Quigley outlines NBN's wireless challenges

Spectrum constraints, inaccurate address data and complaints about towers are the biggest concerns facing NBN Co in rolling out wireless and satellite broadband, CEO Mike Quigley has said.

(Credit: NBN Co)

Last year, NBN Co paid over $120 million for spectrum in the 2.3GHz and 3.4GHz spectrum bands for its fixed-wireless long-term evolution (LTE) network. Earlier this year, it also paid an undisclosed amount for spectrum in the 28GHz band for its satellite service. But despite strong spectrum holdings, Quigley told the Australian Communications and Media Authority's (ACMA) RadComms conference in Melbourne today that it will be a struggle to use all of that spectrum efficiently.

"Spectrum is a scarce resource," he said. "Even with 100MHz of spectrum, we are struggling to maximise the throughputs on that spectrum. Spectral efficiency is increasing all the time, and it has been but it is starting to plateau out."

Nevertheless, Quigley said that NBN Co is dimensioning its network so that all fixed-wireless and satellite users will get exactly the same level of service at 12 megabits per second (Mbps). He said that if customers are getting lower speeds, it is the fault of the retail service provider (RSP).

"We're dimensioning the network, so that we will always be well ahead of whatever our customers are dimensioning [their] bottlenecks, so the end user will not see the limitations of the NBN. They will see the limitations in other parts of the network," he said.

NBN Co has three fixed-wireless sites live across the country for its time-division duplex (TDD) LTE network. Approximately 75 users have been connected so far, 52 tower sites have been approved and construction has commenced at 36 sites. Quigley admitted that local opposition to new towers has been much greater than it has been historically, and is a big issue facing NBN Co.

"These days, it is much more difficult than it was 15 or so years ago to put a tower up. That's an issue you always have to deal with in the 10 per cent. People are worried either being irradiated by the tower, or worried about the visual impact."

NBN Co's TDD-LTE is better suited to the higher-spectrum frequencies that NBN Co has; so far, the network has been deployed in the 2.3GHz spectrum. Quigley said that that the company is hoping to use the 3.4GHz spectrum in the future, but that there aren't many devices being made that utilise the spectrum band at this stage.

NBN Co is working through problems with the accuracy of address data collected by geospatial data company PSMA, with data being inaccurate up to 30 per cent of the time. Quigley said that the company is working with a group known as Biarri, which is made up of industrial mathematicians from the University of Queensland, to solve the problem.

"We saw that the G-NAF [geo-coded national address file] database told us there were 150 [premises], and when we looked at it, it was in the middle of a paddock," he said. "The problem is that you're out here at the tails of the distribution and it is very difficult to model."

Quigley said that Biarri is optimising both the address data and the fibre roll-out to keep the costs as low as possible.

"Trying to do the job of minimising the distances you travel with the fibre, minimising the use of new ducts and pit, and maximising the use of existing ducts, pits and aerial is a huge optimisation job," he said.