Method and apparatus for CDMA signal orthogonalization
First Claim
1. A receiver comprising:
- means for receiving a composite signal;
means for processing said composite signal to produce a processed composite signal;
means for correlating said processed composite signal with a plurality of signature sequences to produce at least one correlation;
means for detecting a particular signal within said composite signal using said at least one correlation;
means for modifying said signature sequences to produce modified signature sequences; and
means for removing said particular signal from said processed composite signal using said modified signature sequences.
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Abstract
Orthogonalization techniques are disclosed which can be used, for example, to improve subtration of CDMA signals from a composite spread spectrum signal or to improve detection of CDMA signals from the composite spread spectrum signal. According to exemplary embodiments, a Gram-Schmidt orthogonalization process is used to modify signature sequences which are each associated with a particular CDMA signal in the spread spectrum composite signal. These modified signature sequences can then be used to spread correlations of the original signature sequences in the subtraction process or in the detection process to improve performance. Pre-orthogonalization according to the present invention, eliminates or mitigates multiple access interference.
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Citations
16 Claims
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1. A receiver comprising:
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means for receiving a composite signal; means for processing said composite signal to produce a processed composite signal; means for correlating said processed composite signal with a plurality of signature sequences to produce at least one correlation; means for detecting a particular signal within said composite signal using said at least one correlation; means for modifying said signature sequences to produce modified signature sequences; and means for removing said particular signal from said processed composite signal using said modified signature sequences. - View Dependent Claims (2, 3, 4)
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5. A receiver comprising:
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means for receiving a composite signal; means for processing said composite signal to produce a processed composite signal; means for correlating said processed composite signal with a plurality of signature sequences to produce at least one correlation; means for detecting a particular signal within said composite signal using said at least one correlation; and means for removing said particular signal from said processed composite signal by a sequence of subtractions, said sequence of subtractions being performed using coefficients related to a modified signature sequence associated with said particular signal. - View Dependent Claims (6, 7, 8)
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9. A receiver comprising:
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means for receiving a composite signal; means for processing said composite signal to produce a processed composite signal; means for additively modifying signature sequences associated with signals which have been combined to form said composite signal; means for correlating said processed composite signal with said modified signature sequences to produce at least one correlation; and means for detecting a particular signal within said composite signal using said at least one correlation. - View Dependent Claims (10, 11)
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12. A receiver comprising:
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means for receiving a composite signal; means for processing said composite signal to produce a processed composite signal; means for correlating said processed composite signal with signature sequences to produce a plurality of correlations; means for combining said correlations corresponding to a plurality of signature sequences to produce at least one statistic associated with a particular signal; and means for detecting a particular signal using said at least one statistic. - View Dependent Claims (13, 14)
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15. A transmitter comprising:
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means for modifying a plurality of signature sequences to produce modified signature sequences; means for spreading information using one or more of said modified signature sequences to produce a plurality of spread signals; means for combining said spread signals to produce a composite spread signal; and means for modulating and transmitting said composite spread signal. - View Dependent Claims (16)
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Specification