60 GHz Analog Radio-Over-Fiber Fronthaul Investigations

Analog radio-over-fiber fronthaul links operating at millimeter-wave frequency band have the potential to offer high bandwidth and high data rate to cater for future 5G mobile communications. In this paper, we propose and investigate two schemes to generate 60.25 GHz millimeter-wave signals based on a variation of optical single sideband (OSSB) and optical double sideband suppressed carrier (DSB-SC) modulation techniques. Both schemes were achieved using two cascaded external modulation stages that relax the stringent requirements for high-speed electrical components. We investigate the link performance incorporating the two schemes for the transmission of different modulation formats radio signals. Thorough analytical models for the two proposed analog fronthaul schemes including noise processes are also developed and verified. Good agreement between the experimental and analytical results was achieved. Our results show that the proposed OSSB scheme can achieve lower receiver sensitivity (-5 dBm) as well as the ability to eliminate radio frequency power fading after transmitting over 10 km single mode fiber that outperforms DSB-SC scheme.