Distortion effect analysis of N-OFDM signal with frequency drifts of carrier wave

In the paper, research results of the distortion effect of an N-OFDM signal are presented. The consequence emerges due to a frequency drift of the carrier wave because of the Doppler effect during user's movement and instability of oscillator frequency, when a transfer of the spectrum is implemented in transmitting and reception path of the communication system. The N-OFDM signal based on the Hartley transform with the QAM modulation of subcarrier was analyzed. The interference immunity of the N-OFDM signal was defined for different frequency spacing between subcarriers and various frequency drifts of the subcarriers for an equivalent low-frequency channel with AWGN. Demodulation was implemented by the modified Cauchy method. The highest possible shift of the frequency subcarriers of the N-OFDM signal was determined by means of simulation experiments in Matlab 7 for the situation, when it is still possible to keep a communication session.