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Deutsche tests 1 Gbps G.fast from Adtran – but still no service

US broadband equipment maker Adtran has put out 4 releases showing momentum in G.fast and broadband – and for the first time directly referred to its relationship with Deutsche Telekom.

The statement in itself is somewhat confusing in that it says that Adtran and Deutsche Telekom are testing G.fast innovations including the latest 212Mhz versions of the chips and also coordinated dynamic time allocation (cDTA).

Our information is that it has yet to test these on the same chips, and it has testbeds on both 106 MHz cDTA and separately on new 212 MHz chips, before the end of the year it is likely to get its hands on devices that can do both.

Interestingly Deutsche Telekom holds the answer to the entire broadband market, right now this is a global pivot in the market shares of equipment vendors Adtran and Nokia, but also between chip vendors Broadcom and Sckipio.

Adtran is the incumbent at Deutsche Telekom, having bought the business when Nokia dropped out of DSL based devices when it was Nokia Siemens Networks in 2011, to focus purely on cellular. Since then it has acquired Alcatel, very much present in fixed broadband, and has product line by product line competition for Adtran equipment. The worry for Adtran, flying high on the back of 13.5% revenues growth in Q2, driven mostly by G.fast device shipments, is that if Nokia sold to DT once, it may be able to unhook Adtran’s position there at some future point in time – So far Adtran has been up to the task for keeping it at bay, which is a considerable achievement given that a the same time Huawei is sniffing around for the business – Huawei is now best of friends with Deutsche Telekom in other technologies and also has its own broadband equipment. Also DT is now very late moving to vectored VDSL, and up the scheme from 17 MHz VDSL2 to the 35B spec version which uses twice as much spectrum and on to G.fast.

DT is only currently selling 100 Mbps service from its website, which implies the 17MHz version of VDSL2, and will have to make any G.fast version that it ships, work alongside this version of VDSL2.

Deutsche for its part seems committed to getting as much out of DSL technology as it can, and to do that it wants a supplier relationship which takes in both Broadcom and Sckipio chips, the two market leaders in G.fast. Adtran is the only equipment vendor we know of committed to being agnostic when it comes to broadband chips and uses both – although there are other suppliers coming to market, Realtek for instance has committed to a 212 MHz version of G.fast chips shortly, but so far has only shown a single port device working, which suggests that it has had trouble handling the crosstalk.

Within the DT account Broadcom and Sckipio seem to have approached their R&D from different directions. Sckipio has gone for being the first to add cDTA, while Broadcom is actively pushing a 212 MHz G.fast chip there already. The chip with double the bandwidth is seen as key to offering an aggregate of 1.5 Gbps capacity, usually discussed as 1 Gbps, because that might be its typical download capacity, with about half as much in upload. But that of course depends on how far the distribution point is from the home, and how it organizes Crosstalk cancellation when it is sharing with vectored VDSL2 ports in the same bundle.

The key to cDTA is two-fold. First it uses the fact that G.fast uses Time Division instead of Frequency Division, to allow a different ratio of upstream to downstream. Because this is dynamic, it can be allocated on the fly using policy algorithms to adapt to changing combinations of upstream and downstream traffic.

But fundamentally if one customer wants to upload UHD video all day to the cloud, and everyone else in the street sharing that cross talk capacity, wants to watch UHD Netflix, there are limits to what can be done. Cross talk can only be cancelled in one direction at a time because attenuation means that all signals are far stronger at their source – so the system has a total capacity and it is dynamically shifting which direction this capacity is applied to.

The second issue is that this extends the reach of signals so that more homes are within reach of a published service level by manipulating the dynamic service allocation algorithms. Michael Weissman VP of marketing for Sckipio explained that this was his company’s first target to build cDTA, because it was tough to do, and it made implementing ultra-broadband cheaper for the operator, because of this reach improvement.

DT will have a series of complex decisions in how it uses these technologies, based on what other cross talk has to be cancelled in binders shared with VDSL2, and where that cross talk is cancelled – Adtran takes it off into the cloud and cancels the crosstalk from multiple devices there, while Sckipio pushes the idea that its crosstalk cancellation capability is both inside the chips, and also can scale as binders get larger, using inter-chip communication and that this was designed in from scratch.

It has certainly built the largest Distribution Point up to 24 ports and is likely to go beyond this, possibly this year with its innovative approach to crosstalk cancellation. Broadband without crosstalk cancellation or vectoring is pretty much stuck at 50 Mbps, because unshielded twisted pairs give off signals sideways when they are bundled together and a cancellation signal needs to be sent with data so that it arrives in the right shape at the other end of the line. If this does not happen G.fast and VDSL2 cannot work properly as there is too much noise to contend with.

So far Adtran says that it has shipped some 10 million vectored lines, and Nokia some 30 million, mostly using VDSL2 chips, and it also says it has shipped around 1 million G.fast ports, although we do not know which chips are used in these and who has the lion’s share of the DT business.

It is likely that a clear picture of the DT broadband service will not emerge for 3 or 4 more years, once it has shifted to G.fast completely.

Adtran delivered results for its Q2 of revenue of $184.7 million up from $162.7 million last year with net income of $12.4 million from $10.2 million in 2016. It also announced that it had won another major contract with the National Broadband Network (nbn) of Australia to install GPON and a multi-vendor DPU management system using cloud microservices. Nbn has taken on the role for bringing broadband to all of Australia.

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