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Know your 4G: The different types of LTE explained

4G is a catch-all name for a wealth of wireless data systems, with each service provider using its spectrum in different ways. If you want a better insight into 4G, 4GX, 4G Plus and beyond, we've got all the 4G flavours explained right here.

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Telstra's new hotspot can hit a max speed of 600Mbps. Shanna Baker

Australia can be pretty confusing when it comes to broadband speeds.

On one side, we've got the woeful state of our fixed broadband network, with our average speeds placing Australia at No. 42 in the global rankings.

But our mobile broadband network is the envy of the world, setting records and world firsts for top speed devices hitting the market. Those speeds are all down to investments and engineering made by local carriers into 4G technology.

But there's different flavours to the country-wide 4G services being offered by the big three -- Telstra, Optus and Vodafone -- so let's break down what's available around Australia.

The 4G/LTE rainbow

To understand the way carriers are delivering amazing speeds across their 4G networks, it's important to be across a few new phrases. With a basic sense of how the range of technologies fit together, you'll be able to quickly cut through the jargon and see what's going on.

LTE: This stands for Long Term Evolution and is, at least colloquially, often used interchangeably with 4G. There are some technical differences, but when you're comparing speed offerings in Australia, you'll find both getting used by the telcos.

Spectrum: The radio waves that send and receive our phone data have to stick to specific radio frequencies. In Australia, mobile broadband operates between the 700MHz and 2,600MHz bands of the wireless spectrum. The 700MHz band was previously occupied by free-to-air TV and was only opened up for mobile broadband in 2014.

The lower frequencies, down near the 700MHz band, give better signal penetration, offering stronger coverage in buildings, carparks, elevators and the like. The higher frequencies up toward the 2,600MHz band have a higher capacity for data.

Carrier Aggregation: This is a major component of LTE-Advanced, more commonly referred to as LTE-A. Carrier aggregation uses multiple bands of a 4G service to speed up data transfers. There are a couple of methods of doing this, called FDD and TDD.

FDD: Frequency Division Duplexing, often called FD, a method of carrier aggregation where data is transferred across multiple bands. For example, Telstra combine the 700MHz and 1,800MHz bands to deliver 4G data in some areas.

TDD: Time Division Duplexing, also TD, doesn't aggregate different bands, but instead uses time allotments on the same frequency to achieve a similar speed boost. Optus uses TDD on its 2,300MHz band.

Category X Device: The speed you experience isn't just about the what the network can offer, it's also about what your mobile device can accept. Category 6 devices, for example, can get a theoretical maximum of 300Mbps, while Category 4 devices get 150Mbps. The higher the Category number, the faster the speeds. Category devices are often shorted to 'Cat', so you may see Category 6 devices labelled as Cat 6.

Telstra

  • Uses FDD
  • Has Cat 9 support for new handsets like the Samsung Galaxy Note 5 and S6 Edge Plus
  • Has just shown off a Cat 11 wireless device with a theoretical top speed of 600Mbps

It was in 2014 that Telstra finally flipped the switch on its new 4G offering, dubbing the network 4GX. The name refers to Telstra's slice of the 700MHz band, which offers better underground and in-building coverage, and the telco's existing 1,800MHz band.

Speed Test results for the Samsung Galaxy S6 Edge on Telstra around the Sydney CBD. Screenshot by Nic Healey/CNET

Telstra's carrier aggregation is delivered via FDD, most commonly on the 700MHz and 1,800MHz bands.

Up until quite recently, its was the Category 6 LTE devices that were getting the best speeds on the 4GX network. These were phones like the LG G4 and the Samsung Galaxy S6 and S6 Edge. These had a theoretical top download speed of 300Mbps. In real-world usage, speeds varied but in testing around the Sydney CBD we would consistently see speeds of 50Mbps and higher for downloads.

Back in May 2014, Telstra first showed off its Category 9 LTE service, using a prototype Cat 9 device. It claimed a world first top download speed of 450Mbps at the time. To achieve Cat 9 speeds, Telstra uses a third 4G band: The high-data-capacity 2,600MHz.

Just last month saw the launch of the Samsung Note 5 and Galaxy 6 Edge+, both of which are Cat 9 devices. Telstra said it was ready and willing to offer a 4G service to match -- going as far as to announce a new Netgear mobile broadband hotspot that would also be Cat 9.

Testing on the two new Samsung phones seems to back up Telstra's bullish attitude: The average download speed was 72Mbps and upload was around 30Mbps. The peak speed was a ridiculous 208Mbps -- well beyond the original 150Mpbs max of Category 4 devices.

Telstra has already one-upped itself, however, with the arrival of the first Category 11 device: The Telstra WiFi 4GX Advanced III Mobile Broadband Hotspot. (What a mouthful!) CNET has seen this hit a peak download speed of 503Mbps and upload of 40Mbps, admittedly during a test at a press event held in the Telstra office in Sydney.

This uses something called three-band Carrier Aggregation, which is essentially three different blocks of FDD carrier aggregation combined for even faster download speeds. How fast? Potentially a maximum of 600Mbps according to Telstra.

In February 2016 Telstra announced that it was working with Netgear on a new hotspot to take advanced of its latest series of planned network upgrades. The Category 16 device will have a theoretical top download speed of 1Gbps and will be available "later in 2016".

Optus

  • Uses TDD
  • Has shown off a triple band carrier aggregation
  • More rollouts happening in 2016
The Samsung Galaxy S6 Edge will work on the new Optus 3x CA network. Juan Garzón/CNET

Optus has also been doing a lot of work on its expanded 4G network, which it occasionally refers to as 4G Plus.

It's a little more complex than Telstra's 4GX -- while Optus is offering a similar 700MHz service it also has the 2,600MHz band as well. The 2,600MHz offering works over shorter distances, but can allow increased bandwidth for data.

Optus still offers 4G on the 1,800MHz and 2,100MHz bands, and is, like Telstra, offering a super-fast LTE-A Carrier Aggregation. For this Optus uses TDD which means it's not aggregating two different bands, but instead using time allotments on the 2,300MHz band. In the early days of the service Optus says this allows for a theoretical download speed of up to 220Mbps, with early tests showing peak speeds of 160Mbps.

However, like Telstra, Optus has seen some big changes since the service was first kicked off. Back in May, Telstra fooled around with offering a mix of both TDD and FDD carrier aggregation across four channels, seeing a maximum top speed of 480Mbps. This was a new technique at the time.

More recently, just at the start of September in fact, Optus turned on its 3x CA in Melbourne. This "three times carrier aggregation" is similar to Telstra's three-band carrier aggregation. Optus says that 3x CA will offer improved speeds to Cat 9 devices but hasn't mentioned anything regarding cat 11.

One component of Optus's 3x CA that is unlike Telstra, is that's comprised of one FDD channel and two TDD channels, made up across the 2,300MHz and 1,800MHz bands. We've not been able to test it in the wild, but Optus is planning to roll out 3x CA in Sydney in early 2016, with Brisbane and Adelaide following mid-next year.

February 2016 saw Optus working with Huawei to trial what its calling 4.5G or LTE-Advanced Pro. In test scenarios this network saw an over the air peak download speed of 1.23Gbps but there's no timeline for when these upgrades might hit the real world.

Vodafone

  • Doesn't use 700MHz, but has 850MHz instead
  • Combines with 1,800MHZ for its carrier aggregation
Vodafone recommends the HTC One M9 for its 4G network CNET

Vodafone is rolling out its own slew of upgrades to its 4G network, all under the banner of 4G+. While Optus and Telstra are using the 700MHz band, Vodafone is going with 850MHz instead. As a low frequency band it'll offer similar benefits to the 700MHz: better coverage in buildings, lifts and even underground.

Vodafone also offers carrier aggregation as part of 4G+. For Vodafone this is FDD across the 1,800MHz and 850MHz bands. In March, Vodafone announced that LTE-A carrier aggregation had been fully deployed.

At the moment, the Vodafone network only supports devices up to Cat 6, so you're not likely to see the 200Mbps-plus download speeds of Cat 9 phones on 4GX. Vodafone also seems to be taking its 4G network a little more cautiously, with none of the strange style experiments we've seen at Optus.

It's worth remembering of course that Vodafone invested significant cash into its network in the wake of Vodafail and we'd imagine that more tweaking and refining will be on the way.