Adaptive pre-distortion method based on two-dimensional polling list in OFDM system

A look-up table and pre-distortion technology, applied to multi-frequency code systems, synchronization/start-stop systems, etc., can solve problems such as performance needs to be improved

Active Publication Date: 2009-07-08
SPACE STAR TECH CO LTD
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Problems solved by technology

This scheme is a simple and efficient predistortion method, but its performance needs to be improved

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  • Adaptive pre-distortion method based on two-dimensional polling list in OFDM system
  • Adaptive pre-distortion method based on two-dimensional polling list in OFDM system
  • Adaptive pre-distortion method based on two-dimensional polling list in OFDM system

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Embodiment Construction

[0066] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0067] figure 2 It is a structural diagram of the non-direct learning structure adaptive pre-distortion system of the present invention, the system combines the non-direct learning structure in the polynomial pre-distortion method with the look-up table adaptive pre-distortion method, and the pre-distortion device of the present invention includes a first pre-distortion unit, a second pre-distortion unit, two pre-distortion look-up table units, an error signal calculation unit and an adaptive algorithm unit.

[0068] Wherein the first pre-distortion unit includes a first look-up table storing pre-distortion coefficients, according to the first look-up table for the input OFDM source signal v i (n) Perform pre-distortion processing, and the pre-distortion processed signal v d (n) respectively sent to the error signal calculation unit and the ext...

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Abstract

The invention relates to a self-adapting predistortion method based on a two-dimension query table in an Orthogonal Frequency Division Multiplexing (OFDM) system comprising error calculation of signals after once predistortion processing and twice predistortion processing for OFDM source signals, self-adapting iteration operation of error signals and renewal of predistortion coefficients which enable the error signals to approach to zero. The predistortion processing employs a method that obtains an amplitude predistortion coefficient and a phase predistortion coefficient through a united index of a first dimension index address X(n) and a second dimension index address Y(n), wherein the second dimension index address Y(n) is calculated by historical input amplitude values. The technical scheme of the invention effectively overcomes memory effect of a power amplifier, and effectively expedites convergence rate of the query table at the same time of not increasing the algorithm complexity, obtains smaller mean error and simultaneously reduces the algorithm hardware implementing complexity.

Description

technical field [0001] The invention relates to the technical field of wireless communication, in particular to an adaptive predistortion method based on a two-dimensional lookup table in an OFDM system. Background technique [0002] Due to the superposition of multiple sub-channel signals in the OFDM system, there will be a large instantaneous peak value in the composite signal in the transmitter of the system, resulting in an excessive peak-to-average power ratio. Distortion occurs when these transient peaks pass through an amplifier with limited linear dynamic range in the transmission system. [0003] Amplifier distortion is divided into two types: linear distortion and nonlinear distortion. Usually the input signal of the amplifying circuit is a multi-frequency signal. If the amplifying circuit has different gain amplitudes or relative phase shift changes for different frequency components of the signal, the output waveform will be distorted. The former is called ampli...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L27/26H04L25/49
Inventor 邢玥邹光南程子敬尹浩琼
Owner SPACE STAR TECH CO LTD
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