Network Computing is part of the Informa Tech Division of Informa PLC
Get Ready For Gigabit Wi-Fi
Most enterprise 802.11n wireless LANs deliver speeds between 450 Mbps and 600 Mbps -- not too shabby. But this is one area where you can't rest on your laurels.
To meet our ever-growing need for speed, the IEEE is working on Enhancements for Very High Throughput for operation in bands below 6 GHz, commonly known as the 802.11ac Wi-Fi standard. Wi-Fi certified products based on a draft of this standard will likely emerge by mid-2013, boosting maximum data rates above 1 Gbps. By late 2014 or early 2015, products aligned with the final 11ac standard will nudge the Wi-Fi speed limit closer to 7 Gbps. For IT, 11ac promises room for growth by focusing on less-cluttered 5-GHz channels, doubling or quadrupling channel widths, using more efficient encoding, doubling maximum spatial streams and eventually letting wireless access points service multiple clients simultaneously.
These benefits are appealing, but IT teams that have barely finished migrating to 802.11n may justifiably wonder why they can't sit back for a year or so. After all, didn't 11n just increase speed an order of magnitude over the 11a/g standard?
Yes, but many 11n WLANs are already suffering growing pains. First off, the small, crowded 2.4-GHz "junk band" has grown far too congested; 11ac kicks migration to 5 GHz into high gear by avoiding 2.4-GHz channels entirely. Second, while many applications operate fine at 11n speeds, some need higher throughput. For example, delivering uncompressed high-definition video to a Wi-Fi display requires 1.5 Gbps to 3 Gbps. Finally, and perhaps most painfully obvious to IT, bring-your-own-device programs have caused an explosion in the number and diversity of Wi-Fi devices access enterprise WLANs. And wireless carriers are encouraging people to off-load smartphone browsing to Wi-Fi to conserve scarce spectrum.
To keep your company's mobile initiatives on track, you'll need 802.11ac. The spec really does make some technological leaps. A biggie is multiuser multiple input, multiple output, or MU-MIMO, an advanced option that lets 11ac access points (APs) simultaneously service as many as four devices at once, using diverse spatial streams to communicate with each other. Today's APs operate similarly to how a single-core CPU handles multiple application processes "at the same time" -- in fact, it's really just rapidly switching among them. With MU-MIMO, an 11ac AP can operate similarly to a multicore CPU -- that is, using different transmit/receive chains to communicate with different users simultaneously.
The new spec also brings incremental improvements in key areas, including modulation, channel width, spatial streams and transmit beamforming. We discuss these in our full report.
Bringing 11ac To Market
As usual, we'll see two distinct Wi-Fi product waves. The first will be based on Draft 4.0 of the emerging IEEE 802.11ac amendment, followed by a second wave aligned with the final IEEE specification, which is expected in the first quarter of 2014. The Wi-Fi Alliance plans to launch a draft AC program in the first half of next year, focused on elements that are in near-final form. "We will avoid areas that we expect might undergo more work in the IEEE," says the group's technical director, Greg Ennis. "However, we're expecting there won't be significant changes to the text of the final standard."
Some consumer "pre-11ac" products are already available from vendors such as Buffalo, D-Link, Netgear and Cisco/Linksys. As for the enterprise, Broadcom product line director Michael Powell says adoption will be driven by the wave of phones, tablets and laptops that employees are bringing to work and that IT teams are scrambling to support. Powell expects to see notebooks with 2x2 11ac by year's end and 3x3 in early 2013. By the third quarter of 2013, 70% of smartphones will ship with 11ac -- mostly single-stream, he says. Still, enterprise WLAN vendors are actively developing 11ac while continuing to sell 11n APs; we break down their plans (see on next page).