Method and system for baseband predistortion linearization in multi-channel wideband communication systems

Abstract

An efficient baseband predistortion linearization method for reducing the spectral regrowth and compensating memory effects in wideband communication systems using effective multiplexing modulation technique such as wideband code division multiple access and orthogonal frequency division multiplexing is disclosed. The present invention is based on the method of piecewise pre-equalized lookup table based predistortion, which is a cascade of a lookup table predistortion and piecewise pre-equalizers.

What is claimed is: 
     
         1 . A method comprising:
 providing a pre-distortion lookup table (LUT) having N first entries, N being an integer equal to or greater than unity;   providing a pre-equalization lookup table (LUT) having M second entries, M being an integer equal to or greater than unity, the pre-equalization LUT being associated with a pre-equalizer;   determining an index based on a magnitude of a baseband input signal;   generating a sample by multiplying the baseband input signal with an entry of the N first entries in accordance with the index; and   pre-equalizing the sample using an entry of the M second entries in accordance with the index to generate a pre-equalized signal,   wherein the baseband input signal is a digital complex signal, and each entry of the pre-distortion LUT comprises complex coefficients, and   wherein the complex coefficients are obtained by:   converting the sample to an analog baseband signal by an analog-to-digital converter while bypassing the pre-equalizer;   frequency upconverting the analog baseband signal to an upconverted signal;   amplifying the upconverted signal by a power amplifier to obtain an amplified signal;   attenuating the amplified signal to an attenuated signal;   frequency downconverting the attenuated signal to a baseband signal; and   performing an indirect learning least mean square (LMS) algorithm using the baseband signal and the baseband input signal to obtain the complex coefficients.