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Ok, I'm trying to get my post count up.


I have a theory on the secret sauce that is used by Extricom and their like-technology competitors.

You must have your full concentration to listen to this next piece of rambling. :)

- The controller controls all functions of the AP's.
- The controller knows which AP's can hear each other.
- The controller knows which AP's can hear which client STA's

Now, imagine this. AP1 send a CTS-to-Self frame with enough duration for: SIFS+DATA+SIFS+ACK+SIFS+DATA+SIFS+ACK+SIFS+DATA+SIFS+ACK.
If you followed that, there are three data frames, three ACKS and SIFS. Notice the absence of DIFS and arbitration.

So, that is the value of the CTS frame. Here is what happens in order: (remember, this is theory but completely plausible)

AP1 send CTS-to-Self
AP1: SIFS+DATA - receiving STA1: SIFS+ACK
AP2: SIFS+DATA - receiving STA2: SIFS+ACK
AP3: SIFS+DATA - receiving STA3: SIFS+ACK

So, what have we accomplished? We have not waited a DIFS, which is longer than a SIFS. We have not had to arbitrate (which can take a while too). This saves a lot of overhead.

If you are good with OmniPeek and know the protocol, this could actually be confirmed with the Delta Time feature which tells you the amount of time that has passed since the last frame.

Ok, this may not be what is going on but if it isn't, it is a way to save on overhead and make 802.11 faster. Remember, you (may have) heard it here first. :)

Gene