US2023137470A1PendingUtilityA1
Active array antenna linearization
Est. expiryNov 13, 2038(~12.3 yrs left)· nominal 20-yr term from priority
H03F 1/3247H03F 2200/451H03F 1/3258H03F 3/68H04L 27/368H04B 1/0475
65
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Claims
Abstract
Systems and methods for linearizing a radio system are disclosed. In some embodiments, a radio system comprises an antenna array, transmit branches comprising respective power amplifiers, a predistortion subsystem comprising predistorters for the transmit branches respectively, a receive antenna element, a transmit observation receiver having an input coupled to the receive antenna element, and an adaptor. The predistorters predistort respective transmit signals to provide predistorted transmit signals to the respective transmit branches for transmission via respective active antenna elements in the antenna array. The transmit observation receiver is operable to receive, via the receive antenna element, a combined receive signal due to coupling between the receive antenna element and the active antenna elements. The adaptor is operable to generate a combined reference signal based on the transmit signals and configure predistortion parameters input to the predistorters based on the combined reference signal and the combined receive signal.
Claims
exact text as granted — not AI-modified1 . A radio system, comprising:
an antenna array comprising a plurality of active antenna elements; a plurality of transmit branches comprising a respective plurality of power amplifiers, the plurality of transmit branches operable to transmit a plurality of predistorted transmit signals via the plurality of active antenna elements, respectively; a predistortion subsystem comprising a plurality of predistorters for the plurality of transmit branches respectively, the plurality of predistorters operable to predistort a respective plurality of transmit signals to provide the plurality of predistorted transmit signals and provide the plurality of predistorted transmit signals to the plurality of transmit branches, respectively; a receive antenna element; a transmit observation receiver having an input coupled to the receive antenna element, the transmit observation receiver operable to receive, via the receive antenna element, a combined receive signal; and an adaptor operable to:
generate a combined reference signal based on the plurality of transmit signals such that the combined reference signal models the combined receive signal; and
configure predistortion parameters input to the plurality of predistorters that define predistortion provided by the plurality of predistorters using an error minimization technique based on the combined reference signal and the combined receive signal.
2 . The radio system of claim 1 wherein the error minimization technique is based on the combined reference signal, the combined receive signal, and known complex valued attenuation factors that define a coupling from the plurality of active antenna elements to the receive antenna element.
3 . The radio system of claim 2 wherein the predistortion parameters are a common set of predistortion coefficients for the plurality of predistorters.
4 . The radio system of claim 2 wherein:
the predistortion parameters are an estimated predistortion coefficient vector, α k+1 , that defines a common set of predistortion coefficients for the plurality of predistorters; and
in order to configure the predistortion parameters, the adaptor is further configured to compute the estimated predistortion coefficient vector, α k+1 , in accordance with:
α
k
+
1
=
α
k
+
η
·
M
k
+
·
[
(
∑
n
=
1
N
β
n
·
x
n
)
-
y
k
]
where
α k is a prior set of predistortion parameters for the plurality of predistorters used to generate the plurality of predistorted transmit signals;
η is a scaling convergence factor;
β n is a coupling factor between the n-th active antenna element and the receive antenna element;
x n is the transmit signal that is predistorted by the respective predistorter to provide the predistorted transmit signal for the transmit branch for the n-th active antenna element;
y k is the combined receive signal; and
M k + =( M k H ·M k ) −1 ·M k H
where
M k =[ y k y k ·|y k | 2 y k ·|y k | 4 . . . ].
5 . The radio system of claim 2 wherein the predistortion parameters comprise a separate set of predistortion coefficients for each of the plurality of predistorters.
6 . The radio system of claim 1 wherein the error minimization technique is based on the combined reference signal, the combined receive signal, and one or more estimated parameters that take into consideration unknown complex valued attenuation factors that define a coupling from the plurality of active antenna elements to the receive antenna element.
7 . The radio system of claim 6 wherein the predistortion parameters are a common set of predistortion coefficients for the plurality of predistorters.
8 . The radio system of claim 6 wherein the predistortion parameters comprise a separate set of predistortion coefficients for each of the plurality of predistorters.
9 . The radio system of claim 6 wherein the receive antenna element is a dedicated antenna element for the transmit observation receiver.
10 . A method of operation of a radio system to linearize the radio system, comprising:
predistorting a plurality of transmit signals via a respective plurality of predistorters of the radio system to thereby provide a plurality of predistorted transmit signals; transmitting the plurality of predistorted transmit signals via a respective plurality of active antenna elements in an antenna array of the radio system; receiving a combined receive signal via a receive antenna element and a transmit observation receiver of the radio system; generating a combined reference signal based on the plurality of transmit signals such that the combined reference signal models the combined receive signal; and configuring predistortion parameters input to the plurality of predistorters that define predistortion provided by the plurality of predistorters using an error minimization technique based on the combined reference signal and the combined receive signal.
11 . The method of claim 10 wherein the error minimization technique is based on the combined reference signal, the combined receive signal, and known complex valued attenuation factors that define a coupling from the plurality of active antenna elements to the receive antenna element.
12 . The method of claim 11 wherein the predistortion parameters are a common set of predistortion coefficients for the plurality of predistorters.
13 . The method of claim 11 wherein:
the predistortion parameters are an estimated predistortion coefficient vector, α k+1 , that defines a common set of predistortion coefficients for the plurality of predistorters; and
configuring the predistortion parameters comprises computing the estimated predistortion coefficient vector, α k+1 , in accordance with:
α
k
+
1
=
α
k
+
η
·
M
k
+
·
[
(
∑
n
=
1
N
β
n
·
x
n
)
-
y
k
]
where
α k is a prior set of predistortion parameters for the plurality of predistorters used to generate the plurality of predistorted transmit signals;
η is a scaling convergence factor;
β n is a coupling factor between the n-th active antenna element and the receive antenna element;
x n is the transmit signal that is predistorted by the respective predistorter to provide the predistorted transmit signal for a transmit branch for the n-th active antenna element;
y k is the combined receive signal; and
M k + =( M k H ·M k ) −1 ·M k H
where
M k =[ y k y k ·|y k | 2 y k ·|y k | 4 . . . ].
14 . The method of claim 11 wherein the predistortion parameters comprise a separate set of predistortion coefficients for each of the plurality of predistorters.
15 . The method of claim 10 wherein the error minimization technique based on the combined reference signal, the combined receive signal, and one or more estimated parameters that take into consideration unknown complex valued attenuation factors that define a coupling from the plurality of active antenna elements to the receive antenna element.
16 . The method of claim 15 wherein the predistortion parameters are a common set of predistortion coefficients for the plurality of predistorters.
17 . The method of claim 15 wherein the predistortion parameters comprise a separate set of predistortion coefficients for each of the plurality of predistorters.
18 . The method of claim 10 wherein the receive antenna element is a dedicated antenna element for the transmit observation receiver.
19 . The radio system of claim 1 wherein the receive antenna element is a dedicated antenna element for the transmit observation receiver.Cited by (0)
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