Performance comparison of 16-QAM and 16-DAPSK systems using nonlinear HPA

When using HPA(High Power Amplifier) to amplify transmit power in a communication system, the nonlinear response of the HPA causes degradation of important performances such as power and spectral efficiency, BER. In this paper, we propose a case where a Saleh model is used as an HPA model in a communication system using 16-QAM (Quadrature Amplitude Modulation) and 16-DAPSK (Multi-level Modulation and Phase Shift Keying) The performance of each system was analyzed. The predistorter and IBO (Input Back Off) techniques were used to compensate for the nonlinear response of HPA. The IBO divided the cases with and without the predistorter and evaluated the performance by deriving the required IBO value according to each case. Simulation results show that the predistorter compensates the nonlinear response due to HPA in the constellation, spectrum and BER performance graph before and after using the predistorter. Also, the IBO value required for each system to be close to the theoretical value was confirmed by applying the IBO value differently.