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To AC or not to AC, that is the Wi-Fi question

On the eve of the IEEE's ratification of the 802.11ac Wi-Fi standard, network managers need to consider whether they should upgrade or not.

One of my favorite holiday poems starts something like “Twas the week before Christmas and all through the air, the IEEE was stirring to ensure 802.11ac would be there.” I say this because the wave 1 version of the next-generation Wi-Fi standard, 802.11ac, was ratified last week. Given the impending ratification, many network managers are now asking, “should I deploy 802.11ac or should I just stick with tried and true 802.11n?" Well, there’s no right answer, so I thought I would go through some points network managers should considering before making the decision to AC or not to AC.

FIRST LOOK: Gigabit Wi-Fi adapters

The first consideration is to understand the technology itself and what’s different about AC versus the current specification. 802.11ac is the next generation of Wi-Fi and extends many of the features introduced with the 802.11n specification. This is similar to the shift when the industry went from b to a/g.

802.11ac will be backwards compatible with previous versions of Wi-Fi allowing for a gradual migration away from legacy devices, although many new features will be available on non-AC devices. The technology brings gigabit speeds to wireless for the first time through the use of more antennas, wider channels and more special streams, as wells as a number of new features such as beam forming and better signal-to-noise ratio to greatly improve performance.

Clients that connect using 802.11ac should also see better battery life and the devices can transmit more data, faster and get off the air faster. One of the things I hadn’t considered is that non-AC devices will also get a performance boost. Last week, I caught up with VP of product and solutions marketing at Aruba, Manav Khurana, and he told me that Aruba customers have seen a 30% improvement of n clients on AC networks primarily because of the improved signal strength.

The technology also introduces something called downlink multi-user MIMO that further improves communications. To date, all 802.11 communications has been one to one or one to all. With AC, the new feature enables access points to transmit different streams to several targeted clients simultaneously.

Some of the benefits of 802.11ac are the following:

  • While AC has been called “gigabit wireless,” the speeds can vary from about half a gig all the way to almost 7 gigabits in future versions, a significant jump from 802.11n.
  • Each AC access point can handle more users than previous versions so the network can handle more devices.
  • The 802.11ac specification uses wider channels. The initial release of AC APs will use channel widths of 20, 40 and 80 Mhz while future versions will allow for 160 Mhz channels.
  • Since 802.11ac operates only in the 5 Ghz spectrum, the networks experience less interference from other devices.

Another key consideration, though, is to understand when many of these newer features will be released. Many of the advanced features I discussed, such as wider streams and mutli-user MIMO, will not be available until wave 2 of 802.11ac, which won’t be available for another 24 months. For the full-feature set, wave 2 802.11ac APs will require POE+ enabled switches for power.

So, for network managers, the questions should be, deploy ac or stay with n? If ac is the choice, deploy now or wait until wave 2?

I would say, in general if an organization were to take a close look at their application usage they would find more use of video, cloud and other bandwidth intensive applications. Additionally, with BYOD being all the rage, the number of devices will likely double, if not triple over the next 24 months. But because 802.11ac is only 5 Ghz, the correct approach will be to deploy 802.11n and 802.11ac together, which is why most of the enterprise Wi-FI vendors offer n+ac APs with two radios, one for each in them.

As far as whether to wait or not, I would say it’s best to upgrade now to wave 1 802.11ac and start enjoying the benefits immediately unless there’s a specific feature (such as MU-MIMO) that you must have. Remember, wave 2 uses POE+ for power and requires uplink speeds of greater than 1 Gig-E so most companies will likely have to upgrade the wired infrastructure to accommodate the new APs. Some organizations many have POE+ in the wiring closet, but it’s very rare to see 10 Gig-E at the access layer. So if the natural upgrade cycle of wired happens to coincide with wave 2 of 802.11ac, then it may make sense to wait. Otherwise, organizations should take advantage of the current version of the technology and create a better, faster, more consistent experience for the users.

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