Feeds

WTF is... 802.11ac?

Next-gen Wi-Fi beamforms in

High performance access to file storage

Wireless networks are never fast enough, but for the moment at least they are generally quicker at shifting packets of data than the broadband connections they're typically linked to.

That's changing. Broadband speeds are rising, especially those fed through fibre-optic lines. Fortunately, Wi-Fi is keeping up. A number of chip and networking kit makers used the recent Consumer Electronics Show (CES) to tout their support for IEEE 802.11ac, a new wireless standard.

The technology uses the 5GHz band already utilised by the old 802.11a - big with corporates, but never a favourite of consumers - and the more recent 802.11n.

The 'n' standard can use 5GHz for speedier operation. The 5GHz band not only runs at a higher frequency than the more commonly used 2.4GHz section of the spectrum - also able to be utilised by 802.11n and its predecessors - but is also far less crowded, not only free from many a neighbour's wireless network but also from noise generated by microwave ovens and other electrical appliances.

Unfortunately, 802.11n is something of a mongrel, an attempt not only to up Wi-Fi's throughput but also to combine all the earlier 802.11 versions. Alas it doesn't mandate including them all, and numerous low-cost 802.11n chips operate only in the 2.4GHz band.

The Evolution of Wi-Fi

Source: Broadcom

Worse, they deliver a throughput barely quicker than the old 802.11g's 54Mbps. One of 802.11n's innovations was the ability to hook up more than two antennae, one for transmission and one for reception, a technique called 'MIMO' - Multiple Input, Multiple Output. But too many cheap 'n' adaptors stick to that '1x1' aerial configuration. That delivers peak throughput of just 72Mbps. Want more speed? Go to 2x2 and get 150Mb/s, or 3x3 and reach 300Mbps. Recent, 4x4 adaptors will take you to 480Mbps.

802.11ac supports even more antennae, up to eight of them, and it allows devices to negotiate dedicated links through specific groups of aerials to manage multi-client networks more efficiently.

One device may also be set to transmit to multiple others, but not receive. That's handy for beaming one HD video stream from a source to multiple screens throughout the home, say.

The standard has other tricks up its sleeve to boost throughput. It widens the 5GHz band's sub-channels from 802.11n's 40MHz to 80MHz and 160MHz, reducing the data-slowing impact of interference from other networks on other channels.

QAM, QAM, thank you, ma'am

Like 802.11n, 802.11ac uses quadrature amplitude modulation (QAM) to encode binary data into the radio signal. The 'n' standard maps bits onto 64 'constellation points' - effectively wave phase values that are used to represent sequences of bits. The more points you use, the more possible phase values can be selected and so the more groups of bits can be generated at the receiver. 802.11ac uses 256 constellation points.

The upshot: faster data transmission, at a cost of a reduced resilience to noise. That can be countered with better error checking, but that reduces the overall data transmission rate.

Range is a problem in the 5GHz band too. The faster frequency means a lower wavelength than 2.4GHz communications, and that has an impact on the distance over which the signal attenuates. However, 802.11ac mandates 'beamforming' techniques to map the wireless environment it's operating in and so steer clear of inefficient signal paths.

Put all these together and you're looking at raw data speeds of up to 3.47Gbps of one, eight-antenna access point and one, four-antenna client. More realistic scenarios with fewer antennae in the access point and in multiple clients call for speeds of between 433Mbps and 1.73Gbps.

Buffalo WZR-1750H 802.11ac router

Buffalo's WZR-1750H 802.11ac router

As yet, the IEEE has not formally approved 802.11ac, but the wireless industry, having been caught out before by the often overlong IEEE ratification process, are gearing up to provide 'draft' 802.11ac spec support, betting that the final standard will not changed much - at least nothing that can't be sorted with a firmware fix - and that interoperability testing will ensure firms' own take on the draft will align with others'.

Chip maker Broadcom is leading the way, outing four 802.11ac chipsets at CES, but its rivals are working on the technology too. Broadcom marketing them as '5G Wi-Fi'. Router makers Buffalo, D-Link and TrendNet had 802.11ac compatible kit on show.

Savvy Wi-Fi users have already hopped into the 5GHz band with 802.11n, and they're likely to grab 802.11ac kit when it becomes available later this year for even faster data throughput. UK-based market watcher IMS Research reckons these folk will buy more than 3m 802.11ac devices this year.

Initially, they'll be routers and add-on adaptors for existing 802.11n machines. Laptops and tablets with 802.11ac on board will follow in due course. But it's though that smartphones will stick with 802.11n for the time being. "We believe it might be 2014 before we see the first 802.11ac-enabled smartphone," says IMS' Filomena Berardi. ®

High performance access to file storage

More from The Register

next story
Feast your PUNY eyes on highest resolution phone display EVER
Too much pixel dust for your strained eyeballs to handle
Samsung Galaxy S5 fingerprint scanner hacked in just 4 DAYS
Sammy's newbie cooked slower than iPhone, also costs more to build
Microsoft lobs pre-release Windows Phone 8.1 at devs who dare
App makers can load it before anyone else, but if they do they're stuck with it
Report: Apple seeking to raise iPhone 6 price by a HUNDRED BUCKS
'Well, that 5c experiment didn't go so well – let's try the other direction'
Rounded corners? Pah! Amazon's '3D phone has eye-tracking tech'
Now THAT'S what we call a proper new feature
Zucker punched: Google gobbles Facebook-wooed Titan Aerospace
Up, up and away in my beautiful balloon flying broadband-bot
Nvidia gamers hit trifecta with driver, optimizer, and mobile upgrades
Li'l Shield moves up to Android 4.4.2 KitKat, GameStream comes to notebooks
AMD unveils Godzilla's graphics card – 'the world's fastest, period'
The Radeon R9 295X2: Water-cooled, 5,632 stream processors, 11.5TFLOPS
Sony battery recall as VAIO goes out with a bang, not a whimper
The perils of having Panasonic as a partner
NORKS' own smartmobe pegged as Chinese landfill Android
Fake kit in the hermit kingdom? That's just Kim Jong-un-believable!
prev story

Whitepapers

Securing web applications made simple and scalable
In this whitepaper learn how automated security testing can provide a simple and scalable way to protect your web applications.
Five 3D headsets to be won!
We were so impressed by the Durovis Dive headset we’ve asked the company to give some away to Reg readers.
HP ArcSight ESM solution helps Finansbank
Based on their experience using HP ArcSight Enterprise Security Manager for IT security operations, Finansbank moved to HP ArcSight ESM for fraud management.
The benefits of software based PBX
Why you should break free from your proprietary PBX and how to leverage your existing server hardware.
Mobile application security study
Download this report to see the alarming realities regarding the sheer number of applications vulnerable to attack, as well as the most common and easily addressable vulnerability errors.