[Battlemesh] [OpenWrt-Users] Batman-adv high TQ and Low throughput

Thu May 1 02:00:14 UTC 2014

What does "iw wlan0 station dump" have to say?  In particular, what is the
ratio of TX packets to TX retries (or failures)?

I've generally seen 10% TX retries, compared to total TX packets, to be
quite ideal.  A substantially higher percentage of TX retries, especially
if over 100%, usually indicates a problem with noise or interference.

On Wed, Apr 30, 2014 at 6:57 PM, cmsv <cmsv at wirelesspt.net> wrote:

> inline reply
>
> On 04/24/2014 05:27 AM, Nicolás Echániz wrote:
> > El 24/04/14 05:34, cmsv escribió:
> >> Recently i have experienced something quite usual to my experience and
> >> that was not happening previously in the same scenario where it is
> >> happening now.
> >>
> >> Here is the example:
> >> 2 nodes at with adhoc at 2.4ghz at a distance of 415 meters
> >> one uses an omni 15 dbi antenna at 18dbi and another 24 dbi grid at 16
> dbi.
> >>
> >> This link was previously providing up to 21 mbit being 17 mbit a the
> >> lowest. Batman-adv TQ value was always around 230 being many times above
> >> 250.
> >>
> >> However this has recently changed the same link with 230~250 TQ and the
> >> same txpower is now outputting 1.93 Mbits/sec
> >>
> >> I have used iperf for bandwidth tests. Batman-adv version is 2013.4.
> >> Although i have considered several types of scenarios that can be
> >> causing this issue i have also tested against some which leaves me
> >> puzzled in regards to the presented TQ quality and dBm values as the
> >> nodes dBm are sometimes bad (ie: -80 ~ -90)
> >>
> >> One of the main questions is: shouldn't batman-adv TQ reflect or be
> >> influenced by dBm values ? How come with -90 dBm i get batman-adv to
> >> show me 230 TQ ?
> >>
> >> Also any feedback based on your experience regarding this type of
> >> scenario is welcome. This situation happened overnight without any
> >> access point new configurations or physical setup changes.
>
> > what's the mcast_rate value?
> >
> > having 230~250 TQ on a -80/-90dBm link seems like you have a very low
> > mcast_rate.
>
> I have always used the driver default setup to decide the bitrate and
> that worked up to a certain moment. Specifying it did not do much better
> but today i found this message
>
> ath: phy0: unsupported hw bitrate detected 0x1f using 1 Mbit
>
> Currently:
> wireless. at wifi-iface[0].mcast_rate=6000
>
> and i tested with up to 36000
>
> But i have also gotten the unsupported hw bitrate message without
> setting mcast_rate
>
> iwinfo reports:
>           Tx-Power: 19 dBm  Link Quality: 36/70
>           Signal: -74 dBm  Noise: -95 dBm
>           Bit Rate: 29.7 MBit/s
>           Encryption: WPA PSK (CCMP)
>           Type: nl80211  HW Mode(s): 802.11bgn
>           Hardware: unknown [Generic MAC80211]
>           TX power offset: unknown
>           Frequency offset: unknown
>           Supports VAPs: yes
>
> iw reports:
>
> Frequencies:
>                         * 2412 MHz [1] (20.0 dBm)
>                         * 2417 MHz [2] (20.0 dBm)
>                         * 2422 MHz [3] (20.0 dBm)
>                         * 2427 MHz [4] (20.0 dBm)
>                         * 2432 MHz [5] (20.0 dBm)
>                         * 2437 MHz [6] (20.0 dBm)
>                         * 2442 MHz [7] (20.0 dBm)
>                         * 2447 MHz [8] (20.0 dBm)
>                         * 2452 MHz [9] (20.0 dBm)
>                         * 2457 MHz [10] (20.0 dBm)
>                         * 2462 MHz [11] (20.0 dBm)
>                         * 2467 MHz [12] (20.0 dBm)
>                         * 2472 MHz [13] (20.0 dBm)
>                         * 2484 MHz [14] (disabled)
>
> And o notice that i am at the moment unable to set 20dBm unless i
> re-flash the device.
>
> wireless.radio0.htmode=HT20
>
>                 Bitrates (non-HT):
>                         * 1.0 Mbps
>                         * 2.0 Mbps (short preamble supported)
>                         * 5.5 Mbps (short preamble supported)
>                         * 11.0 Mbps (short preamble supported)
>                         * 6.0 Mbps
>                         * 9.0 Mbps
>                         * 12.0 Mbps
>                         * 18.0 Mbps
>                         * 24.0 Mbps
>                         * 36.0 Mbps
>                         * 48.0 Mbps
>                         * 54.0 Mbps
>
> I also tested while removing HT functionality but without better results
>
> Horst shows;
> 91% usage for 1M rate
> 3.4% usage for 6M rate
> 4% usage for 36M rate
>
> another node shows me :
> ath: phy0: unsupported hw bitrate detected 0x33 using 1 Mbit
>
> Chips in at the moment in use: Atheros AR9130 rev 2 and Atheros AR9132 rev
> 2
>
> So far it looks like a i have a bug according to atheros mailing lists
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-- 
Ben West
http://gowasabi.net
ben at gowasabi.net
314-246-9434
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