Method and system for device positioning utilizing distributed transceivers with array processing

• US 9,210,683 B2
• Filed: 08/08/2014
• Issued: 12/08/2015
• Est. Priority Date: 07/09/2009
• Status: Expired due to Fees

• Current Assignee: Golba LLC
• Original Assignee: Golba LLC
• Inventors: Moshfeghi, Mehran
• Primary Examiner(s): Fang, Keith
• Application Number:
  US14/455,861
• Publication Number:
  US 20150031391A1
• Time in Patent Office: 487 Days
• US Class Current: 1/1
• CPC Class Codes: G01S 5/0018 Transmission from mobile station to base station
• CPC Class Codes: G01S 5/0226 Transmitters
• CPC Class Codes: H04W 24/02 Arrangements for optimising operational condition
• CPC Class Codes: H04W 4/025 using location based information parameters
• CPC Class Codes: H04W 4/029 Location-based management or tracking services
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A mobile device receives signals from base stations each with multiple distributed transceivers. Each distributed transceiver may operate at different carrier frequencies. Each distributed transceiver is equipped with an independently configurable antenna array handling transmissions of the radio frequency signals to the mobile device. The mobile device generates channel measurements for the received signals, and subsequently receives a position estimate from a remote location server. The location server determines corresponding transmit diversity configurations applied to the base stations for conducting the channel measurements for the mobile device, and channel measurements at scanned locations in a location scanning region. The location server selects and utilize a signature function to calculate the position estimate for the mobile device over the transmit diversity configurations. A multi-level positioning process may be performed by adopting various signature functions, subsets of transmit configurations and/or subspaces of the location scanning region for accurate device positioning.

Claims

1. A method of processing signals, the method comprising:

in a mobile device;

receiving radio frequency signals from one or more base stations, wherein;

each of said one or more base stations comprises a plurality of distributed, transceivers; and

each of said plurality of distributed transceivers comprises an independently configurable antenna array for transmitting said radio frequency signals to said mobile device;

generating channel measurements over a plurality of transmit diversity configurations for said received radio frequency signals; and

receiving a position estimate for said mobile device from a location server,

wherein the transmit diversity configurations are determined by said location server, wherein the transmit diversity configurations comprise antenna patterns of said antenna arrays of said distributed transceivers, said transmit diversity configurations being applied to said one or more base stations for said channel measurements for said mobile device and channel measurements at scanned locations in a location scanning region;

wherein said position estimate for said mobile device over said location scanning region utilizes said channel measurements over said plurality of transmit diversity configurations by optimizing a signature function value based on said channel measurements and a set of channel measurements from a database maintained by said location server; and

wherein a weighted sum is utilized to combine values corresponding to measured channels per transmit diversity configurations when optimizing said signature function, wherein the weighted sum utilizes a set of scaling factors to model a relative reliability and contribution of each channel measurement.

2. The method of claim 1, wherein said signature function is defined in terms of full channel response, receive signal strength indicator, strongest multipath, or angle of arrival for said channel measurements for said mobile device, and said channel measurements at said scanned locations over said transmit diversity configurations.

3. The method of claim 1, wherein said position estimate for said mobile device is updated by said location server based on a resolution of said signature function over said scanned locations in said location scanning region.

4. The method to claim 3, wherein a subset of said transmit diversity configurations and/or a subspace of said location scanning region is selected by said location server based on said resolution of said signature function over said scanned locations in said location scanning region.

5. The method of claim 4, wherein said signature function is utilized by said location server to calculate said updated position estimate for said mobile device over said subset of said transmit diversity configurations and/or over said subspace of said location scanning region.

6. The method to of claim 3, wherein said updated position estimate for said mobile device is calculated by said location server, by utilizing a different signature function for said channel measurements for said mobile device and said channel measurements with said scanned locations over said transmit diversity configurations.

7. The method of claim 1, wherein optimizing the signature function comprises conducting said optimization over the location scanning region determined by said location server.

8. The method of claim 1 further comprising using the position estimate resulting from said optimization of the signature function as a most likelihood location estimate for the mobile device.

9. The method of claim 1, wherein the antenna arrays of each base station are arranged at different directions to create a plurality of independent antenna arrays for estimating the location of the mobile device.

10. The method of claim 1, wherein receiving radio frequency signals from one or more base stations comprises receiving signals reflected from one or more reflectors in an environment between said one or more base stations and the mobile device.

11. The method of claim 1, wherein receiving radio frequency signals from one or more base stations comprises receiving signals reflected from one or more high efficiency passive or active reflectors installed in an environment between said one or more base stations and the mobile device.

12. The method of claim 1 further comprising calculating values of the signature function for the generated channel measurements against a set of previously collected channel measurements over the location scanning region, wherein the position estimate is identified by finding a location coordinates that minimizes the signature function.

13. The method of claim 1, wherein the signature function is selected from a plurality of signature functions based on at least one of a required location accuracy, an availability of antenna arrays, a position acquisition time, a processing power consumption, and multipath environment conditions.

14. The method of claim 1, wherein the signature function with a large gradient versus locations in the location region is selected from a plurality of signature functions to provide a low position estimation error.

15. The method of claim 1, wherein the signature function corresponds to a full channel response, wherein the signature function is generated by coherently comparing amplitude and phase of channel measurements.

16. The method of claim 1 further comprising applying a time-alignment process to said channel measurements during scanning and positioning phases prior to optimizing the signature function.

17. The method of claim 1 further comprising combining a time-alignment process with said optimizing of the signature function value by combining channel measurements during a scanning phase and channel measurements generated by the mobile device.

18. The method of claim 1, wherein the transmit diversity configurations further comprise at least one of a number of transceivers available for each base station, a number of carrier frequencies available for each base station, and phase array coefficients of each base station.

19. The method of claim 1, wherein the functionality of said location server is implemented in one or more of said base stations.

20. The method of claim 1, wherein the functionality of said location server is implemented in said mobile device.

21. The method of claim 1, wherein the functionality of said location server is implemented in a remote location server external to said mobile device and said one or more base stations.