Patent ID: 8705604

Claim:
A method for equalizing a complex digital signal, the method comprising: upsampling a copy of the complex digital signal to obtain an upsampled complex digital signal; separating the upsampled complex digital signal to obtain upsampled in-phase and quadrature components of the complex digital signal; creating real and imaginary nonlinear compensation terms from the upsampled in-phase and quadrature components, respectively, of the complex digital signal; downsampling the real and imaginary nonlinear compensation terms to obtain downsampled real and imaginary nonlinear compensation terms; applying a predetermined phase shift to the downsampled imaginary nonlinear compensation term to obtain a phase-shifted imaginary nonlinear compensation term; combining the downsampled real nonlinear compensation term with the phase-shifted imaginary nonlinear compensation term to obtain an estimated residual distortion; and subtracting the estimated residual distortion from the complex digital signal to obtain an equalized complex digital signal.