The influence of the Doppler effect on the operation of OFDM signal modems

The article analyzes the influence of OFDM signals on the operation of modems in radio channels in which the spectrum of the received signal is shifted due to the Doppler effect, which occurs due to the mutual movement in space of the transmitter and receiver signals. According to the analysis results, it is shown that the Doppler effect has a negative impact on the operation of OFDM signal modems, significantly reduces the noise immunity of OFDM demodulators to the point of disrupting message transmission when the frequency shift exceeds the threshold value. The article suggests measures to reduce and eliminate the negative impact of the Doppler effect on modem operation, including the use of the automatic frequency tuning systems, phase auto-tuning systems, and oscillator synchronization systems in OFDM signal demodulators using reference subcarriers in OFDM signals.