Digital Self Interference Cancellation Method Based on Nonlinear Harmonics Mitigation in In-Band Full Duplex Transceiver

In band full duplex (IFD) has been received a great deal of attention owing to the double utilization of the frequency band over half duplex (HD). To achieve an increase in spectral efficiency in IFD communications, it is necessary to suppress the self interference (SI) signal to a power level that can guarantee the signal to noise ratio of the desired signal. In this paper, we propose a novel digital domain SI cancellation (DSIC) scheme that eliminates both the fundamental component and nonlinear harmonics of an SI signal while reducing the computational complexity compared with a conventional scheme. The proposed method mitigates the nonlinear harmonics of the transmit SI signal by using the linearization digital predistortion (DPD) technique. In addition, we improve the degraded DSIC performance using a non ideal predistorter by adopting the feedback path implemented for DPD estimation as an auxiliary receiving chain for DSIC. At this time, we provide a minimum basis matrix for the real time processing of least square based SI channel estimation in the digital time domain. The simulation results show that our proposed DSIC schemes converge to the optimal SIC performance with a 30% reduced computational complexity when the ASIC gain is greater than 60 dB.