Communications system including phased array antenna providing nulling and related methods
A phased array antenna may include a plurality of antenna elements, at least one respective phase shifter connected to each antenna element, and at least one respective gain element connected to each antenna element. The phased array antenna may further include at least one controller for determining and controlling both phases and gains of the phase shifters and gain elements, respectively, to provide beamsteering in a first direction for a signal of interest. The controller may also iteratively determine and control phases of the phase shifters to provide a null in a second direction for a signal not of interest, and without determining or controlling gains of the gain elements.
1. A phased array antenna comprising:
a plurality of antenna elements;
at least one respective phase shifter connected to each antenna element, each phase shifter having a plurality of digitally selectable phase settings;
at least one respective gain element connected to each antenna element; and
at least one controller for
determining and controlling both phases and gains of said phase shifters and gain elements, respectively, to provide beamsteering in a first direction for a signal of interest, and
iteratively determining and controlling phases of said phase shifters to provide a null in a second direction for a signal not of interest and without determining or controlling gains of said gain elements,
said at least one controller determining the phases to provide the null in the second direction by determining desired phase weights and mapping the desired phase weights to nearest available digital phase settings of said phase shifters.
2. The phased array antenna of claim 1 wherein the desired phase weights comprise an eigenvector.
3. The phased array antenna of claim 2 wherein said at least one controller limits a step in vector space of the eigenvector to a step limit between successive iterations.
4. The phased array antenna of claim 1 wherein said at least one controller determines the desired phase weights based upon a signal covariance and an interference covariance of said antenna elements.
5. The phased array antenna of claim 1 wherein said at least one controller iteratively determines and controls the phases until the null reaches a threshold.
6. The phased array antenna of claim 1 wherein said at least one controller determines the phases and gains of said phase shifters and gain elements to provide beamsteering in the first direction based upon a conjugate beam in the first direction.
7. The phased array antenna of claim 1 wherein said antenna elements are arranged in sub-groups to provide multi-beam operation.
8. The phased array antenna of claim 1 wherein said antenna elements are arranged in an aperiodic array.
9. A phased array antenna comprising:
a plurality of antenna elements;
at least one respective phase shifter connected to each antenna element, each phase shifter having a plurality of digitally selectable phase settings; and
at least one controller for
determining and controlling phases of said phase shifters to provide beamsteering in a first direction for a signal of interest, and
iteratively determining desired phase weights to provide a null in a second direction for a signal not of interest, mapping the desired phase weights to nearest available digital phase settings of said phase shifters, and controlling phases of said phase shifters based thereon.
10. The phased array antenna of claim 9 wherein the desired phase weights comprise an eigenvector.
11. The phased array antenna of claim 10 wherein said at least one controller limits a step in vector space of the eigenvector to a step limit between successive iterations.
12. The phased array antenna of claim 9 wherein said at least one controller determines the desired phase weights based upon a signal covariance and an interference covariance of said antenna elements.
13. The phased array antenna of claim 9 wherein said at least one controller iteratively determines the desired phase weights, maps the desired phase weights, and controls the phases until the null reaches a threshold.
14. The phased array antenna of claim 9 wherein said at least one controller determines the phases of said phase shifters to provide beamsteering in the first direction based upon a conjugate beam in the first direction.
15. The phased array antenna of claim 9 wherein said antenna elements are arranged in sub-groups to provide multi-beam operation.
16. The phased array antenna of claim 9 wherein said antenna elements are arranged in an aperiodic array.
17. A communications system comprising:
a receiver; and
a phased array antenna connected to said receiver and comprising
a plurality of antenna elements,
at least one respective phase shifter connected to each antenna element, each phase shifter having a plurality of digitally selectable phase settings,
at least one respective gain element connected to each antenna element, and
at least one controller for
determining and controlling both phases and gains of said phase shifters and gain elements, respectively, to provide beamsteering in a first direction for a signal of interest, and
iteratively determining and controlling phases of said phase shifters to provide a null in a second direction for a signal not of interest and without determining or controlling gains of said gain elements,
said at least one controller determining the phases to provide the null in the second direction by determining desired phase weights and mapping the desired phase weights to nearest available digital phase settings of said phase shifters.
18. The communications system of claim 17 wherein the desired phase weights comprise an eigenvector.
19. The communications system of claim 18 wherein said at least one controller limits a step in vector space of the eigenvector to a step limit between successive iterations.
20. The communications system of claim 17 wherein said at least one controller determines the desired phase weights based upon a signal covariance and an interference covariance of said antenna elements.
21. The communications system of claim 17 wherein said at least one controller determines the phases and gains of said phase shifters and gain elements to provide beamsteering in the if first direction based upon a conjugate beam in the first direction.
22. The communications system of claim 17 wherein said antenna elements are arranged in sub-groups to provide multi-beam operation.
23. The communications system of claim 17 wherein said at least one controller iteratively determines and controls the phases until the null reaches a threshold.
24. A communications system comprising:
a receiver; and
a phased array antenna connected to said receiver and comprising
a plurality of antenna elements,
at least one respective phase shifter connected to each antenna element, each phase shifter having a plurality of digitally selectable phase settings, and
at least one controller for
determining and controlling phases of said phase shifters to provide beamsteering in a first direction for a signal of interest, and
iteratively determining desired phase weights to provide a null in a second direction for a signal not of interest, mapping the desired phase weights to nearest available digital phase settings of said phase shifters, and controlling phases of said phase shifters based thereon.
25. The communications system of claim 24 wherein the desired phase weights comprise an eigenvector.
26. The communications system of claim 25 wherein said at least one controller limits a step in vector space of the eigenvector to a step limit between successive iterations.
27. The communications system of claim 24 wherein said at least one controller determines the desired phase weights based upon a signal covariance and an interference covariance of said antenna elements.
28. The communications system of claim 24 wherein said at least one controller determines the phases of said phase shifters to provide beamsteering in the first direction based upon a conjugate beam in the first direction.
29. The communications system of claim 24 wherein said antenna elements are arranged in sub-groups to provide multi-beam operation.
30. The communications system of claim 24 wherein said at least one controller iteratively determines the desired phase weights, maps the desired phase weights, and controls the phases until the null reaches a threshold.
31. A method for controlling a phased array antenna comprising a plurality of antenna elements, at least one respective phase shifter connected to each antenna element where each phase shifter has a plurality of digitally selectable phase settings, and at least one respective gain element connected to each antenna element, the method comprising:
determining and controlling both phases and gains of the phase shifters and gain elements, respectively, to provide beamsteering in a first direction for a signal of interest; and
iteratively determining and controlling phases of the phase shifters to provide a null in a second direction for a signal not of interest and without determining or controlling gains of the gain elements by iteratively determining desired phase weights and mapping the desired phase weights to nearest available digital phase settings of the phase shifters.
32. The method of claim 31 wherein the desired phase weights comprise an eigenvector.
33. The method of claim 32 iteratively determining the desired phase weights comprises limiting a step in vector space of the eigenvector to a step limit between successive iterations.
34. The method of claim 31 wherein iteratively determining the desired phase weights comprises iteratively determining the desired phase weights based upon a signal covariance and an interference covariance of the antenna elements.
35. The method of claim 31 wherein determining the phases and gains of the phase shifters and gain elements to provide beamsteering in the first direction comprises determining the phases and gains based upon a conjugate beam in the first direction.
36. A method for controlling a phased array antenna comprising a plurality of antenna elements and at least one respective phase shifter connected to each antenna element, each phase shifter having a plurality of digitally selectable phase settings, the method comprising:
determining and controlling phases of the phase shifters to provide beamsteering in a first direction for a signal of interest; and
iteratively determining desired phase weights to provide a null in a second direction for a signal not of interest, mapping the desired phase weights to nearest available digital phase settings of the phase shifters, and controlling phases of the phase shifters based thereon.
37. The method of claim 36 wherein the desired phase weights comprise an eigenvector.
38. The method of claim 37 wherein iteratively determining the desired phase weights comprises limiting a step in vector space of the eigenvector to a step limit between successive iterations.
39. The method of claim 36 wherein iteratively determining the desired phase weights comprises iteratively determining the desired phase weights based upon a signal covariance and an interference covariance of the antenna elements.
40. The method of claim 36 wherein determining the phases of the phase shifters to provide beamsteering in the first direction comprises determining the phases based upon a conjugate beam in the first direction.