Apparatus and method for determining the location of a mobile device using multiple wireless access points

• US 9,804,256 B2
• Filed: 10/18/2013
• Issued: 10/31/2017
• Est. Priority Date: 10/19/2012
• Status: Expired due to Fees

• Current Assignee: UCL Business PLC (University of London)
• Original Assignee: UCL Business PLC (University of London)
• Inventors: Jamieson, Kyle Andrew, Xiong, Jie
• Primary Examiner(s): Sabouri, Mazda
• Application Number:
  US14/435,505
• Publication Number:
  US 20150234033A1
• Time in Patent Office: 1,474 Days
• CPC Class Codes: G01S 3/12 Means for determining sense of direction, e.g. by combining signals from directional antenna or goniometer search coil with those from non-directional antenna determining direction by amplitude comparison of signals derived by combining directional and non-directional signals G01S3/24, G01S3/34
• CPC Class Codes: G01S 3/46 using antennas spaced apart and measuring phase or time difference between signals therefrom, i.e. path-difference systems
• CPC Class Codes: G01S 5/04 Position of source determined by a plurality of spaced direction-finders
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A method and an apparatus are provided for determining the location of a mobile device using multiple wireless access points, each wireless access point comprising multiple antennas. The apparatus and method are particularly suited to location of a mobile device in an indoor environment, such as a building. The method includes receiving a communication signal from the mobile device at each of multiple antennas of said multiple wireless access points; for each wireless access point, determining angle-of-arrival information of the received communication signal at the wireless access point, based on a difference in phase of the received signal between different antennas; collecting, from each of the multiple wireless access points, the determined angle-of-arrival information for the received communication signal from the mobile device; and estimating the location of the mobile device from the collected angle-of-arrival information.

Claims

1. A method of determining the location of a mobile device using multiple wireless access points, each wireless access point comprising multiple antennas, said method comprising:

receiving a communication signal from the mobile device at said multiple antennas of said multiple wireless access points;

for each wireless access point, determining angle-of-arrival information of the received communication signal at the wireless access point, based on a difference in phase of the received signal between different antennas;

collecting, from each of the multiple wireless access points, the determined angle-of-arrival information for the received communication signal from the mobile device;

estimating the location of the mobile device from the collected angle-of-arrival information;

discriminating against multipath reception of the communication signal at a wireless access point, wherein at least one wireless access point comprises two sets of antennas for discriminating against multipath reception; and

discriminating in favour of a direct path over a multipath by;

using the two sets of antennas at the wireless access point to disambiguate a direct path from the wireless access point to the mobile device from a multipath, based on intra-wireless access point triangulation between the two sets of multiple antennas;

determining a difference in angle of arrival for each component of the received communication signal at each of said two sets of antennas;

determining a source distance for each component of the received communication signal based on said difference in angle; and

identifying the direct path as corresponding to the component of communication signal having the shortest source distance.

2. A method of determining the location of a mobile device using multiple wireless access points, each wireless access point comprising multiple antennas, said method comprising:

receiving a communication signal from the mobile device at said multiple antennas of said multiple wireless access points;

for each wireless access point, determining angle-of-arrival information of the received communication signal at the wireless access point, based on a difference in phase of the received signal between different antennas;

collecting, from each of the multiple wireless access points, the determined angle-of-arrival information for the received communication signal from the mobile device;

estimating the location of the mobile device from the collected angle-of-arrival information;

discriminating against multipath reception of the communication signal at a wireless access point, wherein at least one wireless access point comprises two sets of antennas for discriminating against multipath reception; and

discriminating in favour of a direct path over multipath by;

determining an angle of arrival for each component of the communication signal at each of said two sets of antennas; and

identifying the direct path as corresponding to the component which is detected by both sets of antennas with only a small change in angle of arrival.

3. A method of determining the location of a mobile device using multiple wireless access points, each wireless access point comprising multiple antennas, said method comprising:

receiving a communication signal from the mobile device at said multiple antennas of said multiple wireless access points;

for each wireless access point, determining angle-of-arrival information of the received communication signal at the wireless access point, based on a difference in phase of the received signal between different antennas;

collecting, from each of the multiple wireless access points, the determined angle-of-arrival information for the received communication signal from the mobile device;

estimating the location of the mobile device from the collected angle-of-arrival information;

discriminating against multipath reception of the communication signal at a wireless access point, wherein discriminating against multipath reception of the communication signal at a wireless access point comprises matching angle-of-arrival spectra by correlating individual lobes from two angle-of-arrival spectra with one another;

grouping two or more angle-of-arrival spectra for the same mobile device, if available;

arbitrarily choosing one of the angle-of-arrival spectra as the primary, and removing peaks from the primary that are not paired with corresponding peaks on the one or more other angle-of-arrival spectra; and

outputting the primary angle-of-arrival spectrum.

4. The method of claim 3, further comprising, upon detecting receipt of the communication signal, switching between sets of antennas at a wireless access point to synthesize new angle-of-arrival information from each set of antennas.

5. The method of claim 3, wherein at least one wireless access point supports performing diversity synthesis by:

receiving a known symbol into one antenna of a subset of N antennas, wherein each subset of antennas is associated with one radio receiver;

cycling through each of the N antennas in turn, so as to receive the known symbol in each of the other antennas in succession; and

treating receipt of the known symbol in the subset of antennas as if N symbols were received simultaneously at different radio receivers at the wireless access point.

6. The method of claim 5, wherein N=2, matching the known symbol occurring twice in a specified portion of the communication signal.

7. The method of claim 3, wherein the two or more angle-of-arrival spectra for the same mobile device are determined from different times in the received communication signal.

8. Apparatus for determining the location of a mobile device using multiple wireless access points, each wireless access point comprising multiple antennas, said apparatus being configured to perform a method comprising:

receiving a communication signal from the mobile device at said multiple antennas of said multiple wireless access points;

for each wireless access point, determining angle-of-arrival information of the received communication signal at the wireless access point, based on a difference in phase of the received signal between different antennas;

collecting, from each of the multiple wireless access points, the determined angle-of-arrival information for the received communication signal from the mobile device; and

estimating the location of the mobile device from the collected angle-of-arrival information;

discriminating against multipath reception of the communication signal at a wireless access point, wherein discriminating against multipath reception of the communication signal at a wireless access point comprises matching angle-of-arrival spectra by correlating individual lobes from two angle-of-arrival spectra with one another;

grouping two or more angle-of-arrival spectra for the same mobile device, if available;

arbitrarily choosing one of the angle-of-arrival spectra as the primary, and removing peaks from the primary that are not paired with corresponding peaks on the one or more other angle-of-arrival spectra; and

outputting the primary angle-of-arrival spectrum.

9. Apparatus for determining the location of a mobile device using multiple wireless access points, each wireless access point comprising multiple antennas, said apparatus being configured to perform a method comprising:

receiving a communication signal from the mobile device at said multiple antennas of said multiple wireless access points;

for each wireless access point, determining angle-of-arrival information of the received communication signal at the wireless access point, based on a difference in phase of the received signal between different antennas;

collecting, from each of the multiple wireless access points, the determined angle-of-arrival information for the received communication signal from the mobile device; and

estimating the location of the mobile device from the collected angle-of-arrival information;

discriminating against multipath reception of the communication signal at a wireless access point, wherein at least one wireless access point comprises two sets of antennas for discriminating against multipath reception; and

discriminating in favour of a direct path over a multipath by;

using the two sets of antennas at the wireless access point to disambiguate a direct path from the wireless access point to the mobile device from a multipath, based on intra-wireless access point triangulation between the two sets of multiple antennas;

determining a difference in angle of arrival for each component of the received communication signal at each of said two sets of antennas;

determining a source distance for each component of the received communication signal based on said difference in angle; and

identifying the direct path as corresponding to the component of communication signal having the shortest source distance.

10. Apparatus for determining the location of a mobile device using multiple wireless access points, each wireless access point comprising multiple antennas, said apparatus being configured to perform a method comprising:

receiving a communication signal from the mobile device at said multiple antennas of said multiple wireless access points;

for each wireless access point, determining angle-of-arrival information of the received communication signal at the wireless access point, based on a difference in phase of the received signal between different antennas;

collecting, from each of the multiple wireless access points, the determined angle-of-arrival information for the received communication signal from the mobile device; and

estimating the location of the mobile device from the collected angle-of-arrival information;

discriminating against multipath reception of the communication signal at a wireless access point, wherein at least one wireless access point comprises two sets of antennas for discriminating against multipath reception; and

discriminating in favour of a direct path over multipath by;

determining an angle of arrival for each component of the communication signal at each of said two sets of antennas; and

identifying the direct path as corresponding to the component which is detected by both sets of antennas with only a small change in angle of arrival.