Towards a Triple Mode common operator FFT for software radio systems

A scenario to design a Triple Mode FFT is addressed. Based on a Dual Mode FFT structure, we present a methodology to reach a triple mode FFT operator (TMFFT) able to operate over three different fields: complex number domain ℂ, Galois Fields GF(F_t) and GF(2^m). We propose a reconfigurable Triple mode Multiplier that constitutes the core of the Butterfly-based FFT. A scalable and flexible unit for the polynomial reduction needed in the GF(2^m) multiplication is also proposed. An FPGA implementation of the proposed multiplier is given and the measures show a gain of 18%in terms of performance-to-cost ratio compared to a “Velcro” approach where two self-contained operators are implemented separately.