Do all of my WiFi clients “dumb down” to the speed of the lowest speed client? No, not exactly. WiFi is a broadcast medium, meaning only 1 “station” (AP or client) can talk at one time. Even if a client is not in range of another client, but both are in range of an AP. Collisions can occur and that’s what CSMA/CA helps with.
As a client moves AWAY from an AP, the signal strength goes down. That, combined with the ever-present noise, means your “Signal to Noise Radio” (SNR) goes down. Connecting at high data rates requires a minimum quality level. Like MODEMS with noisy phone lines, if the AIR is dirty, we need to stay connected to our AP, so we decrease our data rate.
WHAT??? It means we T A L K S L O O O O W W W E E E R R R R.
If ony one client can talk, and one of them talks SLOW, that leaves less time for the fast talkers to talk fast.
ENTER OUR HERO: Explicit BeamForming (aka ClientLink)
There’s 2 types of BeamForming. Explicit, which we will talk about, and Implicit, which is PART OF THE 802.11n STANDARD! Trouble is, it’s an optional component and NO CLIENT VENDORS support it!
Explicit BeamForming is cool because it solves the RIGHT PROBLEM. Normally data is served TO THE CLIENT, not the client serving data to the network (unless you’re a surveillance camera).
BeamForming provides a higher SNR allowing the client to stay connected at a higher data rate. This does NOT make your coverage area bigger, but it paints your coverage area with more green.
ALL CISCO AIRONET 802.11n AP’S HAVE ClientLink!!! It’s just part of what you get and is yet another thing that sets Cisco apart from the rest.
Want to see a better video that describes it better? https://www.youtube.com/watch?v=rP3ggDP_Ero