Analysis of a photonics-assisted multi-path interference cancellation system based on the combination of the digital domain and analog domain

In this paper, a photonics-assisted multi-path interference (MI) cancellation system based on the combination of the digital domain and analog domain is proposed and demonstrated. The cancellation in the photonics-assisted analog domain avoids oversaturation of the analog-to-digital converter (ADC) signal at the input while the adaptive feedback control in the digital domain can also compensate for the optical path's undesirable factors, thus making MI cancellation in the best state all the time. Initially, the differences in MI cancellation between small-signal and large-signal modulations are analyzed. Subsequently, the MI residual power of the multi-tap photonics-assisted cancellation system is derived theoretically by modifying the Wiener solution. Finally, the adaptive feedback control algorithm based on the received signal strength indicator (RSSI) is evaluated by simulation, and the simulated multi-path interference cancellation depth (MICD) reaches 48.4 dB when the convergence condition is satisfied. In addition, the compensation effect of the digital domain on the modulator bias point drift is analyzed.