Design of an 8-Channel FFT Processor for IEEE 802.11ac MIMO-OFDM WLAN System

Abstract

In this study, an area-efficient 8-channel 128-point fast Fourier transform (FFT) processor is proposed for IEEE 802.11ac standard MIMO-OFDM system. The proposed FFT processor is based on mixed-radix multi-path delay commutator (MRMDC) architecture and supports eight spatial data streams. Using input memory array transpose architecture and a bit-reversal circuit, the proposed FFT processor can generate eight input and output spatial data streams in natural order. Therefore, the processor can be used directly in MIMO-OFDM systems without additional input or output RAM. The proposed FFT processor is designed using hardware description language and synthesized to a gate-level circuit using a TSMC 90-nm CMOS standard cell library. Compared with other 8-channel MRMDC FFT processors, the proposed FFT processor can reduce the logic gate count of the MRMDC module by approximately 12.5 %.