Hello Pablo,
> I have some problems with some long range links, and I hope that somebody
> can help me.
> I am pretty sure that is a 802.11b timing problem.
There can be other problem ...
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> The two links have these configurations:
> 1- 36 km link
> Soekris boards
> Linux & HostAP
> Senao 200mW
^^^^^
Really 60... 100mW
> 24dBi antennas
Grid ?
> 72m & 60m towers
Rx_level = -115 -20Log(36) +20 +24 +24 = -78 dBm
Use only fixed speed,
for example: only 5.5M or 2M or 1M
> 2- 41 km link
> Soekris boards
> Linux & HostAP
> Senao 200mW
> 1W amplifiers
PC_card 200mW + 1W amplifier NEVER use !!!!!
Amplifier is overloaded !!!
Regards,
Ivan Korshun
http://www.vector.kharkov.ua
> 24dBi antennas (I don't have FCC problems :)
> 90m & 72m towers
>
> All RF calculations and values are ok (good link quality, stable 11Mbit
> rate, >20 dB of system operating marging), the ping responses are excelent
> (I can send 1000 packets, without loose anyone, with a delay time between 4
> and 12 ms), but if I load the link the things come very bad.
> For example, with netperf I have an excelent bandwidht: 0.08 Mbits!!!
> I am pretty sure that is a timing problem. I suppose that the packets start
> to collision with ACK responses, and if the load increase on the link the
> "snowball" starts.
> The ping times go up and up (100, 300, 800, 1500, 4000...).
>
> By the way, I have several <25 km links, they works great with similar
> configurations (speeds over 3.5 Mbit)
>
> I read an explanations about the timing problem on this article:
> http://www.personaltelco.net/index.cgi/MaximumDistance
>
> I found that StarOS solve this problem with the Agere cards, and Cisco has a
> distance factor on they bridges to adjust the 802.11b timing, but this
> require to change the cards or equipments on the towers.
> I will like to found a solution on Prism 2.5, if it exist :)
>
> Does anybody have an idea?
> Does anybody know a working >35km link and what hard/soft it use?
>
> Thanks for your time!
>
> Regards,
> Pablo.
>
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