[Battlemesh] recommendations for 40Km Link / OpenWRT on ubnt ath9k hw ? / AirMax

[fboehm]

Even Airmax is basically (just) a polling-based MAC layer.

Real TDMA would require precise timer synchronization between all 
clients. Long-range outdoor networks may also need a timing-advance 
feature like in GSM.

I only know that FreeBSD has a real TDMA protocol for some Atheros 
chips. But only for PtP as far as I know. Synchronizing dozens of 
clients in a PtMP environment could be a different ball game.

Regards,
Franz

Am 25.03.14 15:08, schrieb Musti:
> Exactly. Anyone working on implementing a time-slot algorithm for ath9k, that would be a very welcome addition. 5GHz band is generally used for longer distances and anything that is multipoint at this range is very likely to have a hidden node problem.
>
> We have tested ad-hoc at 5GHz as well, in the previously described situation, but it performed even worse.
>
> Kind regards,
> Musti
>
>
>
> On 25 Mar 2014, at 14:53, fboehm <fboehm at aon.at> wrote:
>
>> Sounds like a perfect example for a hidden-node(s) situation. It totally makes sense that AirMax is faster in that case. Every other MAC Layer based on polling clients or allocating timeslots would be better than plain CSMA/CA.
>>
>> Regards,
>> Franz
>>
>> Am 25.03.14 14:35, schrieb Musti:
>>> The setup we had running with AirMax for about a year:
>>>
>>> AP on a mountain, about 5 clients around in 20km radius. With AirMax throughput was about 10times what we get now with openwrt, with significantly more packet loss. Prior to that we found out that AirOS without AirMax is comparable to openwrt.
>>>
>>> Regards,
>>> Musti
>>>
>>>
>>> On 25 Mar 2014, at 14:18, Laurent GUERBY <laurent at guerby.net> wrote:
>>>
>>>> On Tue, 2014-03-25 at 13:52 +0100, Musti wrote:
>>>>> Hi,
>>>>>
>>>>> in wlan slovenia network we are slowly looking at migrating from AirOS
>>>>> to openwrt for UBNT devices, however the tests for now show that ath9k
>>>>> performs worse then UBNT AirMax. The difference is rather small in PtP
>>>>> links, however fails horribly at PtM as there is no TDMA.
>>>>
>>>> Hi,
>>>>
>>>> We tested with and without AirMax and found out not much differences
>>>> except in certain case (colocation of close antennas) AirMax
>>>> wasn't working at all (horrible bandwidth performance, slow to access
>>>> web admin). In the end we've been running AirOS without AirMax for a
>>>> while now both PtP and PtM
>>>>
>>>> Do you have detailed performance results with and without AirMax ?
>>>>
>>>> Sincerely,
>>>>
>>>> Laurent
>>>>
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