Postcard from NBN

Here in Australia we're part way through rollout of the next generation broadband network. It sounds great, and I can hardly wait to get access to the speed that the new network will bring.

Or will it?

A previous government designed a network that delivered a fibre-optic strand to each building in Australia. It was an expensive project, but it would give up to 100 Mbs for anyone who wanted or needed it, with the ability to upgrade the speed in the future. A change of government also changed the network design for something considerably cheaper. The trouble is, in spite of what the politicians claim, it's also less capable.

The current design uses fibre from the exchange to a box at the end of the street, and copper from there to the house. It's cheaper because most buildings already have the copper bit in place, and have had for years. The problem comes in two parts.

Firstly, a lot of the copper is old and has degraded over time. This reduces the maximum speed that's going to be available. It's something that a number of people in Australia have to put up with now when they have ADSL, and it seems bad that with a new, better and supposedly faster network, that might not change.

The second issue also relates to speed. Optical fibres can support high speed, but because they use light, there's no interference between two adjacent fibres. That's not the case with copper. Physics says that modulating copper to produce high speed data also makes the wiring act as a radio antenna. That's not a problem if it's a single wire, but when you take a dozen or more and bundle them together, as they are under the street, you get massive interference.

The obvious answer is shield each pair between the box at the end of the street to the house, but that's expensive, and would need every piece of copper in the country to be relaid. If your design specifies that, you might as well go back to the previous idea of an all-fibre network. But that's politically unacceptable.

There are other, technology based solutions that are being looked at, but in the meantime, our wonderful new high speed network will be restricted to providing ADSL 2+ speeds at the most. That's 24 Mbs, way better than I have now, but nothing like the promised 100 Mbs.

For me, the real restriction is upstream speed which will be limited to 1 Mbs rather than the maximum of 40 Mbs a fibre network would provide.

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