Hi John again, John Doe wrote: > Thanks for your answer. > > 2010/2/3 Sebastian Robitzsch <[email protected]>: >> Hi John, >> >> Please find some hints in line ... >> >> John Doe wrote: >>> Hi, >>> >>> I want to build a pbx and wifi router based on the soekris net5501 >>> (together with its standard case), a tdm400 card and a mini-pci wifi card. >>> This box should be 100% reliable, 24x7, as its going to be in a >>> different part of the world, in fact I will build 2 or 3 of these and >>> have them in different countries. >>> >>> I'm planning to have 2 fxo and 2 fxs modules on the tdm400. >>> I know that having fxs modules require additional power for the phones >>> to ring, I have researched a bit into this and some people seem to use >>> the JP15 power connector for this, but there is no definitive statement >>> that this actually works. >>> I would appreciate it if anybody in this list has a similar solution and >>> would like to share his experience. >>> >>> On the wireless side I'm thinking about getting a CM9 (802.11 a/b/g) or >>> a R52n mini-pci (802.11 a/b/g/n) card. >>> 802.11n doesn't seem to be well supported in Linux yet, but I expect >>> this to change soon. >> I don't know what you mean by "soon".. but I'd say that 11n is not >> usable for normal user operation mode, e.g., when planning to deploy an >> operator network. > > Well, I would be satisfied even if the R52n works in a/b/g mode for > now, and in 1 year a kernel update brings in the 802.11n > functionality. > I intend these boxes to work for at least 5 years without any hardware > changes, but I have the possibility to make kernel/software updates > every 1-2 years. > >>> Both of these cards have connectors for 2 antennas, which also brings >>> the question of where do I put the antennas? >> First of all, both connectors on the card gives you "just" diversity... >> these are not two different physical wireless interfaces! Please be >> aware that diversity is enabled by default (in madwifi) - even if no >> antenna is connected to... therefore, the performance could be a little >> bit under what you could get if diversity in enabled but just one >> antenna is attached to the card. >> >> WRT 11n - if you really plan to use mimo you'd need to use the ath9k >> driver... (again: IMO, not ready yet for daily use) >> >>> I haven't seen the case in person, but from the pictures there doesn't >>> seem to be enough space on the back for even one antenna. >> there is one slot for a PCI card - use that to drill a hole into the >> metal strip... that works out well > > As I am planning to use the PCI slot for the TDM card, I can't count > on this space. > > But I just found out a possible solution in these pictures: > http://soekris.kd85.com/images/dsc/tn/dsc07672.jpg.html > http://soekris.kd85.com/images/dsc/tn/dsc07674.jpg.html > > So apparently I have space for just one antenna. > Should I aim for 802.11n with only one antenna or should I just stick > to the a/b/g card?
For the time being I'd stick to .11a/b/g. To be honest, I've never looked into how ath9k deals with the 11n standard and what they have really implemented so far. > Or maybe the antenna count doesn't make a difference at all in speed, > but only in range? If you have a lot of fading and dynamic environment it would make sense to deploy two antennas with a rather larger distance between them (let's say 50cm or more) If you want to understand how diversity works in madwifi: http://madwifi-project.org/wiki/UserDocs/AntennaDiversity Basically, you will improve the possibility to decode frames. Which will lead into less retransmissions which then increase your performance... but the range is not affected at all by that Cheers, Sebastian > > Thanks! > _______________________________________________ > Soekris-tech mailing list > [email protected] > http://lists.soekris.com/mailman/listinfo/soekris-tech -- Mr. Sebastian Robitzsch, Dipl.-Ing. (FH) PhD Candidate University College Dublin School of Computer Science & Informatics Belfield Dublin 4 Ireland Mobile: +353 (0)86 - 22 10 988 (IRL) +49 (0)1 72 - 3 52 80 72 (D) Mail: [email protected] WWW: www.seronline.de Skype: seronline82 Jabber: [email protected] Twitter: www.twitter.com/seronline Delicious: www.delicious.com/seronline Mendeley: www.mendeley.com/profiles/sebastian-robitzsch -----------------------------------------------------
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