Happy Wi-Fi Day!

If you thought 802.11n Wi-Fi was fast, you'll probably love 802.11ac--if you can wait for it.

By  |  Tuesday, August 2, 2011 at 6:04 pm

Qualcomm Atheros created this art to celebrate 802.11 day, a holiday it invented.

I bet you didn’t know it, but today is 802.11 day. (I didn’t know it either until a PR person for Qualcomm Atheros–the Qualcomm division formed after Qualcomm acquired Wi-Fi chipmaker Atheros–e-mailed me.) Not because of any scientific milestone involved in creating the IEEE standard more commonly known as Wi-Fi, but because, well, it’s really 8.02.11. Get it?

The folks at Qualcomm Atheros seized upon the tech equivalent of a bad pun to update a group of journalists about what’s next for the popular connectivity technology–and although the excuse may have been lame, what they had to say was interesting. The last big upgrade, 802.11n, delivered speeds on the order of 100mbps Ethernet, so the standard now in the works is going for the next speed hurdle–1 gigabit.

Maybe they’ll call it gigabit Wi-Fi. But for now, the embryonic standard is simply another IEEE alphanumeric: 802.11ac. (They went through the entire alphabet for various other Wi-Fi related technologies–some of which no one ever cared about–so after 802.11z they started over again with two letters, and 802.11aa and 802.11ab are already taken.)

Qualcomm Atheros technology vice president Bill McFarland estimates it will be a good year and a half before we see actual 802.11ac products, but that would be downright speedy compared to the many years it took 802.11n to get from the IEEE drawing board into my living room. Anyway, here are some things I learned at the briefing:

  • It will operate only in the 5ghz band, so it will not be backwards compatible with the vast majority of current Wi-Fi gear that only supports 2.4ghz Wi-Fi (802.11b/g and 2.4ghz 802.11n). Only 802.11a and 5ghz 802.11n gear will work with 802.11ac radios–but McFarland anticipates that at least initially, vendors won’t release products that don’t support 2.4ghz at all.¬† What we’ll probably see are products that support 802.11ac and 2.4ghz 802.11n.
  • To attain gigabit speeds 802.11ac will be able (among other things) to use wider bandwidth channels to send data streams. Today’s Wi-Fi products use either 20mhz or, at most, 40mhz channels; in contrast, 802.11ac gear must support 80mhz channels–or, optionally, 160mhz channels. And its radio waves will support denser data transmissions than 802.11n, so that one 802.11ac stream will be able to carry roughly the same amount of bandwidth as three 802.11n streams.
  • Access points can send and receive up to 4 8 spatial data streams, twice as many as 802.11n. And 802.11ac devices will be able to intelligently parcel out the streams based on the capabilities of simultaneous clients. If you have two smartphones on the network, each with one 802.11ac antenna (this is typical for smartphones) and one notebook with two antennas, a 4-antenna 802.11ac access point can simultaneously direct one stream to each smartphone and two to the notebooks. An 802.11n device cannot divide streams up this way, so it communicates with one device at a time, which slows things down. Of course, this means that on a network with lots of clients operating simultaneously, nobody will get top speed: the gigabit bandwidth will be divvied up.

How will 802.11ac stack up against WiGig, another high-bandwidth standard in development that operates on the 60ghz band? Basically, WiGig will be faster–but only at relatively short distances where walls and ceilings aren’t involved, making it more suitable for cable-replacement applications. McFarland says he believes the two will co-exist nicely.

Given the generally leisurely pace of new Wi-Fi technology adoption, I imagine it will be several years before 802.11ac becomes as familiar as 802.11n is now. But migration from 2.4ghz, which simply doesn’t have the bandwidth capacity required for the many wireless devices it is called on to support, is long overdue. Ask anyone who’s tried to stream media over a 2.4ghz Wi-Fi network in a big city. I just wish notebook and smartphone makers would be more proactive in supporting 5ghz Wi-Fi: even today, most don’t. Perhaps with gigabit Wi-Fi as a carrot, more people will make sure to demand 5ghz Wi-Fi, with or without support for legacy 2.4ghz gear.

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