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Wifi Base-Station near GSM Base-Station

Posted: Sun Apr 05, 2009 10:29 am
by doush
I will have 4 stella sectors and R5H s on top of the same building.

Im working in 5.8Ghz Frequency.

They are working in 900Mhz - 1900Mhz and there are hell of a lot GSM antennas on the building, as it seems to be a main POP of them.

Should I expect instability ? Will I get effected ?

Re: Wifi Base-Station near GSM Base-Station

Posted: Mon Apr 06, 2009 1:37 am
by InoX
no problem for me and there are 28 antennas on the roof.

Re: Wifi Base-Station near GSM Base-Station

Posted: Mon Apr 06, 2009 8:28 pm
by doush
so neither throughput or pings get effected ?

Re: Wifi Base-Station near GSM Base-Station

Posted: Tue Apr 07, 2009 8:38 am
by normis
Why would they? They are on a completely different band.

Re: Wifi Base-Station near GSM Base-Station

Posted: Tue Apr 07, 2009 8:56 am
by remuss
All are right they are different band there should be no problem but they create electromagnetic wave that can affect; I have the same problem near me at 4m is a GSM tower and it affect my throughput, but it is not significant because I have XR5, you must test and see.

Best Regards Remus

Re: Wifi Base-Station near GSM Base-Station

Posted: Tue Apr 07, 2009 9:04 am
by normis
you could put the device in a shielded metal box ...

Re: Wifi Base-Station near GSM Base-Station

Posted: Tue Apr 07, 2009 11:31 am
by doush
you could put the device in a shielded metal box ...
Can you give an example about a shileded box ? Any metal box would do ?

Re: Wifi Base-Station near GSM Base-Station

Posted: Tue Apr 07, 2009 11:33 am
by normis
yes, most metal boxes will do. this usually helps against interference both from and to the board

something like http://www.nimwave.com/index.php/lang-e ... ve-ag-plus

or ask any dealer from:
http://www.mikrotik.com/mfm.php

Re: Wifi Base-Station near GSM Base-Station

Posted: Wed Apr 08, 2009 12:45 am
by doush
thanks normis

any other action that I can take to minimize the possible effects?

Re: Wifi Base-Station near GSM Base-Station

Posted: Wed Apr 08, 2009 2:17 pm
by momi
doush change the building-we have problems on one mosque in sarajevo with GSM antennas :? :(

Re: Wifi Base-Station near GSM Base-Station

Posted: Wed Apr 08, 2009 7:26 pm
by doush
I cant change the building cos it will delay the operation a lot and currently im setting it up so Im just hoping now.

momi; Did you use shileded metal enclosures ? it didnt help ?

Re: Wifi Base-Station near GSM Base-Station

Posted: Wed Apr 08, 2009 9:26 pm
by noam_chom
I thought that there should not be a problem if you put Wifi near a GSM Base-Station, but recently I've tried and there was a big problem (1km link singnal strength -85dB 5GHz :( ).
I would recommend you if this position is critical to you then put the pole as far as you can from the GSM BS. If there is 5-6m distance between the BS it should be enough.
Interesting part is that we can see the major problem when using 5GHz band.

Good luck :)

Ilija

Re: Wifi Base-Station near GSM Base-Station

Posted: Thu Apr 09, 2009 9:33 am
by momi
yes we did use shielded metal enclosures but it didn't work so well. If you can change height of the antennas e.g 3 or 4 meters above or below GSM equipment it would gain some improvement...

Good lock

Momi

Re: Wifi Base-Station near GSM Base-Station

Posted: Sat Apr 11, 2009 10:25 am
by doush
Someone is suggesting a FARADAYS CAGE . ??

could be helpful ?

Re: Wifi Base-Station near GSM Base-Station

Posted: Tue Apr 14, 2009 10:02 am
by normis
http://en.wikipedia.org/wiki/Faraday_cage

sounds good to me, where will you get one?

Re: Wifi Base-Station near GSM Base-Station

Posted: Tue Apr 14, 2009 11:45 am
by GuJack20
The principle used in metal outdoor enclosures is that of the so called "Faraday Cage". Every carefully constructed metal based enclosure has that effect, causing the outside electromagnetic field to not affect the work of the equipment inside. The biggest problem than, relies in the fact that it isn't the interference directly to the routerboards and cards the only one that causes problems. It's the interference around the cables and antennas the most important one, and you can't put an antenna inside a "Faraday Cage" :)

Re: Wifi Base-Station near GSM Base-Station

Posted: Tue Apr 14, 2009 8:16 pm
by doush
@ Normis
Im currently looking for thick metal enclosure that would act like a Faradays cage. If you know one tell me :)

@ GuJack20
Yes thats how I thought but again Im thinking somehow that an LMR-400 cable can act like a faradays cage since it has enough thickness but not sure though. But I dont know any solution for the antennas as you said.

Grounding the whole equipment including the R5H s may be another safe bet to take.
The site will have more than 100 customers and I dont want to deal with 100 angry customers.
Im confused.

Re: Wifi Base-Station near GSM Base-Station

Posted: Wed Apr 15, 2009 5:17 pm
by steveloomis
Distance from the GSM Antennas is important. Since their antennas transmit towards the horizon, the best place to be is above or below them as far as you can get. This is where their signal will be weakest. The Metal Box is good, make sure you ground it. I suggest a trial system at first, see if you get good performance before committing to the location of equipment.

Steve Loomis
Oklahoma, USA

Re: Wifi Base-Station near GSM Base-Station

Posted: Thu May 14, 2009 10:15 pm
by doush
Ok as an update to this thread

My 2x90deg setup with R5H is completed and have a few customers running on it without any problems for now. Everything looks fine for now.

I have used metal boxes, grounded the boxes, one mpci per board to reduce interference, and got as far as I could from GSM antennas.