System and method for digital timing error correction in a communications system utilizing adaptive predistortion
First Claim
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1. A method for timing error correction in an adaptive predistortion linearized communications system, comprising:
- receiving an input signal comprising discrete signal samples from an input to the communications system;
receiving an output signal comprising discrete signal samples from an output of the communications system;
estimating a timing delay between said input and output signals to a fraction of a sample timing; and
correcting the timing error between said input and output signals using said estimated timing delay;
wherein estimating a timing delay comprises computing a cross-correlation function between said input and output samples and determining the position of the peak of the cross-correlation function;
wherein the values of the cross-correlation computation are discrete and wherein determining the position of the peak of the cross-correlation function comprises approximating selected discrete values of the cross-correlation computation to a polynomial function.
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Abstract
A system and method for rapidly correcting the time difference between two signals is disclosed. In particular, a system and method for very rapidly correcting timing errors to the very high degree of accuracy required for digital predistortion adaptation is disclosed. The method is a signal processing technique, which can be performed in either hardware or software, which employs a correlation computation. The correlation results are processed in a manner that enables very rapid and accurate estimation of the time difference between the two signals.
16 Citations
18 Claims
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1. A method for timing error correction in an adaptive predistortion linearized communications system, comprising:
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receiving an input signal comprising discrete signal samples from an input to the communications system; receiving an output signal comprising discrete signal samples from an output of the communications system; estimating a timing delay between said input and output signals to a fraction of a sample timing; and correcting the timing error between said input and output signals using said estimated timing delay; wherein estimating a timing delay comprises computing a cross-correlation function between said input and output samples and determining the position of the peak of the cross-correlation function; wherein the values of the cross-correlation computation are discrete and wherein determining the position of the peak of the cross-correlation function comprises approximating selected discrete values of the cross-correlation computation to a polynomial function. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for timing error correction in an adaptive predistortion linearized communications system, compressing:
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receiving an input signal comprising discrete signal samples from an input to the communications system; receiving an output signal comprising discrete signal samples from an output of the communications system; estimating a timing delay between said input and output signals to a fraction of a sample timing; and correcting the timing error between said input and output signals using said estimated timing delay; wherein estimating a timing delay comprises computing a cross-correlation function between said input and output samples and determining the position of the peak of the cross-correlation function; wherein determining the position of the peak of the cross correlation function comprises determining the index value of the maximum of the cross-correlation computation, determining the N values on either side of the maximum, where N is an integer, fitting a polynomial of order N to the resulting 2N+1 discrete values of the cross-correlation computation and computing the point where the derivative of the polynomial is zero. - View Dependent Claims (8)
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9. A method for timing error correction in an adaptive predistortion linearized communications system, comprising:
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receiving an input signal comprising discrete signal samples from an input to the communications system; receiving an output signal comprising discrete signal samples from an output of the communications system; computing a cross-correlation function between said input and output signals; initiating a delay-locked loop employing the results of said cross-correlation computation; and adjusting the relative timing of said input and output signals to a fraction of a sample timing using the output of said delay-locked loop. - View Dependent Claims (10, 11, 12, 13)
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14. A system for timing error correction in an adaptive predistortion linearized communications system, comprising:
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a first input receiving a digital input signal from an input to the communications system; a second input receiving a digital output signal from an output of the communications system; a cross-correlation computation block computing a cross-correlation function between said input and output signals; a cross-correlation peak detection block for determining the position of the peak of the cross-correlation function; a timing delay estimator for determining an estimated timing error from said position of the peak of the cross-correlation function; and an interpolator receiving and adjusting one or more of the digital input or output signals to a fraction of a sample timing in response to said estimated timing error, wherein said interpolator comprises a finite impulse response filter. - View Dependent Claims (15, 16, 17, 18)
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Specification