An Efficient QAM Detection via Nonlinear Post-distortion for SC-FDE Transmission under PA Impairments with Memory
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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 first stage and it is followed by a post-distortion unit where nonlinear distortion is reduced. In literature, there are some techniques that are proposed for the memoryless compensation of nonlinear distortion together with FDE. However, in this study, we show that even if a memoryless nonlinearity is utilized, received signal is impaired by nonlinear inter-symbol interference (ISI). Therefore, we propose a class of post-distortion techniques, which use neighbouring received symbols to supress the nonlinear interference. Two different, post-distortion techniques, namely Gaussian process regression (GPR) and neural network (NN) based post-distorters, are considered. In addition, a receiver structure, combining outputs of fractional delayed bank of FDE's, is proposed to overcome performance degradation problem of FDE for highly frequency selective channels under nonlinear distortion. Performance of the proposed techniques are compared with that of the state-of-the-art techniques in terms of bit error rate (BER) and achievable information rate (AIR) metrics via simulations. Simulation results demonstrate that GPR and NN based post-distortion methods outperform state-of-the-art techniques. Lastly, it is observed that proposed receiver architecture performs very close to linear system with the help of proposed fractionally delayed FDE bank.
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