Adaptive polarization array (APA)

• US 8,954,023 B2
• Filed: 06/21/2012
• Issued: 02/10/2015
• Est. Priority Date: 06/24/2011
• Status: Active Grant

• Current Assignee: LHC2 Inc.
• Original Assignee: LHC2 Inc.
• Inventors: Hillstrom, Timothy Leonard, Conley, Robert J.
• Primary Examiner(s): Kim, Wesley
• Assistant Examiner(s): CHAKRABORTY, RAJARSHI
• Application Number:
  US13/529,968
• Publication Number:
  US 20120329416A1
• Time in Patent Office: 964 Days
• Field of Search: 455/1, 455/226.3, 455/562.1, 370/342, 359/301, 375/343
• US Class Current: 455/226.3
• CPC Class Codes: H01Q 21/245 provided with means for varying the polarisation polarising devices H01Q15/24; tracking by comparing linear polarisation compounds G01S3/146; reducing depolarisation effects H04B7/00; polarisation diversity H04B7/10
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity

Abstract

An Adaptive Polarization Array (APA) Algorithm is described for adjusting the polarization orientation of antennas, such as Dual-polarized array antennas. The APA Algorithm searches to find a polarization state that maximizes a signal quality of a received signal in the presence of interfering signals and noise. The search facilitates adjustment of a polarization state of, for example, receive antennas to maximize a signal quality metric. A proxy metric having no local maxima other than the global maximum is used to search the polarization search domain to find a best polarization state.

Claims

1. A method comprising:

combining signals from two receive antennas having non-equal polarization to emulate a single receive antenna having a polarization state, the combining includes;

mapping a surface of a Poincaré

Sphere to a polarization search domain;

searching over the polarization search domain using a proxy metric, the proxy metric being a proxy for an estimated signal quality metric; and

adjusting the polarization state based on the searching, wherein the proxy metric is represented by the following equation;

2. The method of claim 1, wherein the polarization search domain is a rectangular search domain.

3. The method of claim 2, wherein the mapping maps an entire surface of the Poincaré

Sphere to the rectangular search domain.

4. The method of claim 1, wherein the estimated signal quality metric is an estimated Signal to Interference plus Noise Ratio (SINR) metric.

5. The method of claim 4, wherein a maximum in the proxy metric occurs at a same point in the polarization search domain as a maximum of the estimated SINR metric.

6. The method of claim 1, wherein the polarization state of the single receive antenna matches a polarization state of one or more transmit antennas that transmit the signals.

7. The method of claim 1, wherein the proxy metric has a single global maximum over the polarization search domain.

8. The method of claim 7, wherein the proxy metric is absent of local maxima other than the global maximum over the polarization search domain.

9. The method of claim 8, wherein an estimated signal quality metric is an estimated Signal to Interference plus Noise Ratio (SINR) of the signals that are combined and the global maximum is associated with a maximum estimated SINR.

10. The method of claim 1, wherein an estimated signal quality metric is an estimated Signal to Interference plus Noise Ratio (SINR) defined by the following equation:

11. The method of claim 1, wherein the two receive antennas have nominally orthogonal polarization.

12. A method comprising:

combining signals from two receive antennas having non-equal polarization into a single signal having a single polarization state to emulate a single receive antenna having the single polarization state, the combining includes;

mapping a surface of a Poincaré

Sphere to a polarization domain;

solving a closed form solution based at least in part on the polarization domain, wherein the solving includes calculating a real valued signal power array based in part on determining a complex gain applied to a vertical channel complex baseband array; and

adjusting the single polarization state based on the solving, wherein the closed form solution comprises;

Signal_Pwr_i;

=(|a·

vv_i+hh_i |)²

wherein i is an array element index, vv is a vertical channel complex baseband array over a preamble interval, hh is a horizontal channel complex baseband array over the preamble interval, and

13. The method of claim 12, wherein the polarization domain is a rectangular domain.

14. The method of claim 13, wherein the mapping maps an entire surface of the Poincaré

Sphere to the rectangular domain.

15. The method of claim 12, wherein the solving the closed form solution determines a signal quality metric.

16. The method of claim 15, wherein the signal quality metric includes a Signal to Interference plus Noise Ratio (SINR) metric.

17. The method of claim 16, wherein the SINR metric is a maximum SINR in the polarization domain.

19. The method of claim 16, wherein the estimated signal quality metric is an estimated Signal to Interference plus Noise Ratio (SINR) defined by the following equation:

18. A system comprising:

a first receive antenna having a first polarization;

a second receive antenna having a second polarization that is not equal to the first polarization;

a processor to emulate a single receive antenna having a single polarization state by combining a first signal received by the first receive antenna with a second signal received by the second receive antenna, the processor executing computer executable instructions to;

map a surface of a Poincaré

Sphere to a polarization domain;

solve a closed form solution based at least in part on the polarization domain, wherein solving the closed form solution includes calculating a real valued signal power array based in part on determining a complex gain applied to a vertical channel complex baseband array; and

adjust the single polarization state based at least in part on the closed form solution adjusting the single polarization state based on the solving, wherein the closed form solution comprises;

Signal_Pwr_i;

=(|a·

vv_i+hh_i |)²

wherein i is an array element index, vv is a vertical channel complex baseband array over a preamble interval, hh is a horizontal channel complex baseband array over the preamble interval, and