At the 2024 China Optical Network Symposium held recently, Wang Dong, the chief researcher of China Mobile Research Institute, introduced that in response to the higher requirements of the optical transmission network in terms of ultra-large bandwidth, ultra-long distance, and ultra-low latency proposed by the computing power network, China Mobile proposed a new all-optical network architecture based on 400G + OXC. “The 100G scale application has been for 10 years. 400G is a major transformative intergenerational technology that initiates the next cycle of the backbone network and drives optical communication into the broadband spectrum era,” Wang Dong said.
Wang Dong further introduced that 400G is a complex systematic engineering problem. In more than two years, China Mobile has rapidly promoted the research on three key technical directions (defining modulation code types, spectrum planning, and system design), driving the formation of a new 400G QPSK ultra-long-distance technology industrial chain, and achieving an intergenerational technological breakthrough from 100G to 400G based on the “3 + 1” key measures.
Based on technological research and the formulation of a series of standard specifications, China Mobile has coordinated the industry to achieve full maturity of 400G QPSK core technologies such as 130GBd ultra-high-speed devices and 12THz ultra-wide-spectrum active modules, and promoted the further evolution of the optical layer towards C + L integration and modules towards pluggable miniaturization.
China Mobile has planned the eight major hub network construction projects, building a national latency circle of 5ms within hubs and 20ms between hubs, and conducting large-scale centralized procurement of 11,000 400G ports, an increase of nearly ten times compared to the number of 100G OTN ports in the first centralized procurement in 2013. In March this year, China Mobile completed the world’s first 400G “East Data West Computing” link (Beijing – Inner Mongolia), officially initiating the first year of large-scale commercial use of the 400G OTN backbone all-optical network, and plans to fully connect the computing power hubs by the middle of 2024.
For the 400G medium and short-distance technical routes, facing the provincial transmission scenarios, there are two potential technical routes of 400G 16QAM-PCS and QPSK: Converging 16QAM-PCS and QPSK to one modulation format, and adopting a unified technology for all provincial scenarios; or having both 16QAM-PCS and QPSK technical solutions coexist and be selected for use based on the needs of different provinces, with a unified C6T + L6T optical layer. Wang Dong suggests that comprehensive consideration should be given mainly based on transmission capacity and deployment cost.
For the urban area transmission scenarios, there are two potential technical routes of 400G 16QAM and 16QAM-PCS. The deployment of urban area networks needs to consider the introduction cost of OXC networking and optical layer protection. 16QAM can meet the demand for data center interconnection at a low cost. Compared with 16QAM, 16QAM-PCS has a 4dB improvement in transmission performance and can cover the main scenarios of urban area transmission. Comprehensive consideration should be given mainly based on spectral efficiency and low-cost deployment.
Facing the potential applications of medium and short distances such as 800G for data center interconnection, it is possible to share the 400G ultra-long-distance 130G baud rate technology and industry, accelerating the evolution of large-capacity, medium and short-distance transmission scenarios such as data center interconnection to 800G.
