11n channel width

[Johann Hugo]

On Monday 22 October 2012 16:09:50 you wrote:
> On 22 October 2012 06:56, Johann Hugo <jhugo at meraka.csir.co.za> wrote:
> > Hi
> > 
> > What difference in throuput can one expect between ht/20 and a ht/40 ?
> 
> If you're hitting best possible circumstances? Almost 2x.
> 

Is this more or less the troughput what one should expect:

a/20	= 	29.7 Mbits/sec
ht/20	= 	40.6 Mbits/sec
ht/40	= 	44.1 Mbits/sec

HW = gateworks ARM
OS = FreeBSD 10.0-CURRENT (from 2012/10/11)
Build = arm-10-20121011
Wifi = RouterBOARD R52nM = AR9220

*****************************************************************************

mesh-1d04:~ # ifconfig wlan1 channel 28:a/20
mesh-1d04:~ # ifconfig wlan1
wlan1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
        ether 00:0c:42:6c:61:91
        inet 10.50.50.1 netmask 0xffffff00 broadcast 10.50.50.255 
        inet6 fe80::20c:42ff:fe6c:6191%wlan1 prefixlen 64 scopeid 0x8 
        inet6 fde4:7b85:9218:10:20c:42ff:fe6c:6191 prefixlen 64 
        nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
        media: IEEE 802.11 Wireless Ethernet autoselect mode 11a <hostap>
        status: running
        ssid testAP channel 28 (5140 MHz 11a) bssid 00:0c:42:6c:61:91
        regdomain NONE country ZA ecm authmode OPEN privacy OFF txpower 17
        mcastrate 6 mgmtrate 6 scanvalid 60 wme burst dtimperiod 1 -dfs
mesh-1d04:~ # iperf -c 10.50.50.2
------------------------------------------------------------
Client connecting to 10.50.50.2, TCP port 5001
TCP window size: 32.5 KByte (default)
------------------------------------------------------------
[  3] local 10.50.50.1 port 31219 connected with 10.50.50.2 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec  35.5 MBytes  29.7 Mbits/sec

*****************************************************************************

mesh-1d04:~ # ifconfig wlan1 channel 28:a/20
mesh-1d04:~ # ifconfig wlan1
wlan1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
        ether 00:0c:42:6c:61:91
        inet 10.50.50.1 netmask 0xffffff00 broadcast 10.50.50.255 
        inet6 fe80::20c:42ff:fe6c:6191%wlan1 prefixlen 64 scopeid 0x8 
        inet6 fde4:7b85:9218:10:20c:42ff:fe6c:6191 prefixlen 64 
        nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
        media: IEEE 802.11 Wireless Ethernet autoselect mode 11na <hostap>
        status: running
        ssid testAP channel 28 (5140 MHz 11a ht/20) bssid 00:0c:42:6c:61:91
        regdomain NONE country ZA ecm authmode OPEN privacy OFF txpower 17
        mcastrate 6 mgmtrate 6 scanvalid 60 ampdulimit 64k ampdudensity 8
        shortgi wme burst dtimperiod 1 -dfs
mesh-1d04:~ # iperf -c 10.50.50.2
------------------------------------------------------------
Client connecting to 10.50.50.2, TCP port 5001
TCP window size: 32.5 KByte (default)
------------------------------------------------------------
[  3] local 10.50.50.1 port 53324 connected with 10.50.50.2 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.1 sec  48.8 MBytes  40.6 Mbits/sec

*****************************************************************************

mesh-1d04:~ # ifconfig wlan1 channel 28:ht/40
wlan1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
        ether 00:0c:42:6c:61:91
        inet 10.50.50.1 netmask 0xffffff00 broadcast 10.50.50.255 
        inet6 fe80::20c:42ff:fe6c:6191%wlan1 prefixlen 64 scopeid 0x8 
        inet6 fde4:7b85:9218:10:20c:42ff:fe6c:6191 prefixlen 64 
        nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
        media: IEEE 802.11 Wireless Ethernet autoselect mode 11na <hostap>
        status: running
        ssid testAP channel 28 (5140 MHz 11a ht/40-) bssid 00:0c:42:6c:61:91
        regdomain NONE country ZA ecm authmode OPEN privacy OFF txpower 17
        mcastrate 6 mgmtrate 6 scanvalid 60 ampdulimit 64k ampdudensity 8
        shortgi wme burst dtimperiod 1 -dfs

mesh-1d04:~ # iperf -c 10.50.50.2
Client connecting to 10.50.50.2, TCP port 5001
TCP window size: 32.5 KByte (default)
------------------------------------------------------------
[  3] local 10.50.50.1 port 26303 connected with 10.50.50.2 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.1 sec  52.9 MBytes  44.1 Mbits/sec

Johann