Pipelined FFT for wireless communications supporting 128–2048 / 1536 -point transforms

Modern wireless communication systems use orthogonal frequency division multiplexing (OFDM) and multiple input multiple output (MIMO) schemes, which call for fast Fourier transforms (FFT). Traditionally power-of-two FFT lengths have been exploited but recently also non-power-of-two transform lengths have been defined. For example, 3GPP LTE specification defines 1536- point FFT. In this paper, we propose a pipeline FFT architecture, which supports FFT lengths of power-of-two multiple of three. The architecture is basically single delay feedback structure followed by radix-3 computation unit. The proposed architecture is memory optimal as for N-point transform only N - 1 memory locations are needed.