Whistleout - The Blog

Optus held a network event today in which it announced its recent 3GPlus accomplishments and outlined plans for 4G expansion in the near future. The overall focus of the last few months’ worth of data was to do with 3GPlus coverage and consolidation across most of Australia, with particular attention paid towards increasing indoor coverage.

The 4G LTE info was a bit more interesting. It pertained to a new TD-LTE network that has just today launched in Canberra. TD-LTE is different to the more commonly-used FD-LTE currently employed by both Telstra and Optus, as well as foreign providers like AT&T and Verizon Wireless in the US. FD-LTE is the 4G LTE that Australians have come to know and love over the last year or so.

The ‘TD’ stands for ‘Time Division’ and is a different kind of LTE to the more common ‘Frequency Division’ LTE. Both standards are based on the same LTE technology, but operate in a different way.

A good analogy could be that where Frequency Division (FD) operates over two separate channels, one for uploading and one for downloading, Time Division (TD) uses just one for both. As a result the ratio between how much bandwidth is allocated to upload and how much to download can be more drastically controlled in TD, as any part of the overall signal that isn’t being used for one direction of transfer (usually upload is the under-utilised action) can then be utilised by the other (in most cases providing faster download speeds). In FD this is not really possible, as any under-utlised portion of the upload channel cannot then be given over to boosting download bandwidth.

Optus’ TD-LTE network has been tentatively estimated to provide a ratio of 3:1 in this respect, with download receiving triple the preference of upload.

Optus 3GPlus Expansion

Over the last couple of years Optus has focus on improving its 3G Network, as well as breaking ground on new 4G technologies.

It makes sense that 4G developments would get more media coverage, being the new and exciting tech in town. But despite the impressive abilities of 4G, as well as the potential future uses that offers, 3G is still very much the backbone of Aussie mobile carriers. Optus openly admits this, referring to 3G as ‘the workhorse’ of the Optus network.

While 4G offers much faster speeds, it’ll be a while yet until it can be pushed out to a lot of Australians, so it makes sense that Optus would continue 3G improvements until 4G can viably take over as the new ‘workhorse’ for the greater part of Optus’ national customers.

As such Optus has been not only expanding the range and indoor strength of its 3G, but has also been upgrading to what it calls “3GPlus”. 3GPlus is essentially a dual-channel (DC) 3G network based on HSPA+ technology. It can offer speeds up to twice as fast as traditional 3G HSPA+ and doesn’t require the user to own a 4G-capable device. That being said, dual-channel systems like 3GPlus don’t work on every 3G device; like 4G they require handsets and modems that possess the correct hardware.

Unlike 4G, dual-channel support has become common in even low-end devices. Many of Optus’ customers who live outside 4G areas, or do not yet have a 4G-enabled phone, should receive the benefits of this DC 3G rollout.

Some specific areas that Optus has begun focusing on are tourist destinations and areas in which festivals and public events are regularly held. Many of these locations see sudden spikes in usage during the holiday season, or during regularly recurring events. Optus has been seeking to boost 3G reception in these areas in recognition of users’ desire to upload and view photos, connect over social media and use websearch while at events.

We like the thinking behind this and, while it’s a fairly simple concept that one would already expect to be understood by all carriers, both national and foreign, it’s still nice to be reassured that the technology providers that are the backbone of modern culture understand what their services are being used for, when, why and by whom.

Optus already covers 98% of Australians on 3G, with 92% receiving indoor coverage. Over the next 24 months plans are in place to expand indoor 3GPlus to cover 95% of the Australian population, with a further 1000 sites targeted for activation.

4G TD-LTE and FD-LTE Expansion

Optus intends to cover 70% of Australia’s metro population with 4G LTE, using a mix of both TD-LTE and FD-LTE, by mid-2014. This is an impressive goal, considering that when the iPhone made its US debut back in 2007 Optus covered just 60% of the Aussie population (overall; not just metro) with 3G technologies. Not only that, but said 3G technologies would now be considered outdated, even by users who are still restricted to 3G, and have for the most part been replaced or upgraded.

In just two years between ’07 and ’09 that number jumped to a whopping 96% of all Australians. While the 4G expansion can’t be expected to take this exact route, as different technologies present challenges for wide-spread implementation, this definitely leaves us with a hopeful view of what Australian broadband coverage could look like 4 or 5 years from now. But we digress.

For now, Optus will be starting with 12 TD-LTE base stations in Canberra, with a further 20 to be installed over the next ‘few’ months. Further clarification indicated this time frame to be between the third and fourth quarters of this calendar year.

2300MHz TD-LTE sites launched today in Canberra

TD-LTE Device Compatibility

Currently the biggest hurdle that Optus will face with this new TD-LTE rollout is device compatibility. Unfortunately for both Optus and its users alike, FD-ready handsets won’t simply be able to switch over to and work on a TD network. As such Optus should expect a small amount of fragmentation during the initial stages of this new dual-band approach to 4G networking.

The issue will hopefully be short lived. Already countries like Japan have handsets that are both FD and TD enabled. Optus is already in talks with Japanese telco Softbank to provide TD-enabled smartphones within the next year. In the meantime, however, Optus customers may experience a little confusion between the two different kinds of 4G LTE being pushed out by their provider.

In June Optus will begin its TD device rollout with a dongle and WiFi hotspot modem. These devices will function on both the TD-LTE 2300MHz network being rolled out in Canberra, as well as on Optus’ current 1800MHz FD-LTE networks in other areas of Australia.

Dual-band TD-LTE and FD-LTE Coverage

Eventually Optus hopes to have a dual-band 4G network held up by both TD and FD LTE coverage that works on bi-capable devices. Such a network should be able to handle a heavy capacity of bandwidth, especially when distributed over multiple MHz frequencies.

Optus recently acquired a decent chunk of the 700MHz and 2500MHz spectrum bands. While the 2500MHz end is of such a high frequency that it will likely only be used as overflow to better handle congestion, the 700MHz frequency is low enough that it should provide a great basis for 4G LTE coverage.

Low-band frequencies travel further and penetrate solid matter, like buildings, with greater effectiveness. They are better in every way at providing clear and efficient communication networks. As such they are in greater demand, leading to enforced restrictions of how much of each frequency individual telcos are allowed to licence.

These 2500MHz and 700MHz bands, available to Optus (and the other carriers who successfully bid for a piece of them) in 2015, coupled with the already-active 1800MHz and 2300MHz Optus frequencies, provide Optus with what it’s calling “an unrivalled capacity stack”.

What this means is that, while Telstra may be in front of Optus in terms of area coverage, Optus has the capability to handle a greater number of simultaneous users within its 4G-enabled areas. Greater capacity support means faster speeds in heavy-use areas and should help maintain a connection in what might otherwise be a totally blocked area due to traffic congestion, such as what a user might experience at a live music festival.

Optus’ Future

Optus representatives were hesitant to comment on much of what Optus expects in terms of customer draw or what suppliers will be involved with the TD expansion.

In terms of further LTE expansion both TD-LTE and FD-LTE will continue to be increased across Australia. FD-LTE will keep spreading out on the 1800MHz band while Canberra (at first) will see more 2300MHz TD-LTE in the near future. Some sites will start seeing dual-band (both TD and FD) support in the foreseeable future as well, so that Optus can begin experimenting with providing a more stable backbone that utilises both technologies. Obviously this kind of operation requires customers who have both kinds of devices, or devices that support both TD and FD, in order to generate useful information. As such we don’t expect to see any dual band area data until after June/July at the earliest.

The question of voice over LTE was also raised, which is something that is being toyed around with in other countries at the moment. Andrew Smith, Vice President of Mobile Radio Engineering, responded that this is in the cards, but currently there are no real plans. LTE over voice is not an incidental obstacle and requires a certain level of signal strength, coverage and accuracy to provide quality communication. Currently Optus is preferring to focus on building a stable 4G infrastructure so that it can move in to the more technical side of 4G services in the future.

Translation: Voice over LTE isn’t coming any time soon, which isn’t really a big deal anyway.

Ultimately Optus looks to be in a fairly strong position as far as Australia’s 4G future is concerned. Obviously Telstra is still the biggest player here, with its much-larger coverage and shifting focus to faster LTE Advanced (LTE-A) technologies.

Optus has taken a different path – choosing to buckle down and build a dual-band 4G LTE solution that has the potential to provide its users with a more stable backbone, but at the expense of area coverage in the short-term.

What we’re most keen to see is how well Optus will handle this initial TD/FD LTE device fragmentation. It could end up being a big issue or it may come and go without making any real impact in the public domain. It really depends on the kind of device support that Optus can get within the next 12-24 months.

We would be more curious to see any noticeable difference in speed between TD and FD LTE users, but by Optus’ own admission today TD may offer faster max speeds, but mobile device users probably won’t even notice any difference between TD and FD. Few users with mobile broadband connections ever utilise more than around 15Mbps in terms of bandwidth. The difference between 50Mbps and 60Mbps isn’t going to make much of a noticeable impact. Like we said, Optus’ current goal appears to be more keyed towards providing a solid infrastructure from which it can build a reliable and heavy-load 4G network, rather than short-term gains in 4G speeds.

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