Iterative interference cancellation using mixed feedback weights and stabilizing step sizes
First Claim
1. An interference canceller for cancelling interference in a received signal from a channel, the canceller configured for performing at least one iteration to produce at least one interference-cancelled symbol estimate, the canceller comprising:
- a synthesizing module configured for employing a signal basis for sources in the channel to synthesize constituent signals from a plurality of weighted or unweighted symbol estimates, and producing a combined signal therefrom, and a subtraction module configured to subtract the combined signal from the received signal to produce an error signal, anda stabilizing step size module configured for scaling the error signal by a stabilizing step size to produce a scaled error signal.
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Accused Products
Abstract
A receiver is configured for canceling intra-cell and inter-cell interference in coded, multiple-access, spread-spectrum transmissions that propagate through frequency-selective communication channels. The receiver employs iterative symbol-estimate weighting, subtractive cancellation with a stabilizing step-size, and mixed-decision symbol estimates. Receiver embodiments may be implemented explicitly in software or programmed hardware, or implicitly in standard Rake-based hardware either within the Rake (i.e., at the finger level) or outside the Rake (i.e., at the user or subchannel symbol level).
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Citations
45 Claims
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1. An interference canceller for cancelling interference in a received signal from a channel, the canceller configured for performing at least one iteration to produce at least one interference-cancelled symbol estimate, the canceller comprising:
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a synthesizing module configured for employing a signal basis for sources in the channel to synthesize constituent signals from a plurality of weighted or unweighted symbol estimates, and producing a combined signal therefrom, and a subtraction module configured to subtract the combined signal from the received signal to produce an error signal, and a stabilizing step size module configured for scaling the error signal by a stabilizing step size to produce a scaled error signal. - View Dependent Claims (2, 6, 7)
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3. An interference canceller for cancelling interference in a received signal from a channel, the canceller configured for performing at least one iteration to produce at least one interference-cancelled symbol estimate, the canceller comprising:
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a synthesizing module configured for employing a signal basis for sources in the channel to synthesize constituent signals from a plurality of weighted or unweighted symbol estimates, and producing a combined signal therefrom, and a subtraction module configured to subtract the combined signal from the received signal to produce an error signal, and wherein the constituent signals are characterized by at least one of a set of signals, the set comprising received signals associated with a plurality of Rake fingers and received signals associated with a plurality of symbol sources.
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4. An interference canceller for cancelling interference in a received signal from a channel, the canceller configured for performing at least one iteration to produce at least one interference-cancelled symbol estimate, the canceller comprising:
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a synthesizing module configured for employing a signal basis for sources in the channel to synthesize constituent signals from a plurality of weighted or unweighted symbol estimates, and producing a combined signal therefrom, and a subtraction module configured to subtract the combined signal from the received signal to produce an error signal, the canceller further configured for performing iterative interference cancellation in a receiver, wherein the synthesizing module is configured to synthesize the constituent signals to approximate estimated received signals employing the signal basis for all sources in the channel and the plurality of weighted or unweighted symbol estimates. - View Dependent Claims (5)
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8. An interference canceller for cancelling interference in a received signal from a channel, the canceller configured for performing at least one iteration to produce at least one interference-cancelled symbol estimate, the canceller comprising:
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a synthesizing module configured for employing a signal basis for sources in the channel to synthesize constituent signals from a plurality of weighted or unweighted symbol estimates, and producing a combined signal therefrom, and a subtraction module configured to subtract the combined signal from the received signal to produce an error signal, and a decision module configured to produce a decision for a plurality of the symbol estimates, the decision selected from one of a hard decision quantizing at least one of the symbol estimates to a nearby constellation point, and a soft decision scaling, but not quantizing, the at least one of the symbol estimates, wherein the decision module comprises a de-bias module configured to remove bias, as computed on the symbol estimates, before performing the decision.
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9. An interference canceller for cancelling interference in a received signal from a channel, the canceller configured for performing at least one iteration to produce at least one interference-cancelled symbol estimate, the canceller comprising:
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a synthesizing module configured for employing a signal basis for sources in the channel to synthesize constituent signals from a plurality of weighted or unweighted symbol estimates, and producing a combined signal therefrom, and a subtraction module configured to subtract the combined signal from the received signal to produce an error signal, and the canceller configured for performing synthesis and resolution onto the signal basis for all symbol sources in the channel in an outer feedback loop, and updating symbol estimates in an inner feedback loop employing an implementation matrix. - View Dependent Claims (10, 11)
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12. An interference canceller for cancelling interference in a received signal from a channel, the canceller configured for performing at least one iteration to produce at least one interference-cancelled symbol estimate, the canceller comprising:
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a synthesizing module configured for employing a signal basis for sources in the channel to synthesize constituent signals from a plurality of weighted or unweighted symbol estimates, and producing a combined signal therefrom, and a subtraction module configured to subtract the combined signal from the received signal to produce an error signal, and the canceller configured for performing symbol-level interference cancellation on despread signals with a direct implementation of a one-step matrix update equation expressing an explicit matrix representation of user correlations, an implementation matrix, a soft-weighting matrix, a de-biasing matrix, and a scalar stabilizing step size. - View Dependent Claims (13)
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14. An interference canceller for cancelling interference in a received signal from a channel, the canceller configured for performing at least one iteration to produce at least one interference-cancelled symbol estimate, the canceller comprising:
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a synthesizing module configured for employing a signal basis for sources in the channel to synthesize constituent signals from a plurality of weighted or unweighted symbol estimates, and producing a combined signal therefrom, and a subtraction module configured to subtract the combined signal from the received signal to produce an error signal, and the canceller configured as an internal feedback loop and an external feedback loop; the external feedback loop configured to multiply a vector of the input symbol estimates by a weighting matrix and a users'"'"' received correlation matrix to produce an external-feedback vector, and subtracting the external-feedback vector from the despread signal vector for producing a difference error vector that is scaled by a scalar stabilizing step size; and
the internal feedback loop configured to multiply a vector of the plurality of weighted symbol estimates by an implementation matrix to produce an internal-feedback vector, the internal-feedback vector being summed with a vector derived from the scaled error signal. - View Dependent Claims (15)
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16. An interference cancellation method for cancelling interference in a received signal from a channel, the method configured for performing at least one iteration to produce an interference-cancelled symbol estimate, the method comprising:
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providing for employing a signal basis for sources in the channel to synthesize constituent signals from a plurality of weighted or unweighted symbol estimates, and producing a combined signal therefrom, and providing for subtracting the combined signal from the received signal to produce an error signal, and providing for scaling the error signal by a stabilizing step size to produce a scaled error signal. - View Dependent Claims (17, 21, 22)
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18. An interference cancellation method for cancelling interference in a received signal from a channel, the method configured for performing at least one iteration to produce an interference-cancelled symbol estimate, the method comprising:
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providing for employing a signal basis for sources in the channel to synthesize constituent signals from a plurality of weighted or unweighted symbol estimates, and producing a combined signal therefrom, and providing for subtracting the combined signal from the received signal to produce an error signal, wherein the constituent signals are characterized by at least one of a set of signals, the set comprising received signals associated with a plurality of Rake fingers and received signals associated with a plurality of symbol sources.
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19. An interference cancellation method for cancelling interference in a received signal from a channel, the method configured for performing at least one iteration to produce an interference-cancelled symbol estimate, the method comprising:
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providing for employing a signal basis for sources in the channel to synthesize constituent signals from a plurality of weighted or unweighted symbol estimates, and producing a combined signal therefrom, and providing for subtracting the combined signal from the received signal to produce an error signal; and performing iterative interference cancellation in a receiver, wherein providing for employing a signal basis for sources in the channel to synthesize constituent signals is configured to synthesize the constituent signals to approximate estimated received signals employing the signal basis for all sources in the channel and the plurality of weighted or unweighted symbol estimates. - View Dependent Claims (20)
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23. An interference cancellation method for cancelling interference in a received signal from a channel, the method configured for performing at least one iteration to produce an interference-cancelled symbol estimate, the method comprising:
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providing for employing a signal basis for sources in the channel to synthesize constituent signals from a plurality of weighted or unweighted symbol estimates, and producing a combined signal therefrom, and providing for subtracting the combined signal from the received signal to produce an error signal, and providing for producing a decision for a plurality of symbol estimates, the decision selected from one of a hard decision quantizing at least one of the symbol estimates to a nearby constellation point, and a soft decision, scaling, but not quantizing, the at least one of the symbol estimates, wherein providing for producing a decision comprises removing bias computed on the symbol estimates before producing the decision.
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24. An interference cancellation method for cancelling interference in a received signal from a channel, the method configured for performing at least one iteration to produce an interference-cancelled symbol estimate, the method comprising:
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providing for employing a signal basis for sources in the channel to synthesize constituent signals from a plurality of weighted or unweighted symbol estimates, and producing a combined signal therefrom, and providing for subtracting the combined signal from the received signal to produce an error signal, the method configured for performing synthesis and resolution onto the signal basis for all symbol sources in the channel in an outer feedback loop, and updating symbol estimates in an inner feedback loop employing an implementation matrix. - View Dependent Claims (25, 26)
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27. An interference cancellation method for cancelling interference in a received signal from a channel, the method configured for performing at least one iteration to produce an interference-cancelled symbol estimate, the method comprising:
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providing for employing a signal basis for sources in the channel to synthesize constituent signals from a plurality of weighted or unweighted symbol estimates, and producing a combined signal therefrom, and providing for subtracting the combined signal from the received signal to produce an error signal, the method configured for performing symbol-level interference cancellation on despread signals with a direct implementation of a one-step matrix update equation expressing an explicit matrix representation of user correlations, an implementation matrix, a soft-weighting matrix, a de-biasing matrix, and a scalar stabilizing step size. - View Dependent Claims (28)
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29. An interference cancellation method for cancelling interference in a received signal from a channel, the method configured for performing at least one iteration to produce an interference-cancelled symbol estimate, the method comprising:
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providing for employing a signal basis for sources in the channel to synthesize constituent signals from a plurality of weighted or unweighted symbol estimates, and producing a combined signal therefrom, and providing for subtracting the combined signal from the received signal to produce an error signal, the method configured for employing an internal feedback loop process and an external feedback loop process; the external feedback loop process comprising multiplying a vector of the input symbol estimates by a weighting matrix and a users'"'"' received correlation matrix to produce an external-feedback vector, and subtracting the external-feedback vector from the despread signal vector for producing a difference error vector that is scaled by a scalar stabilizing step size; and the internal feedback loop process comprising multiplying a vector of the plurality of weighted symbol estimates by an implementation matrix to produce an internal-feedback vector, and summing the internal-feedback vector with a vector derived from the scaled error signal. - View Dependent Claims (30)
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31. An interference cancellation system for cancelling interference in a received signal from a channel, the system configured for performing at least one iteration to produce an interference-cancelled symbol estimate, the system comprising:
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a synthesizing means configured for employing a signal basis for sources in the channel to synthesize constituent signals from a plurality of weighted or unweighted symbol estimates, and producing a combined signal therefrom, and a subtraction means configured to subtract the combined signal from the received signal to produce an error signal, and a stabilizing step size means configured for scaling the error signal by a stabilizing step size to produce a scaled error signal. - View Dependent Claims (32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45)
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Specification