Methods and Apparatuses for Detection and Estimation with Fast Fourier Transform (FFT) in Orthogonal Frequency Division Multiplexing (OFDM) Communication Systems
First Claim
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1. An apparatus, comprising:
- a plurality of butterfly operators that are operative with respective delay blocks in calculating a Fourier transform of a signal input;
at least one complex multiplier; and
a plurality of multiplexers that are configured to selectively operate the at least one complex multiplier to (i) calculate the Fourier transform of the signal input using the plurality of butterfly operators, or (ii) calculate one or both of an energy signal based upon the signal input, or at least one autocorrelation signal based upon the signal input and at least one delayed input from at least one delay block.
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Abstract
Methods and apparatuses are provided for a fast Fourier transform (FFT)/inverse fast Fourier transform (IFFT) architecture that not only allows for efficient computation of N-point FFT/IFFT transform (N=2n), but also allows for efficient reuse of the multipliers and delay blocks for efficient implementation of signal energy detection and autocorrelation of length or period 2p, where pε{0, 1, . . . , log2(N)−1}. Signal energy detection and autocorrelation may then used for received energy measurement, frame synchronization, including packet detection or symbol timing, and carrier frequency offset estimation.
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Citations
20 Claims
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1. An apparatus, comprising:
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a plurality of butterfly operators that are operative with respective delay blocks in calculating a Fourier transform of a signal input; at least one complex multiplier; and a plurality of multiplexers that are configured to selectively operate the at least one complex multiplier to (i) calculate the Fourier transform of the signal input using the plurality of butterfly operators, or (ii) calculate one or both of an energy signal based upon the signal input, or at least one autocorrelation signal based upon the signal input and at least one delayed input from at least one delay block. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method, comprising:
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providing a plurality of butterfly operators that are operative with respective delay blocks in calculating a Fourier transform of a signal input; providing at least one complex multiplier; and configuring a plurality of multiplexers to selectively operate the at least one complex multiplier to (i) calculate the Fourier transform of the signal input using the plurality of butterfly operators, or (ii) calculate one or both of an energy signal based upon the signal input, or at least one autocorrelation signal based upon the signal input and at least one delayed input from at least one delay block. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification