Introduction to 802.11ac

By ozerdo posted Jan 04, 2012 07:31 PM


First of all, happy new year everyone! 


Our first blog of 2012 is about 802.11ac. As you might already know, we have published the first version of our 802.11ac FAQ in our knowledge base. 


We get a lot of questions about this new upcoming Wi-Fi standard and I thought it would be a good idea to talk to our in-house expert at Aruba on the topic. Here is a video of that conversation with Peter Thornycroft, aka. pthornycroft, a member of Aruba Networks Office of the CTO. 



To summarize, here are the top-3 things you need to be aware of when it comes to 802.11ac. 


1. 802.11ac means more speed

802.11n supports up to 40MHz channel bonding and up to 4 spatial streams. 802.11ac will support up to 160MHz channel bonding and up to 8 spatial streams. Note that this performance increase depends on the capabilities of the Wi-Fi client; due to battery life restrictions, many mobile devices may not support top 802.11ac transmission rates. Possible use of beam forming and multi-user MIMO will further improve the performance and reliability of an 802.11ac enabled WLAN. 


2. 802.11ac is 5GHz only

Wi-Fi clients will need to operate in 5GHz frequency band, need to be enabled with 802.11ac capable Wi-Fi chipsets and need to communicate with a 802.11ac capable AP in order to take advantage of the increased speeds. As Peter mentioned, we expect newer generation of dual-radio enterprise WLAN access points (AP) to be 802.11b/g/n capable on the 2.4GHz frequency band and 802.11a/n/ac capable on the 5GHz frequency band. 


3. 802.11ac will require new client/AP hardware

802.11ac technology cannot be implemented on existing 802.11n based Wi-Fi chipsets, and hence it will require new Wi-Fi client and AP hardware. In addition, greater number of antennas are required to support greater number of spatial streams allowed with 802.11ac. As you might remember, number of antennas on a Wi-Fi client or an AP needs to be greater or equal to the number of spatial streams that it supports. 


Hope this answers some of your questions on 802.11ac - let us know of any additional questions, comments. 


Talk you next time, thanks for tuning in! 

1 view


Sep 17, 2012 05:00 PM

Thats good info thanks for posting it ozwifi

Jan 19, 2012 04:06 PM

Interested in all the 802.11 data rates available for 802.11ac? Here is a great blog post ---


Jan 17, 2012 05:47 PM

Coverage on 802.11ac continues, fueled by CES.


Glad to see the reference to Airheads Social!



Jan 09, 2012 01:55 PM

Great overview Peter! Still remember you explaining 802.11n to me at my first Airheads in Miami with a napkin and some cocktail peanuts :smileyhappy:


My guess on .11ac is that the enterprise won't see the affects for a while here. Perhaps the greatest benefit to us will be the adoption of dual band WiFi cards backward compatable to the .11n on 5Ghz. 


We will really know we have to do something when Apple incorporates this into their new products!



Jan 06, 2012 05:42 PM

Got a note from our engineering team, adding more color to the 802.11n vs. 802.11ac comparison. 


If you analyze the sensitivity requirement (minimum received signal with PER<<10%) for 802.11n (40MHz max BW and 64QAM modulation) versus 802.11ac (160MHz max BW and 256QAM modulation) using an equation such as:


Psens = kT (Thermal Noise floor) + 10*log(BW) + SNR + Front End Noise Figure + Implementation losses


You conclude that for the same sensitivity (i.e. range under equal path losses) an 802.11ac radio has to be approximately 10dBi better. In other words, 802.11ac radios need to provide 10dBi improvements in low noise circuit implementation OR utilize antennas with 10dBi extra antenna gain. 


This fact coupled with multi-user MIMO is the challenge! :)

Jan 06, 2012 02:19 PM

Another great blog entry on 802.11ac:



Jan 06, 2012 02:18 PM

Jan 05, 2012 12:24 PM

Great link Zach, thanks!


Looks like chipsets "recommended" for APs support up to 2 or 3 stream 802.11ac, and the ones "recommended" for Wi-Fi clients support up to 1 or 2 stream 802.11ac... hopefully they can meet in the middle for 867Mbps link rate!


Quite exciting to see transmit and receive beam forming support. 




Jan 05, 2012 09:07 AM


Excellent video. Very informative.


I just thought I'd pass this along. Broadcom announced the first 802.11ac chipset today:


No word on customer availability (aka, when we will start seeing it in devices), but it is definitely a sign of things to come.