Reducing Effect of the Nonlinear Distortion in M-QAM OFDM System by Pilot-Based Automatic Phase Shift

The very high PAPR of M-QAM OFDM systems makes them sensitive to nonlinear distortion caused by HPA, resulting in a steep drop in system performance. There are numerous ways to prevent nonlinear distortion in both the transmitter and the receiver. In OFDM systems, the pilot is used to estimate channels efficiently. It has been found that pilot can be used to help reduce the effect of nonlinear distortion in the system. The use of pilot tones to determine automatically the additional phase shift of subcarriers is presented in this paper. Without relying on the HPA or system specifications, the phase angle is automatically rotated based on the phase mismatch between the transmit and received pilots. © 2024 Seventh Sense Research Group.