Tuesday 16 July 2013

NBN: Numbers Turnbull doesn't want you to see

These are two graphs (from Ericsson and Sandvine) that are inconvenient for Turnbull and the Coalition NBN Plan.

What speeds will the majority of VDSL2 users get under the Turnbull Plan? Close to 25Mbps.

What will the average cost of Download traffic be for the majority of consumers? Under 20% of the "average" figure quoted by Turnbull. High-end users account for 90-95% of Broadband traffic, they subsidise the majority.

While "50Mbps at 500m" might be true, only 40% of people in an 800m reach will get this. Half the people are outside 560m, from simple geometry. From this graph, 60% of people could only get 25-35Mbps. Crosstalk, near-end and far-end, is a major issue with DSL technologies. The very expensive "vectoring" technology Turnbull wants to install later attempts directly to reduce crosstalk. But it will only work over short distances. Again, the majority of consumers will get no benefit.

Crosstalk probably accounts for the lower speed, 30-35Mbps, at 500m of these measurements, vs the 50Mbps claimed by Turnbull. Perhaps the technology has improved since 2006, but the underlying Physics cannot be changed: you must sacrifice distance for speed and the trade-off is diabolical.

The Ericsson graph, from 2006, doesn't include the 30Mhz carrier that BT is using for "Openreach". Higher carrier frequencies do allow higher bitrates, but fall-off much more rapidly. That's why the 2.2Mhz of ADSL2 and 1.1Mhz of ADSL1 still provide the best long-distance performance. The current median distance from Exhanges is around 3500m - completely outside the range of VDSL2, which is why at least 68,000 nodes are needed. But that could be as high as 300,000 for 9M services, another "inconvenient" fact for Turnbull.

The Sandvine traffic distribution data gives the lie to Turnbull using ARPU, Average (Mean) Revenue Per User, figures. Half all users consume just 6.4% of total Download volume. The top 1% consume 1.5 times that, 10%. That's a ratio of 75 times, 7500%, between the highest users and the majority of users.  Averaging those figures is as absurd as averaging Sydney house prices or including super-rich income with ordinary wages. [Murdoch, Packer, Palmer and Gina Rinehart don't earn a wage, their income mostly stays within their companies and the little that is distributed will be "tax-effective" transfers.]

Almost 95% of all Download traffic, and traffic equals revenue, comes from the upper-half of consumers. They pay the majority of charges. This is the perfect "Robin Hood" scenario: the Wealthy subsidise the Majority, not the other way around.

Even the usual best measure, median, doesn't reflect the situation well. Download volumes for this chart are a mean of 38Gb/mth and a median of 16Gb/mth, but the average use for the majority of users will be just 4.8Gb/mth.

The current NBN isn't just a good deal for the majority of Australian Internet users, it is exceptional.

4th-order decay in Bandwidth vs Distance for VDSL2

Highly Skewed Internet traffic/demand distribution, Note non-linear X-Axis.

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