Simultaneous Image-reject Downconversion and Self-interference Cancellation for Full-duplex Communication

A photonics-assisted simultaneous image-reject downconversion and self-interference cancellation for full-duplex communication is proposed. The image rejection is realized by optical sideband filtering and phase control. The intermediate frequency (IF) signal to be transmitted is used as the reference signal and combined with the received signal after image rejection in IF domain to cancel the self-interference caused by the strong transmitted signal. A proof-of-concept experiment is carried out. The experiment results show that an image rejection ratio of 30.5 dB and self-interference cancellation depth of 31.5 dB with 50 MHz bandwidth are realized. The weak signal of interest with 16-QAM modulation is well recovered after the cancellation of the strong interference.