Wireless terminal location using apparatus and methods employing carrier diversity

• US 7,233,800 B2
• Filed: 10/12/2005
• Issued: 06/19/2007
• Est. Priority Date: 10/14/2004
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Laroia, Rajiv, Li, Junyi
• Primary Examiner(s): D AGOSTA, STEPHEN M
• Application Number:
  US11/249,015
• Publication Number:
  US 20060089154A1
• Time in Patent Office: 615 Days
• Field of Search: 455/414.1, 455/414.2, 455/456.1, 455/456.2, 455/456.3, 455/456.5, 455/456.6, 455/457, 370/331, 370/332, 370/333, 370/334
• US Class Current: 455/456.1
• CPC Class Codes: F01D 9/023 Transition ducts between combustor cans and first stage of the turbine in gas-turbine engines; their cooling or sealings
• CPC Class Codes: G01S 5/0226 Transmitters
• CPC Class Codes: G01S 5/0252 Radio frequency fingerprinting
• CPC Class Codes: G06Q 10/00 Administration; Management
• CPC Class Codes: H04B 17/27 for locating or positioning the transmitter
• CPC Class Codes: H04B 17/327 Received signal code power [RSCP]
• CPC Class Codes: H04B 7/022 Site diversity; Macro-diversity using two or more spaced independent antennas H04B7/04
• CPC Class Codes: H04B 7/12 Frequency diversity
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 48/08 Access restriction or access information delivery, e.g. discovery data delivery signalling during connection H04W76/00
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 52/16 Deriving transmission power values from another channel
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

Wireless terminals, e.g., mobile nodes, receive, identify, and measure broadcast signals from a plurality of cells. They determine relative transmission power relationships corresponding to the received measured signals and determine at least two channel gain ratios. A geographic area is determined corresponding to the obtained at least two channel gain ratios and information indicating the geographic region in which such gain ratios may be detected. Each cell'"'"'s base station transmits broadcast signals, e.g., beacon signals, pilot signals, and/or assignment signals for one more carriers. Some base stations use multiple carriers at different power levels. Some adjacent cells use different power levels for the same carrier. This carrier diversity approach tends to reduce overall interference in the system, yet provides mobiles with a variety of different strength signals which may be monitored and which vary as a function of distance from the source transmitter.

Claims

1. A method of operating a wireless communications device to perform a location determination operation, the method comprising:

receiving first, second and third signals from first, second and third base stations, respectively, said first and second signals corresponding to first and second carrier frequencies, respectively, said first and second carrier frequencies being different; and

determining at least two channel gain ratios, said at least two channel gain ratios including a first channel gain ratio and a second channel gain ratio, the first channel gain ratio being a ratio of a first channel gain to a second channel gain, the first channel gain being a channel gain between said first base station and said wireless communications device, the second channel gain being a channel gain between said second base station and said wireless communications device; and

determining a geographic area which corresponds to said at least two determined channel gain ratios;

wherein determining at least two channel gain ratios includes using information indicative of the relative transmission power of the first, second, and third signals transmitted by said first, second, and third base stations, respectively; and

wherein the relative transmission power between said first and second base stations and ii) said second and third base stations is predetermined, said step of determining at least two channel gain ratios including accessing stored information indicating the power relationship.

2. The method of claim 1, wherein receiving said first, second and third signals includes receiving from said first base station a first plurality of signals corresponding to different carriers, and

selecting the strongest one of said first plurality of signals to be said first signal.

3. The method of claim 1, wherein receiving said first, second and third signals includes receiving from said second base station a second plurality of signals corresponding to different carriers, and

selecting the strongest one of said second plurality of signals to be said second signal.

4. The method of claim 1, wherein receiving said first, second and third signals includes receiving from said third base station a third plurality of signals corresponding to different carriers, and

selecting the strongest one of said third plurality of signals to be said third signal.

5. The method of claim 1, wherein said determining a geographic area includes communicating the calculated first and second channel gain ratios to a network node;

and

receiving from said network node geographic location information determined based on the transmitted gain information.

6. The method of claim 1 wherein said determining a geographic area includes:

accessing stored information indicating the geographic location of said first, second, and third base stations; and

determining geographic location information using said retrieved base station location information and said determined at least two channel gain ratios.

7. The method of claim 6, further comprising:

prior to said step of receiving first, second and third signals, storing information indicating the geographic location of said first second and third base stations.

8. The method of claim 1, wherein said first, second and third signals are orthogonal frequency division multiplexing (OFDM) signals.

9. A method of operating a wireless communications device to perform a location determination operation, the method comprising:

receiving first, second and third signals from first, second and third base stations, respectively, said first and second signals corresponding to first and second carrier frequencies, respectively, said first and second carrier frequencies being different; and

determining at least two channel gain ratios, said at least two channel gain ratios including a first channel gain ratio and a second channel gain ratio, the first channel gain ratio being a ratio of a first channel gain to a second channel gain, the first channel gain being a channel gain between said first base station and said wireless communications device, the second channel gain being a channel gain between said second base station and said wireless communications device; and

determining a geographic area which corresponds to said at least two determined channel gain ratios, wherein determining at least two channel gain ratios includes using information indicative of the relative transmission power of the first, second, and third signals transmitted by said first, second, and third base stations, respectively; and

wherein each of said first, second and third signals is a single tone signal over a time interval less than 3 OFDM symbol transmission periods in duration.

10. The method of claim 9,

wherein the relative transmission power between said first and second;

and said second and third base station is predetermined, said step of determining at least two channel gain ratios including accessing stored information indicating the power relationship.

11. The method of claim 10, further comprising:

prior to said step of receiving first, second and third signals, storing information indicating the power relationship.

12. The method of claim 9 further comprising:

receiving broadcast information about the transmission power level used by said first base station;

receiving broadcast information about the transmission power level used by said second base station; and

receiving broadcast information about the transmission power level used by said third base station.

13. A method of operating a wireless communications device to perform a location determination operation, the method comprising:

receiving broadcast information about the transmission power level used by said first base station;

receiving broadcast information about the transmission power level used by said second base station;

receiving broadcast information about the transmission power level used by said third base station;

receiving first, second and third signals from first, second and third base stations, respectively, said first and second signals corresponding to first and second carrier frequencies, respectively, said first and second carrier frequencies being different; and

determining at least two channel gain ratios, said at least two channel gain ratios including a first channel gain ratio and a second channel gain ratio, the first channel gain ratio being a ratio of a first channel gain to a second channel gain, the first channel gain being a channel gain between said first base station and said wireless communications device, the second channel gain being a channel gain between said second base station and said wireless communications device;

determining a geographic area which corresponds to said at least two determined channel gain ratios, wherein determining at least two channel gain ratios includes using information indicative of the relative transmission power of the first, second, and third signals transmitted by said first, second, and third base stations, respectively; and

wherein said broadcast information about said first, second, and third transmission power levels is transmitted by a single one of said first, second, and third base stations.

14. A method of operating a wireless communications device to perform a location determination operation, the method comprising:

receiving broadcast information about the transmission power level used by said first base station;

receiving broadcast information about the transmission power level used by said second base station; and

receiving broadcast information about the transmission power level used by said third base station;

receiving first, second and third signals from first, second and third base stations respectively, said first and second signals corresponding to first and second carrier frequencies, respectively, said first and second carrier frequencies being different; and

determining at least two channel gain ratios, said at least two channel gain ratios including a first channel gain ratio and a second channel gain ratio, the first channel gain ratio being a ratio of a first channel gain to a second channel gain, the first channel gain being a channel gain between said first base station and said wireless communications device, the second channel gain being a channel gain between said second base station and said wireless communications device;

determining a geographic area which corresponds to said at least two determined channel gain ratios, wherein determining at least two channel gain ratios includes using information indicative of the relative transmission power of the first, second, and third signals transmitted by said first, second, and third base stations, respectively; and

wherein each base station transmits power information about the transmission power level used by the transmitting base station.

15. The method of claim 14, wherein said power level information is the transmitted signal power.

16. The method of claim 14, wherein said power level information is a relative power level which is relative to the transmission power level used by another base station.

17. A wireless communications device which determines its geographic location based upon received signals from three or more base stations using at least two different carrier frequencies, the wireless communications device comprising:

a receiver for receiving a plurality of signals including first, second, and third signals from first, second, and third base stations, respectively, said first and second signals corresponding to first and second carrier frequencies, said first and second carrier frequencies being different;

a power measurement module for measuring the received power of said first second and third signals;

a relative transmission power determination module for determining relative transmission powers between said first, second, and third signals;

stored predetermined base station transmission power relationship information, said stored predetermined base station power relationship information being used by said relative power determination module;

a channel gain ratio module for determining at least two channel gain ratios, said at least two channel gain ratios including a first channel gain ratio and a second channel gain ratio, the first channel gain ratio being a channel gain ratio between a first channel gain and a second channel gain, said first channel gain being a channel gain between said first base station and said wireless communications device, said second channel gain being a channel gain between said second base and said wireless communications device, and a third channel gain being a channel gain between said third base station and said wireless communications device; and

a geographic area determination module for determining a geographic area corresponding to said at least two determined channel gain ratios.

18. The wireless communications device of claim 17, further comprising:

a selection module for selecting from among said plurality of signals, when at least one of said first, second and third base stations supports multiple downlink carriers, said first, second and third signals, said first second and third signals each being associated with a corresponding selected carrier.

19. The wireless communications device of claim 18, wherein the selection module selects as a function of the received signal reliability.

20. The wireless communications device of claim 17, wherein said receiver is an orthogonal frequency division multiplexing receiver.

21. The wireless communications device of claim 17, wherein the receiver receives broadcast information including at least one of a base station transmission power level and a base station relative transmission power level, and wherein the received broadcast information is used by said relative power determination module.

22. The wireless communications device of claim 17, wherein said receiver is an orthogonal frequency division multiplexing (OFDM) receiver and wherein said received first, second and third signals are OFDM beacon signals.

23. The wireless communications device of claim 17, further comprising:

a transmitter which transmits first and second channel gain ratio reports to a base station over an uplink wireless communications channel, and wherein said receiver receives geographic location information based upon the transmitted first and second gain ratios, and the geographic area determination module processes the received geographic location information obtaining a geographic area location estimation for the wireless communications device.

24. The wireless communications device of claim 17, further comprising:

stored base station location information, wherein the geographic area determination module uses the stored base station location information in conjunction with said determined at least two channel gain ratios to determine a geographic area location estimation for the wireless communications device.

25. A method of operating a wireless communications device to perform a location determination operation, the method comprising:

receiving first, second and third signals from first, second and third base stations respectively, said first and second signals corresponding to first and second carrier frequencies, respectively, said first and second carrier frequencies being different;

determining at least two channel gain ratios, said at least two channel gain ratios including a first channel gain ratio and a second channel gain ratio, the first channel gain ratio being a ratio of a first channel gain to a second channel gain, the first channel gain being a channel gain between said first base station and said wireless communications device, the second channel gain being a channel gain between said second base station and said wireless communications device; and

determining a geographic area which corresponds to said at least two determined channel gain ratios

wherein said first, second and third signals are orthogonal frequency division multiplexing (OFDM) signals; and

wherein each of said first, second and third signals is a single tone signal over a time interval less than 3OFDM symbol transmission periods, in duration.