Integrated circuit implementation of methods and apparatuses for monitoring occupancy of wideband GHz spectrum, and sensing respective frequency components of time-varying signals using sub-nyquist criterion signal sampling
First Claim
1. An integrated circuit apparatus to determine an N-point Fast Fourier Transform (FFT) of a time-varying signal so as to sense one or more frequency components of the time-varying signal, the apparatus comprising:
- an input/output interface to receive a first sub-sampled set of samples of the time-varying signal sampled at a first sampling rate below a Nyquist rate of the time-varying signal and a second sub-sampled set of samples of the time-varying signal sampled at a second sampling rate below the Nyquist rate of the time-varying signal, wherein the second sampling rate is different from the first sampling rate; and
at least one processor communicatively coupled to the input/output interface to;
A) compute a first Fast Fourier Transform (FFT) for the first sub-sampled set of samples of the time-varying signal; and
B) compute a second FFT for the second sub-sampled set of samples of the time-varying signal,wherein;
each of the first FFT and the second FFT is a low-radix FFT;
the time-varying signal has a frequency bandwidth of interest BW and a Nyquist sampling criteria of N samples in a sampling time T, wherein N=T×
BW;
the first sampling rate is BW/p1 samples/second, wherein p1 is less than N;
the second sampling rate is BW/p2 samples/second, wherein p2 is less than N; and
p2 and p1 are co-prime numbers.
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Abstract
An ASIC for monitoring wideband GHz spectrum to sense respective frequency components present in the spectrum. The ASIC implements Fast Fourier Transform (FFT) techniques to facilitate identification of one or more frequency components of a sparse signal after the signal is sub-sampled at a rate below the Nyquist criterion. The ASIC computes a first Fast Fourier Transform (FFT) of a first sub-sampled set of samples of a time-varying signal representing the monitored spectrum and sampled at a first sampling rate, and further computes a second FFT of a second sub-sampled set of samples of the time-varying signal sampled at a second sampling rate different from the first sampling rate. In one example, each of the first FFT and the second FFT is a low-radix FFT to facilitate a low-power and low-cost ASIC implementation of wideband spectrum sensing.
22 Citations
30 Claims
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1. An integrated circuit apparatus to determine an N-point Fast Fourier Transform (FFT) of a time-varying signal so as to sense one or more frequency components of the time-varying signal, the apparatus comprising:
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an input/output interface to receive a first sub-sampled set of samples of the time-varying signal sampled at a first sampling rate below a Nyquist rate of the time-varying signal and a second sub-sampled set of samples of the time-varying signal sampled at a second sampling rate below the Nyquist rate of the time-varying signal, wherein the second sampling rate is different from the first sampling rate; and at least one processor communicatively coupled to the input/output interface to; A) compute a first Fast Fourier Transform (FFT) for the first sub-sampled set of samples of the time-varying signal; and B) compute a second FFT for the second sub-sampled set of samples of the time-varying signal, wherein; each of the first FFT and the second FFT is a low-radix FFT; the time-varying signal has a frequency bandwidth of interest BW and a Nyquist sampling criteria of N samples in a sampling time T, wherein N=T×
BW;the first sampling rate is BW/p1 samples/second, wherein p1 is less than N; the second sampling rate is BW/p2 samples/second, wherein p2 is less than N; and p2 and p1 are co-prime numbers. - View Dependent Claims (2, 3, 4, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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5. An integrated circuit apparatus to determine an N-point Fast Fourier Transform (FFT) of a time-varying signal so as to sense one or more frequency components of the time-varying signal, the apparatus comprising:
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an input/output interface to receive a first sub-sampled set of samples of the time-varying signal sampled at a first sampling rate below a Nyquist rate of the time-varying signal and a second sub-sampled set of samples of the time-varying signal sampled at a second sampling rate below the Nyquist rate of the time-varying signal, wherein the second sampling rate is different from the first sampling rate; and at least one processor communicatively coupled to the input/output interface to; A) compute a first Fast Fourier Transform (FFT) for the first sub-sampled set of samples of the time-varying signal; and B) compute a second FFT for the second sub-sampled set of samples of the time-varying signal, wherein; each of the first FFT and the second FFT is a low-radix FFT; the input/output interface is configured to provide to the at least one processor; the first sub-sampled set of samples at the first sampling rate; the second sub-sampled set of samples at the second sampling rate; a third sub-sampled set of samples at the first sampling rate and time-shifted from the first sub-sampled set by a first number of samples; and a fourth sub-sampled set of samples at the second sampling rate and time-shifted from the second sub-sampled set by a second number of samples; and the at least one processor further is configured to compute; C) a third FFT for the third sub-sampled set of samples of the time-varying signal; and D) a fourth FFT for the fourth sub-sampled set of samples of the time-varying signal, wherein the N-point FFT of the time-varying signal is based at least in part on A), B), C) and D). - View Dependent Claims (6, 7, 8)
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22. An Application Specific Integrated Circuit (ASIC) apparatus to determine an N-point Fast Fourier Transform (FFT) of a sampled time-varying signal so as to sense one or more frequency components of the sampled time-varying signal, the time-varying signal having a frequency bandwidth of interest BW and a Nyquist sampling criteria of N samples in a sampling time T, wherein N=T×
- BW, the sampled time-varying signal including a first sub-sampled set of B1 samples of the time-varying signal and a second sub-sampled set of B2 samples of the time-varying signal, the apparatus comprising;
an input/output interface to receive the first sub-sampled set of B1 samples and the second sub-sampled set of B2 samples, wherein B1=N/p1, B2=N/p2, and wherein p2 and pi are co-prime numbers and both less than N; and at least one processor communicatively coupled to the input/output interface to; A) compute a first B1-point Fast Fourier Transform (FFT) for the first set of B1 samples of the time-varying signal; B) compute a second B2-point FFT for the second set of B2 samples of the time-varying signal; and C) compute the N-point FFT of the sampled time-varying signal based at least in part on A) and B), wherein; each of the first B1-point FFT and the second B1-point FFT is a low-radix FFT; and the input/output interface is configured to output the N-point FFT from C) so as to provide an indication of the one or more frequency components of the sampled time-varying signal. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29)
- BW, the sampled time-varying signal including a first sub-sampled set of B1 samples of the time-varying signal and a second sub-sampled set of B2 samples of the time-varying signal, the apparatus comprising;
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30. An application specific integrated circuit (ASIC) apparatus for calculating a Fast Fourier Transform (FFT) of a signal, the ASIC apparatus comprising:
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an input/output interface adapted to receive a discrete z-point signal, z being a product of at least two numbers; one or more first xn-word memory blocks configured to store xn signal points sub-sampled by z/xn from the z-point signal; one or more second ym-word memory blocks configured to store ym signal points sub-sampled by z/ym from the z-point signal, wherein x and y are co-prime numbers and n and m are natural numbers, and a microprocessor for calculating the FFT of the signal, the microprocessor comprising; a bucketization microarchitecture to sub-sample the received signal and alias signal points to buckets whose number is less or equal to z, and a reconstruction microarchitecture designed to estimate a magnitude value and a frequency index of one or more frequency components of the z-point signal.
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Specification