I estimated backoff based on these statistics for my project a year back and I got a reasonable estimate.As Mohammad pointed out ,Wire shark is a good tool to verify the retry count.Just check for the retry field in the MAC header. Short retries are for RTS/CTS .Long retries are for the data packets..

Thanks,
Sritej

On Thu, May 20, 2010 at 2:09 PM, <madwifi-devel-request@lists.sourceforge.net> wrote:
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Today's Topics:

  1. Re: ath_tx_processq and long_short retry (Mohammad Abdelhadi)
  2. Re: Help with OpenHAL and 5/10 MHz > channel width (gokulnath A)
  3. Minstrel does not set ni_txrate (Joerg Pommnitz)
  4. Re: Help with OpenHAL and 5/10 MHz > channel width (Aditya Bhave)
  5. Re: Help with OpenHAL and 5/10 MHz > channel width (Pavel Roskin)
  6. Unable to configure MadWifi as a simple AP on Ubuntu
     (Aditya Bhave)


----------------------------------------------------------------------

Message: 1
Date: Mon, 17 May 2010 22:29:00 +0300
From: Mohammad Abdelhadi <mo.jaser@gmail.com>
Subject: Re: [Madwifi-devel] ath_tx_processq and long_short retry
To: Nicolas Barati <nicolas.barati@gmail.com>,
       madwifi-devel@lists.sourceforge.net
Message-ID:
       <AANLkTinWMaMgg18k8xg6KVjcNnyw1zGw_Sgnfrh6R-8T@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"

On Mon, May 17, 2010 at 8:00 PM, Nicolas Barati <nicolas.barati@gmail.com>wrote:

> Hello all,
> In my research on madwifi 's  back-off, eventually I got convinced that
> there is no way to see the current contention window 's value. So I turned
> to something else. I tried to disable backoff and then emulate a backoff
> scheme of my own  on driver level. I disabled backoff by  adding this:
> qi.tqi_qflags |= HAL_TXQ_BACKOFF_DISABLE;   to ath_txq_setup().
> Now I need a measure based on which my backoff emulation will
> increase/decrease  my_CW. I found in ath_tx_status these variables:
> ast_longretry / ast_shortretry. I saw that these values are incremented
> only in ath_tx_processq() which is called from ath_tx_tasklet() or
> ath_tx_tasklet_q0(123)(). I read here : http://www.makelinux.net/ldd3/chp-7-sect-5.shtml
> about tasklet function and what I understood is that these functions are
> some kind of timer/scheduling functions.It sayes: "By scheduling a tasklet,
> you simply ask for it to be executed at a later time chosen by the kernel".
> If It is so and these tasklet functions are called just some time in the
> future (regarding current kernel time)  and the long/shortretry variables
> are incremented only through ath_tx_processq when they are called, how
> accurate these variavles are in regard of the real state of retries. Are
> they to be trusted? Would you suggest that I consider these variables for my
> emulation??? And one more question, is disabling backoff done like how I
> said I did it above? And is there any way to see if it is indeed shut and
> not enabled again in some other part of the code or some time during the run
> time of the driver?
>
> Thank you!
>
>
> ------------------------------------------------------------------------------
>
>
> _______________________________________________
> Madwifi-devel mailing list
> Madwifi-devel@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/madwifi-devel
>
>
Hi,

 ath_tx_tasklet() is responsible to update information of each transmitted
packet, please take a look on
http://mesh.calit2.net/whzhao/madwifi_summary.pdf
<http://mesh.calit2.net/whzhao/madwifi_summary.pdf>
 -  how accurate these variavles are in regard of the real state of
retries. Are they to be trusted? Would you suggest that I consider these
variables for my emulation???

Well, to test the accuracy of these variables, you can use a Network
Analyzer  like Wireshrk, to see how many times a packet has been
retransmitted,

I think that (ts->ts_longretry) is responsible ot store the number of long
reties for each packet, but any way, you can test that and see by your self.

Hope this helps.


Regards,
--
Mohammad Jaser Abdelhadi
----------------------------------------------------------------------------
Communications Engineering-Senior Student
Princess Sumaya University for Technology
Mobile: +962777030924
Email: moh.jaser@ieee.org \ mo.jaser@gmail.com
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------------------------------

Message: 2
Date: Tue, 18 May 2010 17:00:37 +0530 (IST)
From: gokulnath A <gokulnatha@yahoo.co.in>
Subject: Re: [Madwifi-devel] Help with OpenHAL and 5/10 MHz > channel
       width
To: ayb@andrew.cmu.edu
Cc: madwifi-devel@lists.sourceforge.net
Message-ID: <948363.20988.qm@web94807.mail.in2.yahoo.com>
Content-Type: text/plain; charset=utf-8

hi...

you need to edit "madwifi/ath_hal/ah_regdomain.c"  this file to enable the 5Mhz and 10Mhz support in madwifi trunk.

also you need to change the regDmn5GhzFreq[] and regDomains[] structures..

I Changed the frequency bands in INDIA country code (regDmn-APL6) and added 5/10 MHz (quarter/half) channel and bandwidth support in APL6 regulatory domain and i checked .

update me about your results.

Regards
Gokulnath A


> ------------------------------
>
> Message: 4
> Date: Tue, 11 May 2010 13:13:30 -0400
> From: Aditya Bhave <ayb@andrew.cmu.edu>
> Subject: [Madwifi-devel] Help with OpenHAL and 5/10 MHz
> channel width
> To: madwifi-devel@lists.sourceforge.net
> Message-ID: <4BE9903A.2050303@andrew.cmu.edu>
> Content-Type: text/plain; charset=ISO-8859-1;
> format=flowed
>
> Hi,
>
> Where can I find the source code for OpenHAL? Im
> interesting in adding
> support for 5/10MHz channel widths and found this
> discussion
> http://kerneltrap.org/mailarchive/madwifi-devel/2009/6/16/5996253
> However it seems some changes need to be made to OpenHAL to
> get this to
> work. Has anybody worked on this before?
>
> thanks
> regards,
> Aditya Bhave
>
>
>






------------------------------

Message: 3
Date: Tue, 18 May 2010 11:57:28 +0000 (UTC)
From: Joerg Pommnitz <pommnitz@yahoo.com>
Subject: [Madwifi-devel] Minstrel does not set ni_txrate
To: madwifi-devel@lists.sourceforge.net
Message-ID: <loom.20100518T134548-254@post.gmane.org>
Content-Type: text/plain; charset=us-ascii

Hello all,
different from sample.c, Minstrel does not set the ni_txrate field in the
findrate method of the RC algorithm. Because of this the value does not
reflect the currently preferred data rate for a peer. I have made the following
naive change:
--- madwifi-0.9.4/ath_rate/minstrel/minstrel.c
+++ madwifi-0.9.4-new/ath_rate/minstrel/minstrel.c
@@ -383,6 +383,7 @@
                *txrate = sn->rates[ndx].shortPreambleRateCode;
        else
                *txrate = sn->rates[ndx].rateCode;
+       an->an_node.ni_txrate = ndx;
 }


Can somebody confirm that this is the right thing to do or that it at least
won't do any harm?

Thanks in advance and kind regards
 Joerg




------------------------------

Message: 4
Date: Tue, 18 May 2010 10:07:08 -0400
From: Aditya Bhave <ayb@andrew.cmu.edu>
Subject: Re: [Madwifi-devel] Help with OpenHAL and 5/10 MHz > channel
       width
To: gokulnath A <gokulnatha@yahoo.co.in>
Cc: madwifi-devel@lists.sourceforge.net
Message-ID: <4BF29F0C.2070306@andrew.cmu.edu>
Content-Type: text/plain; charset=UTF-8; format=flowed

Hi Gokulnath,

Thanks for your reply.
So you are saying I can do this in the MadWifi SVN trunk code and do not
need OpenHAL?

Can you please suggest what changes need to be made? Im very new to
MadWifi and do not know much about the code internals. I just want to
run some simple experiments with variable channel widths.
Also is there some user-level API (through iwconfig or iwpriv etc) that
can allow me to change the widths at run-time dynamically

Many thanks for your help
regards,
Aditya Bhave



gokulnath A wrote:
> hi...
>
> you need to edit "madwifi/ath_hal/ah_regdomain.c"  this file to enable the 5Mhz and 10Mhz support in madwifi trunk.
>
> also you need to change the regDmn5GhzFreq[] and regDomains[] structures..
>
> I Changed the frequency bands in INDIA country code (regDmn-APL6) and added 5/10 MHz (quarter/half) channel and bandwidth support in APL6 regulatory domain and i checked .
>
> update me about your results.
>
> Regards
> Gokulnath A
>
>
>
>> ------------------------------
>>
>> Message: 4
>> Date: Tue, 11 May 2010 13:13:30 -0400
>> From: Aditya Bhave <ayb@andrew.cmu.edu>
>> Subject: [Madwifi-devel] Help with OpenHAL and 5/10 MHz
>> channel width
>> To: madwifi-devel@lists.sourceforge.net
>> Message-ID: <4BE9903A.2050303@andrew.cmu.edu>
>> Content-Type: text/plain; charset=ISO-8859-1;
>> format=flowed
>>
>> Hi,
>>
>> Where can I find the source code for OpenHAL? Im
>> interesting in adding
>> support for 5/10MHz channel widths and found this
>> discussion
>> http://kerneltrap.org/mailarchive/madwifi-devel/2009/6/16/5996253
>> However it seems some changes need to be made to OpenHAL to
>> get this to
>> work. Has anybody worked on this before?
>>
>> thanks
>> regards,
>> Aditya Bhave
>>
>>
>>
>>
>
>
>
>
>




------------------------------

Message: 5
Date: Tue, 18 May 2010 13:44:20 -0400
From: Pavel Roskin <proski@gnu.org>
Subject: Re: [Madwifi-devel] Help with OpenHAL and 5/10 MHz > channel
       width
To: Aditya Bhave <ayb@andrew.cmu.edu>
Cc: gokulnath A <gokulnatha@yahoo.co.in>,
       madwifi-devel@lists.sourceforge.net
Message-ID: <1274204660.10542.13.camel@mj>
Content-Type: text/plain

On Tue, 2010-05-18 at 10:07 -0400, Aditya Bhave wrote:
> Hi Gokulnath,
>
> Thanks for your reply.
> So you are saying I can do this in the MadWifi SVN trunk code and do not
> need OpenHAL?

OpenHAL has evolved to what is now ath5k, a kernel driver for Atheros
devices.  Historic OpenHAL is not maintained.

MadWifi uses FreeBSD HAL developed by Errno Consulting.  It was a
non-free binary blob in the past, but it was open sourced later.

> Can you please suggest what changes need to be made? Im very new to
> MadWifi and do not know much about the code internals. I just want to
> run some simple experiments with variable channel widths.
> Also is there some user-level API (through iwconfig or iwpriv etc) that
> can allow me to change the widths at run-time dynamically

As far as I know, every channel has a width that cannot be changed.  The
width can be examined by the "wlanconfig" command.

--
Regards,
Pavel Roskin



------------------------------

Message: 6
Date: Thu, 20 May 2010 17:09:08 -0400
From: Aditya Bhave <ayb@andrew.cmu.edu>
Subject: [Madwifi-devel] Unable to configure MadWifi as a simple AP on
       Ubuntu
To: madwifi-devel@lists.sourceforge.net
Cc: madwifi-users@lists.sourceforge.net
Message-ID: <4BF5A4F4.1090902@andrew.cmu.edu>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Hi,

Im trying to configure MadWifi as an AP on laptop A and connecting a
client from laptop B. Although the station B associates correctly, Im
unable to even do a simple ping to the AP

Here is my configuration

Laptop A: Lenovo Thinkpad
Card: lshw -C network
       description: interface
       product: Atheros AR5001X+ Wireless Network Adapter
       vendor: Atheros Communications Inc.
       physical id: 0
       bus info: pci@0000:16:00.0
       logical name: wifi0
       version: 01
       serial: 00:0b:6b:20:40:dd
       width: 32 bits
       clock: 33MHz
       capabilities: bus_master cap_list logical
       configuration: broadcast=yes driver=ath_pci latency=96
maxlatency=28 mingnt=10 multicast=yes
       resources: irq:16 memory:c4000000-c400ffff

Here is the script I used to create an AP
/*********
#!/bin/sh

sudo modprobe -r ath5k || true
sudo modprobe -r ath9k || true
sudo modprobe -r ath_pci || true
sudo modprobe ath_pci autocreate=none

sudo wlanconfig ath1 destroy || true
sudo wlanconfig ath1 create wlandev wifi0 wlanmode ap    # set up the AP
sudo iwpriv ath1 mode 3                    # 11g mode
sudo iwconfig ath1 essid "Aditya"      # essid
sudo iwconfig ath1 key off                # no wep
sudo iwconfig ath1 enc off                # no wep
sudo iwpriv ath1 wpa 0                    # no wpa

sudo ifconfig ath1 up
sleep 1
sudo ifconfig ath1 192.168.1.1 netmask 255.255.255.0

sudo sysctl -w dev.wifi0.diversity=0
sudo sysctl -w dev.wifi0.txantenna=1
sudo sysctl -w dev.wifi0.rxantenna=
************************/

Laptop B: Dell Inspiron
Card: description: Wireless interface
      product: AR928X Wireless Network Adapter (PCI-Express)
      vendor: Atheros Communications Inc.
      physical id: 0
      bus info: pci@0000:0c:00.0
      logical name: wifi0
      version: 01
      serial: 00:15:6d:84:35:8e
      width: 64 bits
      clock: 33MHz
      capabilities: bus_master cap_list logical ethernet physical wireless
      configuration: broadcast=yes driver=ath_pci latency=0
multicast=yes wireless=IEEE 802.11g
      resources: irq:19 memory:dfcf0000-dfcfffff

Here is the script I used to create a STA
/*************
#!/bin/sh

sudo modprobe -r ath5k || true
sudo modprobe -r ath9k || true
sudo modprobe -r ath_pci || true

sudo modprobe ath_pci autocreate=none
sudo wlanconfig ath1 destroy || true
sudo wlanconfig ath1 create wlandev wifi0 wlanmode sta
sudo iwpriv ath1 mode 3     # 11g
sudo iwconfig ath1 essid "Aditya"
sleep 1

sudo sysctl -w dev.wifi0.diversity=0
sudo sysctl -w dev.wifi0.txantenna=1
sudo sysctl -w dev.wifi0.rxantenna=1

***********************/

In NetworkManager, I configured so that address is obtained through DHCP
whenever the STA connects to AP "Aditya"
Here is my dhcpd.conf file
/***************
option domain-name-servers 192.168.1.1;

default-lease-time 86400;
max-lease-time 604800;

authoritative;

# basic setup by ADITYA BHAVE
subnet 192.168.1.0 netmask 255.255.255.0 {
    range 192.168.1.10 192.168.1.20;
    option subnet-mask 255.255.255.0;
    option broadcast-address 192.168.1.255;
    option routers 192.168.1.1;
}
/*****************************/

Firstly, the STA is unable to obtain an address through DHCP.
I then manually gave the STA an address of 192.168.1.10, with a netmask
of 255.255.255.0 and a gateway of 192.168.1.1. I even ran the following
command
route add default gw 192.168.1.1

Inspite of both the above changes, a ping command fails
ayb@AD-DELL:~$ ping -I ath1 192.168.1.1
PING 192.168.1.1 (192.168.1.1) from 192.168.1.2 ath1: 56(84) bytes of data.
 From 192.168.1.2 icmp_seq=1 Destination Host Unreachable
 From 192.168.1.2 icmp_seq=3 Destination Host Unreachable
 From 192.168.1.2 icmp_seq=4 Destination Host Unreachable
 From 192.168.1.2 icmp_seq=5 Destination Host Unreachable
 From 192.168.1.2 icmp_seq=6 Destination Host Unreachable

Can someone please help to diagnose this problem?

Thanks
regards,
Aditya Bhave





------------------------------

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