Cost-efficient parallel lattice VLSI architecture for the IFFT/FFT in DMT transceiver technology

The discrete multitone (DMT) modulation/demodulation scheme is the standard transmission technique in the application of asymmetric digital subscriber lines (ADSL). Although the DMT can achieve a 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. The large block size results in heavy computational load in running programmable DSP processors. It also makes VLSI implementation not feasible. We derive the parallel lattice structure for the IFFT/FFT based on the time-recursive approach. The resulting architectures are regular, modular, and without global communications so that they are very suitable for VLSI implementation. Also, the proposed structure requires only 11% of the multipliers and 9% of the adders compared with the direct implementation approach.