Rtl8187 wireless

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Revision as of 11:00, 22 May 2013 by Opt1mus (Talk | contribs) (Lowering the rate: spelling, grammar)

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This page describes how to get the rtl8187 wifi-driver working

The rtl8187 chip is made for usb-cards/dongles. It supports 802.11(a)/b/g and the following encryptions: WEP, WPA and WPA2. The rtl8187 driver is in the kernel now.

Using the driver

Make sure that you have loaded the rtl8187 module with

# modprobe rtl8187

Then run

# dmesg | grep rtl8187
You should see some output like this
 usbcore: registered new interface driver rtl8187 

If you see that line everything should be OK

If everything is right, you should have two new interfaces: wlan0 and wmaster0 If you do not see wlan0 just run

# ip link set dev wlan0 up

To list all available wifi-networks just run

# iw dev wlan0 scan 

For more information about configuring your wifi-network see here: Wireless management.

What to do if your connection always times out?

The open source driver suffers from a lot of tx excessive retries and invalid misc errors for some unknown reason, resulting in a lot of packet loss and it keeps disconnecting, some times instantly.

Lowering the rate

The solution can be found in this thread: https://bbs.archlinux.org/viewtopic.php?pid=299642

Just set the rate to 5.5

iwconfig wlan0 rate 5.5M auto

Fixed option should ensure that it doesn't change the rate on its own, thus making the connection a bit more stable:

iwconfig wlan0 rate 5.5M fixed 

Alternativelly find the $POST_UP option and append the above options to your profile config file:

POST_UP="iwconfig wlan0 rate 5.5M fixed"

Try various rates until you get the optimal setting, with no disconnection. In this case 12Mbits, as shown below:

POST_UP="iwconfig wlan0 rate 12M fixed"

Now calling;

netfcg2 -c <wireless profile>

or

  netcfg-menu 

and choosing your profile works without extra commands.

Lowering the txpower

You can try lowering the transmit power as well. This may save power as well:

iwconfig wlan0 txpower 5

or even as low as 0. Valid settings are from 0 to 20, auto and off for the stock kernel driver.

Setting rts and fragmentation thresholds

Default iwconfig options have rts and fragmentation thresholds off. These options are particularly useful when there are many adjacent APs or in a noisy environment.

The minimum value for fragmentation value is 256 and maximum is 2346. In many windows drivers the maximum is the default value:

iwconfig wlan0 frag 2346

For rts minimum is 0, maximum is 2347. Once again windows drivers use maximum as the default:

iwconfig wlan0 rts 2347

See also