China Telecom & Huawei Jointly Completed the Industry's First PCS-based 200G/400G Ultra-Long-Haul Field Trial in a Commercial WDM Network

China Telecom and Huawei recently completed the first 200G/400G ultra-long-haul field trial to be performed on a commercial WDM network, putting probabilistic constellation shaping (PCS) to good use and revealing nearly 1200 km of un-regenerated transmission on the live network. An academic paper entitled Field Trial of Probabilistic-Shaping-Programmable Real-Time 200-Gb/s Coherent Transceivers in an Intelligent Core Optical Network, which is based on a real-time field trial in a deploying national WDM network, was accepted as a post-deadline paper (PDP) and presented at the 18th Asia Communications and Photonics Conference (ACP) held in Hangzhou, China. The ACP is the most influential technical conference in optical communications and photonics in the Asia-Pacific region, and the PDP submissions showcase the significance of the latest research results. This paper was presented as the first PDP in the optical transmission and networking category. Figure 1:

This field trial was carried out on an optical mesh network with reconfigurable optical add/drop multiplexers (ROADMs) currently, with Huawei providing the commercial 200G/400G ultra-long-haul WDM equipment that is fully compatible with the live ROADM-based network. The new ultra-long-haul 200G/400G boards use a series of cutting-edge technologies, such as PCS, Nyquist shaping, polarization multiplexing, 16-QAM higher-order modulation etc., so that each 200Gb/s optical channel can be squeezed into a standard 50-GHz ITU channel grid and transmitted over 1142 km in the live network. The tested un-regenerated transmission distance is twice as long as that using the conventional 200Gb/s channels based on PDM-16QAM, thanks to the enhanced tolerance to linear and nonlinear noises provided by PCS. This also doubles the spectrum efficiency compared to today’s 100Gb/s PDM-QPSK based systems. This combination of new technologies provides an easy upgrade to 200Gb/s line rate from 100G legacy networks with the common 50-GHz channel grid, thereby allowing for doubled system capacity without having to reconstruct the optical-layer platform. The system is also readily scalable to 400Gb/s line rate by using 100-GHz channel spacing.

Based on the PCS technology and several other technical breakthroughs in the commercial use of 200G/400G WDM long-haul transmission, China is contributing to the development of the global optical communications industry. As a forerunner in the application of advanced optical networks, China Telecom continues to explore beyond-100G high-speed optical network technologies, advancing the development of the optical communication industry to benefit the global society.