How to transmit at 80MHz with VHT

[Devin Bayer]

Hello,

I have what may be a basic question. I am trying to use 80 MHz channels for
802.11ac and my client station reports that hostapd is always transmitting at 40
MHz. My client does report it's sending at 80 MHz though.

It seems like it isn't even trying to use 80 MHz channels. There is nothing in
the log about it. My card supports WiFi 6, a Qualcomm QCA6391, so it seems like
that shouldn't be the limitation.

I can't find any information online about why this might be. My regdomain
database supports 80 MHz channels. This is what `iw reg get` shows:

> global
> country US: DFS-FCC
> 	(2400 - 2483 @ 40), (N/A, 30), (N/A)
> 	(5150 - 5250 @ 80), (N/A, 23), (N/A), AUTO-BW
> 	(5250 - 5350 @ 80), (N/A, 23), (0 ms), DFS, AUTO-BW
> 	(5470 - 5730 @ 160), (N/A, 23), (0 ms), DFS
> 	(5730 - 5850 @ 80), (N/A, 30), (N/A)
> 	(57240 - 71000 @ 2160), (N/A, 40), (N/A)
> 
> phy#0 (self-managed)
> country US: DFS-FCC
> 	(2402 - 2472 @ 40), (6, 30), (N/A)
> 	(5170 - 5250 @ 80), (6, 24), (N/A), AUTO-BW
> 	(5250 - 5330 @ 80), (6, 24), (0 ms), DFS, AUTO-BW
> 	(5490 - 5730 @ 160), (6, 24), (0 ms), DFS, AUTO-BW
> 	(5735 - 5835 @ 80), (6, 30), (N/A), AUTO-BW
> 

Here is my complete config:

> ssid=box
> hw_mode=a
> channel=149
> 
> vht_oper_chwidth=1
> vht_oper_centr_freq_seg0_idx=155
> 
> wpa=2
> wpa_passphrase=xxxxxxxx
> wpa_key_mgmt=WPA-PSK
> wpa_pairwise=CCMP
> rsn_pairwise=CCMP
> 
> country_code=US
> logger_stdout=-1
> logger_stdout_level=2
> interface=wlan0
> driver=nl80211
> 
> ieee80211n=1
> ht_capab=[LDPC][RX-STBC1][HT40+][SHORT-GI-20][SHORT-GI-40][DSSS_CCK-40][MAX-AMSDU-7935]
> 
> ieee80211ac=1
> vht_capab=[RXLDPC][SHORT-GI-80][TX-STBC-2BY1][SU-BEAMFORMER][SU-BEAMFORMEE][MU-BEAMFORMEE][MAX-A-MPDU-LEN-EXP3][RX-ANTENNA-PATTERN][TX-ANTENNA-PATTERN][RX-STBC-1]
> 
> ieee80211ax=1
> he_su_beamformer=1
> he_su_beamformee=1
> he_mu_beamformer=1
> 
> wmm_enabled=1
> uapsd_advertisement_enabled=1
> 
> wmm_ac_bk_cwmin=4
> wmm_ac_bk_cwmax=10
> wmm_ac_bk_aifs=7
> wmm_ac_bk_txop_limit=0
> wmm_ac_bk_acm=0
> wmm_ac_be_aifs=3
> wmm_ac_be_cwmin=4
> wmm_ac_be_cwmax=10
> wmm_ac_be_txop_limit=0
> wmm_ac_be_acm=0
> wmm_ac_vi_aifs=2
> wmm_ac_vi_cwmin=3
> wmm_ac_vi_cwmax=4
> wmm_ac_vi_txop_limit=94
> wmm_ac_vi_acm=0
> wmm_ac_vo_aifs=2
> wmm_ac_vo_cwmin=2
> wmm_ac_vo_cwmax=3
> wmm_ac_vo_txop_limit=47
> wmm_ac_vo_acm=0
> 
> tx_queue_data3_aifs=7
> tx_queue_data3_cwmin=15
> tx_queue_data3_cwmax=1023
> tx_queue_data3_burst=0
> tx_queue_data2_aifs=3
> tx_queue_data2_cwmin=15
> tx_queue_data2_cwmax=63
> tx_queue_data2_burst=0
> tx_queue_data1_aifs=1
> tx_queue_data1_cwmin=7
> tx_queue_data1_cwmax=15
> tx_queue_data1_burst=3.0
> tx_queue_data0_aifs=1
> tx_queue_data0_cwmin=3
> tx_queue_data0_cwmax=7
> tx_queue_data0_burst=1.5
> 
> ieee80211d=1
> ieee80211h=1
> 
> ap_max_inactivity=10
> utf8_ssid=1
> ctrl_interface=/run/hostapd

A log of a sample session is here:

https://gist.github.com/akvadrako/2fa6ab0588ff3a10c8a41b0b20ace128

If anyone has some pointers, I would be grateful.

~ dev