Single-site localization via multipath fingerprinting

• US 9,084,217 B2
• Filed: 12/18/2012
• Issued: 07/14/2015
• Est. Priority Date: 01/03/2012
• Status: Active Grant

• Current Assignee: Wavion limited (Alvarion Limited)
• Original Assignee: Wavion limited (Alvarion Limited)
• Inventors: Wax, Mati, Kupershtein, Evgeny
• Primary Examiner(s): Magloire, Vladimir
• Assistant Examiner(s): Perez Tolentino, Juan C
• Application Number:
  US13/718,419
• Publication Number:
  US 20130172007A1
• Time in Patent Office: 938 Days
• Field of Search: 4554561-4566, 455/404.2, 342/432, 342450-457, 370/310
• US Class Current: 1/1
• CPC Class Codes: G01S 5/0252 Radio frequency fingerprinting
• CPC Class Codes: G01S 5/0273 using multipath or indirect path propagation signals in position determination
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

Single-site localization of wireless emitters in a rich multipath environment is presented. The localization method is based on exploiting the spatio-temporal characteristics of the multipath signals, referred to as the multipath fingerprint, as captured by the base station antenna array. The method is applicable to all modern communication techniques such as WiFi and LTE and to any rich multipath environment in indoors and outdoors.

Claims

1. A method implemented by a base station for determining a location of a wireless transmitter, the method comprising:

in an off-line phase, pre-collecting and storing by the base station in a database fingerprints and corresponding locations, wherein the fingerprints are extracted from wireless signals received by the base station at a given location from wireless transmitters at known locations in a geographical coverage region;

in an on-line phase, receiving by the base station a signal from the wireless transmitter, extracting a fingerprint from the signal, matching the fingerprint with fingerprints in the database to identify a matching fingerprint having a best match, and selecting as an estimated location of the wireless transmitter a location corresponding to the matching fingerprint;

wherein the base station uses an antenna array and multi-channel receiver to receive the signal;

wherein the fingerprint extracted from the received signal is a single coherent entity implicitly including a directions-of-arrival and differential-delays information of multipath components of the signal and wherein the fingerprint is extracted from a spatio-temporal covariance matrix of the received signal;

wherein the matching of the fingerprints comprises searching the fingerprints in the database for a spatio-temporal signal subspace that maximizes a projection of a received signal sample spatio-temporal covariance matrix onto a subspace.

2. The method of claim 1 further comprising calculating a projection operator corresponding to each location by calculating a space spanned by columns of a matrix A, wherein the columns are composed of direction-delay vectors of signal reflections, and wherein a span of the matrix A is computed from a dominant eigenvectors of the spatio-temporal covariance matrix.

3. The method of claim 1 wherein the matching of the fingerprints further comprises comparing similarity profiles for locations in the database with a similarity profile obtained from the received signal.

4. The method of claim 1 further comprising combining the estimated location of the wireless transmitter with a second estimated location derived from signals received by a second base station from the wireless transmitter to produce an improved estimated location of the wireless transmitter.

5. The method of claim 1 further comprising combining the estimated location of the wireless transmitter with past estimated locations of the wireless transmitter to produce an improved estimated location of the wireless transmitter.

6. A method implemented by a base station for determining a location of a wireless transmitter, the method comprising:

in an off-line phase, pre-collecting and storing by the base station in a database fingerprints and corresponding locations, wherein the fingerprints are extracted from wireless signals received by the base station at a given location from wireless transmitters at known locations in a geographical coverage region;

in an on-line phase, receiving by the base station a signal from the wireless transmitter, extracting a fingerprint from the signal, matching the fingerprint with fingerprints in the database to identify a matching fingerprint having a best match, and selecting as an estimated location of the wireless transmitter a location corresponding to the matching fingerprint,

wherein the base station uses an antenna array and multi-channel receiver to receive the signal,

wherein the fingerprint extracted from the received signal is a single coherent entity implicitly including a directions-of-arrival and different-delays information of multipath components of the signal and wherein the fingerprint is extracted from a spatio-temporal covariance matrix of the received signal,

wherein the matching of the fingerprints comprises searching the fingerprints in the database for a spatio-temporal signal subspace that maximizes a projection of a received signal sample spatio-temporal covariance matrix onto a subspace,

wherein the matching of the fingerprints further comprises comparing similarity profiles for locations in the database with a similarity profile obtained from the received signal, wherein the method further comprises;

in the off-line phase, calculating and storing a projection operator corresponding to each location, and calculating and storing the similarity profiles for each location;

in the on-line phase, calculating the similarity profile obtained from the receiver signal.

7. A method implemented by a base station for determining a location of a wireless transmitter, the method comprising:

in an off-line phase, pre-collecting and storing by the base station in a database fingerprints and corresponding locations, wherein the fingerprints are extracted from wireless signals received by the base station at a given location from wireless transmitters at known locations in a geographical coverage region;

in an on-line phase, receiving by the base station a signal from the wireless transmitter, extracting a fingerprint from the signal, matching the fingerprint with fingerprints in the database to identify a matching fingerprint having a best match, and selecting as an estimated location of the wireless transmitter a location corresponding to the matching fingerprint,

wherein the base station uses an antenna array and multi-channel receiver to receive the signal,

wherein the fingerprint extracted from the received signal is a single coherent entity implicitly including the directions-of-arrival and differential-delays information of multipath components of the signal and wherein the fingerprint is extracted from a spatio-temporal covariance matrix of the received signal,

wherein the matching of the fingerprints further comprises comparing similarity profiles for locations in the database with a similarity profile obtained from the received signal, wherein the method further comprises;

calculating the similarity profile obtained from the received signal by calculated traces of the projection operator corresponding to each location applied to the received signal sample covariance mix.

8. A method implemented by a base station for determining a location of a wireless transmitter, the method comprising:

in an off-line phase, pre-collecting and storing by the base station in a database fingerprints and corresponding locations, wherein the fingerprints are extracted from wireless signals received by the base station at a given location from wireless transmitters at known locations in a geographical coverage region;

in an on-line phase, receiving by the base station a signal from the wireless transmitter, extracting a fingerprint from the signal, matching the fingerprint with signatures in the database to identify a matching fingerprint having a best match, and selecting as an estimated location of the wireless transmitter a location corresponding to the matching fingerprint;

wherein the base station uses an antenna array and multi-channel receiver to receive the signal;

wherein the fingerprint extracted from the received signal is a single coherent entity implicitly including the directions-of-arrival and differential-delays information of multipath components of the signal and wherein the fingerprint is extracted from a spatio-temporal covariance matrix of the received signal,

wherein the matching of the fingerprints further comprises comparing similarity profiles for locations in the database with a similarity profile obtained from the received signal.

9. A method implemented by a base station for determining a location of a wireless transmitter, the method comprising:

in an off-line phase, pre-collecting and storing by the base station in a database fingerprints and corresponding locations, wherein the fingerprints are extracted from wireless signals received by the base station at a given location from wireless transmitters at known locations in a geographical coverage region;

in an on-line phase, receiving by the base station a signal from the wireless transmitter, extracting a fingerprint from the signal, matching the fingerprint with signatures in the database to identify a matching fingerprint having a best match, and selecting as an estimated location of the wireless transmitter a location corresponding to the matching fingerprint;

wherein the base station uses an antenna array and multi-channel receiver to receive the signal;

wherein the fingerprint extracted from the received signal is a single coherent entity implicitly including the directions-of-arrival and differential-delays information of multipath components of the signal and wherein the fingerprint is extracted from a spatio-temporal covariance matrix of the received signal,

wherein the matching of the fingerprints comprises comparing similarity profiles for locations in the database with a similarity profile obtained from the received signal,

wherein the method comprises;

in the off-line phase, calculating and storing a similarity metric corresponding to each location, and calculating and storing the similarity profiles for each location; and

in the on-line phase, calculating the similarity profile obtained from the received signal.

10. A new base station configured to determine a location of a wireless transmitter, the base station comprising:

an antenna array and a multi-channel receiver configured to receive a signal from the wireless transmitter;

a computer processor; and

a database,

wherein the computer processor is configured to, in an off-line phase, pre-collect and store on the database fingerprints and corresponding locations, wherein the fingerprints are extracted from wireless signals received by the antennas array at a given location from wireless transmitters at known locations in a geographical coverage region,

wherein the computer processor is configured, in an on-line phase, to receive by the antenna array a signal from the wireless transmitter, extract a fingerprint from the signal, match the fingerprint with fingerprints in the database to identify a matching fingerprint having a best match, and select as an estimated location of the wireless transmitter a location corresponding to the matching fingerprint,

wherein the fingerprint extracted from the received signal is a single coherent entity implicitly including a directions-of-arrival and differential-delays information of multipath components of the signal and wherein the fingerprint is extracted from a spatio-temporal covariance matrix of the received signal, and

wherein the matching of the fingerprints comprises searching the fingerprints in the database for a spatio-temporal signal subspace that maximizes a projection of a received signal sample spatio-temporal covariance matrix onto a subspace.