Six months from now, enterprise IT groups will be facing a big change for their Wi-Fi networks: the shift to 802.11ac, which promises wireless data rates that start at 433Mbps.
But what's on paper and what happens in the real world are two different things.
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RESEARCH: Resources for 802.11ac 'Gigabit' Wi-Fi
The 11ac overview
The IEEE 802.11ac standard: builds on some of the technologies introduced in 802.11n, makes mandatory some 11n options, uses several ways to dramatically boost Wi-Fi throughput, and works solely in the under-used 5GHz band.
Yet at least one of the most important features, dubbed multi-user MIMO, won't be available until 2014, when the second-generation 11ac chipsets become available. Multi-user MIMO that will let an access point's 11ac radio talk to as many as four clients simultaneously. Today's access point can talk to only one connected client at a time.
With the current draft of the new standard considered stable, some consumer-grade routers and adapters already are available. Cisco, in an unusual move, announced in May that it will introduce in spring 2013 an 802.11ac radio module that will snap into its popular enterprise access point, the Aironet 3600. Other wireless LAN vendors and device makers are expected to introduce enterprise-class products starting in that same period.
The 11ac radios are backward-compatible with 802.11n and 11a radios in the 5GHz bands; and new two-radio access points will likely have the single-band 11ac radio and a dual-band 11n radio to handle legacy clients.
But there are a lot of variables, and together they add up to a wide range of performance possibilities for users and the network alike.
Why is 11ac so much faster?
Vendors say a single-data-stream 11ac radio, which is what most 11ac-equipped mobile devices will have, will yield maximum data rate of 433Mbps using an 80MHz-wide channel, compared to 150Mbps for single-stream 11n radio with a 40MHz channel.
The new Wi-Fi does several things to be faster.
First, the first-generation 11ac chips will support 20MHz, 40MHz, and 80MHz channel widths, compared to 20MHz and 40MHz for 11n. The wider channel is like a fatter pipe: You can push more through it in the same amount of time.
Second, there's a new modulation scheme, called 256 QAM, that essentially lets 11ac pack more information into the radio signal. "Inside a given finite space, the whole process [of 256 QAM] lets you get more data transmitted, with an improved possibility that you send a 1 and receive a 1 on other end," says Dino Bekis, senior director of wireless connectivity at Broadcom.
Third, beam-forming will be standard feature in 11ac instead of the rarely implemented option it is in 11n. Today, some vendors such as Ruckus use specially designed antennas with multiple components that can be used in various combinations to create an optimal signal for each associated client.
