Fibre to the home will be the only way to deliver high end applications such as complete remote computing and full 3D virtual collaboration in Australia, according to NBN Co cheif, Mike Quigley.
Speaking at the ealising Our Broadband Future forum in Sydney, Quigley quashed suggestions that an NBN should include or consist of large segments of wireless broadband.
“While wireless is currently enjoying high growth rates it has inherent limitations compared to fibre,” he said. “It is simply very difficult to overcome the limits imposed by physics. Spectrum is a scare resource and there is just so much you can do to increase spectral efficiency using better modulation techniques and coding schemes.”
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Despite this, real increases in speeds and download capacities of wireless had been seen in the last decade, largely due to the increasing number of cell sites and the shrinking of cell sizes, Quigley said.
“So why can’t we continue to increase the number of cell sites and decrease the size of cells? We still have to haul traffic out of the cell sites and for that we need fibre,” he said. “As traffic demand increases we can decrease the size of fibre connected cells so we end up with a very large number of cells, each serving a small number of premises. But is that likely to be a cheaper option than fibre to the premise? I don’t think so.”
It was also important to remember that wireless was a shared medium, so contention had to be factored into the access traffic calculations, Quigley said.
“Peak speeds may be high and equal to fibre currently, but average speeds are dramatically lower,” he said. “It’s also the case that users at the edge of a cell experience a far lower grade of service than those at the centre.”
Quigley said a user at the centre of a cell in next generation wireless may experience speeds of 150 megabits per second, but at the cell edge the peak may be closer to 10 or 20 megabits per second. Speeds further decreased when multiple users were access connectivity within the cell.
“Despite of these limitations there is a place for wireless in the NBN world. One would be foolish to think otherwise,” he said. “One would be equally foolish to the think that wireless will solve all our traffic needs, particularly as high definition video and other high capacity remote applications proliferate.”
Citing Cisco figures, Quigley added that while global wireline IP traffic was expected to grow to about 55 exabytes a month by 2013, mobile IP data was only forecast to grow to about two exabytes by 2013.
In contrast, current global wireline IP traffic is about 15 exabytes per month against less than one exabyte for wireless.