Method and apparatus of frequency domain echo canceller
AssigneeNetLogic Microsystems, Inc.
InventorYehuda Azenkot
Life of this patent
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Abstract
A frequency-domain based echo and NEXT canceller is provided. The canceller uses log2 encoding to precondition the error signal representing the echo. An improved gradient constraint is applied on at least a portion of a full weight vector in a least-mean-square algorithm. The least-mean-square algorithm is used to compute filter coefficients. The filter coefficients are multiplied by a frequency-domain data vector using a frequency-domain multiplier to generate frequency-domain output vector.
Claims60
A frequency-domain echo canceller comprising:
- an error processing unit configured to transform a time-domain (TD) error signal into a frequency-domain (FD) error signal;
- a gradient constraint unit configured to process at least a portion of a full weight vector;
- a least-mean-square (LMS) adaptation unit, coupled with the error processing unit and an output of the gradient constraint unit, configured to compute filter coefficients;
- a FD multiplier configured to multiply a FD input signal and the full weight vector to generate a FD output signal;
- and
- an output processing unit configured to transform the FD output signal to a TD output signal.
A communication system with adaptive error correction comprising:
- an adaptive frequency-domain (FD) canceller with a gradient constraint unit configured to apply gradient constraint on at least a portion of a full weight vector resulting in a gradient constrained portion of the full weight vector;
- a least-mean-square (LMS) adaptation unit, coupled with the gradient constraint unit, the LMS adaptation unit including a multiplexer configured to select between the gradient constrained portion of the full weight vector, and a sum of the full weight vector and an unconstrained gradient vector;
- and
- a delay compensation unit configured to cancel a FD delay from the adaptive FD canceller.
A method to cancel echo in a communication system comprising:
- applying a least-mean-square (LMS) adaptation algorithm, by a processing unit, to a frequency-domain (FD) error signal to generate a scaled FD gradient vector corresponding to coefficients of the FD error signal;
- applying gradient constraint, by the processing unit, on at least a portion of a full weight vector of the scaled FD gradient vector to generate a FD gradient constraint vector;
- and
- multiplying, by the processing unit, the FD gradient constraint vector with a FD input signal based on a shifting algorithm to generate a FD output signal with cancelled echo.
A frequency-domain echo canceller comprising:
- a gradient constraint unit configured to process at least a portion of a full weight vector;
- and
- a least-mean-square (LMS) adaptation unit, coupled with the gradient constraint unit, the LMS adaptation unit including a multiplexer configured to select between the processed full weight vector and a sum of the full weight vector and a gradient vector.
A frequency-domain echo canceller comprising:
- a gradient constraint unit configured to process at least a portion of a sum of scaled gradient vectors and to apply a gradient constraint to the portion of the sum of the scaled gradient vectors to generate a corrected portion of the sum of the scaled gradient vectors;
- and
- a least-mean-square (LMS) adaptation unit, coupled with the gradient constraint unit, configured to compute filter coefficients based on the sum of the scaled gradient vectors.
Dependencies are inferred from the claim text.