Multi-Tap Self-Interference Cancellation Based on Joint Time-Frequency Domain Channel Measurement in Time-Varying Channel

The increasing demand for more integrated communication systems results in complex radio-frequency environments. Due to the space limitation, communication receivers are extremely vulnerable to being blocked by high-power self-interference (SI) from the transmitter on the shared platform. The multipath amplitude and delay of the wireless channel are time-varying and frequency dispersion. As a result, the multitap self-interference cancellation (SIC) based on equal delay spacing is difficult to adapt to the dynamic changes of the SI channel over time and frequency, which leads to the degradation of SIC performance. The multitap SIC based on joint time-frequency domain channel measurement is proposed in the article. The multitap SIC model is established to analyze the demand for delay matching in the time-varying multipath channel. Under the joint constraints of the coherence time of the time-varying channel, the demand for interference cancellation ratio and delay resolution accuracy, the channel measurement method integrating time-domain correlation and frequency-domain sweep is designed to measure multipath delay. The prior information of the SI channel is provided to reconstruct the multitap SIC in real-time. Finally, the simulation and experiment results show that the proposed method in this article has high-precision delay measurement. The maximum error and standard deviation of the delay measurement are within 1ns and 0.5 ns. When the delay of the SI channel dynamically changes, compared with the equal delay spacing method, the SIC performance of the proposed method can be improved by more than 10 dB.