Radiator localization

Patent metadata

Field	Value
Publication number	US-9763216-B2
Application number	US-201414455095-A
Country	US
Kind code	B2
Filing date	Aug 8, 2014
Priority date	Aug 8, 2014
Publication date	Sep 12, 2017
Grant date	Sep 12, 2017

Abstract

A method of locating a radiator is provided. A channel measurement vector is defined that includes a signal value measured at each of a plurality of antennas in response to a signal transmitted from a radiator. (a) A cell covariance matrix of a first cell from a plurality of cells defined for a region in which the radiator is located is selected. (b) A likelihood value that the radiator is located in the first cell is calculated using the selected cell covariance matrix and the defined channel measurement vector. (a) and (b) are repeated with each cell of the plurality of cells as the first cell. A cell location of the radiator is selected based on the calculated likelihood value for each cell of the plurality of cells.

First claim

What is claimed is:

1. A non-transitory computer-readable medium having stored thereon computer-readable instructions that when executed by a computing device cause the computing device to:
(a) define a test channel measurement vector, wherein the test channel measurement vector includes a test signal value measured at each of a plurality of antennas in response to a test signal transmitted from a test radiator positioned in a first cell of a plurality of cells defined for a region;
(b) calculate a cell covariance matrix for the first cell from the defined test channel measurement vector;
(c) store the calculated cell covariance matrix in association with an indicator of the first cell;
repeat (a) through (c) with each remaining cell of the plurality of cells as the first cell;
define a channel measurement vector, wherein the channel measurement vector includes a signal value measured at each of the plurality of antennas in response to a signal transmitted from a radiator;
(d) select the stored cell covariance matrix of the first cell;
(e) calculate a likelihood value that the radiator is located in the first cell using the selected cell covariance matrix and the defined channel measurement vector;
(f) repeat (d) and (e) with each remaining cell of the plurality of cells as the first cell; and
determine a geographic location for the radiator based on the calculated likelihood value for each cell of the plurality of cells.

2. The computer-readable medium of claim 1 , wherein the likelihood value is calculated using −(log(|Σ b,k |)+h b H Σ b,k −1 h b ), where Σ b,k is the selected cell covariance matrix, Σ b,k −1 is an inverse of Σ b,k , h b is the defined channel measurement vector, and h b H is a complex conjugate transpose of h b .

3. The computer-readable medium of claim 1 , wherein the geographic location is selected based on a cell associated with a maximum value of the calculated likelihood value.

4. The computer-readable medium of claim 1 , wherein before (d), a subset of the plurality of cells is determined that bound a possible location of the radiator, wherein (d) through (f) are performed with the subset of the plurality of cells.

5. The computer-readable medium of claim 1 , wherein the test channel measurement vector is normalized.

6. The computer-readable medium of claim 1 , wherein the plurality of test channel measurement vectors are defined for the test radiator positioned at different locations within the first cell, wherein the cell covariance matrix is calculated based on the plurality of test channel measurement vectors defined for the test radiator positioned in the first cell.

7. The computer-readable medium of claim 6 , wherein the different locations within the first cell are uniformly distributed within the first cell.

8. The computer-readable medium of claim 6 , wherein the cell covariance matrix is calculated using

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where N is a number of the different locations within the first cell, h b (x r,i , y r,i ) is a respective test channel measurement vector at a location x r,i , y r,i of the different locations within the first cell, and h b H (x r,i , y r,i ) is a complex conjugate transpose of h b (x r,i , y r,i ).

9. The computer-readable medium of claim 8 , wherein the cell covariance matrix is a sparse cell covariance matrix further determined using a sparsity mask ={i: Σ b,k (i,i)≧γ Σ b,k (i,i)}, where i is an index to Σ b,k , and γ is a predefined threshold value between zero and one.

10. The computer-readable medium of claim 9 , wherein the predefined threshold value is defined such that Σ iε Σ b,k (i,i)≧ησ 2 , where η is a predefined power fraction value between zero and one, and σ 2 =tr(Σ b,k ) is a total channel power.

11. The computer-readable medium of claim 9 , wherein the cell covariance matrix is defined as [Σ b,k (i,j)] i,jε , where i and j are row and column indices to Σ b,k , respectively, and γ is a predefined threshold value.

12. The computer-readable medium of claim 1 , wherein the defined channel measurement vector is normalized before using the defined channel measurement vector to calculate the likelihood value.

13. The computer-readable medium of claim 12 , wherein the defined channel measurement vector is normalized based on an average channel power in each cell E[∥h b ∥ 2 ], where h b is the defined channel measurement vector.

14. The computer-readable medium of claim 12 , wherein the defined channel measurement vector is normalized so that ∥h b ∥ 2 =1, where h b is the defined channel measurement vector.

15. The computer-readable medium of claim 1 , wherein the channel measurement vector is defined in a beamspace multiple input, multiple output channel representation coordinate system.

16. The computer-readable medium of claim 15 , wherein a beamspace channel matrix is a unitarily equivalent representation of an antenna domain channel matrix.

17. The comput

Assignees

• Wisconsin Alumni Res Found

Inventors

• Sayeed Akbar Muhammad

Classifications

• G01S5/02525

  Gathering the radio frequency fingerprints · CPC title

• G01S5/0252

  Radio frequency fingerprinting · CPC title

• H04W64/00 Primary

  Locating users or terminals {or network equipment} for network management purposes, e.g. mobility management · CPC title

• G01S5/0273

  using multipath or indirect path propagation signals in position determination · CPC title

• G01S5/0278

  involving statistical or probabilistic considerations (G01S5/0252, G01S5/0294 take precedence) · CPC title