Digitized Radio-over-Fiber (DROF) System for Wide-Area Ubiquitous Wireless Network

Site diversity techniques using a distributed wireless access point for a large cell are important to achieve wide-area ubiquitous wireless networks that support embedded ubiquitous services. We propose a digitized radio-over-fiber (DROF) system for ubiquitous wireless network. The DROF system uses standard IP networks as the transmission lines of radio signals for distributed access points and can establish site diversity techniques at low cost. We also propose a network time protocol based reference frequency and time distribution scheme to synchronize distributed access points. Experiment results show that the DROF prototype achieves precise frequency and time distribution over IP based networks