• Where does the term "Greenfield" come from (per the WOTD, specifically HT-greenfield format (11n))?  Is it named after a person? Or is it in reference to something else? 

  • It is covered in the CWNA training in Chapter 11 in the slidedeck (

    What it means is to run the network only in .11n mode with .11n clients

    (e.g. configure the AP Basic rates setting to MCS index only  like MCS 0-7) your AP will beacon at 6.5 Mpbs rates

    (thus only .11n clients can connect). 

    From experience running classes not every client adapter supports it, some can, some cannot connect,

    For backwards compatibility a lower datarate is used like 6 Mbps (or any other configurable value), but it means

    the AP is switching between modulation modes  (e.g. OFDM and HT-OFDM).

    There are 3 other operation modes, the most common one is "Mixed Mode" to support all kind of clients.

    My personal view is that if all clients support .11n and can connect is to move to Greenfield mode for better

    throughput and performance.  The training material has a good slide about the difference in the L-SIG and HT-SIG




  • Not a reference to anyones name.   Just a (marketting ?) indicator for 802.11n ONLY mode  (ie. no a/b/g packets allowed).

    I don't think there was much real impetus for anyone to actually use it.   It automatically made all the older rates unusable. 

    Only 17% of all WFA 802.11n Certified devices ever had it, and only 3% of the 902.11ac dual n/ac certified devices have it.

    It is not mentioned in the 802.11ac standard.

  • Thanks for the reply.  I should have clarified that I knew it was an "exclusive" mode for 802.11n--that being said, Greenfield suggested to me that it was named after some unsung hero in the world of 802.11. 

    If it was for marketing reasons, it almost sounds like folks wrote down something, threw it in a hat, and had somebody randomly draw it out; figuring it had to be called something.

    Also, did not realize that most of the WFA devices you listed did not implement the option when certified.

    Thanks to the both of you for responding promptly.

  • There were even less credible factors, than "picked from a hat", in the creation of the original WEP standard.

  • Hi

    In the real estate market, when you have a "Greenfield" project, it means that you have an area of land where nothing has been built. It comes from the concept of having ( literally ) a "green field" of land. In other words, an empty space with no other buildings.

    With 802.11n, we can imagine the "airspace" as being the "green field" with nothing in it. Instead of not having buildings, we do not have 802.11a,b.g STA's etc.


  • Best answer yet Dave !

    Always glad to get your input.

  • Tks, Howard


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