Determining wireless device locations

• US 20030001776A1
• Filed: 06/29/2001
• Published: 01/02/2003
• Est. Priority Date: 06/29/2001
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Hannah, Eric C., Tennenhouse, David L.
• Granted Patent: US 6,618,005 B2
• Time in Patent Office: Days
• US Class Current: 342/387
• CPC Class Codes: G01S 1/24 the synchronised signals being pulses or equivalent modulations on carrier waves and the transit times being compared by measuring the difference in arrival time of a significant part of the modulations , e.g. LORAN systems
• CPC Class Codes: G01S 5/0081 Transmission between base stations
• CPC Class Codes: G01S 5/021 Calibration, monitoring or correction G01S5/0252 takes precedence
• CPC Class Codes: G01S 5/02216 Timing or synchronisation of the receivers
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: G01S 5/145 Using a supplementary range measurement, e.g. based on pseudo-range measurements

Abstract

Wireless network devices can obtain their geographical location by triangulating with access points that have precise time information. In response to a location prompt, a wireless device can send a transmission to multiple access points that are within its range. The different times at which the transmission is received at different access points can be collected and forwarded to a server, which can compute the location of the wireless device using triangulation techniques. The access points can calibrate their own time bases from time services received from global position satellites.

Claims

1. A system, comprising:

first, second and third wireless access points, each having synchronized time information derived from a common time base;

a wireless mobile device to broadcast a time signal to each of the first, second and third access points; and

a server coupled to the first, second and third access points through communications links to receive data on when the time signal was received at each of the first, second and third access points and to derive positional information on the wireless mobile device from the data.

2. The system of claim 1, wherein:

the common time base is derived from a satellite-based global position system.

3. The system of claim 1, wherein:

the time signal is a ping signal transmitted simultaneously to each of the first, second, and third access points.

4. The system of claim 1, wherein:

the server is to derive positional information by using triangulation techniques based on the data from the first, second and third access points.

5. The system of claim 1, wherein:

the wireless mobile device includes an Internet browser.

6. An apparatus, comprising:

a wireless communication interface to communicate with first, second and third wireless access points; and

logic coupled to the wireless communication interface to broadcast a ping signal to the first, second and third access points.

7. The apparatus of claim 6, further comprising an Internet browser.

8. The apparatus of claim 6, wherein:

the apparatus is a mobile apparatus.

9. A method, comprising:

broadcasting a ping signal from a mobile device to first, second, and third wireless access points;

determining a first time value, representing when the ping signal is received at the first access point and based on a first clock synchronized with a common time base;

determining a second time value, representing when the ping signal is received at the second access point and based on a second clock synchronized with the common time base;

determining a third time value, representing when the ping signal is received at the third access point and based on a third clock synchronized with the common time base; and

determining a location of the mobile device based on the first, second and third time values and on locations of the first, second, and third access points.

10. The method of claim 9, wherein:

determining the location of the mobile device includes;

transmitting the first, second, and third time values from the first, second, and third access points to a server; and

calculating, in the server, the location of the mobile device.

11. The method of claim 9, further comprising:

transmitting the location of the wireless mobile device to the wireless mobile device.

12. The method of claim 9, wherein:

the common time base is derived from a satellite global position system.

13. The method of claim 9, wherein:

broadcasting the ping signal is in response to receiving a request for a ping signal.

15. The method of claim 14, further comprising:

transmitting the location of the mobile device.

16. The method of claim 14, further comprising:

transmitting the location of the mobile device to the mobile device.

17. The method of claim 14, wherein:

the first, second and third time values are derived from a common time base.

19. The method of claim 18, further comprising:

transmitting a ping request to the wireless mobile device.

20. The method of claim 18, further comprising:

receiving the location of the wireless mobile device from the computer system.

21. The method of claim 20, further comprising:

transmitting the location of the wireless mobile device to the wireless mobile device.

14. A method, comprising:

receiving a first time value from a first wireless access point;

receiving a second time value from a second wireless access point;

receiving a third time value from a third wireless access point;

determining a first location of the first wireless access point;

determining a second location of the second wireless access point;

determining a third location of the third wireless access point; and

determining a location of a mobile device based on the first, second and third time values and the first, second and third locations.

18. A method, comprising:

receiving a ping signal from a wireless mobile device;

determining a time value representing when the ping signal was received based on a clock synchronized with clocks in other apparatuses; and

transmitting the time value to a computer system that receives other time values from the other apparatuses and calculates a physical location of the wireless mobile device.

22. A method, comprising:

transmitting pseudo-GPS signals from multiple pseudo-GPS transmitters to a mobile device;

receiving the pseudo-GPS signals at the mobile device; and

calculating a location of the mobile device from timing values derived from the pseudo-GPS signals.

23. The method of claim 22, further comprising:

receiving GPS signals at the pseudo-GPS transmitters from GPS satellites; and

calculating locations of the pseudo-GPS transmitters.

24. The method of claim 22, further comprising:

transmitting the location of the mobile device to a controlling access point.

25. The method of claim 24, further comprising:

transmitting the location of the mobile device from the controlling access point to a server.

27. The medium of claim 26, further comprising:

transmitting a ping request to the wireless mobile device.

28. The medium of claim 26, further comprising:

receiving the location of the wireless mobile device from the computer system.

29. The medium of claim 28, further comprising:

transmitting the location of the wireless mobile device to the wireless mobile device.

26. A machine-readable medium, having instructions stored thereon for execution by at least one processor, said instructions capable of directing the at least one processor to perform operations comprising:

receiving a ping signal from a wireless mobile device;

determining a time value representing when the ping signal was received based on a clock synchronized with clocks in other apparatuses; and

transmitting the time value to a computer system that receives other time values from the other apparatuses and calculates a physical location of the wireless mobile device.