Reduced memory IFFT design for OFDM systems using DIT twiddle factor shifting algorithm

Abstract

In this paper, to reduce the memory size of IFFT for OFDM systems, we propose a new IFFT design based on a mapping of three IFFT input signals: modulated data, pilot and null signals. To reduce the memory cells, the proposed method focuses on reducing the size of memory cells in the bit-reversal part which requires the largest number of memory cells in IFFT. To this end, we propose a DIT(decimation-in-time) twiddle factor shifting algorithm to remove the multipliers in the first two stages. It is shown that the proposed method achieves a memory reduction of about 30% compared with conventional methods.