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Spread spectrum CDMA subtractive interference canceler system

  • US 5,719,852 A
  • Filed: 05/29/1996
  • Issued: 02/17/1998
  • Est. Priority Date: 04/22/1993
  • Status: Expired due to Term
First Claim
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1. A method for reducing interference in a spread-spectrum code division multiple access (CDMA) receiver having N channels, with each of the N channels identified by a distinct chip-code signal, using a first plurality of interference cancelers, comprising the steps of:

  • a. despreading, simultaneously, a plurality of spread-spectrum channels of a spread-spectrum CDMA signal as a plurality of despread signals, respectively;

    b. spread-spectrum processing, simultaneously, using a timed version of a plurality of chip-code-signals, the plurality of despread signals, respectively, with a timed chip-code signal corresponding to a respective despread signal;

    c. subtracting from the spread-spectrum CDMA signal, each of a plurality of N-1 spread-spectrum-processed-despread signals, with the plurality of N-1 spread-spectrum-processed-despread signals not including a spread-spectrum processed despread signal of an ith despread signal, thereby generating a subtracted signal;

    d. despreading the subtracted signal with an ith timed chip-code signal as an ith channel signal, producing a first set of estimates of the N channels;

    e. inputting the first set of estimates to a second plurality of interference cancelers;

    f. repeating steps a through d, using the second plurality of interference cancelers, producing a second set of estimates of the N channels;

    g. inputting the second set of estimates to an Mth plurality of interference cancelers;

    h. repeating steps a through d, using the Mth plurality of interference cancelers, producing an Mth set of estimates of the N channels; and

    i. combining each estimate of the Mth set of estimates to produce an average.

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