Digital-signal-processing-aided ultra-high-speed radio-over-fiber technology for highly resilient mobile backhaul

This paper describes a scenario of highly resilient mobile backhaul using the radio-over-fiber (RoF) technology. RoF-based millimeter-wave high-speed transmission is useful for quick recovery from severe physical damage of the network infrastructure. As a possible approach, we demonstrated polarization division multiplexing optical and 2×2 multi-input multi-output radio seamless hybrid downlink transmission over 20-km-long standard single mode fiber and 0.9-m free space with a digital signal processing technique for the 10-Gbaud QPSK format.