Broadband

OFCOM have published the results of research into how fast data can be transmitted over a copper local loop.

This is a very theoretical study that asks what might be possible some day, while noting that the standards to achieve that level of performance have not been defined and equipment is certainly not available.

It also looks at the relative merits of having xDSL equipment in the exchange as opposed to in a street cabinet, down a hole or up a pole. The exchange location gives the longest line lengths and hence the slowest speed. Putting equipment into the street greatly reduces line lengths and consequently increases potential speeds. 50 Mbits/s is in theory possible for about 18% of households using equipment in the 5,600 exchanges but this coverage rises to nearly 100% at 50M is equipment were installed in 80,000 street cabinets. The cabinets would then be fed by fibre optic from the exchange, the FTTC (fibre to the cabinet) option.

The idea of installing 80,000 of something rather than 5,600 would repel most telecoms engineers, where the economies of scale rule the roost. They would be more interested in using long range GPON fibre to connect up the whole population from less than a hundred centralised exchanges rather than getting into the management and maintenance of ever more pieces of equipment especially with the issues peculiar to street cabinets like vandalism etc.

A number of options were looked at in the study, including a “mix and match” approach combining equipment in the exchange with equipment in street cabinets. If the longest 25% of lines were fed from street cabinets the number of households able to receive 50M would increase from  17.7 to 41.5% (29% would get 100M). Taking the more usual “cherry picking” approach of feeding the best 25% of lines from street cabinets would only improve the coverage of 50M from 17.7 to 24.7%.

While this is an interesting piece of work it is very theoretical and does not address the practicalities of available hardware to deliver the speeds discussed, nor does it address the economics of the different options or provide a comparison with Fibre to the home (FTTH) which many would regard as a better long term solution than Fibre to the cabinet (FTTC).

Tags: Broadband Fibre, fttc, fttp, OFCOM