[Battlemesh] Batman-adv high TQ and Low throughput

[cmsv]

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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