Effects and Feasibility of Switched Radio-Over-Fiber Networks Combining Analog Radio-Over-Fiber and Optical Switching for Future Smart Mobile Fronthaul Networks in the Beyond 5G Era

In the Beyond 5G (B5G) era, faster and higher-capacity communication systems are expected to be realized compared to current 5G. To achieve these goals, the use of higher frequency bands such as millimeter waves and terahertz waves is essential. However, these high frequencies face challenges such as signal attenuation and poor diffraction, making it difficult for signals to pass through obstacles like walls. To address these issues, the use of microcells with a large number of Radio Units (RUs), along with Analog Radio-over-Fiber (A-RoF) technology, has been proposed. A-RoF reduces throughput requirements in the optical transmission section and simplifies RU design, offering the potential for future integration with Power over Fiber (PWoF). In this work, we aim to realize a novel Mobile Fronthaul (MFH) configuration suitable for B5G by efficiently managing a large number of small optically powered antennas. To this end, we focus on the Switched-RoF concept, in which an optical switch is inserted into the optical transmission section of A-RoF signals between antennas and Central Units (CUs) or Distributed Units (DUs). In this paper, we present the architecture of the Switched-RoF and evaluate its effectiveness through computer simulations and testbed experiments. The results confirm the feasibility and energy-saving potential of the proposed system. Thus, the Switched-RoF is a promising MFH configuration for enabling microcell-based communication networks in the B5G era.