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Pre-distorter for orthogonal frequency division multiplexing systems and method of operating the same

A technology of predistorter and communication system, applied in the direction of transmission system, digital transmission system, modulated carrier system, etc., can solve the problems that are not suitable for high-power amplifier systems that change with time, and are complex

Inactive Publication Date: 2008-01-23
RGT UNIV OF CALIFORNIA
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

This has the disadvantage of being complex in modeling and estimation of the Volterra series
[0011] This algorithm is general in the case of high power amplifiers and predistorters using polynomial approximation, but it has the disadvantage of complexity caused by polynomial approximation
[0012] In the case of using the exact inversion model of the traveling wave tube amplifier, this has the disadvantage of being unsuitable for time-varying high power amplifier systems

Method used

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  • Pre-distorter for orthogonal frequency division multiplexing systems and method of operating the same
  • Pre-distorter for orthogonal frequency division multiplexing systems and method of operating the same
  • Pre-distorter for orthogonal frequency division multiplexing systems and method of operating the same

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Embodiment Construction

[0052] System specification

[0053] Figure 1 is a simplified block diagram of the present invention showing a system architecture, generally indicated by the reference numeral 10, for compensation of non-linearity of a high power amplifier of an OFDM system. OFDM baseband module 12 generates a signal in OFDM format to predistorter 14, whose digital output is converted to analog format by digital-to-analog converter 16 to produce phase-shifted QAM output to multipliers 18 and 20, which are combined and phased at adder 22. , and input to a power amplifier 24 for transmission to a wireless or wired communication system. It must be understood that the hardware in Figure 1 can be implemented in many equivalent ways. For example, the predistorter 14 is a digital circuit, which may be a dedicated digital signal processor using hardware and / or a combination of hardware and software, or may be a computer with a suitable signal interface, which is computerized or configured by softwar...

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Abstract

A pre-distorter and a power amplifier are combined in a communication system. The purpose of the power amplifier is to provide as high a power as possible to the orthogonal frequency division multiplexing (OFDM) signal being passed by the high power amplifier to the communication system. The pre-distorter inverts the nonlinearity of the amplifier, so that the combination of pre-distorter and high power amplifier exhibit a linear characteristic beyond the normal linear range of the high power amplifier. The pre-distorter is based on exact analytic expression for the description of the input-output characteristic of the pre-distorter based on an analytic model for the power amplifier. A mixed computational-analytical approach compensates for nonlinear distortion in the high power amplifier even with time-varying characteristics. This leads to a sparse and yet accurate representation of the pre-distorter, with the capability of tracking efficiently any rapidly time-varying behavior of the power amplifier.

Description

[0001] related application [0002] This application is related to US Provisional Patent Application No. 60 / 602,905, filed August 19, 2004, which is hereby incorporated by reference, and which claims priority under 35USC119. technical field [0003] The invention relates to the field of predistorters in communication systems using power amplifiers, wherein the signal-dependent and time-varying parameters of the power amplifiers are linearized by means of a predistorter. Background technique [0004] Orthogonal Frequency Division Multiplexing (OFDM) is a digital modulation method in which a signal is divided into several narrowband channels occupying different frequencies. The technique was first conceived in the 1960s and 1970s during research into minimizing interference between channels with frequencies close to each other. In some respects, OFDM is similar to traditional frequency division multiplexing (FDM). The difference lies in the way the signal is modulated and de...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04K1/02H04L25/03
CPCH04L27/2626H03F1/3241H04L27/368
Inventor 瑞·J·P·德飞格里多李炳冒
Owner RGT UNIV OF CALIFORNIA