Systems and methods for adaptive interference cancellation beamforming
View Patent ↗Methods of operating a transceiver including an antenna having a plurality of antenna feed elements are disclosed. The methods include receiving a plurality of samples of a receive signal from the plurality of antenna feed elements, estimating locations of a plurality of signal sources from the plurality of receive signal samples, identifying a plurality of interference sources from among the plurality of signal sources, generating a plurality of antenna feed element weights w M in response to the locations of the interference sources, forming an antenna beam from the antenna to the geographic region using the antenna feed element weights w M , and communicating information over the antenna beam. Related transceivers, satellite gateways and satellites are also disclosed.
1. A method of operating a transceiver including an antenna having a plurality of antenna feed elements, the method comprising:
receiving a plurality of samples of a receive signal from the plurality of antenna feed elements;
estimating locations of a plurality of signal sources from the plurality of receive signal samples;
identifying a plurality of interference sources from among the plurality of signal sources;
generating a plurality of antenna feed element weights w M in response to locations of the interference sources, wherein generating the plurality of antenna feed element weights comprises defining a plurality of antenna gain constraint values gk associated with a plurality of geographic constraint points within a geographic region and determining interference weighting factors for the geographic constraint points and locations of the interference sources, wherein the antenna feed element weights are generated in response to the interference weighting factors;
forming an antenna beam from the antenna to the geographic region using the antenna feed element weights w M ; and
communicating information over the antenna beam.
2. The method of claim 1 , wherein generating the antenna feed element weights w M comprises generating antenna feed element weights w M that result in antenna response values f K at the geographic constraint points based on the corresponding antenna gain constraint values g K and the interference weighting factors at the interference source locations.
3. The method of claim 1 , further comprising estimating power levels of the interference sources, wherein the interference weighting factors are determined in response to the power levels of the interference sources.
4. The method of claim 3 , further comprising estimating power levels of the interference sources, wherein the interference weighting factors are determined according to the following equation:
[
α
1
,
α
2
…
α
L
]
=
β
p
min
[
p
1
,
p
2
,
…
p
L
]
β
>
1
where:
< 1 to < L are the interference source weighting factors;
p 1 to p L are the power estimates for the interference sources; and
® is a predefined constant.
5. The method of claim 1 , wherein estimating locations of the plurality of signal sources comprises:
estimating an array covariance matrix for the plurality of antenna feed elements in response to the plurality of samples of the receive signal to form an array covariance matrix estimate according to the following equation:
R
^
=
1
N
∑
t
=
1
N
y
(
t
)
y
H
(
t
)
=
E
^
s
Λ
^
s
E
^
s
H
+
E
^
n
Λ
^
n
E
^
n
H
where:
{circumflex over (R)} is the estimated array covariance matrix,
N is the number of samples of the receive signal,
y(t) is the receive signal vector;
Ê s is a matrix of K eigenvectors corresponding to the K largest eigenvalues of the array covariance matrix;
{circumflex over (R)} n is a matrix of M-K eigenvectors corresponding to the M-K smallest eigenvalues of the array covariance matrix, where M is equal to the number of feed elements in the antenna array;
{circumflex over (Λ)} s is a matrix of the K largest eigenvalues of the array covariance matrix; and
{circumflex over (Λ)} n is a matrix of the M-K smallest eigenvalues of the array covariance matrix.
6. The method of claim 5 , wherein estimating locations of the plurality of signal sources further comprises:
generating the spatial spectrum from the array covariance matrix estimate according to the following equation:
Pss
(
θ
,
φ
)
=
a
H
(
θ
,
φ
)
a
(
θ
,
φ
)
a
H
(
θ
,
φ
)
E
^
n
E
^
n
H
a
(
θ
,
φ
)
wherein a(θ, φ) is the array steering matrix; and
estimating directions of arrival of signals from the plurality of signal sources from largest peaks of the spatial spectrum.
7. The method of claim 6 , further comprising defining a threshold └ T and defining eigenvalues of the array covariance matrix R greater than └ T as corresponding to signal space and eigenvalues of the array covariance matrix R less than └ T as defining noise subspace, so that the number of eigenvalues of the array covariance matrix R greater than └ T is equal to the number K of signal sources.
8. A method of operating a transceiver including an antenna having a plurality of antenna feed elements, the method comprising:
receiving a plurality of samples of a receive signal from the plurality of antenna feed elements;
estimating locations of a plurality of signal sources from the plurality of receive signal samples;
identifying a plurality of interference sources from among the plurality of signal sources;
generating a plurality of antenna feed element weights w M in response to locations of the interference sources;
forming an antenna beam from the antenna to the geographic region using the antenna feed element weights w M ; and
communicating information over the antenna beam;
wherein estimating locations of the plurality of signal sources comprises:
estimating an array covariance matrix for the plurality of antenna feed elements in response to the plurality of samples of the receive signal to form an array covariance matrix estimate;
generating a spatial spectrum from the array covariance matrix estimate; and
estimating directions of arrival of signals from the signal sources from largest peaks of the spatial spectrum.
9. The method of claim 8 , wherein generating the spatial spectrum from the array covariance matrix comprises:
performing an eigen-decomposition of the array covariance matrix estimate;
identifying signal eigenvectors and noise eigenvectors for the covariance matrix estimate; and
generating the spatial spectrum in response to the noise eigenvectors and feed array steering data for the antenna array.
10. The method of claim 8 , further comprising:
designating signal sources that fall within a predetermined zero-gain zone as interference sources.
11. A transceiver, comprising:
an antenna having a plurality of antenna feed elements; and
an electronics system including a beam former configured to:
receive a plurality of samples of a receive signal from the plurality of antenna feed elements;
estimate locations of a plurality of signal sources from the plurality of receive signal samples;
identify a plurality of interference sources from among the plurality of signal sources;
generate a plurality of antenna feed element weights w M in response to locations of the interference sources; and
form an antenna beam from the antenna to the geographic region using the antenna feed element weights w M ;
wherein the electronics system is configured to communicate information over the antenna beam; and
wherein the beam former is further configured to:
define a plurality of antenna gain constraint values g k associated with a plurality of geographic constraint points within a geographic region;
determine interference weighting factors for the geographic constraint points and locations of the interference sources; and
generate the antenna feed element weights in response to the interference weighting factors.
12. The method of claim 11 , wherein the beam former is further configured to:
generate the antenna feed element weights w M that result in antenna response values f K at the geographic constraint points based on the corresponding antenna gain constraint values g K and the interference weighting factors at the interference source locations.
13. The transceiver of claim 11 , wherein the beam former is further configured to:
estimate power levels of the interference sources; and
determine the interference weighting factors in response to the power levels of the interference sources.
14. The transceiver of claim 13 , wherein the beam former is further configured to:
estimate power levels of the interference sources, wherein the interference weighting factors are determined according to the following equation:
[
α
1
,
α
2
…
α
L
]
=
β
p
min
[
p
1
,
p
2
,
…
p
L
]
β
>
1
where:
< 1 to < L are the interference source weighting factors;
p 1 to p L are the power estimates for the interference sources; and
® is a predefined constant.
15. A transceiver, comprising:
an antenna having a plurality of antenna feed elements; and
an electronics system including a beam former configured to:
receive a plurality of samples of a receive signal from the plurality of antenna feed elements;
estimate locations of a plurality of signal sources from the plurality of receive signal samples;
identify a plurality of interference sources from among the plurality of signal sources;
generate a plurality of antenna feed element weights w M in response to locations of the interference sources; and
form an antenna beam from the antenna to the geographic region using the antenna feed element weights w M ;
wherein the electronics system is configured to communicate information over the antenna beam; and
wherein the beam former is further configured to:
estimate an array covariance matrix for the plurality of antenna feed elements in response to the plurality of samples of the receive signal to form an array covariance matrix estimate;
generate a spatial spectrum from the array covariance matrix estimate; and
estimate directions of arrival of signals from the plurality of signal sources from largest peaks of the spatial spectrum.
16. The transceiver of claim 15 , wherein the beam former is further configured to:
perform an eigen-decomposition of the array covariance matrix estimate;
identify signal eigenvectors and noise eigenvectors for the covariance matrix estimate; and
generate the spatial spectrum in response to the noise eigenvectors and feed array steering data for the antenna array.
17. The transceiver of claim 15 , wherein the beam former is further configured to designate signal sources that fall within a predetermined zero-gain zone as interference sources.
18. The transceiver of claim 15 , wherein the beam former is further configured to:
estimate an array covariance matrix for the plurality of antenna feed elements in response to the plurality of samples of the receive signal to form an array covariance matrix estimate according to the following equation:
R
^
=
1
N
∑
t
=
1
N
y
(
t
)
y
H
(
t
)
=
E
^
s
Λ
^
s
E
^
s
H
+
E
^
n
Λ
^
n
E
^
n
H
where:
{circumflex over (R)} is the estimated array covariance matrix,
N is the number of samples of the receive signal,
y(t) is the receive signal vector;
Ê s is a matrix of K eigenvectors corresponding to the K largest eigenvalues of the array covariance matrix;
Ê n is a matrix of M-K eigenvectors corresponding to the M-K smallest eigenvalues of the array covariance matrix, where M is equal to the number of feed elements in the antenna array;
{circumflex over (Λ)} s is a matrix of the K largest eigenvalues of the array covariance matrix; and
{circumflex over (Λ)} n is a matrix of the M-K smallest eigenvalues of the array covariance matrix.
19. The transceiver of claim 18 , wherein the beam former is further configured to:
generate the spatial spectrum from the array covariance matrix estimate according to the following equation:
Pss
(
θ
,
φ
)
=
a
H
(
θ
,
φ
)
a
(
θ
,
φ
)
a
H
(
θ
,
φ
)
E
^
n
E
^
n
H
a
(
θ
,
φ
)
wherein a(θ, φ) is the array steering matrix; and
estimate directions of arrival of signals from the plurality of signal sources from largest peaks of the spatial spectrum.
20. The transceiver of claim 19 , wherein the beam former is further configured to:
define a threshold └ T ; and
define eigenvalues of the array covariance matrix R greater than └ T as corresponding to signal space and eigenvalues of the array covariance matrix R less than └ T as defining noise subspace, so that the number of eigenvalues of the array covariance matrix R greater than └ T is equal to the number K of signal sources.
21. A communications satellite, comprising:
an antenna having a plurality of antenna feed elements; and
an electronics system including a beam former configured to:
receive a plurality of samples of a receive signal from the plurality of antenna feed elements;
estimate locations of a plurality of signal sources from the plurality of receive signal samples;
identify a plurality of interference sources from among the plurality of signal sources;
generate a plurality of antenna feed element weights w M in response to locations of the interference sources; and
form an antenna beam from the antenna to the geographic region using the antenna feed element weights w M ;
wherein the electronics system is configured to communicate information over the antenna beam, and
wherein the beam former is further configured to:
define a plurality of antenna gain constraint values g k associated with a plurality of geographic constraint points within a geographic region;
determine interference weighting factors for the geographic constraint points and locations of the interference sources; and
generate the antenna feed element weights in response to the interference weighting factors.
22. A satellite gateway, comprising:
an antenna; and
an electronics system coupled to the antenna and including a beam former configured to:
receive a plurality of samples of a receive signal from a plurality of satellite antenna feed elements;
estimate locations of a plurality of signal sources from the plurality of receive signal samples;
identify a plurality of interference sources from among the plurality of signal sources;
generate a plurality of satellite antenna feed element weights w M in response to locations of the interference sources; and
form an antenna beam from a satellite antenna to a geographic region using the antenna feed element weights w M ;
wherein the electronics system is configured to communicate information over the antenna beam; and
wherein the beam former is further configured to:
define a plurality of antenna gain constraint values g k associated with a plurality of geographic constraint points within a geographic region;
determine interference weighting factors for the geographic constraint points and locations of the interference sources; and
generate the antenna feed element weights in response to the interference weighting factors.