Robust sensing for detecting signals using correlation
First Claim
1. A method for detecting a received signal, comprising:
- adding a pilot value to a reference signal;
upsampling the reference signal to a sampling frequency of the received signal;
correlating the upsampled reference signal with a demodulated baseband signal to produce a correlation value; and
determining that the received signal is present if the correlation value is greater than a predetermined detection threshold value.
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Accused Products
Abstract
To quickly and robustly detect the presence of an incumbent user and rapidly relinquish the spectrum to the incumbent user when necessary, carrier recovery is performed in a receiver of the secondary user'"'"'s cognitive or software radio prior to performing correlation detection with an upsampled reference signal to correct for large frequency offsets and improve the performance of the correlation detector. To detect a received signal, a pilot value is added to a reference signal. The reference signal is upsampled to a sampling frequency of the received signal. The upsampled reference signal is correlated with a demodulated baseband signal to produce a correlation value. It is then determined whether the received signal is present if the correlation value is greater than a predetermined detection threshold value.
14 Citations
13 Claims
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1. A method for detecting a received signal, comprising:
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adding a pilot value to a reference signal; upsampling the reference signal to a sampling frequency of the received signal; correlating the upsampled reference signal with a demodulated baseband signal to produce a correlation value; and determining that the received signal is present if the correlation value is greater than a predetermined detection threshold value.
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2. A method for detecting the presence of a received signal in a sensor, comprising:
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estimating a carrier frequency of the received signal; using the estimated carrier frequency to demodulate the received signal to generate a complex demodulated baseband signal; low-pass filtering the complex demodulated baseband signal; generating an over-sampled local reference signal having the same sampling rate as the received signal; correlating the over-sampled local reference signal with the low-pass filtered complex demodulated baseband signal yielding a complex correlation value; taking the absolute value of the complex correlation value; comparing the absolute value of the complex correlation value to a detection threshold; and determining that the received signal is present if the absolute value of the complex correlation value is greater than the detection threshold. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10)
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11. A sensor for detecting the presence of a received signal in a wireless system, comprising:
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a tuner for receiving one of a radio frequency signal to produce a low IF (LIF) signal; a demodulating unit for demodulating the low IF signal to produce a complex demodulated baseband signal; a first matched filter for performing a matched filtering operation on the first complex signal to produce a second complex signal; a local reference signal generating unit for generating an oversampled local reference signal; a complex correlation unit for performing a complex correlation between the oversampled local reference signal and the second complex signal to produce a third complex signal; an absolute value unit for taking the absolute value of the third complex signal to produce a fourth complex signal; and a threshold detector for comparing the fourth complex signal with a threshold value to determine if the received signal is present. - View Dependent Claims (12, 13)
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Specification