Nanosecond-level optical switching for flexible and resilient fronthaul networks

This paper presents a novel, to the best of our knowledge, ultra-low latency fronthaul networking approach based on nanosecond (ns)-precision optical switching with advanced synchronization. We propose and demonstrate a comprehensive control architecture that integrates precision time protocol (PTP)-based time alignment with semiconductor optical amplifier (SOA)-based optical switches, enabling coordinated, jitter-minimized switching with accuracy as fine as 100 ns. Two primary synchronization methods are explored: a distributed hardware approach employing dedicated timing devices for simultaneous switch configuration, and “SyncNet,” a software-defined networking (SDN) controller utilizing time information inspired by reverse PTP. Experimental validation on a commercial Open RAN 5G system shows that our fronthaul switching framework achieves exceptional reliability, evidenced by only 0.00024% packet loss during link recovery while maintaining steady throughput (uplink: 1.03 Mbps and downlink: 1.01 Mbps) over repeated switching events. The proposed architecture supports dynamic reconfiguration for rapid link recovery and energy-efficient, traffic-adaptive resource allocation. Our results establish a robust foundation for next-generation fronthaul networks, delivering deterministic performance and flexibility aligned with 6G requirements. This work directly addresses the escalating needs for ultra-low latency, high reliability, and energy efficiency in emerging mobile and AI-driven applications.