Telstra's announcement this week that it will roll out a new long term evolution (LTE) mobile network has put LTE firmly back in the headlines. But just what is an LTE network, can it really be described as a 4G network, and why should you care?
Just how many Gs do I need?
Confusion frequently emerges when talking about mobile networks because the same terms get used in two entirely different contexts: engineering and marketing. Telecommunications engineers generally describe networks with lengthy (and sometimes arcane) labels, and will invariably refer to the wavelength of the spectrum used (measured in MHz). While phone and mobile broadband users don't need to worry about exactly how a given network works, they do need to know that their chosen device can handle that particular spectrum. (Mobile network providers have to buy the rights to specific frequencies, which is often an expensive business and a lucrative source of revenue for governments.)
When it comes to marketing those services, telecommunications providers will sometimes use similar labels, but will talk in generic terms about speed and coverage and blur the distinctions between different types of mobile networks. For example, we're used to talking about "3G networks" to describe the currently available services in Australia, but in fact this covers at least four distinct networks:
- The 2100MHz UMTS 3G network built by Telstra in co-operation with 3, which is due to shut down entirely in 2012;
- The now-closed regional CDMA-based network built by Telstra (sometimes derisively referred to as 2.5G)
- The 850MHz UMTS/HSPA network used by Telstra to replace both those options and marketed as Next G;
- The 900/2100MHz UMTS/HSPA-based networks used by Optus and Vodafone.
Older mobile networks based on GPRS and EDGE, which only offered relatively minimal data speeds, are often referred to as 2G (second generation) for contrast, but that label wasn't often used before we all started talking about 3G. (I'm not going to explain those standards in any detail because while they're still in use, especially outside capital cities, they're very much a worst-case alternative these days.)
We're seeing a similar experience with 4G networks: the label is being used to describe any mobile communications service which is faster than current options, whether or not it has anything in common with the systems that went before them. The current services offered by Vividwireless in some capitals, for instance, use WiMAX, which is a standard that's completely unrelated to the existing mobile phone standards used by most carriers. However, they're often promoted as "4G services".
What is LTE and what benefits does it offer?
LTE (or 3GPP LTE if you're being technical) is designed as a successor to the older UMTS standard used on most of our current 3G networks, promising faster speeds and better performance. However, even those first LTE networks aren't technically 4G networks, as we'll see. Setting up LTE requires carriers to install new equipment, though if they are reusing spectrum that was previously employed for other purposes (the approach Telstra is taking) they may be able to reuse some gear.
In theory, an LTE connection should offer downlink speeds of at least 100Mbps and uplinks at 50MBps. As ever, the difference between the theoretical maximum and what can actually be delivered is often large. At a demonstration last year, Optus showed downloads on an LTE network at 43Mbps -- impressive and way above current speeds, but well below the theoretical maximums available on the network.
In practice, you'd be lucky to encounter many sites that could deliver content at those speeds anyway, and raw speed isn't the only factor that's important. It's also overly simplistic to argue that the existence of high-speed wireless means that landline networks are unnecessary or don't require enhancement.
Technically speaking, LTE itself isn't a 4G standard, since the International Telecommunications Union has decreed that the 4G label should only be used for services which can offer speeds of 1 gigabit per second. The 4G mantle is being reserved for LTE-Advanced or LTE-A, which is due to be finalised in 2011. We can expect to see LTE networks migrate to LTE-A over time, but given that there's not yet any live networks for LTE in Australia, that process won't necessarily happen in a hurry. But it certainly won't stop the label "4G' being thrown around with abandon.
When will we see it in Australia?
Every major carrier in Australia has been testing LTE equipment, but Telstra is the first to announce commercial launch plans for a service the general public can actually use, though it hasn't offered a more specific time frame than "the end of 2011". It will use 1800MHz spectrum (which Telstra already owned and used to use for 2G) to offer a service alongside its existing Next G networks, but unlike Next G it won't roll out nationwide.
Instead, it will concentrate on capital cities and regional areas where there is high demand, covering more or less the same area as the higher-speed Ultimate service it rolled out last year. Emphasising the increasing importance of data, Telstra has announced that it will sell a mobile broadband dongle designed to use the new network, but hasn't yet announced any mobile handset plans.
Optus demonstrated potential speed benefits from an LTE trial it ran in Sydney last year, but hasn't made a more specific announcement regarding launch timing. Vodafone has also said it is trialling LTE equipment, but has been even less generous with the details, though both networks have been using 1800MHz spectrum for testing. Vividwireless has also been testing the technology.
One factor that might delay any rollout is the availability of spectrum. It's often assumed that carriers will need to make use of spectrum currently used for analogue TV broadcasts -- which is becoming available as the nation moves to digital-only TV -- to roll out full LTE systems, but that spectrum hasn't yet become available to them.
What can I do to prepare for it?
While lots of mobile phone manufacturers are announcing LTE-ready equipment, it pays to check the details. The Telstra network, for instance, will be 1800MHz, and other tests locally have used that frequency as well, but much of the equipment being announced is initially aimed at Verizon's LTE network in the US, which runs at 700MHz. That shouldn't be a problem with any phone or dongle officially released in Australia, but it might be an issue if you decide to import a device yourself.
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