Mobile phone companies and regulators face a stark choice in the next few years: double the number of cellsites to 5000, allow existing cellsites to be built higher, or take the radical step of sanctioning a single mobile access network that would be shared by all.
The Telecommunications Industry Group (TIG), whose members include Vodafone and Telecom, told the Treasury that 2500 cellsites would need to be built in a few years' time at a cost of $625 million to support 4G mobile networks, unless height restrictions on existing cellsites were loosened.
The alternative was for mobile network operators to club together to build a single 4G access network using shared radio spectrum. 2degrees chief executive Eric Hertz says that idea should be seriously considered and Telecom is open to the idea in principle. Vodafone is non-committal.
Vodafone, Telecom and 2degrees are expected to start making the switch to 4G mobile technology LTE (Long Term Evolution) in 2013 at a cost of billions of dollars, using radio spectrum in the 700MHz band that will be freed up by the closure of analogue television transmissions.
The TIG says that because of the scale of the construction, telcos might need to start buying suitable sites to erect new cellsites as early as next year.
Delivering 4G nationwide would require significantly more cellsites — potentially between 50 percent and 100 percent more — than today's GSM and 3G networks. But doubling the number of cellsites to 5000 risked a public backlash.
It told the Treasury, which is consulting generally on national infrastructure issues, that one option might be to relax height restrictions on existing cellsites, which would make it easier for operators to share towers.
Because of planning regulations, most cellsites in New Zealand are 15 metres to 20m high, about 10m shorter than those in Europe. The result had been "an unnecessary proliferation of masts".
Antennas need to be vertically separated by a few metres to avoid interference and lower antennas provide limited coverage, making it unattractive for network operators to share short towers. If higher cellsites (25m to 30m) were permitted, LTE networks could be built without significant further site acquisition, it says.
TIG chief executive Rob Spray says no-one wants another 2500 cellsites.
He says a single shared 4G network would reduce the need for more or higher towers. "Maybe we don't need lots of different pieces of spectrum, maybe we need one big piece that everyone shares."
Telecom spokesman Mark Watts says sharing of spectrum and co-location are "all issues to be grappled with, but not right now in any detail".
"Sharing has appeal from a cost viewpoint as the industry may struggle at some point to fund widespread LTE deployment at a price to customers that recoups the investment and which customers are happy with."
Vodafone spokesman Paul Brislen says the company is keen to share towers with other operators, but a common mobile access network using shared spectrum and antennas could have wider ramifications.
"I can well imagine there would be anti-competitive concerns."
2degrees' Hertz says a shared network built by a joint venture might make sense. "If you are competing at the retail level it is often hard to have those discussions, but the reality is as we look at 4G and the difficulty around towers there are a lot of incentives to figure out a way to make it happen.
"The network is not something that you necessarily have to differentiate. You can differentiate based on your services and devices."
Vodafone, Telecom and 2degrees invested more than $1 billion in mobile networks last year alone as they sought to leap-frog one another. The competitive dynamic driving that investment could be reduced if infrastructure was shared.
Spray says once telcos have moved to LTE and are on the same technology platform using similar frequency spectrum, it is likely the market will settle down.
"You will see the builds happen around 2013 and I think you will see those networks in place for a very long time."
LTE will deliver peak download speeds of 100 megabits per second, five times the top performance of Telecom and Vodafone's existing networks.