AR9280: very strange upload speed

[Lev Serebryakov]

Hello, Adrian.
You wrote 30 октября 2011 г., 22:15:55:


>  It is AR9280, HostAP, 802.11ng mode, ht/20 channel, 802.11g client
> (only one).
  And speed of upload is very low and unstable. iperf in TCP mode (I
could not find proper combination of keys to force iperf to show real
UDP speed every N seconds) with large windows, Wireless client in
server mode (sends) and wired computer in client mode (receives):

http://lev.serebryakov.spb.ru/wifi/ap-ar9280-802.11ng-ht20-11g-client-wireless2wired-tcp-10sec-window.png

X is seconds from start of experiment, Y is speed in 10 seconds window
(-i 10 key for iperf) in Kbit/s. Speed is oscillate between 400Kbit
and 3Mbit... Please note: 3Mbit, not MegaBYTE!

  If window is 1 second (-i 1) there will be a lot of ZERO samples!

  Speed in other direction (wireless client and wired server) shows
almost stable 10 Mbits/s (not ideal, but much better)...

# ifconfig wlan0
wlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
        ether f4:ec:38:a3:10:6d
        inet6 fe80::f6ec:38ff:fea3:106d%wlan0 prefixlen 64 scopeid 0xc
        inet6 2001:470:923f:2::1 prefixlen 64
        inet 192.168.135.1 netmask 0xffffff00 broadcast 192.168.135.255
        nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
        media: IEEE 802.11 Wireless Ethernet autoselect mode 11ng <hostap>
        status: running
        ssid home.serebryakov.spb.ru channel 9 (2452 MHz 11g ht/20) bssid f4:ec:38:a3:10:6d
        regdomain ROW country RU indoor ecm authmode WPA2/802.11i
        privacy MIXED deftxkey 2 AES-CCM 2:128-bit AES-CCM 3:128-bit
        txpower 30 scanvalid 60 protmode CTS -ampdutx ampdurx ampdulimit 64k
        ampdudensity 8 shortgi wme burst dtimperiod 1 -dfs
# ifconfig wlan0 list sta
ADDR               AID CHAN RATE RSSI IDLE  TXSEQ  RXSEQ CAPS FLAG
00:18:de:08:e8:1d    1    9  54M 19.5    0  13624  51824 EPS  AQE     RSN WME

-- 
// Black Lion AKA Lev Serebryakov <lev at FreeBSD.org>