Interference analysis of FFT-FBMC scheme in time asynchronous contexts

FFT-FBMC waveform was proposed as a modification of the conventional FBMC in order to get rid of the FBMC intrinsic interference. In this paper, we consider the coexistence of two unsynchronized pairs of transmitter/receiver using FFT-FBMC waveform, and analyze the mutual interference caused by their time misalignment. We will show that, like in FBMC, the asynchronous interference is only spread on the immediate adjacent subcarrier. Moreover, the interference level in FFT-FBMC is reduced at least by 10 dB compared to FBMC. Indeed, the interference value in FFT-FBMC has significant variations with respect to timing offset and other designing parameters of the FFT-FBMC waveform. We also evaluate the mean interference averaged with respect to timing offset. Two tables modeling the average interference power are provided and show that, in FFT-FBMC case, the interference is lower than in FBMC case.