An FFT Approach for Efficient OFDM Communication Systems

In the widely used OFDM (Orthogonal Frequency Division Multiplexing) systems, the FFT and IFFT pair are used to modulate and demodulate the data constellation on the subcarriers. This paper presents a high level implementation of a high performance FFT for OFDM Modulator and Demodulator. The design has been coded in Verilog and targeted into Xilinx Spartan3 FPGAs. Radix-2² Algorithm is proposed and used for the OFDM communication system. This algorithm has the same multiplicative complexity as the radix-4 algorithm, but retains the butterfly structure of radix-2 algorithm. The design is parameterizable in terms of input word length, output word length, twiddle factor word length, and processing word length. Also, it is scalable in terms of number of stages.