EURASIP Journal on Applied Signal Processing
Volume 2002 (2002), Issue 9, Pages 961-974
doi:10.1155/S111086570220503X
A Reduced-Complexity Fast Algorithm for Software Implementation
of the IFFT/FFT in DMT Systems
1VXIS Technology Corporation, Taiwan, Hsin-chu, China
2Department of Electrical Engineering, Graduate Institute of Electronics Engineering, National Taiwan University,Taiwan, Taipei 106, China
Received 31 August 2001; Revised 15 May 2002
Abstract
The discrete multitone (DMT) modulation/demodulation scheme is the
standard transmission technique in the application of
asymmetric digital subscriber lines (ADSL) and very-high-speed digital subscriber lines (VDSL).
Although the DMT can achieve higher data rate
compared with other modulation/demodulation schemes, its computational
complexity is too high for cost-efficient implementations. For example, it
requires 512-point IFFT/FFT as the modulation/demodulation kernel
in the ADSL systems and even higher in the VDSL systems.
The large block size results in heavy computational load in running programmable
digital signal processors (DSPs).
In this paper, we derive computationally efficient fast algorithm for the
IFFT/FFT. The proposed algorithm can avoid complex-domain operations that
are inevitable in conventional IFFT/FFT computation. The resulting software
function requires less computational complexity. We show that it acquires
only 17% number of multiplications to compute the IFFT and FFT compared
with the Cooly-Tukey algorithm. Hence, the proposed fast algorithm
is very suitable for firmware development in reducing the MIPS count in
programmable DSPs.