On Wed, Dec 19, 2012 at 3:20 PM, George News [off-list ref] wrote:

Hi all,

I'm using Ubuntu 12.04.1 64bit with a TPLink TL-WN821 v3. The driver used is
ath9k_htc. I'm creating an adhoc/ibss network and want to change the bitrate
of the network.

First of all I disable wireless from the network manager in order to be able
to execute my commands.

These are the commands I execute on both ends:

        master$ sudo ifconfig wlan0 down
        master$ sudo rfkill unblock wifi
        master$ sudo iw dev wlan0 set type ibss
        master$ sudo iw dev wlan0 set bitrates legacy-2.4 1
        master$ sudo ifconfig wlan0 up
        master$ sudo iw dev wlan0 ibss join adhoc_linux 2462
        master$ sudo ifconfig wlan0 1.2.3.4 up
        master$ iperf -s -u -l 1472

        slave$ sudo ifconfig wlan0 down
        slave$ sudo rfkill unblock wifi
        slave$ sudo iw dev wlan0 set type ibss
        slave$ sudo iw dev wlan0 set bitrates legacy-2.4 1
        slave$ sudo ifconfig wlan0 up
        slave$ sudo iw dev wlan0 scan | less
        slave$ sudo iw dev wlan0 ibss join adhoc_linux 2462
        slave$ sudo ifconfig wlan0 1.2.3.5 up
        slave$ iperf -c 1.2.3.4 -u -b 100M -l 1472 -t 25 -i 1

As you can see I want to set the speed to 1 Mbps. However I don't know why I
get 25Mbps from iperf which is more or less the maximun speed for 802.11g
(theoretically 54Mbps but in reality is something like 30Mbps).

The output of `iw dev wlan0 station dump` reports that both nodes are
attached to the same network at 54Mbps.

After testing that I have also tried with another command:

$ sudo iw dev wlan0 ibss join adhoc_linux 2462 basic-rates 1

But I got the same result.

make sure you get this issue with the updated firmware and
driver(compat wireless)
would be best to see the packet rate by observing the ping packets in
a standalone sniffer.

I have tried many many things, putting the iface up, down, leaving the ibss
net, setting the speed while iface up, etc. I'm just stuck.

Any help is more than welcome.

Jorge


P.S.: Please include my email address in the reply as I'm not subscribed to
the list and otherwise I won't be receiving the answer.
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-- 
thanks,
shafi