High-Capacity Wireless Backhaul Network Using Seamless Convergence of Radio-over-Fiber and 90-GHz Millimeter-Wave

We propose and experimentally demonstrate a seamlessly converged radio-over-fiber (RoF) and millimeter-wave system at 90 GHz for high-speed wireless signal transmission. We successfully transmit and demodulate standard orthogonal frequency-division multiplexing-based wireless local access network (WLAN) signals, long term evolution eNB conformance test models, and long term evolution advanced signals over the system. Satisfactory transmission performance over the converged RoF and a 5-m 90-GHz wireless link is achieved. The measured root-mean-square error vector magnitude is well under the requirement defined by the standards. We also investigate the dependence of the transmission performance on the fiber length due to the effect of fiber dispersion and estimate the achievable wireless transmission distance. The estimated transmission range of both the fiber length and wireless link are sufficiently long for practical applications, such as mobile backhaul/fronthaul, wireless access network for WLAN signals. Possible solutions and the estimated transmission range are also discussed to use millimeter-wave and RoF system convergence for uplink transmission. The obtained results confirm the potential to use the system in future high-speed, small-cell mobile networks and in broadband wireless access networks.