Fiber/Free-Space Optics with Open Radio Access Networks Supplements the Coverage of Millimeter-Wave Beamforming for Future 5G and 6G Communication

• Published in: Fibers Vol. 13; no. 4; p. 39
• Main Authors: Yao, Cheng-Kai, Lin, Hsin-Piao, Cheng, Chiun-Lang, Chung, Ming-An, Lin, Yu-Shian, Wu, Wen-Bo, Chiang, Chun-Wei, Peng, Peng-Chun
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.04.2025
• Subjects: 5G mobile communication; 6G mobile communication; Antenna arrays; Antennas; Antennas (Electronics); Architecture; Artificial intelligence; Barriers; Beamforming; Communication; Communications equipment; Cost effectiveness; Cost reduction; Equipment and supplies; Evaluation; Fiber optics; fiber/FSOs communication; Free space optics; Millimeter waves; mmW beamforming; Open architectures; open radio access network; Radiation; Radio; Receivers & amplifiers; Remote regions; Resource allocation; Rural areas; Signal reception; Software; Wireless networks; Taiwan
• ISSN: 2079-6439; 2079-6439
• DOI: 10.3390/fib13040039

Conceptually, this paper aims to help reduce the communication blind spots originating from the design of millimeter-wave (mmW) beamforming by deploying radio units of an open radio access network (O-RAN) with free-space optics (FSOs) as the backhaul and the fiber-optic link as the fronthaul. At frequencies exceeding 24 GHz, the transmission reach of 5G/6G beamforming is limited to a few hundred meters, and the periphery area of the sector operational range of beamforming introduces a communication blind spot. Using FSOs as the backhaul and a fiber-optic link as the fronthaul, O-RAN empowers the radio unit to extend over greater distances to supplement the communication range that mmW beamforming cannot adequately cover. Notably, O-RAN is a prime example of next-generation wireless networks renowned for their adaptability and open architecture to enhance the cost-effectiveness of this integration. A 200 meter-long FSO link for backhaul and a fiber-optic link of up to 10 km for fronthaul were erected, thereby enabling the reach of communication services from urban centers to suburban and remote rural areas. Furthermore, in the context of beamforming, reinforcement learning (RL) was employed to optimize the error vector magnitude (EVM) by dynamically adjusting the beamforming phase based on the communication user’s location. In summary, the integration of RL-based mmW beamforming with the proposed O-RAN communication setup is operational. It lends scalability and cost-effectiveness to current and future communication infrastructures in urban, peri-urban, and rural areas.