802.11ac WiFi could help agencies cope with BYOD

The proliferation of smart phones, tablets and “bring your own device” policies in government agencies naturally means that more mobile devices will be accessing wireless networks, which in turn will lead to a drastic increase in demand for bandwidth.

Your agency’s current WiFi setup might not be able to handle the strain, so it could be time to start looking around to see what’s next in wireless capabilities.

The Institute of Electrical and Electronics Engineers (IEEE) has been working for over a year now to approve the new “ac” amendment to the 802.11 wireless standard for “Very High Throughput” on the 5 GHz band.

With the standard now in Draft Revision 3.0, many manufacturers are not waiting for the final version and have released routers and other devices that use technologies outlined in 802.11ac. The first chipset was released in November 2011, and the first router was put out in April, with several others following. And the amendment isn't expected to get final approval until 2013!

So, what makes this version better than the most recent WiFi standard, 802.11n? Speed and versatility. First, the bandwidth per channel has increased from 40 MHz in “n” to 80 MHz and 160 MHz in “ac.” And of course, a wider pipe can only mean greater throughput. Second, the number of multiple-input/multiple-output antennae is going from four to eight. This not only allows for more potential aggregate throughput for the entire device, but it also drastically increases the device's flexibility.

Each antenna only represents a separate simultaneous data stream if the device it is communicating with has that many antennae. So, for example, if an 802.11ac router only needs to communicate at a certain maximum data rate, the antennae can be split up into stations using one or more of them. This lets you use that router most efficiently, especially when communicating with older devices.

All of these improvements make possible wireless communications with an aggregate capacity of 6.93 gigabits/sec. There are a few considerations, however. First, this assumes the highest modulation and coding rates possible, which might not always be possible or practical. Second, this data rate would only be achievable under ideal testing conditions, and we all know those don’t exist outside of a testing lab.

In real-world conditions, 802.11ac routers are delivering about 400 megabits/sec to 500 megabits/sec speed, according to PC World's tests, which is roughly twice the speed of the 802.11n routers the GCN Lab tested in 2009. That’s a pretty big jump.

But before agencies can really take advantage of the new speeds, though, they’ll have to have laptops, tablets and smart phones that support the standard. Those devices just started to appear this summer, with Asus releasing the first “ac” laptop in June.

Also, unless it is just relaying a wireless signal, the router has to physically connect to a network through one of its Ethernet ports. Since most government networks have standardized to Gigabit Ethernet, users generally won’t be able to avail themselves of wireless speeds faster than about 1 gigabit/sec. All currently available routers using the 802.11ac draft standard have Gigabit Ethernet ports. Networks would have to be overhauled to 10-Gigabit Ethernet in order to take full advantage of 802.11ac.

Another thing to note is that 802.11ac only supports radios in the 5 GHz frequency band. This means that it will only be able to support now-legacy 802.11n devices through their 5 GHz radios, and won’t support any “b” or “g” devices you might still have lingering about. That is the price of progress, I suppose.

The 802.11n standard has proved reliable, and if that’s what your agency has, you’re probably going to be good for a while. But the trend toward greater mobile access is clear, and down the road, “ac” is something to look forward to.

About the Author

Greg Crowe is a former GCN staff writer who covered mobile technology.

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