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January 26, 2006

Demystifying 802.11n

Boxed_1_2MIMO, WMM,WEP, WPA, 802.1x 802.11a/b/g/e/n/d/i/h – consumers just don’t care and are overwhelmed with all the stuff they think they need to know (cuz vendors tell them it's important). But when it comes to Wi-Fi, consumers really care about three simple things: performance (speed and coverage), price and predictability. 

Well the good news is the IEEE unanimously approved the first draft of the 802.11n standard. 802.11n boosts Wi-Fi’s capacity up to a 600 Mbps theoretical speed and is essential for high-bandwidth applications such as supporting multiple HD streams throughout a home.

But the bad news is that 802.11n, in and of itself, won’t solve how to reliably stream video over the air. So claims that it will be the panacea to support multimedia content mislead already confused consumers. 

Wi-Fi (and the “spectrum” that is uses) is a shared, unlicensed medium. This means anyone can use it anytime for anything.  Sure you get a bigger Wi-Fi pipe with 802.11n but if there’s the slightest amount of noise, your video will suck.  In fact, 802.11n actually might make things worse (but don’t get us wrong, we love N for the big pipeness). But here's why things get worse:

802.11n basically sends, at the same time, multiple Wi-Fi signals out over different paths through the environment (multipath), then puts them together at the other end to deliver a higher data rate.  This process (that I’ve described very poorly) is called (sorry about this) “spatial multiplexing.”  It’s sort of like using multiple APs at the same time and combining them at the receiving end to get a faster connection. 

But this is precisely the problem. Because you can’t control the paths that these Wi-Fi signals actually take, when interference is introduced (and there’s always interference), the Wi-Fi signal can actually become more unstable because it’s bouncing around, making it even harder to recover the different signals. In turn, streaming video over 802.11n could be subject to wild bandwidth fluctuations caused by RF noise and other uncontrollable stuff in the spectrum (I think you know where we’re headed).  Making Wi-Fi predictable is a MUCH harder problem to solve. Ironically wired seems to get this :)

Angelina You need to be able to control the paths that signals take and understand the quality of these paths – because we’re talking video here.

If Angelina, when she’s sent from the AP, doesn’t look like Angelina when she reaches the TV, you’ll be pissed.

Our technology makes you not pissed.


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