Re: [gentoo-user] Wireless: Limit rate to strengthen connection?

[Florian Philipp]

On Thu, 2008-03-27 at 20:42 -0400, Richard Marzan wrote:
> On Wed, 2008-03-26 at 19:52 -0700, Grant wrote:
> > > >  > >  > I'm trying to strengthen a wireless connection that spans about 150
> > >  >  > >  > feet and has to go through about 5 walls.  I bought two of these:
> > >  >  > >  >
> > >  >  > >  > http://www.newegg.com/Product/Product.aspx?Item=N82E16833164110
> > >  >  > >  >
> > >  >  > >  > for either end of the connection, but I'm having trouble making it
> > >  >  > >  > work well.  I've noticed the connection will be perfect for a short
> > >  >  > >  > time, but then disappear.  When watching iwconfig during this process,
> > >  >  > >  > it looks like the connection is good when on a low rate, but when it
> > >  >  > >  > goes to 54 Mbps it falls apart.
> > >  >  > >  >
> > >  >  > >  > Should limiting the rate solve this problem?  If so, how can I do
> > >  >  > >  > that?  I'm using hostapd on the AP and wpa_supplicant on the client.
> > >  >  > >  >
> > >  >  > >  > - Grant
> > >  >  > >
> > >  >  > >  Grant,
> > >  >  > >
> > >  >  > >  Yes, lowering the rate to a "slower" speed will help greatly.  The lower
> > >  >  > > rates use less compression and modulation... less complex wave forms
> > >  >  > > better connects over long hauls.
> > >  >  > >
> > >  >  > >  The antennas look very good, but what's driving them? I use and whole
> > >  >  > >  heartedly endorse SENAO products and have had very good luck with these
> > >  >  > >  models:   ECB-3220 (400 mw) or 2611CB3 PLUS (200 mw) at:
> > >  >  > >  http://www.wlansolution.com. Either unit with the high gain antennas you
> > >  >  > >  have,  will penetrate what you stated and probably go pretty high on the
> > >  >  > >  speed scale doing it too.
> > >  >  >
> > >  >  > I'm using a Netgear PCI adapter on the AP and an Edimax USB adapter on
> > >  >  > the client.  Do you know how I can limit the rate?  Should it be done
> > >  >  > on the Gentoo AP or the client?
> > >  >  >
> > >  >  > - Grant
> > >  >
> > >  >  I use wireless-tools from portage. In it is iwconfig. A simple man iwconfig
> > >  >  will show you what you need. Other thing you could do is configure the
> > >  >  Wireless AP for a fixed rate... works for me.
> > >
> > >  I found this:
> > >
> > >  rate_wlan0=( "5.5M" )
> > >
> > >  which isn't documented in net.wireless, but it doesn't seem to have
> > >  any affect.  I've tried it on the router and the client which uses
> > >  wpa_supplicant.  I still see the rate on the client fluctuate all the
> > >  way up to 54 Mb/s in the output from iwconfig.  The router's rate is
> > >  always reported as 0 kb/s.
> > >
> > >  - Grant
> >
> > It appears 'iwconfig wlan0 rate 11M' works (at least as far as the
> > output from iwconfig is concerned) but how can I set /etc/conf.d/net
> > to always use this rate?
> >
> > - Grant
>
> The best way I found to do this is to just write your own script and run
> it at the default runlevel. write a script called wireless-up save it in
> your /root directory. Then in /etc/conf.d/local.start add the script
> name to the list: /root/wireless-up. Make sure the script is executable
> with chmod 666 /root/wireless-up. Here is what mine looks like. I laugh
> when I read this thing that I call a script. I'll be upgrading this in
> the future but for now maybe someone has a better idea and/or script.
>
> #!/bin/bash
> DATE=`date +%m_%d_%Y`
> ifconfig wlan0 up || "echo wlan up failed"
> iwconfig wlan0 essid ACCESSPOINTNAME || "echo setting essid failed"
> iwconfig wlan0 mode Managed || echo "setting mode to managed failed"
> iwconfig wlan0 key restricted YOURKEYHERE || echo "key failed
> verification"
> dhclient wlan0 || echo "wlan0 failed to receive dhcp request response"
> # if [ $DATE -ne `date +%m_%d_%Y -r /tmp/.wireless.*
> rm /tmp/.wireless.*
> iwconfig >> /tmp/.wireless.$DATE
> exit 0
>
>
>

For custom scrips, you can add a preup, failup or postup-function
to /etc/conf.d/net, there should be examples in the file.

Something like

pastup() {
      if [[ ${IFACE} = "wlan0" ]]; then
              iwconfig [...]
      fi
      return 0
}

should work.