[Battlemesh] Meshing with strong/near clients and weak/far nodes

Ben West ben at gowasabi.net
Tue Feb 18 17:31:17 UTC 2014


Thank you for the pointer to JaldiMAC!  Looks it is/was indeed a rough
equivalent of AirMAX for 802.11n Atheros radios.

Unfortunately, I think the JaldiMAC trail goes cold here.  No updates to
this repo I found since 3 years:
https://github.com/shaddi/jaldimac/commits/master


On Tue, Feb 18, 2014 at 11:10 AM, fboehm <fboehm at aon.at> wrote:

> Am 18.02.14 17:40, schrieb Mitar:
>
>  Hi!
>>
>> I think using TDMA would help here. Each client would reserve its time
>> slot and it would not matter how strong they transmit in their time slot.
>>
>> Sadly open source drivers do not (yet) support TDMA. But Ubiquiti ones do.
>>
>>
>> Mitar
>>
>>  I'm curious if list members have found clever approaches for operating
>>> mesh
>>> nodes that must talk simultaneously to near/strong clients and far/weak
>>> clients.  I've found that, at least with atheros / ath5k-based nodes
>>> running OpenWRT AA r39154, which do single-radio meshing via multiple
>>> VIFs,
>>> connecting a particular strong client to the AP VIF of one node can
>>> disrupt
>>> that node's communication with a distant node on the adhoc VIF.
>>>  Admitted,
>>> the ath5k driver is pretty suboptimal, but its weakness does at least
>>> demonstrate the nature of the problem easily.
>>>
>>> This problem is less pronounced with ar71xx-based nodes, e.g. UBNT Airmax
>>> gear, and I do understand it is going to fundamental to single-radio
>>> meshing applications anyway (i.e. hidden node problem).  Likewise, one
>>> can't always control clients' TX strength, besides mounting nodes at
>>> locations such that a client can never be physically too close, e.g. on a
>>> rooftop or high on an exterior wall.
>>>
>>> Acknowledging the limits of the radios, I'm curious if anyone has had
>>> reasonable success in these situations with things the following:
>>>
>>> - RF-Armor style shielding on the back of the mesh node, i.e. to reduce
>>> the
>>> influence of stray noise or reflections
>>> - Setting an RTS value
>>>
>>>
>>>
>>>
>>> _______________________________________________
>>> Battlemesh mailing list
>>> Battlemesh at ml.ninux.org
>>> http://ml.ninux.org/mailman/listinfo/battlemesh
>>>
>>>
>>  It's quite a while since I read it but you might want to have a look at
> "JaldiMAC". It's kind of a 802.11 based polling protocol.
>
> http://matthias.vallentin.net/papers/nsdr10.pdf
>
> By the way. As far as I know AirMAX protocol from Ubiquiti Networks is
> also based on polling the clients. Although it seems to be a quite advanced
> and mature polling protocol.
>
> Franz
>
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> Battlemesh at ml.ninux.org
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>



-- 
Ben West
http://gowasabi.net
ben at gowasabi.net
314-246-9434
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