Force mode 802.11 for station using wpa_supplicant

Vu Hai NGUYEN vh.nguyen
Fri Jul 11 01:51:50 PDT 2014

>>> Hi all,
>>> I wonder if we can use wpa_supplicant to force mode 802.11 for a station when it connects to an AP.
>>> For example my AP using hostapd and was set up in 802.11ac VHT80, channel 36.
>>> Normally all the device support 802.11n can connect to that AP too.
>>> But because the wifi module in my station is the same as my AP and they are all support 802.11ac so
>>> if I set up the channel 36 for my station it connect automatically with my AP in mode 802.11ac VHT80.
>>> Is there any way that I can force my station to connect to my AP in mode 802.11n HT20 or HT40?
>>> I don't see any parameter in the configuration file of wpa_supplicant that allow me to do this.

>> If I set the parameter "disable_vht=1" in the configuration file of wpa_supplicant, my station can connect in
>> mode 802.11nHT40  with my AP (set up in 802.11ac VHT80).
>> Then I add "disable_ht40=1", but my Station still connects to my AP in mode 802.11n HT40 (I verify this
>> by checking bandwidth and rate report from command "iw").
>> I added "disabled_ht20" but this did not create any effect too. Any one gets the same issue like me?
>> Here is an example of my configuration file for wpa_supp:

>Try listing a set of rates that are acceptable, and only put in 802.11b rates?

Thank you for your response, did you mean this parameter  in the config file of wpa? 

# ht_mcs:  Configure allowed MCS rates.
#  Parsed as an array of bytes, in base-16 (ascii-hex)
# ht_mcs=""                                   // Use all available (default)
# ht_mcs="0xff 00 00 00 00 00 00 00 00 00 "   // Use MCS 0-7 only
# ht_mcs="0xff ff 00 00 00 00 00 00 00 00 "   // Use MCS 0-15 only 

But both 802.11nHT40 and HT20 can be config from MCS0 to 23 (I have 3 streams) 
so what can it makes the different?

802.11b work in 2.4Ghz band while my AP is set up in 802.11ac VHT80 I guess this is
not compatible, right?

Route de Mayres - B.P. 9

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