ZTE Corporation together with China Mobile has jointly completed the world's first prototype test of 400G Quadrature Phase Shift Keying (QPSK) and achieved the ultra-high-speed transmission over the distance of 3038km based on G.652.D fiber, which shows the excellent performance of 400G QPSK in long-distance transmission on optical backbone network. 

As the digital economy booms and the national "east-data-west-computing" project launches, China has started the basic infrastructure of computing power network throughout the country. Since optical network is the cornerstone of the digital and computing power era, optical network based on broadband has become the focus of the entire industry. China Mobile is developing its computing power networks rapidly. A great deal of computing power services at the Yangtze River Delta put forward high requirements on data center storage, AI training, and rendering in Guizhou. Therefore, China Mobile considers it necessary to improve the bandwidth of its optical backbone network. 

In July 2022, China Mobile and ZTE jointly simulated the fiber length, loss, and maintenance margin on its existing network in the lab and employed a prototype to test 400G QPSK transmission. The result shows that the 400G QPSK optical module with 3D optical/electrical chipset can fulfill 49-span 3,038km transmission distance without electrical regeneration base on G.652.D optical fiber by adopting power fluctuation control algorithm and backward Raman amplification in some spans. It will allow Ultra-Long-Haul transmission for China Mobile to deliver massive large-bandwidth services, drives the growth of China Mobile's optical networks, and lays a foundation for global digital and intelligent optical networks. 

China Mobile and ZTE have cooperated closely in the 400G LH transmission for a long term. In 2019, they tested the single carrier 400G 16QAM in China Mobile’s network, and hit the industry’s record by transmitting 600km. In October 2021, they verified the world's first ultra-wide-spectrum single-wavelength 400G large-capacity optical transmission by using the 11THz ultra-wide-spectrum C+L extended band in the existing network of China Mobile, with a transmission distance of over 1000km. 

Moving forward, ZTE will continue researching and exploring optical networks, and work with global operators to build digital and intelligent optical networks.