What Is 'Category 9' 4G?

As much as we might like to complain about our mobile internet coverage and the speed of our connections, Australia’s mobile data networks are actually world class. Along with Korea and Sweden, Australia leads the way in the adoption and take-up of new super-fast 4G LTE-Advanced standards — and the latest is Category 9, a fancy frequency-meshing network capable of 450Mbps downloads.

The impetus for Category 9 LTE-Advanced in Australia actually comes from third-party devices, rather than big investments in the network itself — namely that shiny new Samsung Galaxy Note 5 and Galaxy S6 Edge+ announced overnight in New York.

Category 9 is the successor to Category 6, itself the technical successor to Category 4. It all centres around 4G mobile network frequencies, spectrum allocation, and upload plus download speeds — Telstra has detailed the differences on its Exchange blog today.

Here’s a bit of background; in the past, LTE Category 4 used the full potential of (up to) a 20MHz chunk of contiguous mobile network frequency spectrum, and promised theoretical data transfer speeds of up to 150Mbps download and 50Mbps upload. In the real world, we see best-case speeds of around 50Mbps and 35Mbps uploads, with rate limits and network overhead coming into play.

LTE Category 6 takes one chunk of spectrum, and another different chunk of spectrum, and welds them together to effectively double the bandwidth available and therefore double download speeds — theoretically 300Mbps downloads, although uploads (for most users, much less important) remain at 50Mbps. In Telstra’s case it relies, in part, on the telco’s 4GX 700MHz spectrum allocation, along with the 1800MHz that it has used for 4G for some time now. Cat 6 is available in some metro areas, and in testing we’ve seen real-world download speeds of 150Mbps and uploads still around the 35-50Mbps mark.

Category 9 LTE-Advanced is the logical continuation of that idea — it doesn’t weld together just two 4G mobile spectrum bands, but three. And that means theoretical download speeds of 450Mbps, with the potential for upload speeds to be higher as well at 75Mbps or thereabouts. To do this, you actually have to have the spectrum allocation to play with, and Telstra is using that 4GX 700MHz plus its 1800MHz and higher 2600MHz frequency all at once. Real world speeds will be interesting to see, but I’d be confident of seeing 200-plus-Mbps downloads and hopefully true 50Mbps uploads. Coverage areas, for what it’s worth, will only likely be limited to the densest inner-city and metropolitan areas at least for the first couple of months and years.

It actually makes a lot of sense for the telcos to implement Category 9, and to buy up a wide range of spectrum to get there. As a general rule, the lower the frequency of the spectrum the longer-ranged it is, with better building penetration and therefore a wider coverage area. Higher frequency spectrum has a larger capacity of users and of overall data throughput. With a combo of low, middling and high frequency spectrum allocation — like the 700, 1800 and 2600MHz that Telstra is using for Category 9 — a telco can achieve good coverage, fast speeds and the holy grail of ultra-fast speed in selected coverage-overlapping areas.

The first Category 9 devices will drop in Australia later this year — unless a competitor swoops in first, that’ll be Samsung with its Galaxy Note 5 and Galaxy S6 Edge+. Importantly, the network infrastructure is already in place — it’s almost just a matter of flicking the switch.

There’s also a Category 9-rated LTE-Advanced mobile hotspot on the way from Netgear, according to Telstra — and from looking carefully at the Speedtest screenshot that the telco has shared, it looks like it’ll be the first in the AirCard 8XX series hotspot family, and may be called the 853S or 863S.

Whatever it is, we’ll know “in the next couple of months”. Telstra has teased 11 hours of battery life, as well as a data usage meter and up to 10 devices connected simultaneously over Wi-Fi a la the Wi-Fi 4G Advanced II, also known as the Netgear AirCard 790S.

We’re getting in touch with Vodafone and Optus to ask how their LTE-Advanced plans are going with Category 6, which Telstra is already in the early stages of rolling out to metropolitan areas, and whether they have any concrete plans for Category 9 on the horizon.

Update: Optus has Cat 6 and Cat 9 infrastructure in place too. In fact, it has the world’s first using both FDD and TDD LTE distribution methods: “Optus’ network supports Cat 6 devices in all capital cities, bar Perth, and 20 regional centres.

“In terms of Cat 9, we have capability in select suburbs in Newcastle already ahead of the availability of the new Cat 9 devices, and have plans to provide the capability in the Melbourne CBD in early September. We expect to announce additional capital cities in the new year.”


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