Interference analysis of filtered multitone modulation over time-varying fading channels

We consider in this paper filtered multitone (FMT) modulation over frequency-selective time-varying fading channels. Due to the phase and amplitude distortion introduced by the fading channel, not only is the orthogonality among different subcarriers destroyed, but also the perfect Nyquist sampling condition of the baseband matched filters is no longer valid. Consequently, interchannel as well as intersymbol interference will cause distortions to the transmitted signals. In this paper, the interference caused by the time-frequency dispersive channel is quantified by analyzing the demodulated signals at the receiver under several different fading channels conditions. An analysis of the average carrier to interference (C/I) ratio of the filtered multitone system is provided in order to demonstrate the underlying trade-off between spectral efficiency and system performance. For comparison purposes with other multicarrier communication systems (or modulation techniques), the C/I ratio of the conventional OFDM system is also provided and compared with that of the FMT system under the same channel conditions and spectral efficiency. Finally, numerical and simulation results are given that confirm the C/I ratio results obtained