[WLANware] Mesh with 2 radios (help with 5 ghz)

[Sven-Ola Tuecke]

Hi,

5Ghz, Ad-Hoc + Madwifi-NG still needs fiddeling in my opinion. Here are some 
hints which may be helpful:

- The Current madwifi-ng offered as 
http://downloads.sourceforge.net/madwifi/madwifi-0.9.2.1.tar.bz2?modtime=1165501216&big_mirror=0 
has severe problems with Ad-Hoc (2.4 Ghz). Compiled it on Kubuntu (dapper) 
and experienced a lot of kernel oopses then. The SVN version (I am currently 
using 2006-12-12) is ok.

- Madwifi-ng has some major freeze (stops to send packets after a while) in 
Ad-Hoc. Obviously no more TX-interrupts from the hardware. Here's a small 
hack to overcome this: 
http://olsrexperiment.de/sven-ola/nylon/packages/madwifi/files/sven-ola-txstophack.patch

- Ad-Hoc in 5 Ghz needs a so-called "Channel Master" (on node beeing elected 
to scan the channel and inform the other nodes to swith channel if 
military/satelite radio signal is detected). There is no such thing in the 
madwifi-ng sources. To be on the legal side, you want to use a Master/Client 
setup.

// Sven-Ola

"Frederico Marques" <frederico at marques.cx> schrieb im Newsbeitrag 
news:E9F6AAC3-34FE-4A2A-BC08-CF7DC0E8C44B at marques.cx...
Hi list,

First, thank you for your nice Freifunk Firmware and OLSR
development. It was very easy to setup a very small Mesh (about 6
nodes) with WRT54G's for a small portuguese community near my town
(Ourém). I'm using wifidog for the captive portal & authentication of
all Mesh with some iptables hacks to solve the multi-splash problems
(every node has wifidog authentication for the users). I'm injecting
a 0.0.0.0 route from a local cable provider in just one node.
Everything works fine. I'm trying to build a P-t-P link to other
area, 1,2km distance with a WRAP board and 2 radios. One radio is for
the local 2.4 Ghz Freifunk Mesh, and the other radio I want to use is
configured in a 5Ghz to remote location. Both radios are Wistron CM9
mini-pci. On the other side there is another WRAP Box with two CM9
radios. I have *clear* LOS and I have two pannel antennas pointed at
each other, both are 5 Ghz 19 dbi from Pacific Wireless. I'm using
Voyage Linux with OLSRd running on both radios/interfaces (ath0/
ath1). The 2.4 Ghz 6 node Mesh can communicate with the WRAP Box, and
all routes are propagated, so, no problems with routing. Since I'm
not a RF guy, I ask you any advice for the 5 Ghz link. I can't
connect both WRAP's at 5 Ghz! I know it is very difficult to try to
figure out the problem since it can be anything, but I ask what I
should check? Some more info:

- Checked the link, with each antenna/wrap 5m away in my lab, no
problems whatsoever.
- Both WRAP's are in the same frequency/channel, but with other
channels I don't even have a signal, neither a lousy one.
- I've made the cables with lmr200 and n type connectors. I'm on
expert on cables or RF, but I did a fast check with a signal injector
and all was well (I hope). Cable problems?
- Tried different polarizations, but no success.
- Maybe it's a problem with adhoc and atheros/madwifi ?
- Do I need to setup any antenna diversity settings or use the defaults?
- Do I need to check the long distance settings (ack timeout...) on a
1,2km link?
- Could be a problem of pigtails? I use UFL-to-N-bulkhead ones.
- Checked the link with a 2.4ghz and two Omni 2.4 12 dbi Pacific
Wireless, and it was great! Good SNR and about 48Mbit rate connection.
- Is there any voodoo or some secret informations about 5 Ghz P-t-P
links?

I welcome any advice you may have. I'm sorry if this is list is not
the most appropriate to ask for help.


Fred

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