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An Orthogonal Polynomial-Based Analytical Expression of Nonlinear Power Amplifier for FBMC Systems

A filter bank multicarrier modulation (FBMC) is a strong promising solution for the fifth generation (5G) and beyond in broadband wireless communications. Nonetheless, one of the main disadvantages of the multicarrier techniques-based communication systems is the high peak-to-average power ratio (PAPR) of transmitting signals resulting in a nonlinear distortion of the signals, which is caused by a high power amplifier (HPA). Many kinds of research related to the nonlinear distortions induced by HPA have been proposed. However, there are solely limited studies on the analytical derivation of the nonlinear HPA characteristic. In this paper, an orthogonal polynomial based-analytical expression of a nonlinear power amplifier for baseband uniform, exponential, and Rayleigh input distribution of FBMC systems is proposed. The probability of error performances (BER) comparison between the proposed orthogonal polynomial method and the conventional polynomial method is determined. In addition, a theoretical performance analysis of the proposed method is derived to evaluate the BER performances in the frequency-selective Rayleigh fading channel. In the simulation, the BER performance of a nonlinearly amplified FBMC systems is investigated at a different IBO. The simulation results indicate that the proposed orthogonal polynomial method significantly outperforms the conventional polynomial method in terms of a normalized mean squared error (NMSE) and BER performance. Moreover, the theoretical error probability is compared with the simulation results and it could be found that the theoretical BER performance is relatively close to the simulated result.