Low-Energy GPS

• US 20120146850A1
• Filed: 12/09/2010
• Published: 06/14/2012
• Est. Priority Date: 12/09/2010
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Inventors: Liu, Jie, Priyantha, Nissanka Arachchige Bodhi, Filho, Heitor Soares Ramos
• Granted Patent: US 9,684,080 B2
• Time in Patent Office: Days
• US Class Current: 342/357.42
• CPC Class Codes: G01S 19/09 providing processing capability normally carried out by the receiver
• CPC Class Codes: G01S 19/34 Power consumption

Abstract

This document describes various techniques for implementing low-energy GPS on a mobile device. A GPS module is activated, a sub-millisecond pseudo-range estimate is received from the GPS module, the GPS module is deactivated, the sub-millisecond pseudo-range estimate and a time stamp are transmitted to a remote entity, and location information based on the sub-millisecond pseudo-range estimate and time stamp is received from the remote entity.

Claims

1. A method comprising:

activating, at a first point in time, a global positioning system (GPS) module configured to receive GPS signals;

receiving, from the GPS module, a sub-millisecond pseudo-range estimate based on GPS signals received, and a time at which the GPS signals are received by the GPS module corresponding to a time stamp;

deactivating, at a second point in time, the GPS module after receiving the sub-millisecond pseudo-range estimate, the second point in time occurring after the time indicated by the time stamp;

concurrently transmitting the sub-millisecond pseudo-range estimate and the time stamp to a remote entity; and

receiving, from the remote entity, location information based on the sub-millisecond pseudo-range estimate and the time stamp.

2. The method as recited in claim 1, wherein the location information received from the remote entity includes positional coordinates or data associated with a location-based service.

3. The method as recited in claim 1, wherein the act of receiving the sub-millisecond pseudo-range estimates receives a plurality of sub-millisecond pseudo range estimates from the GPS module.

4. The method as recited in claim 3, further comprising averaging the received sub-millisecond pseudo range estimates to produce an average sub-millisecond pseudo range estimate and wherein the act of transmitting transmits the average sub-millisecond pseudo-range estimate.

5. The method as recited in claim 3, further comprising transmitting pseudo-random noise (PRN) numbers of GPS satellites associated with the sub-millisecond pseudo range estimates.

6. The method as recited in claim 1, wherein an amount of time elapsing between the first point in time and the second point in time is 11 milliseconds.

7. The method as recited in claim 1, further comprising transmitting information relating to an approximate location to the remote entity and wherein the received location information is based on the sub-millisecond pseudo-range estimate, the time stamp, and the information relating to the approximate location.

8. The method as recited in claim 7, wherein the approximate location is based on previously received location information, a unique identifier of a cell-tower, or a media access address of a wireless network access-point.

9. The method as recited in claim 1, wherein the act of transmitting transmits data using free space of a data packet queued for transmission.

10. A method comprising:

concurrently receiving, from a remote entity, a sub-millisecond pseudo-range estimate associated with GPS signals received by the remote entity, a time stamp corresponding to the sub-millisecond pseudo-range estimate that indicates when the GPS signals were received by the remote entity, and information relating to an approximate location of the remote entity;

determining a position of the remote entity based on the information relating to the approximate location of the remote entity, the sub-millisecond pseudo-range estimate, and the corresponding time stamp; and

transmitting location information to the remote entity based on the determined position.

11. The method as recited in claim 10, wherein the sub-millisecond pseudo-range estimate is an average of sub-millisecond pseudo-range estimates.

12. The method as recited in claim 10, wherein the act of receiving receives a plurality of sub-millisecond pseudo-range estimates.

13. The method as recited in claim 10, wherein the information relating to an approximate location is based on a previously determined position, a unique identifier of a cell-tower, or a media access address of a wireless network access-point.

14. The method as recited in claim 10, wherein the location information includes positional coordinates of the determined position of the remote entity or information associated with a location-based service.

15. The method as recited in claim 10, wherein the location information is information relating to entities proximate the determined position of the remote entity.

16. A mobile device comprising:

a low-energy GPS engine capable of;

duty-cycling a GPS module configured to receive GPS signals at less than a ten percent duty cycle, the duty cycle having a period of one second; and

providing sub-millisecond pseudo-range estimates based on received GPS signals and a time stamp corresponding to the sub-millisecond pseudo-range estimates that indicates a reception time at the GPS module of the received GPS signals, the reception time indicated by the time stamp occurring during an active portion of the GPS module'"'"'s duty cycle; and

a service data relay capable of;

concurrently transmitting the sub-millisecond pseudo-range estimates and the corresponding time stamp to a remote entity over a wireless interface; and

receiving data associated with a location-based service from the remote entity over the wireless interface.

17. The mobile device recited in claim 16, wherein the GPS module is duty cycled at less than a five-percent duty cycle.

18. The mobile device as recited in claim 16, wherein the GPS module is duty cycled at a one-percent duty cycle.

19. The mobile device as recited in claim 16, wherein the low-energy GPS engine is further capable of providing information relating to an approximate location of the mobile device and the service data relay is further capable of transmitting the information relating to an approximate location of the mobile device to the remote entity over the wireless interface.

20. The mobile device as recited in claim 19, wherein the information relating to an approximate location of the mobile device is based on previously received location data, a unique identifier of a cell-tower, or a media access address of a wireless network access-point.