The RF geeks are finding ways to utilise the increased processing power of modern DSP chips to now push Gigabit type speeds over short runs of twisted pair telephone cable. G.fast has reached a key milestone with the initial approval of the standard by the ITU and the designation of the name G.9700.
This new standard promises aggregate speeds of 150 Mbps over 250m of telephone wire and much faster speeds on shorter lengths such as 650 Mbps over 50m. This is achieved by using a much wider frequency spectrum than VDSL2 (profile 17a in the UK currently has a maximum frequency of 17 MHz), G.9700 stretches all the way to 212 MHz and the new standard takes into account the requirement to avoid destroying FM radio reception.
For those where full fibre optic connectivity with a fibre into the home is the only real solution this new standard will be seen as a waste of time, but the appeal to the telecoms operator is that you can run fibre to a small unit serving a dozen or so customers from a pole, pavement chamber or even install the kit in the telecoms cupboard of a block of flats. This avoids the need to gain entry to every property and that final run across peoples property, which if old estimates of 7 hours per install from Openreach for FTTP are correct will be welcomed.
It is unlikely that G.9700 will have any impact on the current BDUK projects, as full ratification is not expected until 2014 and there will then be a couple of years before anyone decides to deploy commercially. Thus G.9700 is probably more about extending speeds in a post 2018 broadband landscape.
Tracking down solid information on upstream speeds is proving difficult, but one key aspect is that crosstalk can have a major impact on G.9700 performance meaning we are likely to see the vectored variant if the aim is to get the best possible speeds. Alcatel-Lucent has some useful data on the performance of G.fast/G.9700.