Gigabit WiFi with SPR & The 4x4 MT7915

Intro

In this post we'll cover how to configure hostapd with the mt7915 to run 160 MHz channels over 5ghz. This allows stations to break gigabit speeds for WiFi with only 2 spatial streams.

Requirements

• A 160Mhz capable card on the SPR device, for example AsiaRF's AW7915-NP1
• 160MHz capable client wifi card, such as Intel's AX210. Intel's AX201 and AX200 also have 160Mhz support for 5ghz.

Preparation

• Set up your AP device according to the SPR Setup Guide
• For mt7915, run a mainline kernel or a kernel with fixes from https://github.com/openwrt/mt76 and the latest firmware. I'll publish some updates to building SPR with these in the near future. Fixes are needed for DFS support.

Hostapd configuration

1. Modify config/wifi/hostpad.conf
2. Make sure vht_capab includes [VHT160] and [SHORT-GI-160]
3. Make sure to set vht_oper_chwidth/he_oper_chwidth set to 2.
4. For the channel configuration, the following are valid 160mhz centers on 5ghz: [50, 114, 163]. Set the vht/he_oper_centr_freq_seg0_idx to these values and the channel to the center value - 14.
5. Set ieee80211ax to 1

ctrl_interface=/state/wifi/control
country_code=US
interface=wlan0
ssid=TestLab
hw_mode=a
ieee80211d=1
ieee80211h=1
ieee80211n=1
ieee80211ac=1
ieee80211ax=1
he_su_beamformer=1
he_su_beamformee=1
he_mu_beamformer=1
wmm_enabled=1
preamble=1
ht_capab=[LDPC][HT40+][HT40-][GF][SHORT-GI-20][SHORT-GI-40]
vht_capab=[MAX-MPDU-7991][SU-BEAMFORMEE][SU-BEAMFORMER][VHT160][RXLDPC][SHORT-GI-160][SHORT-GI-80][MAX-A-MPDU-LEN-EXP3][RX-ANTENNA-PATTERN][TX-ANTENNA-PATTERN][TX-STBC-2BY1][RX-STBC-1][MU-BEAMFORMER[[MU-BEAMFORMEE]
vht_oper_chwidth=2
he_oper_chwidth=2
channel=36
vht_oper_centr_freq_seg0_idx=50
he_oper_centr_freq_seg0_idx=50
auth_algs=1
wpa=2
wpa_key_mgmt=WPA-PSK WPA-PSK-SHA256 SAE
rsn_pairwise=CCMP

# Security parameters

# Isolate stations and per-station group keys
ap_isolate=1
multicast_to_unicast=1

# Mitigate krack attack
wpa_disable_eapol_key_retries=1

# VLAN
per_sta_vif=1

# Passwords

sae_psk_file=/configs/wifi/sae_passwords
wpa_psk_file=/configs/wifi/wpa2pskfile

2. Restart hostapd

root@pirouter:~/super# docker compose restart wifid

If anything has gone wrong, check the docker compose logs for the wifid service.

Perf Test

Running iperf3 on the SPR device, and iperf3 on a client with AX210 chip, we see the following:

On SPR:

iw wls6 info

Interface wls6
        ifindex 5
        wdev 0x1
        addr 00:0a:52:07:32:c9
        ssid testlab
        type AP
        wiphy 0
        channel 100 (5500 MHz), width: 160 MHz, center1: 5570 MHz
        txpower 23.00 dBm
        multicast TXQ:
                qsz-byt qsz-pkt flows   drops   marks   overlmt hashcol tx-bytes        tx-packets
                0       0       246     0       0       0       0       27114           272

iperf3 -s

On the station:

iperf3 -c 192.168.2.1

Performance results

Accepted connection from 192.168.2.26, port 56156
[  5] local 192.168.2.1 port 5201 connected to 192.168.2.26 port 56158
[ ID] Interval           Transfer     Bitrate                                                         
[  5]   0.00-1.00   sec   139 MBytes  1.17 Gbits/sec                   
[  5]   1.00-2.00   sec   126 MBytes  1.06 Gbits/sec                  
[  5]   2.00-3.00   sec   141 MBytes  1.18 Gbits/sec                  
[  5]   3.00-4.00   sec   137 MBytes  1.15 Gbits/sec                  
[  5]   4.00-5.00   sec   152 MBytes  1.27 Gbits/sec                  
[  5]   5.00-6.00   sec   153 MBytes  1.28 Gbits/sec                  
[  5]   6.00-7.00   sec   155 MBytes  1.30 Gbits/sec                  
[  5]   7.00-8.00   sec   148 MBytes  1.24 Gbits/sec                  
[  5]   8.00-9.00   sec   145 MBytes  1.21 Gbits/sec                  
[  5]   9.00-10.00  sec   119 MBytes   995 Mbits/sec                                                  
[  5]  10.00-10.00  sec   482 KBytes  1.22 Gbits/sec