The G.fast technology, which boosts data speeds over existing copper lines, was hailed as a cost-effective alternative to fiber for broadband access and also for backhaul and fronthaul. But the system may have missed its window of opportunity, especially in Europe, because of the rapid rise of more affordable fiber options including better access to dark fiber.
The main problem, according to one of the largest G.fast chip suppliers, Sckipio, is that regulators are hostile. The Israeli firm admitted last week that it was “worried” about the European market. It launched upgrades to its G.fast products, but these developments will take a year to be in commercial roll-outs, and in the meantime, the technology may be further pressurized by European regulators’ pro-fiber stance.
A year ago, Tony Shortall, a director of consulting group Telage, said the European Commission’s new regulatory framework was driving operators to a lower range of technologies for high speed data, heavily oriented to fiber. Current G.fast technologies would not measure up to regulatory requirements over long distances and will take a year or more to catch up – though there may still be a role in small cell backhaul and last meter access.
This will be bad news for the UK’s BT, one of the most enthusiastic G.fast supporters, which is targeting a cabinet-based roll-out of the technology to complement its fiber-to-the-cabinet deployment and to deliver 330Mbps speeds to 10m premises by the end of 2020. It has also trialled G.fast as a backhaul and fronthaul technology. SO far, though, progress has been slow – the new target is to cover 1m premises by the end of this year, three years on from the first G.fast trials.
This is partly because BT, and others, are currently restricted to first generation G.fast technologies(based on Amendment 1 and Amendment 2 of the G.fast standard, which limit the number of ports in a distribution point unit (DPU) to 16 – second generation systems will boost this to 48 or 96-port cabinets, and will also double the frequency range to 212 MHz, and enhance vectoring, which eliminates crosstalk interference.
Last week, Sckipio unveiled iits first Amendment 3 chip but the resulting 96-port DPU is unlikely to appear in commercial products until next autumn. “Amendment 3 is at least a year away. It is not certified or interoperable and there is a lot that has to be done to make products ready,” said the company in an interview with LightReading. “For sure there are global markets that require the speed of 212MHz and for sure those customers are waiting.”
In the race to second generation G.fast, Sckipio has been in a race against Broadcom for mind share and market share. Both firms now have second generation chips.
The Sckipio solution is a three-chip system called the 23000 and claims features which will differentiate itself from Broadcom. It is vital that Sckipio maintains its lead over the larger chip firm, because despite an investment by Intel, it does not have the brand and long term relationships that Broadcom can muster. It needs the technical edge.
But that’s what makes this fight interesting, and Sckipio has once again leapfrogged Broadcom, coming up with bonding off the bat, so that two pairs of twisted pair can be used for one service at roughly 3Gbps PHY rate with distributed vectoring – meaning that as long as the vectoring boards on each DPU can talk directly to one another, they can cancel cross talk from all lines in any single binder, up to 96 ports.
The 96 ports have been a target for quite a while (BT is believed to have mandated it). What Sckipio has launched is a 48-port device DPU, made up of two 24-port systems, which can be connected together to support 96 ports. Sckipio makes the point that reverse power feeding cannot work with one customer powering 96 or 48 lines, so claims this as a bit of a strategic win, whereby they have reverse power feeding on 24 lines, and then have four of these talk to one another. Doing it with a single crosstalk cancellation server makes that harder to do, and so it usually offloads the cancellation to another single device (which will likely add to the expense).
Sckipio is widely rumored to have all or part of a contract with AT&T, which is known to be connecting its fiber directly to the coax which DirecTV customers in multiple dwelling units (MDUs) use to receive the TV service. This means it has to get its fiber up the side of buildings to the roof above apartments, but not to the basement.
Recently the Broadband Forum did device certification on products from Adtran, Exfo and Viavi, to go with those from Arris, Calix, Huawei, Metanoia, Nokia and Technicolor, which had already passed certification. The chips are all from either Broadcom, Metanoia or Sckipio.
Michael Weissman, VP of marketing for Sckipio, told analysts at Wireless Watch’s sister service, Faultine: “Cross-DPU vectoring, needs a superhighway to talk to one another on, but it allows you to start small, get systems to pay for themselves before growing as your revenue grows. You can start with a 16-node installation then install another alongside it and plug the two together.”
The other feature with which Sckipio has been tantalizing telcos is cDTA (Collective Dynamic Time Assignment). This exploits G.fast’s use of TDD (rather than symmetrical FDD) to allow a variable ratio of upstream to downstream. Because this is dynamically switchable, it can be allocated on the fly using policy algorithms to adapt to changing combinations of upstream and downstream traffic. This can mean that operators can reach longer distances by allocating more or all of the capacity at any point in time, in one direction to pass a service level test.
The ability to bond was used in the previous generation of AT&T’s broadband, using ADSL2+ bonding back in the 2007 timeframe, and in many instances it is already configured to work with two twisted pairs. Bonding will also likely mean that 1 Gbps can be introduced further away from the DPU as well. Broadcom’s move.