OFDM interference analysis in nonlinear time-varying radio channels with frequency offsets

Nonlinear distortions and frequency offsets are two major problems of OFDM transmission that essentially affect its reliability. In this paper, we analyze OFDM by taking into account both effects. For a wide-sense stationary uncorrelated scattering channel we derive an approximate analytical expression for the signal - to - total interference power ratio. The obtained formula directly involves maximal Doppler shift, transmitter - receiver frequency offset and characteristics of the nonlinear power amplifier (amplifier gain and linear gain). The simulation results confirm that the derived formula provides a close approximation of the exact expression for a wide range of Doppler shifts and transmitter-receiver frequency offsets. Simplicity and accuracy of the obtained expression as well as its fitting for realistic scenarios where the transmitter-receiver frequency offsets are random, makes it convenient for practical applications.