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802.11ac series intro: Moving into the fast lane

By Matthew Gast in · Experts · January 21, 2013
Matthew Gast, Aerohive's Director of Product Management, explains what 802.11ac is, how it works, and why it's needed.

No doubt about it, 802.11ac is exciting. Here at Aerohive, we like anything that increases Wi-Fi speeds, so there’s nothing more exciting going on in Wi-Fi. As a result of all the questions I’m getting on this emerging technology, I’ve decided to write a series of blog posts here to answer questions I’m frequently asked.

Why 802.11ac Helps Every Network

Perhaps most importantly in light of the success of Wi-Fi over the past decade, I’ll start off with the backward compatibility question.  Upgrading to 802.11ac increases capacity and therefore decreases network load. In the 802.11 radio link, the load is measured in demand for airtime, not in terms of demand for the transfer of bits.  By increasing the data rate, it’s possible to transfer more data while decreasing the load on the radio network. Decreased loads are like traffic-free roads – they are good for everybody that uses the road.


Real-world 802.11ac speeds: QAM and channel width

Although a bit of 802.11ac makes every network better, the real purpose of the upgrade is to provide speed. What everybody first notices about 802.11ac is that it’s fast.  Really fast. Just like 802.11n, the newer specification introduces several techniques to improve end-user speeds. In that post, I plan to describe the protocol features that create higher speeds, and tell you what it means for building the hardware that you use to build your networks.


802.11ac channel bandwidth sharing

One of the major techniques for increasing speed in both 802.11n and now 802.11ac is wider channels. As an industry, we learned a great deal from the 40 MHz channels in 802.11n, and those lessons drove some neat features in 802.11ac to share channels. With 80 MHz channels, some overlap is inevitable.  802.11ac has some cool features to share wide channels on demand and to signal the bandwidth needed to transmit a frame. These features are not talked about much, but have the potential to really drive throughput increases that your network needs to support.

Spectrum Series

Wider channels are important to increasing speed, and the available radio spectrum drives network capacity. The recent announcement by the FCC chairman of new spectrum was a shock wave that really helped Wi-Fi. I wrote about it recently, and as I think about it more there are several implications for Wi-Fi in general and 802.11ac in particular. Other spectrum-related blogs I've recently written include NTIA weighs in on FCC's 195 MHz spectrum announcement and Why we lost the weather radar channels.

Next up, I’ll tackle two commonly asked questions. As 802.11ac is used with older 802.11a/b/g/n equipment, though, backwards compatibility is a concern. IEEE specifications are generally excellent at providing backwards compatibility, and 802.11ac is no exception. Many people ask me what the requirements around supporting older networks are. It’s a complex part of the 802.11 specification that has grown organically, so I will put together a post to try and explain the basics. See: A Shining Beacon in the Night: Selecting Data Rates in 802.11ac

All Posts In This Series:

How to Set Up Online Donations Using The Cloud And School Wi-Fi
Let Technology Help Fund Your School By Simplifying Recurring Online Donations

802.11ac Series Intro: Moving Into the Fast Lane

Why 802.11ac Helps Every Network

Real-World 802.11ac Speeds: QAM and Channel Width

802.11ac Channel Bandwidth and Sharing

A Shining Beacon in the Night: Selecting Data Rates in 802.11ac

Matthew Gast (@MatthewSGast)

Matthew Gast is Director of Advanced Technology at Aerohive Networks. He currently serves as chair of both the Wi-Fi Alliance's security task groups, was the first chair of the Wireless Network Management Marketing task group, and is the past chair of the IEEE 802.11 revision task group. Matthew is also the author of 802.11 Wireless Networks: The Definitive Guide (O'Reilly), which is now in its second edition and has been translated into six languages. His companion book, 802.11n book, 802.11n: A Survival Guide (O’Reilly), was recently published and provides information on how 802.11n works and what it means for the WLAN planning process. Most recently, Matthew completed 802.11ac: A Survival Guide (O'Reilly).


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