  Most of the conventional multicarrier waveforms explicitly or implicitly
involve a generalized frequency division multiplexing (GFDM)-based modem as a
core part of the baseband processing. Some are based on GFDM with a single
prototype filter, e.g. orthogonal frequency division multiplexing (OFDM) and
others employ multiple filters such as filter bank multicarrier (FBMC).
Moreover, the GFDM degrees of freedom combined with multiple prototype filters
design allow the development and optimization of new waveforms. Nevertheless,
GFDM has been widely considered as a complex modulation because of the
requirements of odd number of subcarriers or subsymbols. Accordingly, the
current state of the art implementations consume high resources. One solution
to reduce the complexity is utilizing radix-2 parameters. Due to the
advancement in GFDM filter design, the constraint of using odd parameters has
been overcome and radix-2 realization is now possible. In this paper, we
propose a unified low complexity architecture that can be reconfigured to
provide both time-domain and frequency-domain modulation/demodulation. The
design consists of several radix-2 fast Fourier transform (FFT) and memory
blocks, in addition to one complex multiplier. Moreover, we provide a unified
architecture for the state of the art implementations, which is designed based
on direct computation of circular convolution using parallel multiplier chains.
As we demonstrate in this work, the FFTbased architecture is computationally
more efficient, provides more flexibility, significantly reduces the resource
consumption, and achieves similar latency for larger block size.
