WTF is... 802.11ac?
Next-gen Wi-Fi beamforms in
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.
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'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. ®
COMMENTS
Gotta love copper
I had a bit of a diatribe written about wireless networking and how every time I think the new standard could finally rid me of copper at home, yet by the time it's available my needs have moved beyond it. I deleted it because it was a bit rambling, and I have a better point to raise.
Why do so few new houses these days come with data cabling? Seriously, it's a wired world. 802.11 is all very convenient, but for throughput and reliability you can't beat a bit of copper wire. TVs are coming with ethernet ports, surround-sound receivers are coming with them, as are telephones, DVD/BD players, games consoles, network video players (well, duh...), printers, music players, you name it. Sure, some of them come wireless too, but for streaming data (for video in particular, but also games or software updates) a wired connection is just better.
It wouldn't add much to the cost of a new house, and it would be a value-added differentiator in the market. As would under-floor heating and solar water-heating panels.
Anyway, 802.11ac - all jolly clever and a good fallback for when there's no cable. But why the hell is there never any cable? And my sympathies to the folks in rented accommodation who have *no* chance of running cables...
Really?
"Faster frequency" and "lower wavelength?" Seriously?
How about "higher frequency" and "shorter wavelength."
What?
That is backwards logic to wiring a house up with ethernet. Really, it should be part of all new housing plans to at least have one point in each room.
Cost: £80 for 100m Cat6 Shielded / £20 Faceplates / Free drill-walls / £30 8-Port Switch (one-off investment of £130)
Then you can add a wi-fi access point (£50) in a cental location (living room?) and spend less upgrading kit. More static devices (TVs, Radios etc) are coming along with ethernet ports. 1Gbps around the home will be enough for the next 10 - 15 years or so. My bug bear is leaving the routing/switching/wi-fi to one device. Why not distribute CAT6 to modularise all the kit? And you can run any cable from the port under carpets or through some nice thin trunking to tidy it up. Unlike the cabling is going to run past 100m in total from switch to device.
Anyway, I've lost count how many people have asked me to sort out their "wireless" connection at home. It's still too complicated in terms of the comms/negoiating security protocols and always fails somehow in a multi-functioned router (mostly the bottom of the barrel kit from most ISPs).
How about powerline tech? Not perfect, but I'm sure that tech will be refined for 1Gbps connections in future.
Never mind homes more than 40 years old in the UK, try the continent now. Reinforced concrete is de rigeur for modern housing construction over here. A nice thick bit of concrete with steel mesh in it is all but impenetrable to 5Ghz stuff. Like you I am stuck in heavily congested 2.4Ghz.
Fortunately my router does 2.4 and 5 simultaneously, so things close enough to it can still get the benefit.
Um..
I think it's somewhat unlikely punters are going to jump at 802.11ac routers unless/until there's a sufficient groundswell of products which would connect to them. And we're not just talking about laptops with dongles any more - phones, tablets, media streamers, consoles, remote controls even. All stuff that uses B/G and or N, which isn't easily upgradeable like your average PC.
It's a bit chicken and the egg though - nobody will buy the routers without the clients and nobody will make clients until there's an established demand through people having routers.
As a bare minimum, the routers have to be backwards compatible and even then you're talking about several years of natural wastage of equipment before the new .ac compatible kit achieves critical mass. By which point of course home broadband will have moved on again...
Basically put, there needs to be something more than the 'ooh, shiny' about it for it to get adopted in anything less than geological time. I don't really hear a lot of people complaining about how their home wifi isn't speedy enough, and most people right now are too skint to think about upgrading their entire wifi setup for what may not immediately be an obvious benefit.
It strikes me a bit like 3D telly. Yes, at a technical level there is a USP there. But I think they're going to have a hard time convincing people their current kit isn't 'good enough'.
