Spectrally constrained impulse shortening filter for a discrete multi-tone receiver
View Patent ↗A channel in a multiple carrier communication system is equalized by computing a target spectral response, shortening the impulse response of the channel so that a significant part of an energy of the impulse response is confined to a region that is shorter than a target length and filtering the signal based on the target spectral response.
1. A method for selecting an impulse response for a spectrally constrained impulse shortening filter in a multiple carrier communication system, the method comprising:
measuring received noise power spectral density;
computing a cost function using the noise power, the cost function being dependent on the impulse response;
reducing the dimensionality of a space over which the cost function is defined; and minimizing the cost function.
2. The method of claim 1 , wherein the communication system includes a discrete Fourier transform and the noise power spectral density is measured at an output of the discrete Fourier transform.
3. The method of claim 1 , wherein the cost function is used to compute coefficients for the spectrally constrained impulse shortening filter.
4. Software on a processor readable medium comprising instructions for causing a processor in a communication system to perform the following operations:
measure received noise power spectral density;
compute a cost function using the noise power, the cost function being dependent on an impulse response of a spectrally constrained impulse shortening filter;
reduce the dimensionality of a space over which the cost function is defined; and minimize the cost function.
5. The software of claim 4 , wherein the cost function is used to compute coefficients for the filter.
6. A method for equalizing a channel in a multiple carrier communication system, the channel being configured to receive a signal and including a spectrally constrained impulse shortening filter, the method comprising:
measuring received noise power spectral density;
computing a target spectral response having a magnitude constraint that is based on the measured noise power spectral density;
selecting a frequency response of the spectrally constrained impulse shortening filter based on the target spectral response; and
filtering the communication signal with the spectrally constrained impulse shortening filter.
7. An article comprising a machine-readable medium storing machine-readable instructions that when applied to the machine cause the machine to:
measure received noise power spectral density;
compute a target spectral response having a magnitude constraint that is based on the measured noise power spectral density;
select a frequency response of a spectrally constrained impulse shortening filter based on the target spectral response; and
filter a communication signal with the spectrally constrained impulse shortening filter.
8. An article comprising a machine-readable medium storing machine-readable instructions that when applied to the machine cause the machine to:
compute a target spectral response having a magnitude constraint that is based on measured noise power spectral density;
shorten an impulse response of a channel in a multiple carrier communication system so that a significant part of an energy of the impulse response is confined to a region that is shorter than a target length; and
filter a signal having a cyclic prefix based on the target spectral response.