BT and Alcatel-Lucent push 1.8 Gbps over a copper pair
G.fast with its headline 300 to 500 Mbps ultrafast vision which has BT planning to reach 10 million premises by 2020 has just had that speed eclipsed by lab work in conjunction with Alcatel-Lucent. Lab trials have now shown 5.6 Gbps pushed across 35 metre of cable, with an aggregate speed of 1.8 Gbps over a more useful 100m of copper telephone line. The catchy name for this new technology is XG.fast and is part of the reason why BT is confident that G.fast will allow them to deliver speeds needed in the next ten to fifteen years.
G.fast is not sitting still reducing power consumption and other tweaks to extend its reach are on going and both Qualcomm and Alcatel-Lucent are talking about higher port densities for G.fast DSLAMs of 32, 48 and 96 ports.
In a technological world new developments like this are always interesting, but it will be some time before XG.fast appears in the average street and in the UK the focus is less about pushing the envelope speed wise but rather about increasing coverage at the more usual superfast type speeds and for those not already getting superfast increased roll-out cannot arrive fast enough. This pressure on roll-out time scales and limited budgets are often what is driving the push to 'sweat the copper'.
Alcatel-Lucent was far from being the only chipset manufacturer delivering kit and showing off working G.fast at Broadband World Forum 2015 but their slides had the most useful detail. The above slide shows where four deployment scenarios with FTTCurb being a new scenario driven by Openreach requirements, to give them increased flexibility. The single port DPU (~FTTH) scenario is not one previously envisaged but reflects some deployments in Hong Kong and France, where single port G.fast kit is used to serve a single flat, why? Because it means a provider can fit the kit without any need to enter each individual apartment which a full FTTH or FTTB with Gigabit Ethernet deployment would require.
While G.fast with improvements and more real world data lead the speed charge outside the labs XG.fast broke the speed records. An interesting new middle ground in the form of Vplus (35b) or VDSL2 Annex Q (what Huawei call it) was discussed which makes use of increased bits per tone, higher power levels and increased bandwidth to 35 MHz with the extra bandwidth going towards downstream speeds could result in speed boosts out to 700m from existing VDSL2 cabinets, the idea being that this could be delivered by line card swaps. No word on adoption by Openreach, but it adds another tool to the technology toolkit.
For those thinking all this xDSL talk means Openreach is abandoning its Gigabit FoD2 FTTP product, it was emphasised in various talks that premium fibre giving Gigabit speeds was a clear part of the G.fast roadmap, the expectation that the SME sector that needs more speed than even G.fast or VDSL2 can provide will opt for this. Alas no commitment to ball park pricing yet, but we keep pestering so hopefully will know as soon as they have some firm figures.