Apr 24 2014

Here Comes the Next Wi-Fi

More speed and better connections are on the horizon for wireless networks.

In January, the Institute of Electrical and Electronics Engineers released 802.11ac, the next-generation wireless networking standard. Based on the 802.11n standard that is in widespread use today, 802.11ac was
conceived to address two common requirements of wireless network users: greater bandwidth and support for more client devices.

On paper, 802.11ac should be up to three times faster than 802.11n. But as implementers of previous wireless stand­ards know, real-world conditions are the ultimate arbiters of wireless performance. Therefore, agencies interested in deploying 802.11ac should do extensive testing to determine how their environments may impact 802.11ac operation.

An important consideration in evaluating 802.11ac-based networks is the new standard's range. Because 802.11ac works around the 5-gigahertz frequency band, its range is actually shorter than older 802.11 technologies based on the 2.4GHz band. Wireless devices based on 802.11ac compensate for this limitation through a technique known as beamforming, in which a wireless access point broadcasts directly to a client device, rather than blasting out a wireless signal in all directions.

Beamforming improves the reliability of wireless links. In theory, it should compensate for any distance limitations of the 5GHz band. But again, agencies interested in 802.11ac should test its range, as well as the number of mobile devices it can support simultaneously.

Although 802.11ac was just released, products based on early, draft versions of the standard — access points and client devices — have been on the market for more than a year. These products are known as first-wave technologies. Soon, second-wave technologies, based on the final standard, will become available. It's expected these products will be more powerful (in terms of support for simultaneous connections and other functionality) than early products. Agencies should be cautious about acquiring first-wave 802.11ac products because they may suffer from interoperability problems. Second-wave 802.11ac products will be eligible for Wi-Fi Alliance certification as inter­operable based on the final standard.

Backward Compatibility

As interoperable, second-wave products hit the market, most will come with a helpful deployment feature: backward compatibility. If desired, new access points can be set to fall back to 802.11n for clients that don't support 802.11ac.

2.4 GB The average monthly data traffic per notebook ­computer in 2013, up from 2.1GB in 2012

SOURCE: "Cisco Visual Networking Index: Global Mobile Data Traffic Forecast Update, 2013–2018" (Cisco Systems, February 2014)

Unfortunately, some other characteristics of 802.11ac may complicate the transition. Most notably, 802.11ac access points will each require two Gigabit Ethernet ports and cables, not one, so new cable runs may be necessary. Also, unlike previous 802.11 iterations, which made several wireless channels available, 802.11ac will use only one or two channels, depending on the size of the channels. This may cause interference problems among 802.11ac networks.

One final note: Network managers should be relieved to hear that 802.11ac doesn't introduce new security features. It uses 802.11n's robust security model, but with one change: It permits only AES-based encryption, prohibiting earlier, flawed methods. It's possible to employ older forms of encryption by making an 802.11ac access point fall back to 802.11n, but be aware that such connections will be made at 802.11n speeds, not faster 802.11ac speeds.


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