Alcatel-Lucent and BT have announced trial speeds of up to 1.4Tb/s with a record spectral efficiency of 5.7 bits per second per Hertz (b/s/Hz) on an existing core fibre connection. The companies say this is believed to be the fastest speed ever achieved in commercial grade hardware in a real-world environment, and is equivalent to transmitting 44 uncompressed HD films in a single second.
The field trial, conducted over an existing fibre link between the BT Tower in London and BT’s Adastral Park research campus in Suffolk, used a new ‘flexible grid’ infrastructure (Flexgrid) to vary the gaps between transmission channels, usually set at 50 gigahertz (GHz). By increasing the density of channels on the fibre, this approach achieved up to 42.5 per cent greater data transmission efficiency compared to today’s standard networks.
The trial was conducted through the overlaying of an 'alien super channel' comprised of seven 200 gigabits per second (Gb/s) channels bundled together to provide a combined capacity of 1.4Tb/s. Reducing the spectral spacing between the channels from 50GHz to 35GHz using the 400Gb/s Photonic Services Engine (PSE) technology on the 1830 Photonic Service Switch (PSS), meant that spectral efficiency was enhanced by almost 43 per cent. The 1830 PSS can be used as an optical extension shelf of the 7750 Service Router (SR) and the 7950 Extensible Routing System (XRS). The super channel is 'alien' because it operates transparently on top of BT’s existing optical network.
BT says the trial has demonstrated how flexgrid could increase the company’s core network capacity using the existing infrastructure, reducing the expense of laying more fibre.
