Method and apparatus for selectively applying interference cancellation in spread spectrum systems
First Claim
1. A method for selectively enabling signal interference cancellation, comprising:
- identifying a plurality of signal paths in a searcher;
for a set of said identified signal paths, determining an observed signal strength in a finger processor;
identifying at least one of said signal paths as a potential interferer based at least in part on the observed signal strength;
creating in an interference canceller at least a first interference cancelled signal stream by cancelling the interference from the at least one said potential interferer;
determining whether providing said at least a first interference cancelled signal stream to at least a first signal processor will improve a signal to noise ratio of at least a first signal path assigned to said at least a first signal processor; and
in response to determining that said at least a first interference cancelled signal stream will improve a signal to noise ratio of said signal path at least a first signal stream assigned to said at least a first signal processor, providing said at least a first interference cancelled signal stream to said at least a first signal processor.
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Abstract
The present invention is directed to the selective provision of interference canceled signal streams to demodulating fingers in a communication receiver. According to the present invention, potential interferer signal paths are identified. Signal streams having one or more potential interferer signals removed or canceled are created, and a correlation is performed to determine whether the strength of a desired signal path increased as a result. If the correlation indicates that the strength of a desired signal path was increased by the signal cancellation, the interference canceled signal stream is provided to the demodulation finger assigned to track the desired signal path. If the correlation determines that the strength of the desired signal path did not increase as a result of performing interference cancellation, the raw or a different interference canceled signal stream is provided to the demodulation finger.
147 Citations
42 Claims
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1. A method for selectively enabling signal interference cancellation, comprising:
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identifying a plurality of signal paths in a searcher; for a set of said identified signal paths, determining an observed signal strength in a finger processor; identifying at least one of said signal paths as a potential interferer based at least in part on the observed signal strength; creating in an interference canceller at least a first interference cancelled signal stream by cancelling the interference from the at least one said potential interferer; determining whether providing said at least a first interference cancelled signal stream to at least a first signal processor will improve a signal to noise ratio of at least a first signal path assigned to said at least a first signal processor; and in response to determining that said at least a first interference cancelled signal stream will improve a signal to noise ratio of said signal path at least a first signal stream assigned to said at least a first signal processor, providing said at least a first interference cancelled signal stream to said at least a first signal processor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for selecting a signal interference cancellation scheme, comprising:
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populating a cancellation list in a cancellation controller with an identity of at least a first signal path that has been identified as an interfering signal path; establishing a connection between a demodulating finger and one of a raw signal stream and an interference cancelled signal stream based on an entry in said cancellation list; wherein the raw signal stream is provided to a first demodulating finger and the interference cancelled signal stream is provided to a second demodulating finger. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A method for selectively enabling signal interference cancellation, comprising:
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identifying in a searcher at least one signal path in a set of signal paths; for the at least one signal, determining an observed signal strength in a processing finger; identifying at least one of said signal paths as a potential interferer based at least in part on the observed signal strength; producing an interference cancelled signal stream, wherein said at least one signal path identified as a potential interferer is cancelled from said signal producing an interference cancelled stream; and correlating said interference cancelled signal stream with a reference signal; and in response to a strength of a desired signal having a strength that is not improved as a result of using said interference cancelled signal, providing a signal including said at least one signal path to a demodulation finger assigned to demodulate said desired signal. - View Dependent Claims (26)
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27. A method for selectively enabling signal interference cancellation, comprising:
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providing to a cancellation controller a set of signal paths comprising at least one desired signal path; identifying at least one signal path in the set of signal paths as a potential interferer with the desired signal path; determining whether removing the at least one signal path in the set of signal paths will improve a signal to noise ratio (SNR) of the desired signal path by at least a selected threshold; and when the SNR of the desired signal path is improved by at least the selected threshold, removing the at least one signal from the signal stream in an interference canceller to form an interference canceled signal stream. - View Dependent Claims (28, 29, 30)
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31. A method for selecting a signal path for interference cancellation, comprising:
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comparing in a cancellation controller a cancellation candidate list with a cancellation list, wherein each of the cancellation candidate list and cancellation list comprise at least a finger identifier and a signal identifier of an interfering signal path; replacing any entry on the cancellation list with each entry in the cancellation candidate list that is not on the cancellation list; and updating a signal strength of each entry on both the cancellation and cancellation candidate lists with a signal strength on the cancellation candidate list. - View Dependent Claims (32, 33, 34)
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35. A method for selecting a signal path for interference cancellation, comprising:
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identifying in a cancellation controller at least one potentially interfering signal path in a signal stream; removing said at least one potentially interfering signal path from said signal stream in an interference canceller; searching said interference cancelled signal stream in a searcher, from which the at least one potentially interfering signal path has been removed, for each PN offset having a corresponding signal path possessing at least one of (a) a strength above a selected threshold and (b) a signal-to-noise improvement above a selected threshold; and providing said interference cancelled signal stream to each demodulating finger assigned to each PN offset having at least one of (a) and (b). - View Dependent Claims (36)
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37. A receiver configured for processing a raw signal stream, comprising:
- a plurality of demodulation fingers;
a cancellation controller operable to selectively provide either or both of the raw signal stream and at least one interference cancelled signal stream to the plurality of demodulation fingers; and at least one cancellation module configured with the cancellation controller and operable to remove at least one replica of an interfering signal path from the raw signal stream to generate one of the at least one interference cancelled signal streams. - View Dependent Claims (38, 39, 40, 41, 42)
- a plurality of demodulation fingers;
Specification