China Mobile Sends 1.6Tb/s Signal over 960 Km of Standard Fiber
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China Mobile transmitted a real-time 1.6 terabits per second single-wavelength signal over 960 kilometers of standard backbone fiber using a symbol rate of 230 gigabaud, state media reported on November 11, 2026.
The test represents the carrier’s longest single-wavelength 1.6T transmission to date and sets a technical benchmark for long-haul optical links running on legacy G.652.D glass.
Carried out with unnamed equipment partners, the field trial pushed symbol rates to 230 gigabaud to multiply throughput without widening spectral allocations. G.652.D single-mode fiber forms the physical core of most national and international telecommunications grids, yet engineers designed it decades before multi-terabit optical transport existed. Demonstrating that existing fiber paths can sustain 1.6T over nearly 1,000 kilometers indicates network operators can defer costly civil works by upgrading optoelectronics at terminal nodes instead.
Baud Rates Drive Capacity Gains
Baud rate measures the volume of signal transitions transmitted every second. Raising this rate allows a carrier to pack more data into an individual wavelength while leaving the underlying modulation format unchanged.
China Mobile began deploying commercial 400G systems across its all-optical backbone network at scale in 2024, relying primarily on 130 gigabaud transceivers. Subsequent metropolitan trials at 1.2T demonstrated that 130-gigabaud optical engines lacked the reach required for inter-provincial links, prompting the operator’s research division to target symbol rates exceeding 200 gigabaud. Developing the hardware components necessary to reach 230 gigabaud required two years of laboratory and fabrication work.
Backbone Cable Capital Costs
For telecommunications operators and cloud infrastructure providers across the Asia-Pacific region, transmission reach determines capital allocation. Trenched fiber remains the most expensive asset in digital networks, frequently requiring years of municipal approvals and civil construction across diverse terrain.
“Carried out with unnamed equipment partners, the field trial pushed symbol rates to 230 gigabaud to multiply throughput without widening spectral allocations.”
Alternative high-capacity hardware on the international market targets shorter spans. Commercial systems such as Ciena’s WaveLogic 6 Extreme support single-carrier 1.6T using 200 gigabaud, but network builders deploy them primarily across metropolitan routes rather than long-distance trunk lines. Proving 1.6T stability over 960 kilometers of standard fiber shifts optical engineering priorities, proving that high-density artificial intelligence compute clusters can interconnect across regional boundaries without dedicated proprietary cabling.
Missing Data on Vendor Systems
Technical risks persist for carriers attempting to replicate these transmission distances in operational commercial settings. China Mobile conceded that unresolved optical impairments, including non-linear distortions linked to subcarrier processing, demand further investigation before commercial procurement begins.
Significant operating variables remain undisclosed. Test disclosures did not identify participating equipment vendors, operating channel spacing, modulation schemes, forward error correction margins, or the geographic route of the trial. Without published margins, network architects cannot verify how close the 960-kilometer run pushed optical transceivers to forward error correction thresholds.
International Standard Contributions
The trial builds on structured contributions China Mobile made to global telecommunications rule-making bodies over recent quarters. The broader industry considers 1.6T the next standard transport speed above 400G, directing initial specifications toward high-throughput data center interconnects.
During the International Telecommunication Union’s Study Group 15 plenary in July 2026, China Mobile led the formal completion of phase one for G.709.5, an architecture defining 1.6T transport. The state-owned operator has now initiated standardization drafting for G.696.1, which establishes optical-layer system parameters for long-haul backbone spans. Technical data recorded from the 960-kilometer transmission will form the baseline dataset submitted to that study group.
Regulatory delegates and network operators will review the formal G.696.1 optical-layer proposals at upcoming ITU-T standardization sessions as international carrier bodies define final production parameters for global 1.6T systems.
Questions & Answers
Q.Why is achieving 1.6T transmission over legacy G.652.D fiber significant for network operators?
Why is achieving 1.6T transmission over legacy G.652.D fiber significant for network operators?
Most national and international telecom grids rely on legacy G.652.D glass laid decades ago. Proving it can carry 1.6 terabits per second over nearly 1,000 kilometres allows operators to avoid expensive civil works and trenched cabling by upgrading optoelectronics at terminal nodes instead.
Q.What technical hurdles and undisclosed factors prevent immediate commercial deployment?
What technical hurdles and undisclosed factors prevent immediate commercial deployment?
China Mobile must still investigate unresolved optical impairments, including non-linear distortions linked to subcarrier processing, before procurement begins. Crucial operational data also remains undisclosed, including the forward error correction margins, modulation schemes, operating channel spacing, and the identities of participating equipment vendors.
Q.How does this trial contribute to international optical transport standards?
How does this trial contribute to international optical transport standards?
Data from the 960-kilometre trial will serve as the baseline dataset for drafting ITU-T standard G.696.1, which defines optical-layer parameters for long-haul networks. This follows China Mobile leading the completion of phase one for the G.709.5 1.6T transport architecture in July 2026.
Q.Why did China Mobile develop optoelectronics capable of 230 gigabaud?
Why did China Mobile develop optoelectronics capable of 230 gigabaud?
Earlier 1.2T trials showed that existing 130-gigabaud optical engines lacked the reach required for inter-provincial links. Increasing the symbol rate to 230 gigabaud allows the carrier to multiply data capacity on an individual wavelength without widening spectral allocations, securing the range needed for long-haul routes.