Parameter estimation for linearization of nonlinear component
Disclosed is a method comprising selecting a mathematical model associated with a nonlinear component, determining an error signal associated with the nonlinear component, wherein the error signal indicates a difference between a first signal and a second signal, estimating one or more parameters that minimize the error signal based on the mathematical model, and estimating and/or linearizing the nonlinear component based on the estimated one or more parameters.
1 . An apparatus, comprising:
at least one processor; and
at least one memory including computer program code, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to:
select a mathematical model associated with a nonlinear component;
determine an error signal associated with the nonlinear component, wherein the error signal indicates a difference between a first signal and a second signal;
estimate one or more parameters that minimize the error signal based on the mathematical model, wherein a dither and fixed-point arithmetic are used for estimating the one or more parameters;
estimate and/or linearize the nonlinear component based on the estimated one or more parameters.
2 . The apparatus according to claim 1 , wherein the dither comprises a value that is determined based at least partly on a least significant bit.
3 . The apparatus according to claim 1 , wherein one or more reference coefficients are used for estimating the one or more parameters, said one or more reference coefficients being configured based on an input signal with a higher power and/or a wider bandwidth than a current input signal, or based on a time variant input signal with a varying amplitude and/or frequency hopping.
4 . The apparatus according to claim 1 , wherein a gradient descent algorithm is used for estimating the one or more parameters.
5 . The apparatus according to claim 1 , wherein a least-mean-squares algorithm is used for estimating the one or more parameters.
6 . The apparatus according to claim 1 , wherein an artificial neural network is used for estimating the one or more parameters.
7 . The apparatus according to claim 6 , wherein the artificial neural network utilizes backward error propagation for estimating the one or more parameters.
8 . The apparatus according to claim 1 , wherein the nonlinear component is a power amplifier and the mathematical model is a power amplifier model.
9 . The apparatus according to claim 8 , wherein the first signal is an output from the power amplifier and the second signal is an output from the power amplifier model.
10 . The apparatus according to claim 1 , wherein a linear model is used for the mathematical model associated with the nonlinear component.
11 . The apparatus according to claim 10 , further comprising performing pulse insertion and/or wideband estimation of the linear model.
12 . The apparatus according to claim 1 , further comprising performing matched filtering of the error signal.
13 . A method, comprising:
selecting a mathematical model associated with a nonlinear component;
determining an error signal associated with the nonlinear component, wherein the error signal indicates a difference between a first signal and a second signal;
estimating one or more parameters that minimize the error signal based on the mathematical model, wherein a dither and fixed-point arithmetic are used for estimating the one or more parameters;
estimating and/or linearizing the nonlinear component based on the estimated one or more parameters.
14 . The method according to claim 13 , wherein the dither comprises a value that is determined based at least partly on a least significant bit.
15 . The method according to claim 13 , wherein one or more reference coefficients are used for estimating the one or more parameters, said one or more reference coefficients being configured based on an input signal with a higher power and/or a wider bandwidth than a current input signal, or based on a time variant input signal with a varying amplitude and/or frequency hopping.
16 . The method according to claim 13 , wherein a gradient descent algorithm is used for estimating the one or more parameters.
17 . The method according to claim 13 , wherein a least-mean-squares algorithm is used for estimating the one or more parameters.
18 . A non-transitory computer-readable medium comprising instructions encoded thereon that, when executed on an apparatus, cause the apparatus to:
select a mathematical model associated with a nonlinear component;
determine an error signal associated with the nonlinear component, wherein the error signal indicates a difference between a first signal and a second signal;
estimate one or more parameters that minimize the error signal based on the mathematical model, wherein a dither and fixed-point arithmetic are used for estimating the one or more parameters; and
estimate and/or linearize the nonlinear component based on the estimated one or more parameters.