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Systems and method for orthogonal frequency divisional multiplexing

  • US 7,957,265 B2
  • Filed: 10/29/2007
  • Issued: 06/07/2011
  • Est. Priority Date: 02/06/1995
  • Status: Expired due to Fees
First Claim
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1. A multi-carrier modem, the modem comprising:

  • a receiver configured to de-modulate symbols from at least one of a plurality of spectrally overlapping carrier signals;

    a transmitter configured to modulate symbols onto at least one of a plurality of the spectrally overlapping carrier signals;

    a processor coupled to the transmitter, wherein the processor outputs data for transmission by the transmitter, wherein the processor applies an inverse Fourier transform to the data transmitted by the transmitter;

    a controller programmed to instruct the transmitter to transmit a coarse timing adjustment followed by at least one secondary timing adjustment, wherein the secondary timing adjustment is a fine tuning adjustment with respect to the coarse timing adjustment;

    the controller further programmed to instruct the transmitter to transmit an adjustment instruction modulated using the inverse Fourier transform to at least one of a plurality of remote units, the adjustment instruction instructing the at least one of the plurality of remote units to vary a phase of transmissions transmitted from the at least one of the plurality of remote units.

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