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

• US 9,918,198 B2
• Filed: 12/07/2015
• Issued: 03/13/2018
• Est. Priority Date: 08/06/2010
• Status: Expired due to Fees

• Current Assignee: Golba LLC
• Original Assignee: Golba LLC
• Inventors: Moshfeghi, Mehran
• Primary Examiner(s): Fang, Keith
• Application Number:
  US14/960,873
• Publication Number:
  US 20160165400A1
• Time in Patent Office: 827 Days
• 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 determining a position of a mobile device, the method comprising:

performing a first estimate for the position of the mobile device within a scanning region;

selecting a subset of the scanning region based on the first estimate for the position of the mobile device, the subset of the scanning region smaller than the scanning region;

generating channel measurements over a plurality of transmit diversity configurations from a plurality of radio frequency signals received at the mobile device from one or more base stations, each of said one or more base stations comprising a plurality of distributed transceivers, each of the plurality of distributed transceivers comprising an independently configurable antenna array for transmitting said radio frequency signals to said mobile device, the transmit diversity configurations comprising antenna patterns of said antenna arrays of said distributed transceivers;

defining a signature function based on said channel measurements and a set of previously collected channel measurements retrieved from a database, the set of channel measurements retrieved from the database taken at a plurality of scanned locations within the subset of the scanning region over the plurality of transmit diversity configurations, the values of the signature function for the channel measurements calculated against the set of previously collected channel measurements over the subset of the scanning region; and

receiving a second estimate for the position of the mobile device from a location server, the second estimate determined by finding a set of location coordinates that minimizes a value of the signature function.

2. The method of claim 1, wherein performing the first estimate for the position of the mobile device within the scanning region comprises utilizing one of a GPS-based positioning method, a coarse angle-of-arrival positioning method, and a WLAN-based positioning method.

3. The method of claim 1, wherein performing the first estimate comprises utilizing (i) a subset of the transmit diversity configurations and (ii) a signature function that are identified to provide a low positioning accuracy with a full coverage over the scanning region.

4. The method of claim 3, wherein the transmit diversity configurations further comprise a set of carrier frequencies available for each base station, wherein the first estimate utilizes a first set of carrier frequencies for the transmit diversity configurations, wherein the second estimate utilizes a second set of carrier frequencies for the transmit diversity configurations, wherein the first set of carrier frequencies comprises lower frequencies than the second set of carrier frequencies.

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

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

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

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

9. The method of claim 1, wherein said signature function is defined in terms of full channel response, receive signal strength indicator (RSSI), strongest multipath, or angle of arrival (AoA) for the generated channel measurements and the channel measurements at said scanned locations over said transmit diversity configurations.

10. 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 position of 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 reflectors in an environment between said one or more base stations and the mobile device.

12. 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.

13. The method of claim 1, wherein the subset of the scanning region is a first subset of the scanning region, wherein the signature function is a first signature function, wherein the plurality of transmit diversity configurations are a first plurality of transmit diversity configurations, the method further comprising:

selecting a second subset of the scanning region based on the second estimate for the position of the mobile device, the second subset of the scanning region smaller than the first subset of the scanning region;

generating channel measurements over a second plurality of transmit diversity configurations from a plurality of radio frequency signals received at the mobile device from one or more base stations;

defining a second signature function based on said channel measurements and a set of channel measurements retrieved from the database, the set of channel measurements retrieved from the database taken at a plurality of scanned locations within the second subset of the scanning region over the second plurality of transmit diversity configurations; and

receiving a third estimate for the position of the mobile device from a location server, the third estimate determined by minimizing a value of the second signature function.

14. The method of claim 13, wherein the second plurality of transmit diversity configurations and the second signature function are identified to provide a higher positioning accuracy for the third estimate than the first and second estimates.

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

16. 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.

17. The method of claim 1, wherein defining the signature function comprises selecting, from a plurality of signature functions, a signature function with a large gradient versus locations in the subset of the scanning region to provide a low position estimation error.

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

19. The method of claim 1 further comprising applying a time-alignment process to said channel measurements prior to optimizing the signature function.

20. 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.

21. The method of claim 1, wherein defining the signature function further comprises defining the signature function based on the selected subset of the scanning region.