Nokia Bell Labs claims to have delivered a “world first” by demonstrating a prototype of their new XG-CABLE technology, which can achieve full duplex speeds of 10Gbps upstream and downstream simultaneously on Hybrid Fibre Coax (HFC) cable operators like Virgin Media in the United Kingdom.
At present the existing Data Over Cable Service Interface Specification (DOCSIS3 / EuroDOCSIS) standard for cable networks can deliver download speeds of several hundred Megabits per second, although upload speeds are often significantly slower. For example, Virgin Media’s current top speed via the technology is 300Mbps and its uploads are only 15Mbps (a rise to 30Mbps may be coming).
CableLabs has also developed the new DOCSIS 3.1 standard, which in theory could deliver peak speeds of 10Gbps (Gigabits per second) by boosting the amount of radio spectrum available to it and making better use of Orthogonal Frequency Division Multiplexing (OFDM). But this technology is still fundamentally asymmetric and thus upload speeds remain limited to around 1Gbps.
Since then a lot of work has been going on behind the scenes and in February 2016 CableLabs claimed to have achieved a breakthrough, which they said “proves the viability of full duplex communication” (here). Now Nokia’s new XG-CABLE proof of concept technology has taken this a big step further by demonstrating (lab test) a working symmetric 10Gbps network via a DOCSIS 3.1 compatible network.
Federico Guillén, Nokia’s President of Fixed Networks, said:
“The XG-CABLE proof of concept is a great example of our ongoing effort and commitment to provide the cable industry with the latest innovations and technology needed to effectively address the growing demand for gigabit services.
The [demo shows] that providing 10 Gbps symmetrical services over HFC networks is a real possibility for operators; it is an important achievement that will define the future capabilities and ultra-broadband services cable providers are able to deliver.”
The demo network itself made use of traditional copper coaxial cable, albeit via a point-to-point topology and using 1.2GHz of spectrum. However the key ingredient was Nokia’s new echo cancelling technologies, which helped to iron out much of the usual interference.
The Two XG-CABLE Test Scenarios
* Leveraging a point-to-point 100 metre coaxial drop cable, XG-CABLE was able to deliver 10 Gbps symmetric data speeds with 1.2 Ghz of spectrum.
* Using HFC network topologies that utilize a Fiber-to-the-Last-Amplifier (point-to-multipoint coax drop) approach, XG-CABLE was able to deliver 7.5 Gbps of symmetrical data speeds.
The downside is that such speeds were only achievable over the last 200 meters or less from an operator’s distribution point (e.g. local cabinet), which is the reality when using metal coax cable instead of a pure fibre optic line. Adopting reduced speeds might however be able to reach further into the network and cover more premises.
Mind you most European operators won’t be offering such speeds for a fair few years and will instead increase their DOCSIS 3.1 performance gradually. Likewise consumers won’t actually need Gigabit speeds for a little while, unless the ISP marketing departments decide otherwise and networks allow. Not forgetting that vanilla DOCSIS 3.1 with its 1Gbps upstream is hardly poor.
As it stands Liberty Global, which owns Virgin Media, intends to start rolling out DOCSIS 3.1 by the end of 2016 and it’s nice to know that full duplex upgrades like XG-CABLE are being prepared for when the day comes that a Gigabit of speed is finally the new normal.