China Mobile Sends 1.6 Terabits on One Wavelength Over 960 km
China Mobile has run a single wavelength carrying 1.6 terabits per second across 960 kilometres of ordinary G.652.D backbone fibre, its longest result at that rate, using a symbol rate of 230 gigabaud.
The trial, reported by Xinhua, is the operator's own claim to the industry's first long haul 1.6 terabit verification at that baud rate, and its partners on the test were not named.
And the numbers matter because of what they leave out. A higher baud rate packs more bits into the same slice of spectrum, so the jump from the 130 gigabaud used for China Mobile's 400 gigabit rollout in 2024 to 230 gigabaud is the whole point, and IT Home reports the increase took two years to achieve.
The fibre is the second half of the story. G.652.D is the most widely deployed single mode fibre in backbone networks and was never designed for these speeds, so a working long haul link over it suggests operators could upgrade equipment rather than dig up and replace cable.
That is a different proposition from the commercial record. Ciena's WaveLogic 6 Extreme offers single carrier 1.6 terabit at 200 gigabaud, aimed mainly at metro distances, so China Mobile's claim is about reaching 960 kilometres on standard fibre rather than about being first to the rate.
And the standards work is where the result is headed. At an ITU-T study group plenary earlier this year China Mobile led completion of the first phase of G.709.5, a core standard for 1.6 terabit transmission, and it has begun G.696.1 for optical layer systems on long haul links, which the 960 kilometre test is meant to feed.
But the disclosure is thin in ways that matter to engineers. The reports named no equipment vendors and gave no modulation format, channel spacing, margin figures or test route, and the operator acknowledged that new impairments introduced by techniques such as subcarriers still need study.
The context is that 1.6 terabit is the next rate step after 400 gigabit, agreed in standards bodies and driven mostly by links between data centres, so a long haul demonstration on legacy fibre widens the cases where the rate can be used.
So the result is a useful marker in a standards race rather than a product announcement, and the figure to watch is whether the same 960 kilometre link holds up when the modulation and margins are published.
China Mobile sent 1.6 terabits per second on one wavelength over 960 kilometres
The link used standard G.652.D fibre at 230 gigabaud
The operator calls it the industry's first long haul test at that baud rate
Vendors, modulation format and margins were not disclosed
The results will feed a draft ITU-T standard for 1.6 terabit long haul systems
Source: Pandaily
