The last few days have seen a number of internet service providers announce new broadband services of 20mbps or more. But is it all smoke and mirrors?
Could be. According, at least, to internet analysts, Point Topic who have conducted research on Local Loop Unbundling (LLU) – the opening up of local exchanges to BT competitors.
In what looks like to most lay people like a major setback for new ultra-high speed connections, Point Topic assert that in reality very few customers will be able to enjoy 20Mbps plus broadband.
They base their claims on the fact that the bandwidth DSL technologies can deliver over a telephone line falls off sharply with distance. States Point Topic: “For example, ADSL2+ can deliver its maximum of 24Mb only within 300 metres of the telephone exchange. Bandwidth continues to fall with distance dropping to 8Mb at most by 3000 metres (roughly 10,000 feet).
So far as is known BT has not published the actual numbers for the distribution of its local loop length, but it has provided enough information for Point Topic to reverse-engineer this graph and to create a model which estimates the actual length of each end-user’s line as a function of their linear distance from the telephone exchange. It shows, for example, that only 5% of end users have local loops of 1200 metres or less, 45% have 3km or less, and 85% are within 5km.”
Point Topic has used this model to estimate the “most likely” loop length for homes and businesses in every postcode in the UK. But to find out you will need to subscribe. Using their info, Point Topic say it is possible to estimate data rates for any chosen areas.
Conclude Point Topic: “Despite these uncertainties the conclusion is that ADSL2+ high-speed services will be unavailable to a large percentage of the population unless and until there is some major investment in extending fibre deeper into BT’s access network.”
How much weight can be attached to findings that are “reverse engineered” or extrapolated is open to question. What are undoubted are the laws of physics and the physical limits of copper wire.
