Method and apparatus for determining remote unit location using phased array antenna elements

• US 6,252,867 B1
• Filed: 09/30/1999
• Issued: 06/26/2001
• Est. Priority Date: 09/30/1999
• Status: Expired due to Term

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Rottinghaus, Alan P., Pfeil, Jeff L., Tapia, Javier J., Henderson, Stephen W.
• Primary Examiner(s): Vu, Huy D.
• Assistant Examiner(s): Harper, Kevin C.
• Application Number:
  US09/409,546
• Time in Patent Office: 635 Days
• Field of Search: 370/320, 370/335, 370/342, 370/328, 370/343, 370/344, 370/345, 370/347, 370/319-321, 370/326, 370/478-479, 370/329, 455/422, 455/560-562, 455/132, 455/137, 455/140-141, 455/146-148, 455/206, 455/209, 455/456
• US Class Current: 370/335
• CPC Class Codes: G01S 5/12 by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial
• CPC Class Codes: H04B 7/086 using weights depending on external parameters, e.g. direction of arrival [DOA], predetermined weights or beamforming
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

An apparatus (100) and method dynamically allocates radio frequency receive path resources as required by a programmable location engine (112). The programmable location engine (112) employs cascaded time of arrival and direction of arrival algorithms to determine per remote unit location data. The apparatus (100) employs a phased array antenna (104) and a programmable receiver switching apparatus (108). A plurality of radio frequency receivers (102a-102n) receive a plurality of different carriers, such as CDMA carriers, on each of a different phased array antenna element (106a-106d). An RF switching matrix (126) and mobile location shared resource controller (110) dynamically switch the plurality of radio frequency receivers (102a-102b) to not only receive the different carriers on each of the different phased antenna radio elements to determine time of arrival information, but alternately receive a same carrier signal over all or a portion of the phased array antenna element to determine direction of arrival information.

Claims

1. A method for locating a remote unit comprising the steps of:

(a) receiving a plurality of different carriers on each of a different phased array antenna element;

(b) dynamically switching a plurality of receivers coupled to each of the different phased array antenna elements to receive a same carrier signal, from the plurality of different carriers, over a plurality of the different phased array antenna elements; and

(c) reassigning the plurality of receivers back to different carrier frequencies to obtain additional time of arrival data for the remote unit, wherein the plurality of different carriers include remote unit access probe signals and wherein the step of reassigning the plurality of receivers back to different carrier frequencies, is performed as a function of where remote unit identification data is located within the remote unit access probe signals.

2. The method of claim 1 including the step of controlling a local oscillator frequency for each of the plurality of receivers to different frequencies and subsequently to a same carrier signal frequency for use in determining a location of the remote unit.

3. The method of claim 2 wherein the plurality of different carriers are CDMA multi-carriers containing CDMA carrier data.

4. The method of claim 3 including selectively controlling a plurality of mobile location CDMA carrier buffers wherein each of the plurality of mobile location CDMA carrier buffers is controlled to receive CDMA carrier data on a per carrier basis.

5. The method of claim 4 including the step of evaluating CDMA carrier data stored in the plurality of mobile location CDMA carrier buffers multiple times to generate time of arrival data for a selected remote unit.

6. The method of claim 1 wherein the step of dynamically switching the plurality of receivers coupled to each of the different phased array antenna elements to receive the same carrier includes dynamically changing local oscillator frequencies associated with each of the plurality of receivers to a same frequency during remote unit access probe signals to determine a location of the remote unit.

7. The method of claim 1 wherein the step of dynamically switching the plurality of receivers coupled to each of the different phased array antenna elements to receive the same carrier includes dynamically changing local oscillator frequencies associated with each of the plurality of receivers to a same frequency during traffic channel signals to determine a location of the remote unit.

8. The method of claim 1 including the steps of:

determining time of arrival (TOA) data, on a per remote unit basis, for remote units assigned to each of the plurality of different carriers on each of the different phased array antenna elements;

determining direction of arrival (DOA) data, on a per remote unit basis, in response to dynamically switching the plurality of receivers coupled to each of the different phased array antenna elements to receive a same carrier signal; and

determining direction of arrival (DOA) data, on a per remote unit basis, for remote units assigned to at least a subset of remaining carriers of the plurality of different carriers by dynamically switching the plurality of receivers coupled to each of the different phased array antenna elements to commonly receive each of the subset of remaining carriers.

9. The method of claim 1 including the step of (c) reassigning the plurality of receivers back to different carrier frequencies to obtain additional time of arrival data for the remote unit.

10. A method for locating a remote unit comprising the steps of:

(a) receiving a plurality of different CDMA carriers on each of a different phased array antenna element located at a single site to determine time of arrival data on a per remote unit basis;

(b) dynamically switching a plurality of receivers coupled to each of the different phased array antenna elements at the single site, to receive a same CDMA carrier signal, from the plurality of different CDMA carriers, over a plurality of the different phased array antenna elements to determine direction of arrival data on a per remote unit basis; and

(c) reassigning the plurality of receivers back to different CDMA carrier frequencies to determine additional time of arrival data for remote units assigned to the plurality of different CDMA carriers, wherein the plurality of different CDMA carriers include remote unit access probe signals and wherein the step of reassigning the plurality of receivers back to different carrier frequencies, is performed as a function of where remote unit identification data is located within the remote unit access probe signals.

11. The method of claim 10 including the step of controlling a local oscillator frequency for each of the plurality of receivers to different frequencies and subsequently to a same CDMA carrier signal frequency for use in determining a location of a remote unit.

12. The method of claim 10 wherein the step of dynamically switching the plurality receivers coupled to each of the different phased array antenna elements to receive the same CDMA carrier signal includes dynamically changing local oscillator frequencies associated with each of the plurality of receivers to a same frequency during remote unit access probe signals to determine a location of the remote unit.

13. The method of claim 10 wherein the step of dynamically switching the plurality of receivers coupled to each of the different phased array antenna elements to receive the same carrier signal includes dynamically changing local oscillator frequencies associated with each of the plurality of receivers to a same frequency during traffic channel signals to determine a location of the remote unit.

14. The method of claim 10 including the steps of:

determining time of arrival (TOA) data, on a per remote unit basis, for remote units assigned to each of the plurality of different CDMA carriers on each of the different phased array antenna elements;

determining direction of arrival (DOA) data, on a per remote unit basis, for remote units assigned to the same CDMA carrier signal in response to dynamically switching the plurality of receivers coupled to each of the different phased array antenna elements to receive the same CDMA carrier signal; and

determining direction of arrival (DOA) data, on a per remote unit basis, for remote units assigned to a subset of remaining carriers from the plurality of the different CDMA carriers by dynamically switching the plurality of receivers coupled to each of the different phased array antenna elements to commonly receive each of the subset of remaining CDMA carriers.

15. The method of claim 14 including selectively controlling a plurality of mobile location CDMA carrier buffers wherein each of the plurality of mobile location CDMA carrier buffers is controlled to receive CDMA carrier data on a per carrier basis.

16. The method of claim 15 including the step of evaluating CDMA carrier data stored in the plurality of mobile location CDMA carrier buffers multiple times to generate time of arrival data for a selected remote unit.

17. An apparatus for determining a location of at least one remote unit comprising:

a plurality of radio frequency (RF) receivers, operatively coupled to a phased array antenna, that receives a plurality of different carriers on each of different phased array antenna elements for a first period of time;

a receiver switching apparatus, operatively coupled to the plurality of RF receivers, wherein the receiver switching apparatus reassigns the plurality of receivers back to different carrier frequencies to obtain additional time of arrival data from the plurality of different carriers, wherein the plurality of different carriers include remote unit access probe signals and wherein the reassigning of the receivers back to different carrier frequencies is performed as a function of where remote unit identification data is located within the remote unit access probe signals; and

has

a controller, operatively coupled to the plurality of RF receivers and to the receiver switching apparatus, having control signals to control the receiver switching apparatus to control the plurality of RF receivers to receive a same carrier signal for a second period of time, from the plurality of different carriers, over a plurality of different phased array antenna elements.

18. The apparatus of claim 17 wherein the receiver switching apparatus includes:

a radio frequency (RF) switching matrix operatively coupled to provide a local oscillator frequency for each of the plurality of RF receivers; and

a programmable local oscillator, operatively coupled to the controller, having a local oscillator output operatively coupled to an input of the frequency switching matrix,

wherein the RF switching matrix, under control of the programmable local oscillator, dynamically switches the plurality of receivers coupled to each of the different phased array antenna elements to different carrier frequencies and subsequently to a same carrier signal frequency for use in determining a location of the remote unit.

19. The apparatus of claim 17 wherein the receiver switching apparatus dynamically changes local oscillator frequencies associated with each of the plurality of receivers to a same frequency to detect remote unit access probe signals to determine a location of the remote unit.

20. The apparatus of claim 17 wherein the receiver switching apparatus dynamically changes local oscillator frequencies associated with each of the plurality of receivers to a same frequency to detect traffic channel signals to determine a location of the remote unit.

21. The apparatus of claim 17 including a programmable location engine, operatively coupled to the controller, that determines time of arrival (TOA) data on a per remote unit basis, for remote units assigned to each of the plurality of different carriers received from each of the different phased array antenna elements;

that determines direction of arrival (DOA) data, on a per remote unit basis, for remote units assigned to the same carrier signal, in response to dynamic switching of the plurality of receivers coupled to each of the different phased array antenna elements, to receive the same carrier signal; and

that determines direction of arrival (DOA) data, on a per remote unit basis, for remote units assigned to a subset of remaining carriers of the plurality of different carriers in response to dynamic switching of the plurality of receivers coupled to each of the different phased array antenna elements to commonly receive each of the subsets of remaining carriers.

22. The apparatus of claim 21 wherein the plurality of different carriers are CDMA multi-carriers containing CDMA carrier data and further including a plurality of mobile location CDMA carrier buffers wherein each of the plurality of mobile location CDMA carrier buffers is controlled to receive CDMA carrier data on a per carrier basis.

23. The apparatus of claim 22 wherein the programmable location engine evaluates CDMA carrier data stored in the plurality of mobile location CDMA carrier buffers multiple times to generate time of arrival data for a selected remote unit.