With all of BT’s DSL-based products, there is an initial phase, now completed for FTTC, during which a modem and faceplate filter are included as part of the installation, which must be undertaken by a BT engineer. As of late September 2014, FTTC’s initial phase is over, making it easier for providers like Evolving Networks to simplify the installation process and deploy alternative, better hardware.
The distance from the customer premises to the street cabinet is is vitally important in determining whether or not the line will support FTTC. Unfortunately, BT supplies conflicting information on when they will and won’t supply an FTTC service.
For customers on long lines suffering less than 2mbps on an ADSL service, even an upgrade to 5mbps would be a useful boost. FTTC is often denied to those users, while customers connected to the same cabinet and marginally closer to it are allowed the faster speeds.
VDSL2 was designed to be able to serve long lines, unsuitable for VDSL. In this respect its purpose is essentially to replace ADSL, allowing old ADSL kit to be decommissioned in favour of VDSL2 hardware that can cope with both short and long runs of copper. There are still many areas where customers are not close to their street cabinets, a situation which will not change in the near future.
There are newer technologies, which in the future will be available to further shorten the length of copper wire, without having to build new street cabinets. These technologies will involve new nodes being deployed on poles and in other distribution points. This is discussed further here, when talking about Fibre To The Remote Node (FTTRN) and Fibre To The Distribution Point (FTTdp).
BT’s commercial FTTC roll out has now been completed. Further installations are being performed as part of BDUK, the government project to help plug some of the gaps in delivery, funded by central government and local councils across the country.
Each project is run separately by local projects such as Connecting Cambridgeshire and Superfast North Yorkshire, with individual local authorities having their own targets and installation timeframes.
Most of the money for FTTC has gone to BT as the primary supplier. There are question marks over how the tender process was run, as other major suppliers pulled out, essentially leaving BT as the only credible supplier.
Furthermore, in addition to the BDUK roll outs all having different FTTC coverage targets, determination of the likely bandwidths for each location is often vague, to the extent that it can be unclear whether FTTC will actually deliver any more bandwidth than the minimum 2mbps, itself now seen as the base level for any form of broadband. Timescales also vary and are generally broken into distinct phases, with some areas getting FTTC before others.
There is no central place where all the BDUK information is officially compiled, although increasebroadbandspeed.co.uk has a good list, showing the varying targets and promises.
Determining how fast a service any given FTTC line will deliver has become an unnecessarily complicated process over the last few years.
With ADSL circuits, there is a simple estimate, based on length of the copper pair, giving a figure and an estimated range of possible speeds. When UK deployment began, this was the approach used with FTTC circuits, but more recently, BT have updated their checker to include a staggering eight different values in FTTC line speed predictions.
With lines split into Range A and Range B, and then split again into high and low figures for download and upload, assessing the speed that any new circuit is actually likely to deliver has become difficult indeed. The ranges are determined by the circuit’s predicted loop loss (attenuation) and read from a table of values which matches loss with predicted values. The High and Low figures are actually the 80th and 20th percentile values.
This in itself has important ramifications, because that means 20% of customers are likely to be below the Low value. There is a hidden third value that is even lower, which represents the 10th percentile value for downstream (in both Range A and Range B). This is the figure that BT considers sufficiently low that the customer has the right to terminate their new FTTC circuit within the first 90 days.
The customer could get any speed within a very wide spread. An 80mbps line could be 58% slower before being considered by BT to be too slow. A 30mbps line could be 72% slower. A line more like an ADSL2+ service (which has a top end value of 18mbps) could actually run a whopping 78% slower, at 2.8mbps.
To further compound matters, and the longer the line is, the greater the percentage drop in value from top to bottom will be.
It’s important to note that there is no BT check, either before or after a circuit is installed, as to whether the BT system thinks that a line is either Clean or Impacted. This makes it very difficult to give any level of certainty to potential customers over how their service should perform.
This range is for circuits that are deemed to be free of any copper line faults or wiring issues in the customer’s premises. This range is often very wide for both upload and download, and does beg the question of why a copper line fault may exist without being fixed.
This range is for circuits that may have copper line faults and/or internal wiring issues at the customer’s site. The term Impacted could be useful, as crosstalk is is sometimes mentioned as impacting on line speeds, but there is no official word from BT on whether either Range A or Range B takes into account the effects of crosstalk. You can read more about this here.
The trouble with all of the above ranges is that defining which lines will be Clean and which will be Impacted is impossible. There is no way of determining if a line is subject to crosstalk from neighbouring lines. There is no way of predicting if, in either range, a line will be at the High end, the Low end, or even lower.
BT’s FTTC products are capped, raising the question of how the 80mbps High value can be an 80th percentile figure, when bandwidths higher than this are not available: what are the top 20% getting if they can’t get higher than 80mbps? With the hidden 10th percentile figures taken into account, a line with a predicted top speed of 80mbps as its High Range A value could actually run as slowly as 33.89mbps. If it didn’t run lower than that after its 10 day training period, it would be considered a working circuit, delivering what BT intended.
Because of this, the scope for overly high customer expectations is extensive. Over-hyped marketing of FTTC as a saviour technology, coupled with many customers being more than 500m from their cabinet, is resulting in end users slowly discovering that FTTC is not always all it’s cracked up to be.