To the Nth Degree: 802.11n Supercharges Enterprise WLANs

and more voice over Wi-Fi, plus ultramobile terminals, users don't want to break that link just because they go into a hallway.”

The MIMO technology leverages the obstacles in the environment to make the signal stronger. MIMO has a two-by-two, three-by-three or four-by-four configuration, with two, three or four completely independent radios operating on the same frequency channel, with the assumption that there are multiple paths a signal can take between AP and client due to reflections in the RF environment caused by doors, walls, furniture and the like. The paths are uncorrelated, so different transmissions take different pathways, and the signals don’t bump into each other. Instead, what you get is a much more efficient, and redundant, transmission system. “The MIMO technology means the APs are capable of picking up more signals more reliably, even if those signals are weaker,” explained Tennefoss. “So you can get better performance out of a/b/g devices.”

That becomes especially important when VoIP is involved. “If you have clients only running b/g, that's fine,” said Roy. “The value of .11n with MIMO is that voice quality becomes much better. We've seen the increase in quality not just by measurements, but you can actually notice it with the ear. Sometimes with a/b/g you can hear clicks, especially when roaming from one AP to another.”

Security is another aspect partners should be able to talk about fluently. “As you start migrating more and more voice and data traffic to all-wireless, chances are you’ll be encrypting that traffic via WPA2,” said Tennefoss. “So the architecture and encryption processing become limiting factors as far as all-over performance. So, you’ll need to design and test for high-performance encryption throughput.”

Understanding the different options in architecture is another requirement. “In terms of architecture, the thin AP with a controller was really winning the race,” said Roy. “But now the traffic could increase by five or six times, so you have to ask if it makes sense to bring all the traffic back to the controller. You could have a hybrid approach, where you tunnel some traffic to the controller, and also bridge some traffic locally on the AP. It will depend on a case-by-case basis.”

For instance, a company might want to tunnel voice traffic for seamless roaming. But video is a more portable application, so one could locally bridge that traffic. “You have to look at the reasons and value when it comes to architecture,” Roy said. “Are you going to dedicate a 10GigE backbone just to bring that traffic back to the controller? That's egregious, especially in recessive times.”

Davis-Felner said 802.11n represents an industry bellwether. “It’s a turning point,” she said. “The enterprise is becoming increasingly wireless and mobile. Ands fits that trend. People will be doing a lot more and a lot more effectively over the WLAN.”