US 6,304,545 B1 · Method and circuit arrangement for the correction of phase and/or frequency errors in digital multicarrier signals

Abstract

In an OFDM system, the so-called self-noise component, which represents that noise component of the respective carrier which is caused by the carrier itself and is mapped onto itself, can be estimated and corrected by shifting all the carriers back in the receiver by multiplication by a factor which is determined by averaging. The so-called external-noise component, which is caused by adjacent carrier interference from the so-called leakage effect of the Fast Fourier transform (FFT2) used in the receiver for demodulation cannot be corrected using this method. In addition to the demodulation FFT, a further FFT (FFT1) is used in the receiver to estimate the self-noise component (ψe). The estimated self-noise component is used to reproduce the orthogonality between the carriers by correction before the demodulation FFT, to thereby prevent crosstalk. The additional FFT (FFT1) may have a shorter length than the demodulation FFT (FFT2), so that the additional complexity is negligible.

Claims15

Dependent claims

Method for correcting phase or frequency errors in digital multicarrier signals which are transmitted on N different carriers and are subjected in a receiver to Fourier transformation for demodulation, phase noise being composed of a self-noise component and an external-noise component, the self-noise component representing that noise component which is caused by a carrier itself and is mapped onto itself and the external-noise component being caused by adjacent carrier interference, comprising the steps of:

estimating the self-noise component by a further Fourier transformation before said Fourier transformation for demodulation, and
correcting the digital signals as a function of the estimated self-noise component.

Circuit arrangement for the correction of phase or frequency errors in digital multicarrier signals, comprising:

means for estimating a self-noise component, said means supplying a correction signal for the digital multicarrier signals;
a delay stage to which samples of the digital multicarrier signals are provided in order to delay these signals for compensation of the calculation time of the means for estimating the self-noise component;
a frequency mixing unit by means of which adapted phase or frequency signals are produced from the delayed samples in response to the correction signal;
transformation means to which the samples of the digital multicarrier signals are provided for a first transformation step, the transformed signals from the first transformation step being provided to the means for estimating the self-noise component, and to which the adapted phase or frequency signals are provided for a second transformation step, from which signals complex coefficients of the carriers are demodulated by means of the second transformation step, wherein the transformation means have means for carrying out a Fourier transformation for determining the correction signal and means for carrying out a further Fourier transformation for demodulation of the adapted phase or frequency signals.

1 more element

Dependencies are inferred from the claim text.

Method and circuit arrangement for the correction of phase and/or frequency errors in digital multicarrier signals

Life of this patent

Method and circuit arrangement for the correction of phase and/or frequency errors in digital multicarrier signals

Life of this patent

Abstract

Claims15