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Old 02-12-2011, 02:12 PM
mike cloaked
 
Default Change wireless interface "sens" value how?

I am trying to resolve some wireless issue with a laptop running F14,
and I need to change the "sens" (i.e. Sensitivity) value for the
wireless interface.

However when trying to run the following command as root it fails:

iwconfig wlan0 sens -65

gives output:
Error for wireless request "Set Sensitivity" (8B08) :
SET failed on device wlan0 ; Operation not supported.

and yet the command "man iwconfig" gives for this section:
sens Set the sensitivity threshold. This define how sensitive is the
card to poor operating conditions (low signal, interference).
Positive values are assumed to be the raw value used by the
hardware or a percentage, negative values are assumed to be dBm.
Depending on the hardware implementation, this parameter may
control various functions.
On modern cards, this parameter usually control handover/roaming
threshold, the lowest signal level for which the hardware
remains associated with the current Access Point. When the sig‐
nal level goes below this threshold the card starts looking for
a new/better Access Point. Some cards may use the number of
missed beacons to trigger this. For high density of Access
Points, a higher threshold make sure the card is always associ‐
ated with the best AP, for low density of APs, a lower threshold
minimise the number of failed handoffs.
On more ancient card this parameter usually controls the defer
threshold, the lowest signal level for which the hardware con‐
siders the channel busy. Signal levels above this threshold make
the hardware inhibits its own transmission whereas signals
weaker than this are ignored and the hardware is free to trans‐
mit. This is usually strongly linked to the receive threshold,
the lowest signal level for which the hardware attempts packet
reception. Proper setting of these thresholds prevent the card
to waste time on background noise while still receiving weak
transmissions. Modern designs seems to control those thresholds
automatically.
Example :
iwconfig eth0 sens -80
iwconfig eth0 sens 2

So the command should work according to the man command section above.

Can someone tell me if there is some workaround for this or is this a bug?

I have already reported as https://bugzilla.redhat.com/show_bug.cgi?id=677008

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Old 02-12-2011, 02:30 PM
mike cloaked
 
Default Change wireless interface "sens" value how?

On Sat, Feb 12, 2011 at 3:12 PM, mike cloaked <mike.cloaked@gmail.com> wrote:
> I am trying to resolve some wireless issue with a laptop running F14,
> and I need to change the "sens" (i.e. Sensitivity) value for the
> wireless interface.
>
> However when trying to run the following command as root it fails:
>
> iwconfig wlan0 sens -65
>
> gives output:
> Error for wireless request "Set Sensitivity" (8B08) :
> * * SET failed on device wlan0 ; Operation not supported.
>

I had some private exchanges with another Fedora user - who suggested
that the driver for this card may not support changing sens!

I tested a different laptop with different wireless card:

03:03.0 Network controller: Intel Corporation PRO/Wireless 2200BG
[Calexico2] Network Connection (rev 05)

[root@lapmike2 ~]# lsmod|grep ipw
ipw2200 116546 0
libipw 21037 1 ipw2200
cfg80211 110951 2 ipw2200,libipw
lib80211 4107 3 lib80211_crypt_ccmp,ipw2200,libipw

For that laptop I can change the value of sens!

So I suppose that for the netbook it will not be possible to achieve
what I needed and only if the driver supports the sens value - I
really wish this was easier information to find!
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Old 02-12-2011, 02:48 PM
mike cloaked
 
Default Change wireless interface "sens" value how?

On Sat, Feb 12, 2011 at 3:30 PM, mike cloaked <mike.cloaked@gmail.com> wrote:

> I tested a different laptop with different wireless card:
>
> 03:03.0 Network controller: Intel Corporation PRO/Wireless 2200BG
> [Calexico2] Network Connection (rev 05)
>
> [root@lapmike2 ~]# lsmod|grep ipw
> ipw2200 * * * * * * * 116546 *0
> libipw * * * * * * * * 21037 *1 ipw2200
> cfg80211 * * * * * * *110951 *2 ipw2200,libipw
> lib80211 * * * * * * * *4107 *3 lib80211_crypt_ccmp,ipw2200,libipw
>
> For that laptop I can change the value of sens!
>

This driver seems to refuse sens values in dBm - but only as positive
numbers - so I am unsure what the appropriate value is in this case -
but it seems that if the wireless driver is able to change the sens
value and it can be set in dBm then your advice is good - however I
did not realise there was so much variation in support on the driver
side and this whole issue is a lot more complicated than I first
realised!

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Old 02-12-2011, 05:09 PM
JD
 
Default Change wireless interface "sens" value how?

On 02/12/2011 07:48 AM, mike cloaked wrote:
> On Sat, Feb 12, 2011 at 3:30 PM, mike cloaked<mike.cloaked@gmail.com> wrote:
>
>> I tested a different laptop with different wireless card:
>>
>> 03:03.0 Network controller: Intel Corporation PRO/Wireless 2200BG
>> [Calexico2] Network Connection (rev 05)
>>
>> [root@lapmike2 ~]# lsmod|grep ipw
>> ipw2200 116546 0
>> libipw 21037 1 ipw2200
>> cfg80211 110951 2 ipw2200,libipw
>> lib80211 4107 3 lib80211_crypt_ccmp,ipw2200,libipw
>>
>> For that laptop I can change the value of sens!
>>
> This driver seems to refuse sens values in dBm - but only as positive
> numbers - so I am unsure what the appropriate value is in this case -
> but it seems that if the wireless driver is able to change the sens
> value and it can be set in dBm then your advice is good - however I
> did not realise there was so much variation in support on the driver
> side and this whole issue is a lot more complicated than I first
> realised!
>
I am also plagued by the same problem for rt2xxx driver.
So I opened a bug:
https://bugzilla.kernel.org/show_bug.cgi?id=28972
You might want to add your comment to this bug and report
your device and loaded wireless drivers.

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Old 02-12-2011, 08:59 PM
mike cloaked
 
Default Change wireless interface "sens" value how?

On Sat, Feb 12, 2011 at 6:09 PM, JD <jd1008@gmail.com> wrote:
> On 02/12/2011 07:48 AM, mike cloaked wrote:
>> On Sat, Feb 12, 2011 at 3:30 PM, mike cloaked<mike.cloaked@gmail.com> *wrote:
>>
>>> I tested a different laptop with different wireless card:
>>>
>>> 03:03.0 Network controller: Intel Corporation PRO/Wireless 2200BG
>>> [Calexico2] Network Connection (rev 05)
>>>
>>> [root@lapmike2 ~]# lsmod|grep ipw
>>> ipw2200 * * * * * * * 116546 *0
>>> libipw * * * * * * * * 21037 *1 ipw2200
>>> cfg80211 * * * * * * *110951 *2 ipw2200,libipw
>>> lib80211 * * * * * * * *4107 *3 lib80211_crypt_ccmp,ipw2200,libipw
>>>
>>> For that laptop I can change the value of sens!
>>>
>> This driver seems to refuse sens values in dBm - but only as positive
>> numbers - so I am unsure what the appropriate value is in this case -
>> but it seems that if the wireless driver is able to change the sens
>> value and it can be set in dBm then your advice is good - however I
>> did not realise there was so much variation in support on the driver
>> side and this whole issue is a lot more complicated than I first
>> realised!
>>
> I am also plagued by the same problem for rt2xxx driver.
> So I opened a bug:
> https://bugzilla.kernel.org/show_bug.cgi?id=28972
> You might want to add your comment to this bug and report
> your device and loaded wireless drivers.

I am unsure if the responsibility for drivers is directly kernel? Or
is there an upstream driver devel list for each of the drivers
separately? For example in my case the ath5k driver does not support
the sens parameter but the ipw2200 driver on another laptop I use does
support it but not measured in dBm but a positive integer - so it is
quite hard to know what those numbers mean in terms of the signal
level. It seems that there is wide variation in the way the drivers
were written and minimal documentation about this in an easy to access
form. Certainly you seem to have to chase up info and spend time doing
the research!

I have been getting help from the networkmanager upstream list but in
the end it looks like it is necessary to get onto whichever upstream
list corresponds to the driver for your hardware - and I have a
collection of different chipsets all having different drivers
(ipw2200, iwl3945, iwl4965, ath5k, rtl8712 which is also supported by
8912 etc)

So I think I will have to do some looking up on which the relevant
upstream list should be in each case - I guess in your case it will be
the list for the Realtek driver which is of course not full gpl! There
is an 8912 driver which is in the kmod staging tree but is not in the
mainstream kernel - though can be loaded via rpmfusion - not sure if
this will drive your device though?

Certainly there is lots to learn for sure!
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Old 02-12-2011, 09:16 PM
mike cloaked
 
Default Change wireless interface "sens" value how?

On Sat, Feb 12, 2011 at 6:09 PM, JD <jd1008@gmail.com> wrote:

> I am also plagued by the same problem for rt2xxx driver.
> So I opened a bug:
> https://bugzilla.kernel.org/show_bug.cgi?id=28972
> You might want to add your comment to this bug and report
> your device and loaded wireless drivers.

It might be worth looking through the info at
http://rt2x00.serialmonkey.com/wiki/index.php?title=Main_Page which is
where the driver for your system is documented?

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Old 02-12-2011, 09:21 PM
mike cloaked
 
Default Change wireless interface "sens" value how?

On Sat, Feb 12, 2011 at 10:16 PM, mike cloaked <mike.cloaked@gmail.com> wrote:
> On Sat, Feb 12, 2011 at 6:09 PM, JD <jd1008@gmail.com> wrote:
>
>> I am also plagued by the same problem for rt2xxx driver.
>> So I opened a bug:
>> https://bugzilla.kernel.org/show_bug.cgi?id=28972
>> You might want to add your comment to this bug and report
>> your device and loaded wireless drivers.
>
> It might be worth looking through the info at
> http://rt2x00.serialmonkey.com/wiki/index.php?title=Main_Page which is
> where the driver for your system is documented?

and the list at http://rt2x00.serialmonkey.com/phpBB/viewforum.php?f=5
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Old 02-12-2011, 10:04 PM
JD
 
Default Change wireless interface "sens" value how?

On Sat, Feb 12, 2011 at 1:59 PM, mike cloaked <mike.cloaked@gmail.com> wrote:

On Sat, Feb 12, 2011 at 6:09 PM, JD <jd1008@gmail.com> wrote:

> On 02/12/2011 07:48 AM, mike cloaked wrote:

>> On Sat, Feb 12, 2011 at 3:30 PM, mike cloaked<mike.cloaked@gmail.com> *wrote:

>>

>>> I tested a different laptop with different wireless card:

>>>

>>> 03:03.0 Network controller: Intel Corporation PRO/Wireless 2200BG

>>> [Calexico2] Network Connection (rev 05)

>>>

>>> [root@lapmike2 ~]# lsmod|grep ipw

>>> ipw2200 * * * * * * * 116546 *0

>>> libipw * * * * * * * * 21037 *1 ipw2200

>>> cfg80211 * * * * * * *110951 *2 ipw2200,libipw

>>> lib80211 * * * * * * * *4107 *3 lib80211_crypt_ccmp,ipw2200,libipw

>>>

>>> For that laptop I can change the value of sens!

>>>

>> This driver seems to refuse sens values in dBm - but only as positive

>> numbers - so I am unsure what the appropriate value is in this case -

>> but it seems that if the wireless driver is able to change the sens

>> value and it can be set in dBm then your advice is good - however I

>> did not realise there was so much variation in support on the driver

>> side and this whole issue is a lot more complicated than I first

>> realised!

>>

> I am also plagued by the same problem for rt2xxx driver.

> So I opened a bug:

> https://bugzilla.kernel.org/show_bug.cgi?id=28972

> You might want to add your comment to this bug and report

> your device and loaded wireless drivers.



I am unsure if the responsibility for drivers is directly kernel? *Or

is there an upstream driver devel list for each of the drivers

separately? For example in my case the ath5k driver does not support

the sens parameter but the ipw2200 driver on another laptop I use does

support it but not measured in dBm but a positive integer - so it is

quite hard to know what those numbers mean in terms of the signal

level. It seems that there is wide variation in the way the drivers

were written and minimal documentation about this in an easy to access

form. Certainly you seem to have to chase up info and spend time doing

the research!



I have been getting help from the networkmanager upstream list but in

the end it looks like it is necessary to get onto whichever upstream

list corresponds to the driver for your hardware - and I have a

collection of different chipsets all having different drivers

(ipw2200, iwl3945, iwl4965, ath5k, rtl8712 which is also supported by

8912 etc)



So I think I will have to do some looking up on which the relevant

upstream list should be in each case - I guess in your case it will be

the list for the Realtek driver which is of course not full gpl! There

is an 8912 driver which is in the kmod staging tree but is not in the

mainstream kernel - though can be loaded via rpmfusion - not sure if

this will drive your device though?



Certainly there is lots to learn for sure!

--

mike c

Actually, my chipset is the RalinkTech RT2860, which is now supported
by mainline (AFAIK). It seems serialmonkey no longer maintains this driver???

At any rate, I have had other issues with the rt2xxx driver re: setting the Tx power.

After I opened a bug at bugzilla.kernel.org, I received a patch which took care
of the problem.

So, I am hoping that they will pay attention to this and provide a patch.


Cheers,

JD
*
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Old 02-13-2011, 10:50 AM
les
 
Default Change wireless interface "sens" value how?

On Mon, 2011-02-14 at 01:08 +1030, Tim wrote:
> mike cloaked appears to be having a conversation with himself:
> > This driver seems to refuse sens values in dBm
>
> Surely it wouldn't be specified in "dBm"?
>
> 0 dBm is 1 milliwatt into 600 ohms. Is the antenna really 600 ohms?
> That would be an unusual antenna impedance.
>
> --
> [tim@localhost ~]$ uname -r
> 2.6.27.25-78.2.56.fc9.i686
>
> Don't send private replies to my address, the mailbox is ignored. I
> read messages from the public lists.
>
>
>

600 ohms is usually an audio reference. i.e. 0dbm is 1mw on 600ohms.
RF is usually specified to 50 ohms regardless of the actual impedance
(0dbm rf is 1mw on 50ohms), and a transformation is needed to arrive at
the voltage, current losses for other impedances. Some VHF specs are at
150 or 300 ohms, and there could be a new standard developing for 600 as
some patch antennas do have that high an input impedance.

Regards,
Les H

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Old 02-13-2011, 01:38 PM
Tim
 
Default Change wireless interface "sens" value how?

mike cloaked appears to be having a conversation with himself:
> This driver seems to refuse sens values in dBm

Surely it wouldn't be specified in "dBm"?

0 dBm is 1 milliwatt into 600 ohms. Is the antenna really 600 ohms?
That would be an unusual antenna impedance.

--
[tim@localhost ~]$ uname -r
2.6.27.25-78.2.56.fc9.i686

Don't send private replies to my address, the mailbox is ignored. I
read messages from the public lists.



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