Photonics-Assisted Adaptive Analog Wideband Self-Interference Cancellation Based on Digital Pre-modeling Search and Two-Tap Delay Adjustment

A photonics-assisted adaptive analog wideband self-interference cancellation (SIC) approach for in-band full-duplex (IBFD) systems is proposed based on a digital-assisted delay and amplitude pre-modeling search method, as well as a two-tap delay adjustment method. By jointly using the pre-modeling search method, our previously reported segmented search method, and the two-tap delay adjustment method, the delay search and adjustment accuracy can be greatly improved without upsampling, while the search results can be obtained in one iteration only using an 8-μs search signal. An experiment is performed. By using the proposed approach, an analog cancellation depth of 23 dB can be achieved when the center frequency and baud rate of the self-interference are 1 GHz and 1 Gbaud.