Time domain equalization using frequency domain operations
AssigneesSTMicroelectronics S.r.l., STMicroelectronics Belgium NV
InventorsFabio Pisoni, Roland Hug, Marco Bonaventura
Life of this patent
Estimating the term…
Abstract
An equalizer for a multi carrier transmission system, converts a transmitted multi carrier signal into sampled frequency domain signals, and suppresses time domain delay dispersion, on the sampled frequency domain signals. It exploits circulant decomposition of a Toeplitz matrix to enable the computationally heavy evaluation of a matrix multiplied by a vector, to be avoided. Increased precision arises from the frequency domain processing being equivalent to a longer time domain FIR filter than is normally practical. The amount of compensation for different carriers can be adjusted, which can lead to increased precision.
Claims16
An equalizer for a multi-carrier transmission system, for at least reducing delay dispersion in a signal, the equalizer comprising:
- a convertor arranged to use a sequence of consecutive samples of a multicarrier signal to derive oversampled frequency domain signals for reduction of dispersion of at least one symbol, the sequence having a length of at least two symbols;
- and a suppressor for suppressing time domain delay dispersion on the oversampled frequency domain signals using frequency-domain dispersion parameters, the suppressor being adaptive according to feedback provided by a suppressed dispersion frequency-domain output signal through updating of the frequency-domain dispersion parameters, the suppressor comprising:
- a parameter generator arranged to adaptively generate a set of updated frequency domain dispersion parameters to be implemented in the suppressor based at least in part, on an update;
- and an updating unit arranged to provide an update to the parameter generator based, at least in part, on the feedback;
- wherein the suppressor being is arranged to carry out Fourier transform based operations on odd frequency domain samples and separately carry out Fourier transform based operations on even frequency domain samples.
A method of equalizing for multi-carrier transmission using one or more processors, for at least reducing delay dispersion in a signal, the method comprising:
- converting a multi carrier signal into sampled frequency domain signals, the converting being arranged to use a sequence of consecutive samples of the multicarrier signal for reduction of dispersion of at least one symbol, where the sequence has a length, of at least two symbols;
- separating odd and even samples of the oversampled frequency domain signals before suppressing time domain delay dispersion on the sampled frequency domain signals;
- suppressing time domain delay dispersion on the sampled frequency domain signals using frequency-domain dispersion parameters to produce a suppressed dispersion frequency domain output signal;
- and updating the frequency-domain dispersion parameters using the one or more processors based, at least in part, on feedback provided by a suppressed dispersion frequency domain output signal.
A signal processor for use with a dispersive signal transmission path carrying multicarrier signals, the signal processor carrying out a time domain matrix type operation on at least one multicarrier signal, the signal processor comprising:
- a converter arranged to convert the at least one multicarrier signal into oversampled frequency domain samples;
- and
- a transformer arranged to carry out frequency domain transform operations on the frequency domain samples using a processor, the converter being arranged to use a sequence of consecutive samples of the at least one multicarrier signal, the sequence having a length of at least two symbols and the transformed frequency domain samples being modified based on a frequency response of the dispersive signal transmission path, wherein the transform operations are based on the equation:
- 2Yi=diag(Λeven)W+FNP*FN*diag(Λodd)FNPFN*W
- where Y is the processed output,
- W are frequency domain signal processing parameters which can be adapted
- F is the Fourier transform operator,
- P is the diagonal operator, and
- Diag(Λeven) are even ones of frequency domain samples, and diag(Λoddshift) are odd ones of frequency domain samples.
A computer readable medium encoded with at least one computer program that, when executed on a computer, carries out a method of equalizing for multi carrier transmission, for at least reducing delay dispersion in a signal, the method comprising:
- converting a multi carrier signal into sampled frequency domain signals, the converting being arranged to use a sequence of consecutive samples of the multicarrier signal for reduction of dispersion of at least one symbol, where the sequence has a length of at least two symbols;
- separating odd and even samples of the oversampled frequency domain signals before suppressing time domain delay dispersion on the sampled frequency domain signals;
- suppressing time domain delay dispersion on the sampled frequency domain signals using frequency-domain dispersion parameters to produce a suppressed dispersion frequency domain output signal;
- and updating the frequency-domain dispersion parameters based, at least in part, on feedback provided by a suppressed dispersion frequency domain output signal.
Dependencies are inferred from the claim text.