Difficulties with settings 802.11 b/g/n

Hello guys, at this point, I'm starting to have too many entries in my /etc/config/wireless.

My goal, is set 802.11n as default (and only available) standard for wireless comunication. I ignore 802.11ac because device has no 802.11ac support.
Now lets see what I have.

option hwmode '11n'
option require_mode 'n'
option legacy_rates '0'
option greenfield '1'

hwmode "Selects the wireless protocol to use", now I have 802.11n, right?
require_mode "Set the minimum mode that connecting clients need to support to be allowed to connect.", so I have "n"
legacy_rates "Setting legacy_rates to 0 disables 802.11b data rates." [1]
greenfield "Receive Greenfield - treats pre-80211n traffic as noise."

Maybe it's time to think little bit about simpler solution with one variable. If there is reason to have all these variables alongside, it's not clear to (I'd say advanced) end-users like me.

[1] https://git.lede-project.org/?p=source.git;a=commitdiff;h=e194e1b3c838a301178effb639804c28fe67354d
UPDATE - added "greenfield"

hwmode has nothing to do with the version of 802.11. it has to do with what kind of modulation is used. 11b = OFDM and 11g = TDMA.

It should be set to 11a if 5ghz or 11g if 2.4ghz.

edit: yeah I think you only need require_mode.

FYI 802.11b uses DSSS