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Method and apparatus for synchronizing a carrier frequency of an orthogonal frequency division multiplexing transmission system

  • US 6,219,333 B1
  • Filed: 02/25/1998
  • Issued: 04/17/2001
  • Est. Priority Date: 02/25/1997
  • Status: Expired due to Fees
First Claim
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1. A method for synchronizing a carrier frequency of an OFDM transmission system, comprising the steps of:

  • selecting one of a coarse mode for correcting an integer part of a carrier frequency offset and a fine mode for correcting a prime part of the carrier frequency offset;

    calculating a strength of a carrier which is received in each subchannel when the coarse mode is selected;

    accumulating the calculated strength of the carrier and a strength of a previous carrier delayed for a duration of one symbol for a predetermined period until the accumulated value reaches a predetermined threshold value;

    correcting the integer part of the carrier frequency offset using the accumulated value;

    extracting a pilot signal from the carrier when the fine mode is selected;

    calculating a phase difference between the extracted pilot signal and a previously extracted pilot signal which is delayed for a duration of one symbol; and

    correcting the prime part of the carrier frequency offset within a predetermined frequency by controlling a gain of the calculated phase difference.

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