Femtocell configuration using spectrum sensing
AssigneesXilinx, Inc., The Provost, Fellows, Foundation Scholars, and the Other Members of Board, of the College of the Holy and Undivided Trinity of Queen Elizabeth Near Dublin
InventorsJorg Lotze, Baris Ozgul, Juan J. Noguera Serra
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Abstract
An embodiment of the present invention provides for the ad-hoc configuration of femtocells using spectrum sensing for the selection of spectrum channels. One or more embodiments of the invention determine frequency bands that are not reserved by macrocells in a location, and perform spectrum sensing to determine communication channels in unreserved frequency bands that are being used by other femtocells in range. In this manner, femtocells can be deployed and configured in an ad-hoc manner without external coordination or control between deployed femtocells.
Claims20
A method of determining available wireless communication channels, comprising:
- determining unreserved frequency bands in a location;
- selecting a first channel within one of the determined unreserved frequency bands;
- monitoring signals received on the first channel for a time duration;
- estimating a power spectral density of the signals during the time duration;
- determining a spectral moving average of the estimated power spectral density;
- determining a detection threshold for the first channel;
- normalizing the spectral moving average of the estimated power spectral density;
- determining a percentage of a bandwidth of the spectral moving average of the estimated power spectral density that exceeds the detection threshold;
- in response to the determined percentage being less than a selected percentage, storing data indicating the first channel is available;
- and
- in response to the determined percentage being greater than or equal to the selected percentage:
- determining whether the normalized spectral moving average of the estimated power spectral density is consistent with a selected signal shape;
- and
- in response to determining the estimated averaged power spectral density is not consistent with the selected signal shape, storing data indicating the first channel is available.
A system for determining available wireless communication channels, comprising:
- means for receiving signals transmitted on a plurality of communication channels and output signals received on a selected channel;
- a data bus coupled to the means for receiving;
- means, coupled to the data bus, for determining unreserved frequency bands in a location;
- means for selecting the selected channel from one of the determined unreserved frequency bands and configuring the means for receiving signals to output signals received on the selected channel;
- means for determining a power spectral density of the signals output by the receiver unit;
- and
- means for determining from the power spectral density whether the signals received on the selected channel are consistent with a selected signal shape and strength indicating the channel is not available.
A circuit for determining available wireless communication channels, comprising:
- a receiver circuit configured to receive a plurality of transmitted signals;
- a signal processing circuit coupled to an output of the receiver circuit;
- a channel analysis circuit coupled to the signal processing circuit;
- and
- a channel selection controller circuit coupled to the channel analysis circuit and to the receiver circuit;
- and
- wherein:
- the channel selection controller circuit is configured to:
- monitor the plurality of transmitted signals received by the receiver circuit;
- determine unreserved frequency bands in a location;
- select a first channel within the determined unreserved frequency bands;
- and
- configure the receiver circuit to output signals received on the first channel;
- the signal processing circuit is configured to determine and output a power spectral density of signals output by the receiver circuit;
- and
- the channel analysis circuit is configured to:
- determine a spectral moving average of the power spectral density output by the signal processing circuit;
- determine a signal detection threshold level;
- determine the percent of bandwidth of the first channel with the power spectral density above the signal detection threshold level;
- normalize the determined spectral moving average;
- determine a peak and a slope of the normalized spectral moving average;
- and
- determine from the determined percentage of bandwidth and the peak and the slope whether the first channel is available.
Dependencies are inferred from the claim text.