Implementation of Predistorter for HPA Nonlinearity Mitigation on OQAM FBMC System

Using Cyclic Prefix (CP) and rectangular filter in orthogonal frequency division multiplexing (OFDM) system causes losing spectral efficiency, high OOB(Out-of-Band) emission, and high PAPR which leads to performance degradation. A new multicarrier modulation technique called filter bank multicarrier (FBMC), considered as a potential candidate for 5G. Due to the pulse shaping filter and no CP used, FBMC has low OOB emission, Low PAPR, and also better spectral efficiency compared to OFDM. FBMC with offset quadrature amplitude modulation (OQAM) offers better spectral efficiency than the other variant of FBMC. FBMC-OQAM only transmitted real-valued to keep real orthogonality condition, but it leads to intrinsic interference caused by imaginary part. Intrinsic interference leads to performance degradation, moreover the presence of nonlinear distortion by nonlinear High Power Amplifier (HPA). In this paper, we proposed a predistortion technique to compensate for the nonlinear distortion effect. The simulation result that using a predistorter can improve the BER performance of 12dB on the HPA OFDM-4QAM nonlinear system and 18dB on the HPA FBMC-40QAM nonlinear system for IBO=-8.5dB.