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System and method for digital memorized predistortion for wireless communication

  • US 8,326,238 B2
  • Filed: 10/27/2005
  • Issued: 12/04/2012
  • Est. Priority Date: 05/01/2002
  • Status: Expired due to Term
First Claim
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1. In a wireless transmission system adapted for use with a portable mobile device, a method for processing signals in preparation for wireless transmission, wherein the wireless transmission includes use of a power amplifier, the method comprising:

  • maintaining a lookup table that contains pre-computed distortion contributions determined by monitoring the power amplifier following initialization of the power amplifier and prior to transmission, wherein determining distortion contributions includes;

    squaring an in-phase component of a signal representative of power amplifier output to produce a squared in-phase output value;

    squaring a quadrature component of the signal representative of power amplifier output to produce a squared quadrature output value;

    squaring an in-phase component of a signal representative of an input signal to produce a squared in-phase input value;

    squaring a quadrature component of the signal representative of the input signal to produce a squared quadrature input value;

    determining an in-phase difference between the squared in-phase input value and the squared in-phase output value; and

    determining a quadrature difference between the squared quadrature input value and the squared quadrature output value, the distortion contributions being based on the in-phase difference and the quadrature difference;

    accepting a value that reflects information to be communicated, the value hereinafter referred to as original value;

    generating a lookup-table key based on the original value, wherein the lookup-table key is digital;

    retrieving from the lookup table, using the lookup-table key, a pre-computed distortion contribution for the original value;

    distorting the original value based on the pre-computed distortion contribution to obtain a distorted value to pre-compensate for nonlinear characteristics of the power amplifier; and

    wirelessly transmitting based on the distorted value.

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