Cutting the fibre short: Alcatel-Lucent demos Gig DSL
This is Alcatel-Lucent putting a ‘keep watching this space’ stamp on its copper-extending activities in DSL as it repositions itself firmly in the IP and broadband access market.
It claims it’s worked with Austria Telekom on a trial of Bell Labs copper turbo-charging technologies to help extend the useful life of the copper network. The trials have shown that it’s possible to wring over 1 Gbit/s out of good quality copper over very short distances (70 metres). Ropey unshielded copper, prone to crosstalk, was still able to be cranked up to 500 Mbit/s by applying both Bell Labs wideband G.fast technology and vectoring over 100 metres.
Alcatel-Lucent claims that, “in many real-world applications, such as fiber-to-the-building, the copper lines serving neighboring homes are packed closely together: this results in crosstalk interference between lines, which significantly reduces the potential speed of data transmission. G.fast vectoring removes this crosstalk, stabilises the transmission quality and enables the technology to perform to its full potential.”
This approach is being pushed as a low-fibre alternative to digging or stringing fibre into each premises (especially residential premises). Fibre can be taken as far as the local node and then existing copper used for the final drop, putting off the evil day, it’s claimed, when a huge and expensive fibre upgrade will be necessary.
Alcatel-Lucent explains the recent trial thus:The trial, conducted with Austria Telekom and using a Bell Labs prototype, first tested G.fast over a single, good quality cable, achieving a maximum speed of 1.1 Gbps over 70 meters and 800 Mbps over 100 meters.On older unshielded cables, typical of most in-building cabling in Austria, the trial achieved speeds of 500 Mbps over 100 meters on a single line. However, when a second line was introduced, creating crosstalk between the two, the G.fast speed fell to only 60 Mbps.Vectoring was then enabled, removing the crosstalk and bringing the speed back up to 500 Mbps over 100m. This is a huge improvement over widely deployed DSL networks, which typically offer speeds of 5-30 Mbps, or VDSL2 vectoring networks supporting up to 100 Mbps. Fiber-to-the-home services typically range from 100 Mbps to 1 Gbps.
Alcatel-Lucent says it will be a few years before it has deployable G.fast/vectoring products available.