At the OFC 2014 Conference in San Francisco, Huawei introduced a 400G WDM prototype for ultra-long-haul transmission that employs Faster Than Nyquist (FTN) technology to increase the 400G transmission distance beyond 3000 km.
Huawei said its FTN technology breaks the limit of the Nyquist sampling theorem, which defines a maximum transmission speed for a fixed channel bandwidth, by leveraging spectrum compression and signal distortion compensation algorithms. This enables the FTN technology to achieve long-haul transmission of high baud-rate signals on existing networks (similar to transmitting a large file that has been compressed, which requires less bandwidth than transmitting the original file).
The technology enables two types of 400G WDM solutions based on 100 GHz channel spacing — a short-haul solution and the ultra-long-haul solution unveiled at OFC 2014. The ultra-long-haul solution, which applies to backbone transmission, adopts 2SC-PDM-QPSK modulation and supports a record transmission distance of over 3000 km. The short-haul solution, which applies to metropolitan area network (MAN) transmission, adopts 1SC-PDM-16QAM modulation and allows high-quality 400G transmission over a single carrier wave. Huawei's single-carrier 400G solution was recently tested on EXATEL's live network in Poland.
“Huawei has been investing heavily in the high-speed WDM field. The new FTN technology introduced in the prototype exceeds traditional technological limits to deliver ultra-long-haul 400G transmission, breaking new ground for the 400G industry,” said Jack Wang, President of the Huawei transmission network product line.