• Could you please let me know the MCS table for 11AC ?

    What is the significance of MCS 8 and 9 ?

  • By Howard - edited: March 8, 2019

    Aruba says:

    "The MCS 8 and MCS 9 rates are new and enabled by advances in chip technology. MCS 9 is not applicable to all channel width/spatial stream combinations."

    From their whitepaper at:

  • It's worth getting hold of a copy of the Matthew Gast 802.11ac book to find out more about the standard.

    Here is an extract in Google books which details what your after I believe:


  • Rashmi,

    I should have noted that VHT MCS 8 & 9 both use QAM-256.   Just guessing, I would bet these both have ridiculously high SNR requirements.

  • I didn't follow the links; I hope this is not redundant.

    MCS 8 and 9 are also different in that they are optional.  Only 0 - 7 are required.

    There are some combinations of modulation, coding, and channel width that don't work.  It isn't just MCS9 with 256-QAM.

    I highly recommend Gast's book.  In fact, I recommend all of them.

    @Howard  Gast says 256-QAM requires about 5dB more signal than 64-QAM.  I vaguely remember the IEEE saying that it was more like 6, but I have no idea where.  Gast also says that we should get a one to two dB increase from LDPC, which is also optional.

  • Thanks all

  • If you understand the basics on modulation and coding, here is a great resource many overlook

  • I literally have no Idea about as I have started my study abroad education recently.

    I just got it here-->

  • By Howard - edited: March 8, 2019


    Thanks for the nicely laid out MCS table.

    Back in the day, I used to keep all this data in my head.  Anymore, I find that exercise absurd.   The tables are so large, so many values are non-integers or "N/A's", and with redundancies all over it's a waste of time for me to try.   That's what books are for I guess.

    They don't even give you a handy-dandy, easy to remember, formula anymore.

    For lack of column space, many reporting tools truncate their table entries, and since some drivers only report the maximum possible,  rather than the current running rate, it's impossible to figure out what's actually happening.

    On top of all that, I bet if you actually mapped the rates used in a facility, over a week's time, that some AP's/clients never use all the possible rates - because incremental differences aren't worth the time or effort to dynamically change them.  

    With some chip sets a products "horse power" is often a big problem, especially in handheld products, and they don't have the luxury to try all the possibilities.

    What a great excuse to bury a products limitations in its "secret sauce".

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