• Hello all, 

    Question 11 of the chapter 19 in the new CWNA-106 guide (kindle version) asks about what technologies are part of explicit beamforming. One of the options given is channel sounding. However, after checking the answers in the appendix-A channel sounding has not been included as a valid one. Am I skipping anything? Or is it because channel sounding is the name of the process more than a technology itself?

    Any comment is more than welcome


  • This is a terribly late reply.  I'm writing for the benefit of searchers and lurkers.

    Explicit beam forming is the process of two devices getting together to figure out how the sender (beamformer) can best transmit to the receiver (beamformee.)  The receiver analyzes the transmission and puts together a report (I've seen them called CSI, steering feedback, and a feedback matrix) which it sends back to the transmitter.  The transmitter uses that information to calculate a steering matrix, which it uses to adjust its transmission radiation pattern.

    Clear Channel Assessment has to be done before transmitting.  It is the act of listening to the channel to make sure that no one else transmitting and that there is no strong background noise (which could be a non-802.11 device transmitting.)  Without a clear channel, nothing else happens.

    802.11ac: a Survival Guide by Matthew Gast has a chapter, IIRC.

    Disclaimer:  There are people here who know a lot more than me; I'm taking my CWNA in two hours.  And I haven't reread or proofed this note.  I'm avoiding doing my last minute studying :-)  

    Good luck!


  • Hi Dan, 

    Thanks for your answer!

    Yep, maybe a bit late but no worries,  I did pass my exam like 3 weeks ago, I am now into CWAP :)

    Good luck!


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