Abstract—Next-generation wireless systems use the non-orthogonal modulation technique known as generalized frequency division multiplexing (GFDM). The nonlinearity of the high-power amplifier (HPA) greatly affects the performance of the wireless system. Without phase distortion and only amplitude distortion in the GFDM system using HPA Model Rapp. The effects of nonlinear distortion that occur involve distortion of the amplitude, signal constellation distribution, and spectral distribution. There are two contributions to this paper. First, the impact of HPA Model Rapp's nonlinear distortion on the GFDM system in the AWGN (additive white Gaussian noise) and Rayleigh channels was investigated. The simplicity of this model is the reason it was picked and has an AM/AM (amplitude modulation/amplitude modulation) curve. Second, the linearization of HPA with the use of a predistorter method in GFDM systems has been proposed. The nonlinear distortion impact of HPA can be mitigated by this predistorter. This technique is implemented in the transmitter section. The system performance investigated is determined by a bit error rate (BER) analysis, a constellation diagram, and a spectrum analysis. HPA generates a 55 dB rise in out-of-band (OOB) in the signal spectrum. The HPA effect was successfully compensated for by a 55 dB decrease in the OOB value of the predistorter system.