Significant debate has occurred in Australia over the past 2 years regarding the deployment of a Next Generation Network based on Fibre to the Node technology.

In 2003, the Broadband Advisory Group reported that the creation of a ubiquitous “True Broadband Network” would deliver $12-30billion growth in GDP. The definition used for a True Broadband network is one that can deliver a Symmetrical 10Mbps. Why Symmetrical? Because it is the upstream capacity that provides the benefits even our common Internet applications need today. However applications which provide more value to the community that demand the high upstream capabilities include teleworking, video conferencing, eHealth, and Education to mention only a few.

The Myth of FTTN is the belief that it can deliver ubiquitous 12Mbps symmetrical capacity as demanded by the Government in their National Broadband Network policy. Existing FTTN proposals cannot deliver on these Government requirements. Certainly this statement may be seen as contentious but the engineering evidence can certainly back this up.

Today the Annex M extension to ADSL2+ can provide up to 24Mbps in the downstream, but this is significantly dependant on the quality of the copper and distance from the node. However the upstream is limited to a maximum of 3Mbps over short distances, however typical loop lengths see the speed more in the 1.5 – 2Mbps range. Even the new VDSL2 technology – frequently quoted as delivering 100Mbps over copper – cannot deliver symmetrical 12Mbps over the existing copper infrastructure using FTTN.

Previous proposals lodged last year with the former Government where based on the installation of nodes ensuring every home is within a maximum of 1500 metres of Fibre. At this range VDSL2 offers a maximum of 25Mbps downstream and 5Mbps upstream using 24AWG cable. However the current copper deployed within the existing telecommunication network is at best 26AWG and frequently the smaller 28AWG.

We also know there are many bad joints and bridge taps in the aging plant which cause high attenuation, thus reducing the speed even more. These speeds are also based on transmitting at full power. Discussion within the Communication Alliance working group on VDSL2 deployment has suggested lowering transmit power levels at Nodes to lessen the impact of mid-span crosstalk.

The following graph from the DSL forum shows both the downstream and upstream performance of VDSL2. At full power (US 24) using 24AWG cable, VDSL2 can deliver 12Mbps upstream at a maximum distance of 750 metres. Cable based on 26AWG reduces the distance to approximately 600 metres, and 450 metres for 28AWG. These are the best possible distance with minimal attenuation losses caused through bad or corroding joints.

When taking all these issues into account, it will be highly improbable for a FTTN network to meet the 12Mbps Symmetrical speed requirement set by the Government. The only way to get the speeds higher (particularly the upstream) is to push the nodes closer (within 300-500m) to the home and/or to replace the copper. This means more nodes, more cost and more problems (both technical and environmental).

Furthermore while 12Mbps today may be sufficient to meet the immediate demand, the introduction of even a basic application such as IPTV will drive bandwidth demands to greater than 40Mbps. A typical HD television stream is about 14-16Mbps, and if we run multiple channels at the same time (i.e. watch one – record one), we could easily be streaming 25-35Mbps of TV alone.


At 04 April, 2008 16:20 Anonymous said...

like anyone gives a flying f*ck what u wrote

At 04 April, 2008 19:56 Stephen Davies said...

Interesting contribution.

At least I have met with the Minister on several occations and made meaningful contributions to the industry.

What have you provided? Happy to publicly debate the for and against what I have written.

At 04 April, 2008 21:35 Don Gould said...

I wonder if I count as "Any One"?

I do give a "flying f**k". Very useful content.

Cheers Don

At 08 April, 2008 22:22 Scott said...

Sad to see that this "Anonymous" fellow shows up even in blogs down under. I had thought he was only an American pariah.

Keep up the good work, and if you even need a consultant/sycophant to fly down to Australia (or New Zealand) for a few days or weeks, I'd be willing to suffer.

At 12 April, 2008 10:56 Anonymous said...

Who said anything about symmetrical?

Certainly not the government!

I'd say we are talking about aggregate throughput.

At 12 April, 2008 11:21 Anonymous said...

From the media release:
National Broadband Network will deliver minimum download speeds of 12 megabits per second to 98 per cent of Australian homes and businesses.
It will support high quality voice, data and video services including symmetric applications such as high-definition video-conferencing.

It's easy to see where you got the symmetrical 12Mbit/s from, but HD video conf only needs between 1-4Mbit/s symmetrical using modern codecs. That the NBN may be non-symmetrical will not break HD video conf, just as long as it has sufficient bandwidth both ways.

At 13 April, 2008 10:22 Stephen Davies said...

Actually HD Video conferencing - particulary Telepresence requires 10-20Mbps bi-directional.

And yes the government has been saying all along that it is 12Mbps symmetrical, its just not reported by the press that way.

I have meet with the Minister on several occations, before and after the election.

It is most certainly 12Mbps symmetrical. To be specific the way he discribed it was a little different.

He said it had to be a minimum of 12Mbps downstream, and 12Mbps upstream. However he was happy to see 25Mbps downstream and 12Mbps upstream. So its 12Mbps symmetrical as a base line, but after that it does not need to be symmetrical unless the application dictate that.

At 16 April, 2008 00:23 Anonymous said...

as long as my internet is better than it is now, and I can get a plan 10GB+ capped for at least 12mbps for under $40 id be happy. :D

At 11 September, 2009 13:57 Justin said...

When are we gonna start behaving more like the USA and have our internet plans ALL UNLIMITED and only be priced based on the speeds u choose.
Much, much more sense in that.


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