority Date: 05/07/2010
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Finlow-Bates, Keir, Viskari, Joonas V. T., Ngo, Terry FK
• Primary Examiner(s): HUYNH, KHOA B
• Application Number:
  US12/954,490
• Time in Patent Office: 1,287 Days
• Field of Search: None
• US Class Current: 370/241
• CPC Class Codes: G01S 1/68 Marker, boundary, call-sign, or like beacons transmitting signals not carrying directional information
• CPC Class Codes: G01S 19/05 providing aiding data
• CPC Class Codes: G01S 19/10 providing dedicated supplementary positioning signals

Abstract

A system and method are disclosed for improving the speed of operation and accuracy of GPS receivers. The system comprises a RFID assisted GPS (RAGPS) receiver and geographically dispersed RFID assistance tags. The RAGPS receiver and the RFID assistance tags store location data comprising current location estimate, almanac, and ephemeris data. The location data is time stamped. The RFID assisted GPS (RAGPS) receiver comprises a GPS receiver, a RFID tag reader, a RFID transmitter and a controller. The controller comprises software that transfers the location data to and from the RAGPS receiver and a RFID assistance tag. The method discloses the RAGPS receivers reading up-to-date location data from a nearby RFID assistance tags and similarly if the RAGPS receivers have up-to-date location data already, the RAGPS receivers may write that location data to a nearby assistance tags that lacks up-to-date location data.

Claims

1. A radio frequency identification assisted global positioning system (RAGPS) receiver comprising:

a global positioning system (GPS) receiver to receive up-to-date location data;

a radio frequency identification (RFID) subsystem including an RFID tag reader and a RFID transmitter, the RFID tag reader to read location data stored in a RFID assistance tag in communication with the RAGPS receiver, the RFID transmitter to transmit up-to-date location data to the RFID assistance tag, wherein the RFID assistance tag is positioned in a location in which GPS signals are blocked; and

a controller in communication with the GPS receiver and the RFID subsystem, the controller to determine whether the RFID assistance tag stores location data that is more up-to-date than location data stored in the RAGPS receiver, the location data stored in the RFID assistance tag including a timestamp having both an update time and an expiration time;

wherein the controller is further configured to (i) cause the RFID transmitter to transmit location data to the RFID assistance tag if the location data stored in the RAGPS receiver is more up-to-date than the location data stored in the RFID assistance tag, and (ii) transfer the location data stored in the RFID assistance tag to the GPS receiver if the location data stored in the RFID assistance tag is more up-to-date than the location data stored in the RAGPS receiver.

2. The RAGPS receiver of claim 1, wherein the location data stored in the RFID assistance tag further includes a current location estimate designating an estimated longitude and latitude of the RFID assistance tag, and ephemeris data and almanac data related to previous locations of orbiting GPS satellites associated with the current location estimate.

3. The RAGPS receiver of claim 2, wherein in response to the timestamp indicating that the location data stored in the RFID tag is expired, the controller determines whether the ephemeris data is usable to estimate updated ephemeris data for the orbiting GPS satellites associated with the current location estimate.

4. The RAGPS receiver of claim 3, wherein in response to determining that the ephemeris data is usable, estimating updated ephemeris data for the orbiting GPS satellites.

5. The RAGPS receiver of claim 1, wherein the controller is further configured to cause the RFID transmitter to overwrite expired location data stored in the RFID assistance tag.

6. The RAGPS receiver of claim 1, wherein the location data stored in the RAGPS receiver is updated by a network connection.

7. The RAGPS receiver of claim 1, wherein the location data stored in the RAGPS receiver is updated by GPS satellites.

8. The RAGPS receiver of claim 1, wherein the RAGPS receiver comprises one or more integrated circuits.

9. The RAGPS receiver of claim 1, wherein the RFID assistance tag comprises one or more integrated circuits.

10. A method for updating location data, the method being performed by a radio frequency identification assisted global positioning system (RAGPS) receiver that includes a global positioning system (GPS) receiver, the method comprising:

determining whether a radio frequency identification (RFID) assistance tag is in range of the RAGPS receiver, the RFID assistance tag being positioned in a location in which GPS signals are blocked, the RFID assistance tag storing location data including a timestamp having both an update time and an expiration time;

connecting to the RFID assistance tag if the RFID assistance tag is in range;

determining an up-to-date status of the location data stored in the RFID assistance tag by comparing location data stored in the RAGPS receiver to the location data stored in the RFID assistance tag;

transmitting location data to the RFID assistance tag if the location data stored in the RAGPS receiver is more up-to-date than the location data stored in the RFID assistance tag; and

transferring the location data stored in the RFID assistance tag to the GPS receiver if the location data stored in the RFID assistance tag is more up-to-date than the location data stored in the RAGPS receiver.

11. The method of claim 10 wherein the location data stored in the RFID assistance tag further includes a current location estimate designating an estimated longitude and latitude for the RFID assistance tag, and ephemeris and almanac data related to previous locations of orbiting GPS satellites associated with the current location estimate.

12. The method of claim 11, further comprising:

in response to determining that the location data stored in the RFID assistance tag is up-to-date;

reading the current location estimate of the RFID assistance tag and a number of previous RAGPS receivers that have contributed to the current location estimate of the RFID assistance tag;

determining a longitude difference between a longitude stored in the RAGPS receiver and the estimated longitude of the RFID assistance tag;

calculating a new longitude for the RFID assistance tag by adding the estimated longitude of the RFID assistance tag to the longitude difference divided by the number of previous RAGPS receivers;

determining a latitude difference between a latitude stored in the RAGPS receiver and the estimated latitude of the RFID assistance tag;

calculating a new latitude for the RFID assistance tag by adding the estimated latitude of the RFID assistance tag to the latitude difference divided by the number of previous RAGPS receivers; and

transmitting the new longitude and new latitude to the RFID assistance tag as a part of an updated current location estimate.

13. The method of claim 11, wherein in response to determining that neither the RAGPS receiver nor the RFID assistance tag store up-to-date location data, disconnecting with the RFID assistance tag.

14. The method of claim 11, wherein determining the up-to-date status of the location data stored in the RFID assistance tag includes individually comparing the current location estimate, the ephemeris data, and the almanac data stored in the RFID assistance tag to the location data stored in the RAGPS receiver, and individually determining an up-to-date status for each of the current location estimate, the ephemeris data, and the almanac data from the individual comparisons.

15. The method of claim 14, further comprising:

in response to individually determining the up-to date status for each of the current location estimate, the ephemeris data, and the almanac data, individually updating at least one of the RFID assistance tag or the RAGPS receiver with a respective up-to-date current location estimate, respective up-to-date ephemeris data, and respective up-to-date almanac data.

16. The method of claim 11, wherein in response to the timestamp indicating that the location data stored in the RFID tag is expired, determining whether the expired ephemeris data is usable to estimate updated ephemeris data for the orbiting GPS satellites.

17. The method of claim 16, wherein in response to determining that the ephemeris data is usable, estimating updated ephemeris data for the orbiting GPS satellites.

18. The method of claim 10, further comprising:

overwriting the location data stored in the RFID assistance tag if the up-to-date status indicates that the location data stored in the RFID assistance tag is expired.