Mitigating self-echo in public cellular access networks using counter-propagating light wave interferometry: Mitigating Self-echo in public cellular access

Public Cellular Access Networks based on Radio over Fiber technology (PCN-RoF) seamlessly integrate connections among individuals, devices, and services across diverse sectors. The proposed PCN-RoF, using in-band full duplex technology (IBFD), allows simultaneous signal transmission and reception between user stations and central office stations within the same frequency band. However, a drawback of IBFD-based PCN-RoF systems is the self-echo interference caused by simultaneous transmission and reception. To address this, we propose a self-echo cancellation (SEC) system based on Counter-Propagating Light wave Interferometry. The system employs a dual parallel Mach–Zehnder modulator (DPMZM) for SEC, with a frequency downconverting system using an electrical local oscillator and an FBG-based sensor to mitigate dispersion effects. Achieving cancellation depths of 52.99 to 56.74 dB and conversion efficiency from 23.55 to 27.70 dB, this SEC technique can enhance smart city implementations by enabling efficient communication among diverse devices, infrastructure, and sensors.