Full-duplex multi-band 5G/6G coexistence mobile fronthaul network based on RoF with RF self-interference cancellation

A bidirectional multi-band mobile fronthaul network based on the radio over fiber technology is proposed, which allows three different radio frequency (RF) bands at 3.5 GHz, 26 GHz, and 60 GHz full-duplex transmission, and 2.1 GHz RF band transmission as supplementary uplink, aiming for fifth-generation (5G)/sixth-generation (6G) mobile communication coexistence. The proposed scheme uses a dual-drive Mach-Zehnder modulator and dualpolarization binary phase-shift keying modulator to alleviate the interference between multiple RF bands. The transmission performance of the proposed system is evaluated by the simulation. The error vector magnitude of the system conforms to the 3GPP specification when the received optical powers of downlink and uplink are above -2.2 and -4.6 dBm, respectively. The Y-polarized optical carrier in the downlink is reused as the carrier of the uplink signals. Besides, a dual-parallel Mach-Zehnder modulator is used to realize RF self-interference cancellation at 60 GHz RF band in the uplink of the in-band full-duplex transmission. The cancellation depth of 27.08 dB is achieved by the proof-of-concept simulation.