Method of providing an estimate of a location

• US 20020008662A1
• Filed: 06/15/2001
• Published: 01/24/2002
• Est. Priority Date: 06/16/2000
• Status: Active Grant

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Yule, Andrew T., Dooley, Saul R., Wilcox, Martin S.
• Granted Patent: US 6,646,603 B2
• Time in Patent Office: Days
• US Class Current: 342/458
• CPC Class Codes: G01S 19/05 providing aiding data
• CPC Class Codes: G01S 19/09 providing processing capability normally carried out by the receiver
• CPC Class Codes: G01S 19/235 Calibration of receiver components
• CPC Class Codes: G01S 19/25 involving aiding data received from a cooperating element, e.g. assisted GPS
• CPC Class Codes: G01S 19/46 the supplementary measurement being of a radio-wave signal type
• CPC Class Codes: G01S 5/0072 Transmission between mobile stations, e.g. anti-collision systems

Abstract

A method of providing an estimate of the location of first and second devices MS1, MS2 comprising the steps of obtaining at least one range measurement from the first device MS1 to a known reference point BS1, GPS SVs; obtaining at least one range measurement from the second device MS2 to a known reference point BS1, GPS SVs, the second device MS2 being located near to the first device MS1; and calculating an estimate of the location of the devices MS1, MS2 using range measurements obtained in respect of both the first and second devices MS1, MS2.

Claims

1. A method of providing an estimate of the location of first and second devices comprising the steps of:

obtaining at least one range measurement from the first device to a known reference point;

obtaining at least one range measurement from the second device to a known reference point, the second device being located near to the first device; and

calculating an estimate of the location of the devices using range measurements obtained in respect of both the first and second devices.

2. A method according to claim 1 wherein the or each range measurement obtained in respect of the second device and for each such range measurement an indication of the associated reference point is provided to the first device for calculating an estimate of the location of the devices.

3. A method according to claim 2 wherein the or each range measurement obtained in respect of the second device and for each such range measurement an indication of the associated reference point is provided to the first device using a wireless communications link.

4. A method according to claim 2 or claim 3 wherein the estimate of the location of the devices is provided from the first device to the second device.

5. A method according to any of claims 2 to 4 wherein the first and second devices have reciprocal functionality in that the or each range measurement obtained in respect of the first device and for each such range measurement an indication of the associated reference point may also be provided to the second device for calculating an estimate of the location of the devices.

6. A method according to claim 1 wherein the or each range measurement obtained in respect of both the first and second devices and for each such range measurement an indication of the associated reference point is provided to a third device for calculating an estimate of the location of the first and second devices.

7. A method according to any preceding claim wherein it is impossible to unambiguously determine the location of the first device using only its range measurements.

8. A method according to any preceding claim wherein it is impossible to unambiguously determine the location of the second device using only its range measurements.

9. A method according to any preceding claim wherein at least one range measurement obtained in respect of either the first or the second device is a pseudorange range measurement.

10. A method according to claim 9 wherein the position determining means of the second device includes a GPS receiver;

and wherein at least two range measurements obtained in respect of the second device are pseudorange measurements from a GPS SV.

11. A method according to claim 10 wherein the position determining means of the first device also includes a GPS receiver;

wherein at least two range measurements obtained in respect of the first device are pseudorange measurements from a GPS SV; and

wherein at least 5 pseudorange are obtained in respect of either the first or the second device in total.

12. A method according to claim 10 or claim 11 wherein in order to calculate an estimate of the location of the first device using pseudorange measurements obtained in respect of both first and second devices, clocks errors of both the first and second devices are resolved.

13. A method according to claim 9 wherein the position determining means of the first and second device both includes a GPS receiver;

wherein a single range measurement obtained in respect of either the first or second device is a pseudorange measurement from a GPS space vehicles (SV); and

wherein the first and second device are synchronised.

14. A method according to any preceding claim wherein at least one range measurement obtained in respect of either the first or the second device is a range measurement to a ground based reference point.

15. A method according to claim 14 wherein at least one range measurement obtained in respect of either the first or the second device is an absolute range measurement determined by a time-of-arrival measurement with respect to a fixed base station.

16. A method according to claim 15 wherein either the first or the second device is a mobile cellular telephone able to communicate directly with the other device using a wireless communications link which is independent of any cellular basestation network;

and wherein the time-of-arrival measurement is provided from the mobile cellular telephone and a cellular telephone network basestation.

17. A method according to any preceding claim wherein for at least one range measurement, the indication of the associated reference point is in the form of a position co-ordinate.

19. A device able to provide an estimate of its location by a method according to any of the preceding claims.

18. A method of providing an estimate of the location of first and second devices substantially as hereinbefore described with reference to the accompanying drawings.

20. A device able to provide an estimate of its location comprising ranging means for obtaining at least one range measurement from the device to a known reference point;

a receiver for receiving ranging information relating to at least one range measurement from another device located near to the device to a known reference point; and

a processor for calculating an estimate of the location of the device using range measurements obtained by both its ranging means and from the ranging information.

21. A device according to claim 20 further comprising a transmitter for transmitting the estimate of the location of the devices to the nearby device.

22. A device according to claims 20 further comprising a transmitter wherein upon receiving a request for ranging information from another device located nearby the device transmits its range measurements together with an indication of the associated reference point to that device.

23. A device according to any of claims 20 to 22 wherein the ranging means is adapted to obtaining at least one pseudorange measurement.

24. A device according to claim 23 wherein the processor is adapted to calculate an estimate of the location of the device using pseudorange measurements obtained by both its ranging means and from the ranging information.

25. A device according to claim 24 wherein the processor is adapted to resolve clocks errors associated with pseudorange measurements obtained by both its ranging means and from the ranging information.

26. A device according to claims 20 to 26 wherein the ranging means includes a GPS receiver.

27. A device according to claims 20 to 26 in the form of a mobile cellular telephone able to communicate directly with the another device located nearby using a wireless communications link which is independent of any cellular basestation network.

28. A device according to claim 27 wherein the cellular telephone is adapted to provide a time-of-arrival measurement from the mobile cellular telephone to a cellular telephone network basestation.

29. A device able to provide an estimate of its location substantially as hereinbefore described with reference to the accompanying drawings.

30. A method of determining the position of a first GPS receiver with the assistance of a second, portable GPS receiver comprising the steps of:

acquiring GPS signals in the first GPS receiver and deriving GPS signal information therefrom;

providing the GPS signal information from the second GPS receiver to the first GPS receiver; and

acquiring GPS signals in the first GPS receiver using the GPS signal information provided by the second GPS receiver.

31. A method according to claim 30 wherein the first and second GPS receivers have reciprocal functionality in that the first GPS receiver may also acquire GPS signals and derive GPS signal information therefrom, and provide GPS signal information to the second GPS receiver;

and that the second GPS receiver may acquire GPS signals using the GPS signal information provided by the first GPS receiver.

32. A method according to claim 30 or claim 31 wherein the second GPS receiver is unable to determine its position.

33. A portable GPS receiver unit comprising a GPS receiver and a communication transmitter and receiver for communicating with another GPS receiver unit located nearby;

wherein the GPS receiver unit has a first mode of operation in which the GPS receiver acquires GPS signals and derives GPS signal information therefrom, and the communications transmitter transmits the GPS information to a nearby GPS receiver unit.

34. A portable GPS receiver unit according to claim 33 wherein the GPS receiver unit has a second mode of operation in which the communications receiver receives GPS signal information from another GPS receiver unit located nearby and the GPS receiver acquires GPS signals using the GPS signal information provided.

35. A portable GPS receiver unit according to claim 33 or claim 34 wherein, in the first mode of operation, the communications transmitter transmits the GPS information to a nearby GPS receiver unit wherein the portable GPS receiver unit is unable to determine its position.