Wi-Fi Goes Gigabit+ with 802.11ac, Broadcom First in Line
It seems like just yesterday that network equipment manufacturers were falling all over themselves to release Draft-N Wi-Fi devices so that they could squeeze in a whole product cycle before the IEEE finalized the 802.11n spec. The idea of a wireless network that could send data at 150Mps meant that it just might be possible to place that HTPC anywhere in the house without convincing the significant other that, yes, the 100m Ethernet cable tacked to the wall really is necessary. Of course, real world performance might suffer if one were to try to add a couple of wireless HTPCs to the network, or pop some microwave popcorn during the movie.
Well, the IEEE has heard our consternation and 802.11ac is now in draft form, and Broadcom has announced that they will be the first company to release a line of devices for the fledgling spec. The expectation is that the company can address any changes made to the spec before 802.11ac is finalized in late 2012/early 2013 through software updates. To be honest, although I knew that work on a new Wi-Fi standard was underway, I was not familiar with what was in store. The new standard supports up to 1.3Gps, and with wider channel bandwidth, improved beamforming, and 256QAM encoding, there is good reason to believe that this new 5GHz only Wi-Fi will have better real world performance than it predecessors. I expect a number of other companies will be showing Draft-802.11ac devices at CES. After all, the clock is now ticking if they are going to once again squeeze in a product cycle ahead of IEEE ratification.
We’ll enjoy the benefits of less interference as 802.11ac is a 5GHz-only standard as well as much higher performance thanks to wider channels and 256QAM encoding. Transmit power efficiency should also go up if we get wireless APs with sophisticated beam forming support. All of this will work together to deliver many times the performance we currently get over 802.11n without significant downsides.
Quote:the new standard
[quote]the new standard supports up to 1.3Gps, and with wider channel bandwidth,[/quote]
Just like 802.11N and how it was able to accomplish great speeds, the wider channel bandwidth has issues from an RF perspective.
Original wifi in the 2.4ghz spectrum used 20mhz channels, with the given range of those channels, or the “width” of those channels, that gave us 3 non overlapping channels. Meaning you could effectively have 3 access points one running channel 1, one on channel 6 and one on channel 11.
Now with 5ghz, you had the original 5ghz (ETSI Band and Uni1 Band) you had 8 non overlapping 20mhz channels or widths.
When you took Uni1, Uni2, Uni2 extended, and now Uni3 all within the 5ghz bands you get 14 non overlapping 20mhz channels.
Now what 802.11N did to all of that was combine two of the 20mhz widths together to make 40mhz.
So with 802.11N on 2.4ghz it combined 1 and 6 or 6 and 11, it can not combine 1 and 11. Which is why you see channel 6 as one of the most interfered channel with wireless.
Now with 5ghz the problem with that is, physics, the higher the frequency the less distance it can travel, and how well it penetrates through walls, specially plaster, brick on other dense materials drastically reduces the distance you can get from the AP.
With 802.11N and 40mhz bandwidth, it left you with 5 non overlapping channels to choose from. Which is great. But now when you effectively double the channel width, which is what 802.11AC is doing, you are left over with 2 non overlapping channels.
With 802.11AC you have the lower band, the middle band and the upper band. If you choose the middle band you could overlap with another AP using the lower or the upper. So just like channel 6 on 2.4ghz you are left with only two real choices which will effectively over saturate the 5ghz spectrum and make it unusable which is what we are already seeing with the 2.4ghz spectrum.
I am always for advancement in technologies but working as a wireless network engineer for a living I dread the day when I have to deal with 802.11AC.
[quote]improved beamforming,[/quote]
Beamforming doesn’t work period. great read about beamforming and how it doesn’t work http://revolutionwifi.blogspot.com/2010/07/beamforming-clientlink-and.html
-Josh
umdivx wrote:
So with
[quote=umdivx]
So with 802.11N on 2.4ghz it combined 1 and 6 or 6 and 11, it can not combine 1 and 11. Which is why you see channel 6 as one of the most interfered channel with wireless.
[/quote]
Awesome, just checked and my WiFi was on channel 6. LOL Moved it 11 and noticed some improvements. Damned neighbors. Thanks for the info.
I was thinking I need to
I was thinking I need to check the same thing when I get home tonight. Great follow-up post, Josh!
If anyone doesn’t think they
If anyone doesn’t think they need to read that above they are wrong..
This is so true, I see it all the time when I am at people’s house and they are having wireless issues. Many routers are defaulted to this…
802.11AC is exciting but very dissapointing ne the implenting of it…
Great follow up Josh!
Not a problem guys! When it
Not a problem guys! When it comes to wifi this is what I nerd out on big time.
-Josh