  In this paper, we propose a novel receiver structure for single-carrier
transmission with frequency domain equalization (FDE) that is exposed to power
amplifier (PA) nonlinearities. A two-stage approach is adopted, in which linear
communication channel is equalized at the first stage, and it is followed by a
post-distortion where nonlinear distortion is reduced. In literature, nonlinear
processing techniques are proposed, which performs memoryless compensation of
nonlinear distortion together with FDE. However, in this study, we show that
even if a memoryless nonlinearity exists, the received signal is impaired by
nonlinear inter-symbol-interference. Therefore, we propose a class of symbol
rate post-distortion techniques, which use neighboring received symbols to
suppress the nonlinear interference. Two different post-distortion techniques,
Gaussian process regression (GPR) and neural network (NN) based
post-distorters, are considered. Also, a decision metric, combining outputs of
fractional delayed bank of FDE's after post-distortion, is proposed to overcome
performance degradation of FDE for frequency selective channels under nonlinear
distortion. Performances of the proposed techniques are compared with that of
the state-of-the-art techniques in terms of bit error rate and achievable
information rate metrics via simulations. Simulation results demonstrate that
GPR and NN based post-distortion methods together with bank of FDE outperform
state-of-the-art techniques.
