name: IFFT
full_form: Inverse Fast Fourier Transform
context: is a mixed-radix FFT with a combination of radix-2 and radix-4 FFT butterflies. Each radix-2 butterfly requires 1 complex multiply, 4 real additions, and 1 table look-up, and there are (NFFT / 2) such radix-2 butterflies. Each radix-4 butterfly requires 3 complex multiplies, 16 real additions, and 3 table look-ups, and there are a total of (NFFT / 4) log4(NFFT / 2) radix-4 butterflies. Once again, the FFTs are performed at the OFDM symbol rate, 1/Ts. For the 1024-point FFT required for parameter set 2, a radix-4 FFT can be used. Each butterfly in a radix-4 FFT requires 3 complex multiplies, 22 real additions, and 3 table look-ups (with a complex value returned per table look-up). This count does not take into account the fact that some of the twiddle factors lead to trivial multiplications (i.e. multiply by +1, or âj). There are a total of (NFFT / 4) log4NFFT butterflies, which for a 1024-point FFT equals 1280 butterflies. The FFTs are performed at the OFDM symbol rate, 1/Ts. Note
description: The Inverse Fast Fourier Transform (IFFT) is a digital signal processing technique used in the generation of OFDM signals. It transforms frequency-domain data into time-domain data, enabling the creation of orthogonal sub-carriers and the modulation of data symbols onto these sub-carriers.
explanation: The context describes IFFT as a specific technique used in telecommunications for signal generation. Its application in transforming data for OFDM signals places it firmly within the category of Technology.
section_title: 4.1.3	Practical OFDM Signal Generation Using IFFT Processing
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