Scalable FFT kernel designs for MIMO OFDM based communication systems

In this paper, we propose a novel scalable FFT processor design capable of handling various transform sizes and data channels for multi-standard MIMO processing. The basic building blocks are split-radix 2/4/8 FFT modules in a modified MDC (multi-path delay commutator) form, pre- ordering data buffer, radix-2 butterfly module and twiddle factor module. Via proper data flow reconfiguration plus two alternative working frequencies, the processor can support 64, 128, 512, 1024-point transforms plus 1 to 4 MIMO channels. The hardware utilization is kept as 100% under various working modes. The implementation results in TSMC 0.18 um process indicate the design has a core size of about 5.5 mm², and a power consumption of 320 mW at 100 MHz. The delivered performance qualifies the proposed design for 802.1 In and 802.16e applications.