ADSL2+: Turbo-charged broadband, at last

If you've been holding out on upgrading to broadband, you will soon lose your last excuse. Telstra's move this month to launch ADSL2+ and uncap its ADSL1 services means the nation will shortly be drowning in super-speed broadband.

Of course, not everyone can immediately take advantage of the higher speeds -- ADSL2+ is still primarily sold in population-dense metropolitan areas, and it will take some time before other Internet service providers work out deals with Telstra where they too can offer uncapped ADSL1 across the nation.

Nonetheless, Telstra's move, along with the ever-expanding ADSL2+ networks of other telcos represents a major jump in Internet bandwidth that is finally paving the way for Australians to get access to the kind of broadband that other countries have been enjoying for years.

What is ADSL2+?
ADSL2+ is a souped-up version of ADSL (Asymmetric Digital Subscriber Line) technology, which transmits data using a certain frequency range on the copper 'local loop' cable connecting the phone in your house with your local telephone exchange.

When it was first introduced, ADSL was a significant step forward in Internet access, since it didn't require the availability of cable service and could coexist with voice phone services.

Other types of DSL, such as SDSL (Symmetric Digital Subscriber Line), are used by businesses requiring a particular type of connection, but ADSL proved ideal for Internet use, with a download channel many times faster than its upload channel.

ADSL1 performance varies with distance from the exchange, but could reach 8 megabits per second (Mbps) within 1.5km of the exchange. Telstra has previously limited ADSL1 to 1.5Mbps downstream and 256kbps upstream, but on 10 November the telco uncapped ADSL1 to allow up to 8Mbps downstream and 384kbps upstream.

ADSL2+, officially known as ITU G.992.5, boosts the download channel to a maximum of 24Mbps and offers a more modest increase to upstream speeds to let you send data at around 1Mbps (some ISPs such as Internode have started trialling boosted upstream speeds up to 2.5Mbps, under the 'Annex M' standard).

It does this through tweaking of the methods ADSL used to push data over your last-mile wire, with new technologies improving transmission efficiency and providing greater resilience to noise. (As a side note, don't confuse ADSL2+ with ADSL2 [ITU G992.3 and 992.4], a short-lived improvement on ADSL that was simply passed over in Australia and most other countries.)

Some providers such as iiNet, Internode, Adam Internet and others have been offering uncapped ADSL1 and ADSL2+ speeds in limited areas for some time.

Why do I need higher speeds?
Upstream speed is mainly important if you frequently send pictures or video to people, but the increased download speeds of ADSL2+ will be the real kicker, since it will deliver content at far faster speeds and enable the rapid transport of massive files, particularly videos and feature films.

If you're a big iPod user, for example, that means you will be able to download a feature-length movie from Apple's iTunes Store about 15 times faster than you could under the old 1.5Mbps speeds offered by most ISPs -- whenever Apple gets around to releasing movies on the Australian version of the store, that is.

Indeed, movie downloads will be an obvious early target for any ADSL2+ provider: in July, for example, ADSL2+ aspirant Netspace snatched up online DVD rental service WebFlicks. This deal gives Netspace a relatively successful real-world movie distribution business which, when backed by a high-speed ADSL2+ service, would seemingly pave the way for downloads on demand.

Telstra already offers some movie downloads through its BigPond Movies site, and does not count data from that site towards the download quota of its broadband services.

Although video downloads will likely be a popular first destination for ADSL2+ users, the overall faster Web experience will also pave the way for home users to broaden their use of a range of data services.

With that much bandwidth coming into your home, it will be possible for a single data connection to support multiple Internet radio, videoconferencing, voice over IP (VoIP) and even live TV signals at the same time -- and here's where it gets interesting.

Such 'triple-play' services have been talked about for many years, and are becoming a reality in other countries where more proactive carriers have worked overtime to bring new services to the market. In those environments, a single ISP could bundle data, voice and digital TV services over a single connection that does not, as is currently the case, have to be a cable TV connection.

ADSL2+ is your best bet for being able to buy decent triple-play services. A recent report by the national competition regulator found that ADSL was the most popular broadband technology Down Under, with around 72 percent of broadband services being ADSL.