The Promise of a New World Pt 2

Last month in “The Promise of a New World” I introduced you to 802.11ac, the next generation of WiFi capability.  This month we start to look at it in a little more detail in terms of how it affects the computing space and the planning and design of the network.

Just like its predecessor, 802.11n, equipment not developed for 802.11ac cannot take advantage of its higher speeds.  In fact, like all preceding WiFi standards the presence of devices from previous generations will actually slow the whole process down as the radio nodes (access points, wireless routers, whatever the particular manufacturer wants to call them) will need to switch communication schemes back and forth to accommodate the mixed environment.


Setting realistic expectations in technology is important to do when newer methods are being implemented.  Last month I mentioned that some devices won’t be able to match the performance of others in 802.11ac.  You see 802.11ac advances a method developed for 802.11n called multi-streaming.  Instead of a single stream a data flowing between the access point and a device these technologies send multiple streams at once, slightly out of phase with each other, which are them reassembled into the message being sent.  It’s like printing a book by sending each chapter to a different printer at the same time and then having someone reassemble it as the chapters print.  The method, however, requires the devices to be equipped with multiple antennas and processors capable of doing the teardown and reassembly.  Devices like small tablets and smartphones are already taxed for space and cramming more antennas to handle multiple streams of data will be very hard to accomplish.  They also don’t have wireless chipsets or processors capable of doing the computing work.

If you have a wireless network now don’t expect to take the old access points down, put up new 802.11ac ones and get anywhere near the performance promised.  For one thing, 802.11ac is for the 5GHz frequency band only, what is also known as the 802.11a band.  This is because the 2.4GHz 802.11b/g band is not large enough to use the wider channels needed for 802.11ac.  In the long run this is a good thing.  It means migrating devices that need the higher bandwidth to 5GHz and keeping the legacy, slower devices on the 2.4GHz band.  This will alleviate some of the annoyances like having older equipment slow everybody down.  So, create a new higher-speed path for the newer equipment and take advantage of the technology.

In addition, you may find that really using the new technology to its fullest will require even smaller cells of coverage than if you had implemented a properly designed voice-grade wireless system.  Just like listening to a speed talker requires more concentration and less background noise, the same is true for 802.11ac.  Access point placement, avoidance of same channel interference, signal power management and coverage overlap will be even more important than they are now.

The best course of action is to contact somebody that has experience designing large-scale wireless networks and a thorough understanding of networking in general.  Understanding your applications helps a lot, too.

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