Huawei, a leading global information and communications technology (ICT) solutions provider, and EXATEL, a telecommunications operator in Poland, have jointly announced that that they have successfully tested the first 400G WDM (Wavelength Division Multiplexing) system with a single carrier wave on the live network, which is a significant technical breakthrough in the high-speed transmission field.

Currently, the mainstream commercial 40G/100G WDM systems use a single carrier wave. However, on a 400 Gbit/s system, the baud rate doubles, which causes serious distortion of high-speed signals and unstable clocks. To solve these issues, existing 400G systems use multiple aggregated carrier waves, that is, multiple sub-carrier waves are aggregated to form a super channel.
 
Huawei innovatively adopts the Faster Than Nyquist (FTN) compensation and recovery algorithm, proprietary clock recovery technology, and adaptive soft decision FEC (Adaptive-SDFEC) technology, to address the world-class problems of high-speed signal distortion and unstable clocks. In the test on the existing G.652-based optical network of EXATEL in Warsaw city, Huawei successfully transmits 400 Gbit/s signals over a single carrier wave.
 
Different from a 400G system with multiple aggregated carrier waves, a 400G WDM system with a single carrier wave requires only one optical transceiver system. Therefore, a 400G system with a single carrier wave features high integration, high availability, and low power consumption. At the same time, because only one carrier wave is used, the management and scheduling are easy. A 400G WDM system with a single carrier wave is a significant direction for the evolution of customers' network.
 
"In order to guide the evolution to the next-generation optical network, Huawei invests a lot on the research of 400G technologies. We look forward to cooperating with more leading operators in the research to gain more achievements", says Jack Wang, President of the Transport Network Product Line of Huawei.
 
Huawei has deployed over 150 commercial 100G networks worldwide and made several breakthroughs in the beyond-100G field. In June 2012, Huawei and KPN International completed the world's first 400G field trial. In December 2012, Huawei conducted the world's first 2T field trial with Vodafone, achieving 2 Tbit/s transmission over a distance of up to 3,325 km. In March 2013, Huawei unveiled a 40T WDM prototype, the highest capacity in the industry, at the OFC/NFOEC2013 event in America.