SYSTEM AND METHOD FOR JOINT COMPENSATION OF POWER AMPLIFIER'S DISTORTION

摘要

The system and method for joint compensation of power amplifier's distortion provides a linearization scheme for transmitter power amplifiers driven by orthogonal frequency division multiplexing signals. A pre-compensated over-driven amplifier is employed at the transmitter. The over-driven amplifier's distortions are considered as a sparse phenomenon and compressive sensing (CS) algorithms are employed at the receiver to estimate and compensate for these distortions. A bandwidth efficient data aided scheme which does not require reserving subcarriers specifically for CS measurements is utilized.

主权项

1. In an orthogonal frequency division multiplexing (OFDM) telecommunication system having an OFDM transmitter sending OFDM signals amplified by a power amplifier to an OFDM receiver, a method for joint compensation (at the transmitter and the receiver) of the power amplifier's distortion, comprising the steps of:
(a) compensating distortion of the OFDM signals caused by the power amplifier at the transmitter; (b) overdriving the linearized power amplifier to increase transmission power efficiency of the OFDM signals; (c) estimating and further compensating the distortion of the OFDM signals using compressive sensing at the receiver, said compressive sensing being performed without reserving subcarriers specifically for said compressive sensing, thereby enhancing spectral efficiency of the OFDM signals; and (d) using a priori knowledge about the sparsity of the overdrive distortion to recover the distortion introduced at the transmitter thereby facilitating the estimation and compensation step (c), wherein the receiver performs the following steps: iteratively estimating a modulated data vector until a maximum number, j=Jmax, of modulated data vectors has been estimated; iteratively comparing a jth estimated modulated data vector Uj with a constellation of size P (P representing a number of data-free/pilot carriers) to produce a vector set of reliable carriers SR′; iteratively performing compressive sensing based on inputs of the vector set of reliable carriers SR′ and the estimated modulated data vector Uj, output of the iterative compressive sensing providing {circumflex over (x)}dj; subtracting said {circumflex over (x)}dj from an {circumflex over (x)}j output of a front end compressive sensing and equalization step, said subtracting said {circumflex over (x)}dj from said {circumflex over (x)}j forming a compensation signal {circumflex over (x)}j+1; performing a discrete Fourier transform (DFT) on the compensation signal {circumflex over (x)}j+1 to provide an updated estimated modulated data vector Uj+1 as input to said iterative constellation comparison and iterative compressive sensing steps; and demodulating and removing the data-free/pilot carriers of said enhanced, linearized OFDM signals when the maximum number, j=Jmax, of modulated data vectors has been estimated.