ITERATIVE METHOD FOR SYNTHESIZING DIGITAL FILTERS FOR SHAPING A SIGNAL

• US 20150163076A1
• Filed: 12/11/2014
• Published: 06/11/2015
• Est. Priority Date: 12/11/2013
• Status: Active Grant

• Current Assignee: Thales SA
• Original Assignee: Thales SA
• Inventors: BAPTISTE, Francois
• Granted Patent: US 9,425,996 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04L 2025/03611 Iterative algorithms
• CPC Class Codes: H04L 2025/037 Detection of convergence state
• CPC Class Codes: H04L 25/03012 operating in the time domain H04L25/03165, H04L25/03178 take precedence
• CPC Class Codes: H04L 25/03057 with a recursive structure H04L25/03031 takes precedence
• CPC Class Codes: H04L 25/03853 Shaping by digital methods other than look up tables or up/down converters
• CPC Class Codes: H04L 25/03885 adaptive
• CPC Class Codes: H04L 25/03949 equalizer selection or adaptation based on feedback multiple signaling inclusive of a precoding command for adapting the transmitter H04L1/0031; feedback for transmit diversity systems H04B7/0619; selection of codebook or precoding matrix for MIMO diversity systems H04B7/0456
• CPC Class Codes: H04L 27/01 Equalisers baseband equalizers at the transmitter end H04L25/03343; in analogue transmission systems H04B3/04, H04B7/005

Abstract

An iterative method for synthesizing digital filters comprises the following steps: generation of a transmit filter intended to be applied to a signal to be transmitted; and generation of a receive filter intended to be applied to a received signal. The method comprises the following iteratively executed steps: convolution of the transmit filter and the receive filter in order to generate a transmission filter; determination of a criterion that is representative of the level of intersymbol interference on said transmission filter and whether the level of intersymbol interference is higher than a given level; calculation of an equalizing filter for the intersymbol interference; replacement of the transmit filter with the convoluted transmit filter having the equalizing filter or the replacement of the receive filter with the convoluted receive filter having the equalizing filter.

Claims

1. An iterative method for synthesizing digital filters, comprising:

generating a transmit filter intended to be applied to a signal to be transmitted, and

generating a receive filter intended to be applied to a received signal,

wherein the method further comprises the following iteratively executed steps;

convolution of the transmit filter and the receive filter in order to generate a transmission filter,

determinating a criterion that is representative of the level of intersymbol interference on said transmission filter and whether the level of intersymbol interference is higher than a given level,

calculating an equalizing filter for the intersymbol interference, and

replacing the transmit filter with the convoluted transmit filter having the equalizing filter or the replacement of the receive filter with the convoluted receive filter having the equalizing filter.

2. The iterative method for synthesizing filters according to claim 1, in which the convolution of the equalizing filter with the transmit filter or the receive filter is chosen on the basis of a desired frequency template for the transmit filter and/or the receive filter.

3. The iterative method for synthesizing filters according to claim 1, in which the execution iterations are stopped when the level of intersymbol interference is below a given threshold.

4. The iterative method for synthesizing filters according to claim 1, in which the criterion that is representative of the level of intersymbol interference on the transmission filter is taken to be equal to the ratio between the sum of the absolute values of the coefficients of said filter except the central coefficient and the absolute value of the central coefficient of said filter.

5. The iterative method for synthesizing filters according to claim 1, in which the equalizing filter is multiplied by a weighting window, the type of weighting window being selected on the basis of the desired speed of convergence of the iterative method.

6. The iterative method for synthesizing filters according to claim 1, in which the transmit filter and the receive filter are root raised-cosine filters.

7. The iterative method for synthesizing filters according to claim 6, in which the root raised-cosine filters are multiplied by a weighting window.

8. A computer program having instructions for executing the iterative method for synthesizing filters according to claim 1 when the program is executed by a processor.

9. A transmit filter or receive filter obtained from the execution of the iterative method for synthesizing filters according to claim 1.