more info needed about using wifi in high reflective enviroment

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Jul 18th, 2009
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I am looking for documents about using wifi in highly reflective enviroments: rooms with aluminium floor, walls and ceiling en very little materials that absorb rf. (cleanroom enviroment)

Any hints are appreciated.

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mat.edwards Sun, 07/19/2009 - 02:22
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How large are the rooms? Are you talking about large open plan areas such as kitchens or corridors with small/medium rooms located either side?

From experience as long as the AP's you install and the clients support antenna diversity you shouldn't have too much trouble. Your best bet would be using 'N' as it likes highly reflective spaces and uses multipath to its advantage. Keep antennas at least 1 metre away from reflective materials if possible. If you have high ceilings, use low gain omni antennas.

I have installed in plenty of highly reflective environments and never had any problems as long as it is planned correctly. If you give me a better idea of the layout (Upload a plan if you wish and can run over it with you) then I can point out any potential RF problems you may run into.



joopv Mon, 07/20/2009 - 03:34
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Thanks for your reply Mat,

The cleanroom enviroment (ASML semiconductor industry) is a large room about 30 * 60 meter and 7m high. In this room are smaller cabinets (about 20) where the actual work is done. Here you can see some pictures:

In full production there are about 120 engineers working with their 802.11b/g equipped laptops.

Every wall, floor, ceiling, door is made with aluminium sandwich panels. We have major troubles getting a reliable wifi enviroment, and also DECT and GSM telefony is hardly working at all.

Right now we have 10 AP's is the large room, and we are contemplating installing 1 AP in every cabinet with low power setting and using attenuators. We are also considering the use of leaky coaxial cable.

Migrating to 802.11N is not really an option since the clients are b/g equipped.

I will upload a plan soon.

Robert.N.Barrett_2 Wed, 07/22/2009 - 07:28
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If you can get rid of your 802.11b clients, the 802.11n 1250/1140 APs from Cisco will still provide benefit to your 802.11g clients in this highly reflective environment (though MIMO and beamforming).

If you are not using a wireless controller and lightweight AP's, then you'll need to stick with the 1252's since they are the only Cisco 802.11n AP's that can operate in standalone mode. Standalone IOS firmware for the 1140's has not been released, yet.

1 AP in every cabinet sounds expensive. You could go that route (with testing first!!!), but you would really want to crank the power down as low as possible.

Frank Lindner Thu, 07/23/2009 - 01:19
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Hi joopv!

Had you allready thought about an professional WLAN-planning? This cost a bit, but you will get good WLAN performance everywhere you need at a minimum count of AP.


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