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US 8,275,057 B2Granted
Methods and systems to estimate channel frequency response in multi-carrier signals
AssigneeIntel Corporation
InventorsThushara Hewavithana, Bernard Arambepola, Parveen K. Shukla
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Abstract
Methods and systems to determine channel frequency responses corresponding to multi-carrier signals, such as OFDM signals, including to filter or mask noise from channel frequency response estimates in a time domain.
Claims18
A method, comprising:
- determining channel frequency responses corresponding to scattered pilot frequencies of a plurality of symbols of an orthogonal frequency division multiplex (OFDM) signal;
- converting the channel frequency responses to a sequence of time domain samples;
- band-pass filtering in the time domain by masking portions of the sequence of time domain samples that are outside of one or more dispersal regions of the time domain samples;
- converting the masked sequence of time domain samples to a frequency domain;
- and
- frequency interpolating the frequency domain representation of the masked sequence of time domain samples to generate channel frequency responses at non-scattered pilot frequencies of the symbols,
- wherein the masking includes:
- identifying one or more dispersal regions of the time domain samples;
- generating a mask corresponding to the one or more dispersal regions;
- and
- multiplying the sequence of time domain samples by the mask.
8 more elements
A system, comprising:
- a scattered pilot frequency channel frequency response system to determine channel frequency responses corresponding to scattered pilot frequencies of a plurality of symbols of an orthogonal frequency division multiplex (OFDM) signal;
- an Inverse Fast Fourier Transform system to convert the channel frequency responses to a sequence of time domain samples, for each of the plurality of symbols, to produce sequences of time domain samples;
- a mask system to mask, and thereby band-pass filter in the time domain, one or more portions of the sequences of time domain samples that are outside of one or more dispersal regions of the corresponding sequence of time domain samples;
- a Fast Fourier Transform system to convert masked sequences of the time domain samples to a frequency domain;
- and
- a frequency interpolator to interpolate channel frequency responses of non-scattered pilot frequencies of the symbols from corresponding frequency domain representations of the sequences of the time domain samples,
- wherein the mask system includes:
- a mask generator to generate a mask corresponding to the one or more dispersal regions, for each of the sequences of time domain samples;
- and a mask applicator to multiply the sequences of time domain samples by corresponding points of the mask.
6 more elements
A system, comprising:
- a receiver front-end to receive and frequency down-convert an orthogonal frequency division multiplex (OFDM) signal;
- and
- a signal processor coupled to the receiver front-end, the signal processor including a channel frequency response system and one or more of a channel equalizer and an inter-carrier-interference cancellation module coupled to an output of the channel frequency response system, the channel frequency response system including,
- a scattered pilot frequency channel frequency response system to determine channel frequency responses corresponding to scattered pilot frequencies of a plurality of symbols of an OFDM signal,
- an Inverse Fast Fourier Transform system to convert the channel frequency responses to a sequence of time domain samples, for each of the plurality of symbols to produce sequences of time domain samples,
- a mask system to mask, and thereby band-pass filter in the time domain, one or more portions of the sequences of time domain samples that are outside of one or more dispersal regions of the corresponding sequence of time domain samples,
- a Fast Fourier Transform system to convert masked sequences of the time domain samples to a frequency domain, and
- a frequency interpolator to interpolate channel frequency responses of non-scattered pilot frequencies of the symbols from corresponding frequency domain representations of the sequences of the time domain samples,
- wherein the mask system includes:
- a mask generator to generate a mask corresponding to the one or more dispersal regions, for each of the sequences of time domain samples;
- and a mask applicator to multiply the sequences of time domain samples by the corresponding masks.
8 more elements
Dependencies are inferred from the claim text.