The next major advance in Wi-Fi, the still-in-draft IEEE 802.11ac standard, seems like a slam-dunk: It promises data rates ranging from 433Mbps to, in some configurations, 1.3Gbps, hence the label "Gigabit Wi-Fi." What's not to like?
But as is usual in wireless networking, the actual implementation of 11ac in products, their deployment and use make for a more complicated picture.
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There are already consumer-focused access points, routers and adapters based on the existing 11ac draft, which is not expected to change much by the final IEEE ratification in late 2013 or early 2014. And some analysts are forecasting very rapid 802.11ac adoption by client devices. ABI Research recently forecast that in 2015, 70% of smartphones shipping will have 802.11ac radios.
To achieve its high data rates, 802.11ac uses several techniques. One is bigger channels, up to 80MHz wide compared to the maximum 40MHz for 802.11n. A new modulation scheme essentially packs more information in the radio signal. Beamforming is a mandated feature instead of an option as in 802.11n: it optimizes the signal between the access point and each connected client.
But the actual performance will depend on a range of variables: how many data streams the radio supports (a maximum of eight for 11ac), range from the access point or hot spot, the number of other clients associated, the kind of applications being used, and so on. [See "11ac will be faster, but how much faster really?"]
Apart from the magnitude of the data rate improvements - three or four times that of today's widely deployed 802.11n networks - 802.11ac provides a host of other benefits. Users can expect higher-quality radio links, and see higher data rates (compared to 802.11n) maintained consistently as the distance from the access point increases. There will be much less traffic and interference in the 5GHz band, which is the only frequency band 802.11ac uses, compared to the 2.4-GHz band used by a majority of Wi-Fi clients today. And beamforming and the improved signal quality will compensate somewhat for the lower range of 5GHz vs. 2.4GHz.
Finally, 802.11ac is much more power efficient than 802.11n, reducing battery demand for mobile devices. And the much faster data rates mean that users can send and receive a given amount of data much faster, reducing time "on the air" and, again, using less power.
You can expect a range of 802.11ac product demonstrations and announcements (for the consumer market) at the upcoming Consumer Electronics Show in Las Vegas, Jan. 8-13.
In early 2013, the Wi-Fi Alliance will launch its 802.11ac testing, designed to certify 802.11ac interoperability of different 802.11ac products and brands. The "Wi-Fi Certified" brand will help to make 802.11ac a mainstream technology in short order.
Enterprise access points will begin appearing by midyear. One example is Cisco's previously announced 802.11ac plug-in module for its Aironet 3600 high-end access point. Cisco, and its rivals, have been upgrading their access points and controllers, adding memory, CPU power and other changes to handle the higher data rates as well as the anticipated higher demands that mobile Wi-Fi clients put on backend services such as encryption and authentication.
Vendors say they expect enterprises to phase in Gigabit Wi-Fi by adding 802.11ac radios first to high-density areas - with lots of clients or demanding applications or both. At some point, enterprises may have to upgrade WLAN controllers, wireline Ethernet backhaul, or switches (or some combination), and RADIUS and other backend network services.
For this infrastructure market, the radios will support two, three or four data streams. Chipmaker Marvell announced Dec. 3 the first 4x4 802.11ac system-on-chip, a companion to its client-focused 2x2 product. It's targeted at enterprise WLANs, carrier Wi-Fi networks, and video distribution applications.
One infrastructure segment to watch will be the carrier market. At least some mobile operators have been turning to and expanding use of Wi-Fi as a companion service for subscribers to use at least sometimes as an alternative to their cellular data plans. 802.11ac's faster data rates, capacity, improved signal quality and other features could trigger a rapid build-out of such services.
At about this same time, new models of mobile devices, as well as plug-in adapters, will start to appear, incorporating 802.11ac silicon. Redpine Signals, for example, announced a year ago the release of a 802.11ac chip for integration with smartphone-class processors. Smartphones and possibly tablets will almost certainly be limited to single-stream chips, with a maximum data rate (based on using 80-MHz-wide channels) of 433Mbps. Throughput will be much less, and will be reduced even more as more clients connect to the access point, and the distance grows between client and network.
PC World's Michael Brown evaluated the five available 802.11ac routers on the market in a September 2012 report. "We're talking real-world throughput of 400 to 500 megabits per second (mbps) at close range; that's twice the speed of the best 802.11n routers," he writes. "And at very long range, where most 5GHz 802.11n routers peter out, an 802.11ac router can deliver throughput of between 50 mbps and 100 mbps more than enough bandwidth to stream high-definition video."
Right now, without adapters, using these products is awkward: Brown had to use one 802.11ac router connecting wirelessly to a dedicated 802.11ac bridge or a second 802.11ac router configured as a bridge, with devices attached to the bridge by Ethernet cables.
But by mid-2013, you can wave goodbye to awkwardness and just revel in speed.
John Cox covers wireless networking and mobile computing for Network World.
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