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Cancelling non-linear power amplifier induced distortion from a received signal by moving incorrectly estimated constellation points

  • US 8,355,466 B2
  • Filed: 09/25/2009
  • Issued: 01/15/2013
  • Est. Priority Date: 09/25/2009
  • Status: Active Grant
First Claim
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1. A method for reducing power amplifier induced distortion, comprising:

  • receiving a received signal corresponding to a channel affected version of a transmitted signal, wherein the transmitted signal comprises transmit data that was distorted by a transmit power amplifier prior to transmission over the channel;

    iteratively estimating distortion induced by the transmit power amplifier prior to transmission in the received signal via an estimation routine to generate estimated power amplifier distortion;

    iteratively cancelling the estimated power amplifier distortion present in the received signal via a cancellation routine executed after each iteration of the estimation routine;

    comparing, after each iteration of the cancellation routine, a current estimated power amplifier distortion to a previous estimated power amplifier distortion to determine whether difference between the current estimated power amplifier distortion and the previous estimated power amplifier distortion is less than a convergence threshold;

    temporarily stopping the cancellation routine when the difference between the current estimated power amplifier distortion and the previous estimated power amplifier distortion is less than the convergence threshold;

    determining M-QAM constellation points corresponding to estimates of the transmit data, and determining particular ones of the M-QAM constellation points that are incorrectly estimated and in error; and

    executing, for each of the M-QAM constellation points, a M-QAM constellation point correction routine designed to move the incorrectly estimated M-QAM constellation points that are in error towards expected quadrants of those incorrectly estimated M-QAM constellation points.

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