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DSL rate adaptation

  • US 6,310,909 B1
  • Filed: 05/11/1999
  • Issued: 10/30/2001
  • Est. Priority Date: 12/23/1998
  • Status: Expired due to Term
First Claim
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1. A method for providing digital communication via twisted pair telephone lines and the like, the method comprising the steps of:

  • defining a frequency spectrum having a predetermined bandwidth within which communication between two transceivers is to be performed, the frequency spectrum comprising a beginning (Fstart) at a low frequency end thereof and an end (Fstop) at a high frequency end thereof;

    defining at least one channel within the frequency spectrum, the channel having an initial bandwidth which is substantially less than the bandwidth of the frequency spectrum;

    communicating via the channel while varying the spectral allocation of the channel and while maintaining a constant constellation size;

    determining a potential bit rate for each of a plurality of the spectral allocations at which communication was performed, the potential bit rate being determined using a potential constellation size for each spectral allocation determined via the measured signal to noise ratio (SNR) for that spectral allocation, a desired minimum signal to noise ratio (SNR) margin, and a given overall target bit rate, according to the formula;

    potential bit rate=(symbol rate) (FEC payload percentage) log2 (maximum constellation size);

    wherein the symbol rate is determined by the bandwidth for each spectral allocation; and

    wherein the constellation size is calculated according to the formula;

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