Title :
Computing partial DFT for comb spectrum evaluation
Author :
He, Shousheng ; Torkelson, Mats
Author_Institution :
Dept. of Appl. Electron., Lund Univ., Sweden
fDate :
6/1/1996 12:00:00 AM
Abstract :
A comb spectrum evaluation problem arises in the (de)modulation for orthogonal frequency division multiplexing-based (OFDM-based) multichannel communication system. Efficient algorithms for this special type of partial discrete Fourier transform (DFT) computation are studied. For an M-component comb spectrum evaluation with transform length N, it is shown that only O(N+MlogM) multiplications are needed, compared with O(NlogM) multiplications necessary for a narrowband spectrum evaluation. Pruning radix-2 decimation-in-time fast Fourier transform (FFT) requires only (N/4+M/2log/sub 2/M-M) nontrivial complex multiplications. The frequency shift technique has also been applied to allow a modularized mixed-radix structure for the computation of comb spectrum with an initial component not starting from zero frequency point.
Keywords :
computational complexity; demodulation; digital arithmetic; discrete Fourier transforms; frequency division multiplexing; mobile communication; modulation; spectral analysis; OFDM-based multichannel communication system; comb spectrum evaluation; demodulation; efficient algorithms; fast Fourier transform; frequency shift technique; mobile communication; modularized mixed-radix structure; modulation; narrowband spectrum evaluation; orthogonal frequency division multiplexing; partial DFT; partial discrete Fourier transform computation; radix-2 decimation-in-time FFT; transform length; zero frequency point; Discrete Fourier transforms; Discrete transforms; Fast Fourier transforms; Filtering theory; Frequency division multiplexing; Interference; Mobile communication; Narrowband; OFDM;
Journal_Title :
Signal Processing Letters, IEEE