Pest Control: 802.11n's Dirty Little Secret

There's a big elephant in the Wi-Fi room and it's not just Cisco. 

But no one (read vendors) seems to want to talk about it in front of customers.  We will. 

The biggest problem with 802.11n systems today is lack of consistency of performance. There's no getting around it.

Under certain conditions 802.11n devices yield tremendous performance gains over older .11g/.11a systems (and these are the numbers vendors typically quote), but under a wide variety of conditions that are typically encountered in real world deployments their performance suffers.

Inconsistent performance of .11n is one of the huge unspoken problems in the Wi-Fi industry. No one wants to talk about it since most vendors don’t have adequate means to address the problem. 

Most vendors – both from the systems and chip side – would like customers to believe this is all being solved by interoperability issues getting hammered out as we move into 2^nd and 3^rd generation .11n implementations. While that certainly has been a significant factor affecting performance consistency to date, as those issues slowly get resolved the remaining issue of dynamically managing the multipath environment to ensure predictable spatial streaming becomes the 800 pound gorilla sitting in the corner.

Have you seen today's 802.11n APs with all these di-pole, omni-directional antennas sticking up?  Each one can be "articulated" in a different direction. The problem is, how the hell is an IT person supposed to know which one to point where?  The answer is: they have NO idea (and they shouldn't!).

And even if it were possible for a normal IT guy to understand this, how the hell (we say hell a lot at Ruckus) would you manage a large deployment with hundreds of access points?

Any informed CIO or IT manager in the enterprise space that is considering an 802.11n deployment should question why the six antennas that protrude from the typical dual band .11n AP that you get from Cisco or other enterprise WLAN vendors includes very flexible ways to adjust the orientation of the antennas - yet there are no instructions on how these should actually be adjusted, under what conditions they should be adjusted, and what difference does it make in terms of the operation and performance of the AP.

Beyond that, this variation in performance is dependent on which client the AP is communicating with, how the client is oriented, whether there are any changes in physical environment occurring in real time, etc.

The net-net is that there is no possible way to statically configure the position of fixed antenna systems that will adequately ensure consistent .11n performance under real world conditions. This is why no equipment vendor wants to talk about this.

We’ve found that relatively minor changes in the orientation of the typical rubber duckie type dipole antennas that are provided on typical enterprise .11n access points can introduce MASSIVE variations in performance with respect to a given client.

Anyone can easily demonstrate this by just charting throughput as a function of antenna position or by rotating an AP to slightly different positions particularly at moderately difficult locations.

We benchmark this type of phenomenon all the time in our lab as a point of comparison with respect to how our products stack up against the market leaders, and the performance variation of competitive enterprise WLAN products as you vary the antenna and access point position is huge. But no one believes us, because we're the only people that have really solved this problem. Go figure.

But screw it.  Test one and see for yourself.  If you know what you're doing, you'll see we aren't full of poopage.