Generalized frequency division multiplexing (GFDM) is a flexible non-orthogonal waveform candidate for 5G which can offer some advantages such as low out-of-band emission and high spectral efficiency. This paper investigates the effects of nonlinear behavior of practical power amplifier (PA) on the GFDM spectrum. A closed form expression for power spectral density (PSD) of GFDM signal is extracted. Then, 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 orthogonal frequency division multiplexing modulation.

通用频分复用（GFDM）是5G的一种灵活的非正交波形候选者，可以提供一些优势，例如低带外发射和高频谱效率。本文研究了实际功率放大器（PA）的非线性行为对GFDM频谱的影响。提取GFDM信号的功率谱密度（PSD）的闭式表达式。然后，根据输入功率和非线性多项式PA模型的系数，得出PA输出处的PSD。另外，评估了相邻信道功率（ACP）和ACP比率，这是两个重要的性能指标。仿真结果证实了导出的解析表达式的准确性。此外，为了验证非线性PA后GFDM调制的性能，