Mitigating Self Echo in Public Cellular AccessNetworks Using Counter Propagating Light wave Interferometry

Abstract Public Cellular Access Networks based on Radio over Fiber technology (PCN-RoF) seamlessly integrate connections among individuals, devices, and servicesacross diverse sectors. The proposed PCN-RoF, using in-band full duplex technol-ogy (IBFD), allows simultaneous signal transmission and reception between userstations (US) and central office stations (COS) within the same frequency band.However, a drawback of IBFD-based PCN-RoF systems is the self-echo (SE)interference caused by simultaneous transmission and reception. To address this,we propose a self-echo cancellation (SEC) system based on Counter-PropagatingLight wave Interferometry (CPLI). The system employs a dual parallel Mach-Zehnder modulator (DPMZM) for SEC, with a frequency downconverting systemusing an electrical local oscillator (ELO) and an FBG-based sensor to mitigatedispersion effects. Achieving cancellation depths of 52.99 dB to 56.74 dB andconversion efficiency from 23.55 dB to 27.70 dB, this SEC technique can enhancesmart city implementations by enabling efficient communication among diversedevices, infrastructure, and sensors.