Excess delay estimation using total received power

• US 8,725,161 B2
• Filed: 12/08/2004
• Issued: 05/13/2014
• Est. Priority Date: 12/08/2003
• Status: Expired due to Fees

• Current Assignee: Koninklijke Philips N.V., Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Rick, Roland Reinhard
• Primary Examiner(s): Shen, Qun
• Application Number:
  US11/569,396
• Publication Number:
  US 20080094277A1
• Time in Patent Office: 3,443 Days
• Field of Search: 455/456, 455/504, 455/456.1, 455/456.5, 455/456.6
• US Class Current: 455/456.1
• CPC Class Codes: G01S 19/06 employing an initial estimate of the location of the receiver as aiding data or in generating aiding data
• CPC Class Codes: G01S 19/46 the supplementary measurement being of a radio-wave signal type
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

To determine the position of a mobile device located within a coverage area of a base station, the time of arrival (TOA) of the CDMA signal received by the mobile device from the base station is reduced in proportion to the received power of the CDMA signal. The mobile device uses the reduced TOA of the CDMA signals together with the received GPS signals to detect its position. Alternatively, the mobile device transmits the TOA and power measurements of the received CDMA signals to a position determination entity (PDE). The PDE biases the TOA to estimate the position of the mobile device and transmits assistance data to the mobile device, thereby enabling the mobile device to receive GPS signals. The received GPS signals alone, or in combination with the biased TOA are then used to recompute the position of the mobile device.

Claims

1. A method comprising, with a mobile device:

receiving a signal from a base station in a wireless communication network;

measuring a time of arrival and a power of the received signal at the mobile device;

determining an excess delay value for the received signal based, at least in part, on an exponential relationship in which the excess delay value increases exponentially as the measured power decreases, the excess delay value representing an additional distance or an additional time that the received signal is estimated to have traveled from the base station to the mobile station with respect to a distance or a time corresponding to a direct line of sight path from the base station to the mobile station,

wherein the exponential relationship is indicative of a likelihood of signal deflection, which increases as a function of a distance traveled from the base station;

generating a biased time of arrival for the received signal based, at least in part, on the measured time of arrival and the excess delay value; and

estimating a position of the mobile device based, at least in part, on the biased time of arrival.

2. The method of claim 1, wherein the exponential relationship is determined, at least in part, by:

E=A exp(−

BP_dBm)

where E represents the time delay, P_dBm represents the received power in dB, and A, B are constants.

3. The method of claim 1, wherein the excess delay value is based, at least in part, on previously gathered data.

4. The method of claim 1, and further comprising transmitting the estimated position to the base station.

5. The method of claim 1, and further comprising:

estimating the position of the mobile device based further, at least in part, on at least one signal received from at least one GPS satellite.

6. A mobile device comprising:

a processing unit or hardware module to;

receive a signal from a base station in a wireless communication network;

measure a time of arrival and a power of the signal;

determine an excess delay value for the received signal based, at least in part, on an exponential relationship in which the excess delay value increases exponentially as the measured power decreases, the excess delay value representing an additional distance or an additional time that the received signal is estimated to have traveled from the base station to the mobile station with respect to a distance or a time corresponding to a direct line of sight path from the base station to the mobile station, wherein the exponential relationship is indicative of a likelihood of signal deflection, which increases as a function of a distance traveled from the base station;

generate a biased time of arrival the received signal based, at least in part, on the measured time of arrival and the excess delay value; and

estimate a position of the mobile device based, at least in part, on the biased time of arrival.

7. The mobile device of claim 6, wherein the exponential relationship is determined, at least in part, by:

E=A exp(−

BP_dBm)

where E represents the time delay, P_dBm represents the received power in dB, and A, B are constants.

8. The mobile device of claim 6, wherein the excess delay value is based, at least in part, on previously gathered data.

9. The mobile device of claim 6, the processing unit or hardware module to further initiate transmission of the estimated position to the base station.

10. An apparatus comprising:

a processing unit or hardware module to;

receive, from a mobile station, a time of arrival and a power for a received signal as measured at the mobile station, the received signal having been previously transmitted-from a base station of a wireless communication network and received by the mobile station;

determine an excess delay value for the received signal based, at least in part, on an exponential relationship in which the excess delay value increases exponentially as the measured power decreases, the excess delay value representing an additional distance or an additional time that the received signal is estimated to have traveled from the base station to the mobile station with respect to a distance or a time corresponding to a direct line of sight path from the base station to the mobile station,

wherein the exponential relationship is indicative of a likelihood of signal deflection, which increases as a function of a distance traveled from the base station;

generate a biased time of arrival the received signal based, at least in part, on the measured time of arrival and the excess delay value; and

estimate a position of the mobile device based, at least in part, on the biased time of arrival.

11. The apparatus of claim 10, wherein the exponential relationship is determined, at least in part, by:

E=A exp(−

BP_dBm)

where E represents the time delay, P_dBm represents the received power in dB, and A, B are constants.

12. The apparatus of claim 10, wherein the excess delay value is based, at least in part, on previously gathered data.

13. The apparatus of claim 10, the processing unit or hardware module to further estimate the position of the mobile device based, at least in part, on at least one signal transmitted by at least one GPS satellite.

14. The apparatus of claim 10, wherein the apparatus comprises a position determination entity.

15. A mobile device comprising:

means for receiving a signal from a base station in a wireless communication network;

means for measuring a time of arrival and a power of the signal;

means for determining an excess delay value for the received signal based, at least in part, on an exponential relationship in which the excess delay value increases exponentially as the measured power decreases, the excess delay value representing an additional distance or an additional time that the received signal is estimated to have traveled from the base station to the mobile station with respect to a distance or a time corresponding to a direct line of sight path from the base station to the mobile station, wherein the exponential relationship is indicative of a likelihood of signal deflection, which increases as a function of a distance traveled from the base station;

means for generating a biased time of arrival for the received signal based, at least in part, on the measured time of arrival and the excess delay value; and

means for estimating a position of the mobile device based, at least in part, on the biased time of arrival.

16. The mobile device of claim 15, wherein the exponential relationship is determined, at least in part, by:

E=A exp(−

BP_dBm)

where E represents the excess delay value, P_dBm represents the received power in dB, and A, B are constants.

17. The mobile device of claim 15, wherein the excess delay value is based, at least in part, on previously gathered data.

18. The mobile device of claim 15, and further comprising means for transmitting the estimated position to the base station.

19. An apparatus comprising:

means for receiving, from a mobile station, a time of arrival and a power for a received signal as measured at the mobile station, the received signal having been previously transmitted from a base station of a wireless communication network and received by the mobile station;

means for determining an excess delay value for the received signal based, at least in part, on an exponential relationship in which the excess delay value increases exponentially as the measured power decreases, the excess delay value representing an additional distance or an additional time that the received signal is estimated to have traveled from the base station to the mobile station with respect to a distance or a time corresponding to a direct line of sight path from the base station to the mobile station, wherein the exponential relationship is indicative of a likelihood of signal deflection, which increases as a function of a distance traveled from the base station;

means for generating a biased time of arrival the received signal based, at least in part, on the measured time of arrival and the excess delay value; and

means for estimating a position of the mobile device based, at least in part, on the biased time of arrival.

20. The apparatus of claim 19, wherein the exponential relationship is determined, at least in part, by:

E=A exp(−

BP_dBm)

where E represents the time delay, Pd_dBm represents the received power in dB, and A, B are constants.

21. The apparatus of claim 19, wherein the excess delay value is based, at least in part, on previously gathered data.

22. The apparatus of claim 19 further comprising means for further estimating the position of the mobile device based, at least in part, on at least one signal transmitted by at least one GPS satellite.