Telstra is investigating the viability of using its remaining 2G mobile spectrum stocks to deploy the second phase of its 4G mobile network.
The telco has sought to begin conversations with global chip makers, manufacturers and other carriers in the Asia Pacific to raise support for building devices that support Long Term Evolution technology over the 900 MHz frequency.
The telco became the first Australian carrier to launch an LTE network in September last year, using 1800 MHz spectrum it had ‘refarmed’ or repurposed from 2G services.
Rival carriers Optus and Vodafone plan to use equivalent 1800 MHz holdings to do the same sometime this year.
All three carriers are anticipating the forthcoming sell-off of digital television spectrum later this year to provide a second and more popular frequency range to roll out future LTE networks, allowing for greater device choice and coverage.
But Telstra director networks and access technologies Mike Wright told iTnews the telco is planning to use whatever spectrum it can to roll out future mobile technologies.
“When we look at spectrum holistically we just cannot see that at some point in the future we won’t want to use every bit of spectrum available to us,” he said.
“It’s not necessarily a critical time frame; we think it will eventually get there anyway. What we’re trying to do is move it along a bit.”
The carrier has not made a firm decision on using the 900 MHz spectrum for an LTE Advanced network - an upgrade on current LTE technologies - but Wright said investigations into the spectrum and required technology made sure that “technically, it’s very viable”.
The telco has been a first-mover in several mobile technologies globally, including rolling out HSPA+ and dual carrier HSPA technologies to provide theoretical speeds of up to 42 Mbps over its current 3G network.
Despite the recent LTE rollout, Wright confirmed the company is still contemplating whether to further boost its 3G network with upgraded dual carrier HSPA technology, which provides theoretical downlink speeds of 84 Mbps using the same MIMO technology that underpins the LTE standard.
Each step along the roadmap provides a little bit more capacity on what is increasingly becoming a struggling network as Telstra introduces more and more customers.
Challenges of 900 MHz
Plans to use the 900 MHz band for LTE technology - or any other technology yet to face global demand - are hampered by current poor take-up internationally by other carriers and interest from rival parties, resulting in a shortage of compatible devices, baseband chips and mobile base stations equipment required to make it possible.
Like the 1800 MHz spectrum before it, Telstra’s plans for the stocks are ahead of worldwide demand, which have in recent years focused on equivalent 700 MHz and 2.5 GHz digital dividend spectrum and potentially using the 2.6 GHz band as a globally harmonised roaming band.
Locally, Vodafone and Optus have used much of their respective 900 MHz stocks for 3G technology, further decreasing demand for devices and compatible equipment in the LTE space at least in the medium term.
The Australian Communications and Media Authority is concurrently investigating a potential replan of the 900 MHz band, reallocating unused parts of the spectrum for future mobile networks. It does not expect to make a decision on the spectrum until 2014.
Wright said the telco hoped to raise the same awareness and support for LTE use in the 900 MHz frequency band as it did with 1800 MHz.
“It’s a classic case of just starting that discussion and getting the ecosystem going where you look to go to probably what would be the most efficient re-use of the spectrum,” he said.
“It’s certainly not going to happen this year. We really need to keep working with the industry, see what type of scale we could get behind it and see if we can take advantage of the technology roadmap.”
Read on for Telstra's plans to win regional support for 900 MHz LTE - and for an indication of when it might switch off the 2G network.
Telstra’s spectrum plans hinge on support from carriers in surrounding countries to build the demand necessary for global device and chip manufacturers to support the frequency over LTE technology.
But Wright said an inconsistency in the way carriers speak about and label spectrum had caused headaches for a standardised ecosystem.
The problem is most apparent in the way carriers talk about the ‘digital dividend’; the refarming of spectrum once used for analogue television to new mobile services.
While the Australian Government is selling off primarily spectrum in the 700 MHz band, using the same name in the US actually refers to quite distinct frequencies while European carriers have referred to similar frequencies as the 800 MHz band.
The inconsistency in frequencies used globally has led to device fragmentation, most recently requiring Apple to launch two distinct versions of the third generation iPad to serve US carriers, without supporting capable LTE networks outside North America.
“As an industry the challenge that we really need to be looking at is how we create an Asia Pacific demand for digital dividend which would then lead to scale, volume and manufacturers wanting to build a device for that handset that supported that frequency,” Wright said.
“We all need to work on the critical timing when there’s enough scale and mass to see enough demand that the handset makers can produce these devices and know that they’ll see enough of them.”
Though Telstra’s 900 MHz plan would eat into what remains of the spectrum it uses for a 2G network, Wright said he could not predict the end of GSM just yet.
The network still services 15 percent of Telstra’s mobile customers.
“We wouldn’t necessarily need to refarm all of [the 900 MHz spectrum],“ he said.
“When you’ve got a low-traffic volume you can compress traffic up into other bits of spectrum.”
Much of Telstra's LTE rollout so far has focused on capital cities and regional centres.
Like the company’s fastest portions of the 3G network - which cover only 60 percent of the Australian population - it remains unclear whether LTE would provide significant national coverage in the near-time future.
While Telstra switched off its CDMA network just two years after the launch of Next G, Wright said it would be “very hard to predict” a similar demise for the 2G technology.
“We’re not at this stage advocating absolutely turning off 2G,” he said.
“I think it’s a very long term outcome but I don’t think we need to worry about that at this stage.”