EML-Based Multi-Path Self-Interference Cancellation With Adaptive Frequency-Domain Pre-Equalization

In this letter, for the first time, we propose to employ the adaptive frequency-domain pre-equalization (FDPE) into an electro-absorption modulator laser (EML)-based optical self-interference cancellation (OSIC) system to suppress the time-varying multipath radio frequency (RF) self-interference (SI) signal, which is implemented for in-band full-duplex (IBFD) communication. Faced with time-varying multipath wireless channel, the OSIC system estimates multipath channel response using a least square estimation algorithm, and adjusts the coefficients of frequency-domain pre-equalizer adaptively to combat time-varying multipath SI. Based on the proposed FDPE-aided OSIC, the IBFD transmission of OFDM RF signals with time-varying multipath channel is demonstrated experimentally, achieving 30-dB OSIC depth over 1.22-GHz broad baseband.