System for spectrum sensing of multi-carrier signals with equidistant sub-carriers
AssigneeQrc, Inc. Dba Qrc Technologies
InventorsSinisa Peric, Thomas F. Callahan, III
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Abstract
A multi-carrier signal is typically comprised of many equidistant sub-carriers. This results in periodicity of spectrum within the bandwidth of such a multi-carrier signal. An unknown multi-carrier signal with equidistant sub-carriers can thus be sensed together with its sub-carrier spacing by finding a discernible local maximum in the cepstrum (Fourier transform of the log spectrum) of the multi-carrier signal.
Claims21
A system for sensing a presence of a multi-carrier signal with equidistant sub-carriers in a spectral sample, the system comprising:
- a spectral sample collection system configured to obtain a spectrum sample;
- a cepstrum processor configured to perform operations comprising transforming the spectrum sample to obtain a cepstrum;
- and
- a carrier identification processor configured to perform operations comprising:
- determining a bin location within the cepstrum having a maximum bin magnitude;
- determining whether the maximum bin magnitude at the cepstrum bin location exceeds a predetermined threshold;
- and
- issuing an alert that the multi-carrier signal has been sensed in the spectrum sample when the maximum bin magnitude at the cepstrum bin location exceeds the predetermined threshold.
A system for detecting a presence of a multi-carrier signal with equidistant sub-carriers in a spectral sample, the system comprising:
- a spectral sample collection system configured to obtain a spectrum sample;
- wherein the spectrum sample is larger than a maximum expected signal spectrum bandwidth;
- a cepstrum processor configured to perform operations comprising:
- obtaining from the spectrum sample a plurality of spectrum subsets, wherein each spectrum subset has a bandwidth that is approximately equal to the maximum expected signal spectrum bandwidth;
- and
- transforming each of the plurality of spectrum subsets to obtain a cepstrum of each spectrum subset;
- a carrier identification processor configured to perform operations comprising:
- determining a bin location having a maximum bin magnitude across all of the spectrum subsets;
- determining whether the maximum bin magnitude at the cepstrum bin location exceeds a predetermined threshold;
- and
- issuing an alert that a multi-carrier signal has been sensed in the spectrum sample when the maximum bin magnitude at the cepstrum bin location exceeds a predetermined threshold.
A system for detecting a presence of a multi-carrier signal with equidistant sub-carriers having a known sub-carrier spacing and a known spectrum bandwidth in a spectral sample, the system comprising:
- a spectral sample collection system configured to obtain a spectrum sample, wherein the spectrum sample is larger than a known signal spectrum bandwidth;
- a cepstrum processor configured to perform operations comprising;
- obtaining from the spectrum sample a plurality of spectrum subsets, wherein each spectrum subset has a bandwidth that is approximately equal to the known signal spectrum bandwidth;
- transforming each of the plurality of spectrum subsets to obtain a magnitude of a particular cepstrum bin location within each spectrum subset, wherein the particular cepstrum bin location corresponds to the known sub-carrier spacing;
- a carrier identification processor configured to perform operation comprising:
- determining whether the bin magnitude at the particular cepstrum bin location of any of the spectrum subsets exceeds a predetermined threshold;
- and
- issuing an alert that the multi-carrier signal having the known sub-carrier spacing and the known spectrum bandwidth has been sensed in the spectrum sample when the bin magnitude at the particular cepstrum bin location of any of the spectrum subsets exceeds a predetermined threshold.
Dependencies are inferred from the claim text.