  General frequency division multiplexing (GFDM) is a flexible non-orthogonal
waveform candidate for 5G which can offer some advantages such as low
out-of-band (OOB) emission and high spectral efficiency. In this paper, the
effects of nonlinear behavior of practical PAs on GFDM signal are studied. In
the first step, a closed form expression for power spectral density (PSD) of
GFDM signal is extracted. Then, the PSD at the output of PA as a function of
input power and the coefficients of nonlinear polynomial PA model is derived.
In addition, the adjacent channel power (ACP) and ACP ratio, as two important
performance metrics, are evaluated. The simulation results confirm the accuracy
of derived analytical expressions. Moreover, to validate the performance of
GFDM modulation after nonlinear PA, it is compared with OFDM modulation.
