Telstra's 4G LTE mobile network turned on today: plus, its 4G strategy explained

Demand for mobile data continues to explode, with the latest Cisco Visual Networking Index forecasting that by 2015 there will be two devices connected to IP networks for every person on earth. Overall mobile traffic will grow 26 times between 2010 and 2015, with Asia Pacific internet traffic growing at 35 per cent annually to reach 24 exabytes per month.

That's a whole lot of data, and carriers are investing heavily in equipment upgrades and network expansions to keep up. Up to 50 LTE (Long Term Evolution) networks are expected to be live by the end of next year, with over 50 other operators in 41 countries committed to roll out the technology.

While VHA and Optus bulk out their existing 3G networks, Telstra turned on its fourth-generation LTE services in May and recently launched them into the Sydney, Melbourne and Brisbane markets. Today it announced the first mass consumer rollout of the technology in Australia after trialling and a commercial pilot for business customers.


Telstra claims customers using its USB 4G mobile broadband modem in 4G coverage areas will enjoy "typical download speeds ranging from 2Mbps to 40Mbps – up to ten times faster than 3G speeds currently claimed by other Australian telecommunications companies." Upload speeds are said to range between 1Mbps and 10Mbps. The modem is available on a range of consumer and business plans.

In Australia, Telstra faces challenges both from dense city populations, and the need to cover massive areas with relatively long-distance mobile cells in rural areas.

APC covered the mechanics of LTE in our August 2010 issue, but we'll say here that the standard uses a number of techniques to densely encode and pack information into a range of frequency bands of different widths. It has a 'flatter' architecture that reduces latency and complexity, and its spectral efficiency is higher than that of 3G services: its encoding schemes allow it to cram more information than 3G in the same space.

These characteristics explain Telstra's push to use LTE to keep up with surging subscriber numbers and increasing data demands. "This rollout is largely about maintaining the user experience and capacity on our network," says Mike Wright, Telstra's executive director of networks. "The objective is to make sure we have sufficient spectrum and capacity to deal with the dense areas of the network where demands are highest."

The 1,800MHz question

Although Telstra will lead Australia's mobile market into LTE, it has made some technical accommodations that make its service different than most. Foremost among these is the carrier's decision to roll out its initial LTE services within the 1,800MHz radiospectrum band.

The significance of that band can be understood in considering that 2G and 3G mobile services have traditionally been rolled out in a number of common bands – each of which is a particular range of transmission frequencies that carriers buy licences to access.

Second-generation mobiles can operate in 14 different frequency bands, but carriers typically support the 850MHz, 900MHz, 1,800MHz and 1,900MHz ranges. Third-generation services variously run in the 850MHz, 900MHz, 1,500MHz, 1,700MHz, 1,800MHz, 1,900MHz, 2,100MHz and 2,600MHz bands – with Telstra's Next-G network sitting in the 850MHz band and the 900MHz, 1,800MHz and 2,100MHz also commonly used by Australian carriers.

As a rule of thumb, the higher the frequency a signal travels at, the more data it can carry – but the shorter the distance the signal can go before it is attenuated so much that it's unusable. Lower-frequency signals can travel longer distances and better penetrate obstacles such as buildings, which partly explains why Telstra's Next-G network is held to have better coverage and performance than its 900MHz rivals.


Given the importance of good coverage and a strong signal, 4G mobile operators are clamouring for access to the lower-frequency 700MHz band, which has been occupied by analogue TV signals for decades and will be freed up when the transition to digital TV is complete on the last day of 2013.

Planned auctions of this 'digital dividend' spectrum will no doubt fetch a pretty penny, with carriers desperate to access the spectrum to keep up with growing device numbers that regularly cause coverage issues in areas where many people gather. If you've tried to ring friends at a concert or footy game, you know exactly how increasing density can affect signal quality.

This is why Telstra has its eyes on the 1,800MHz band: it can get the first-mover advantage by rolling out LTE in that band now, then add on 700MHz services later once the digital dividend is freed up. At that point, the company will be able to build a dual-mode network that combines 1,800MHz LTE's high speed and call density in metropolitan areas with the longer reach and more reliable coverage of 700MHz services in both metropolitan and rural areas.

Distance vs time

Given Australia's unique geographical challenges, Telstra has been doing a considerable amount of work figuring out how to best configure its LTE network to suit our population and geography. Last year, a widely publicised field test saw Nokia Siemens Networks engineers successfully tweak LTE to push data at 100Mbps from Victoria's Mount Hope to Mount Burrumboot, 75km away.

As in Bredbandskollen's Stockholm testing, the test used 20MHz of spectrum, running in an experimental 2.6GHz spectrum. Average downloads sat at around 88.1Mbps and average uploads ran at 29.6Mbps – providing great hope that Telstra can use LTE to provide blanket coverage and good speeds over great distances.

One of the technically appealing aspects of LTE is that it offers great flexibility in its configuration, says Kursten Leins, general manager of strategic marketing with Ericsson, whose equipment powers Next-G and has been working with Telstra on LTE. For example, handshaking timing can be adjusted so the base station waits long enough for the signal to reach a faraway handset, then respond.

"Radio planning is a bit of a black art," says Leins. "You have to take into account a lot of different factors, but you can tune the network for particular characteristics. The [Mount Hope] trials aren't something you would build with the 1,800MHz network today, but were more about pushing the network to see what it could do. When the digital dividend becomes available, you would expect much larger cell sizes outside urban areas."

Telstra is in a good position to execute on this strategy, because it already owns the 1,800MHz spectrum for its 2G services – which are these days predominantly used as a fallback mechanism when 3G services are inaccessible. With 2G usage steadily dropping over time, Telstra has loads of spare capacity in its licensed 1,800MHz band – and plans to fill it with LTE data sessions.

There is a catch to Telstra's strategy, however: with most carriers holding out until the 700MHz spectrum is freed, Telstra could be getting ahead of itself. Most smartphone makers don't currently make 4G handsets capable of running on 1,800MHz spectrum, which means that for now the LTE network will only be relevant for mobile broadband users employing the Telstra USB dongle.

However, today Telstra (with HTC) also took the opportunity to announce the 'HTC 4G', which will be the first smartphone to work on the network and is due for release in early 2012.  

In the long term, Telstra is positioning LTE as a natural complement to its 3G Next-G network: if you're in a 4G coverage area, your handset will use it. Ditto 3G. And if you travel between coverage areas, Telstra is working to deliver automatic handover so your session isn't disconnected.

Getting there, however, will require hard work and patience on Telstra's part. The company is already advancing its efforts, having founded an 1,800MHz LTE special interest group at the beginning of the year and promoting its 700MHz/1,800MHz dual strategy to vendors that it would like to see making compatible handsets.

"We're optimistic that we'll see handsets within the 12 month timeframe," Wright says. "The US market has moved very aggressively into LTE. While it usually takes a little while for the industry to adopt newer technologies, we're trying [through the forum] to speed that up."

This story is an edited extract from APC's October 2011 issue on sale now in print and digital (iPhone and iPad) editions.