China Unicom Launches Its First Free-Space Optical Communication Service
ICC Information News--As network generations evolve, optical networks are also trending towards spatial synchronization alongside terrestrial advancements, especially in the era of 5G-Advanced (5G-A) and 6G. Under the core project "Research and Application of Key Technologies for Future Optical Networks Oriented Towards F5.5G," led by the Basic Network Technology Research Department of China Unicom Research Institute, extensive research has been conducted both technically and in practical applications. Leveraging technological innovations to solve real-world network issues, China Unicom has taken the lead in initiating international standards (G.fso) within ITU-T, simultaneously developing industry reports and corporate standards. Based on these standards, short-range space laser communication devices were developed to address low internet speeds and poor user experiences in remote areas.
In January 2025, the Research Institute of China Unicom, along with Jiangsu Unicom and LASER LINK, conducted an on-site inspection of the developed equipment. The deployment involved a 1.5-kilometer cross-lake link to an island equipped with a 10G-PON network for space backhaul. Given the unique scenario, standard wavelengths defined by ITU-T were used for transmission. During on-site testing under PRBS code transmission, no packet loss was observed at 10Gbps with a bit error rate of zero. When launching the 10G-PON service, three terminals (each capable of up to 1Gbps) were connected simultaneously, achieving download speeds of 938Mbps, 996Mbps, and 985Mbps respectively—50% higher than previous microwave transmissions. The service validation lasted for 10 hours, during which temperature fluctuations and lake turbulence did not disrupt the connection. On the day of acceptance, despite light fog, the visibility was excellent. With a transmission power of 12dBm and reception sensitivity of -14dBm, the link loss was calculated to be approximately 20dB, indicating sufficient power margin to withstand harsher weather conditions. The laser terminal utilized advanced tracking, capture, and targeting technologies, completing stable operation and service transmission within 10 minutes after startup—an industry-leading achievement.
Free-space optical communication technology has long been in experimental stages without extensive real-world deployments. China Unicom leads in integrating space-ground integrated optical networks through standardization and application promotion. From identifying specialized directions, laying out standards and patents, developing equipment, to conducting field tests, numerous challenges have been overcome over many years. The official launch of this service validates its feasibility in real-world applications and marks a significant milestone as a pioneering effort by China Unicom.
From the perspective of addressing user needs, island residents previously faced limitations in accessing FTTR services due to speed constraints, while commercial tourist attractions and homestays were under development, requiring better network support. The implementation of FSO technology provided crucial support for new user development and existing user network upgrades on the island. As the sole network provider on the island, China Unicom has enhanced customer satisfaction and maintained its brand image, aligning with the national strategy of strengthening the country through robust networks.
This pilot project offers valuable experience and data references for similar scenarios, particularly in mountainous regions or across rivers and lakes where deploying fiber optic cables is challenging or costly. Additionally, it can serve as a rapid deployment solution for emergency communications. China Unicom aims to expand the scale of such applications and promote their deployment in similar environments.
Looking ahead, operators will integrate into space-ground integrated strategies, leveraging their strengths and resources to expand business domains. Specifically, in satellite connectivity, this technology plays a pivotal role. China Unicom’s focus on "ground + low-altitude + satellite" integrated optical network research positions it well to adapt quickly to market demands. Furthermore, as part of the critical process of converting scientific research into practical applications, this self-developed achievement opens potential internal and external transformation opportunities, aligning with the tasks outlined in the initial 2025 work meeting of the Research Institute. This ensures that research outcomes are effectively translated into practical use rather than remaining theoretical studies detached from real-world networks.
