optimizing wireless signal in warehouse

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May 31st, 2009
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Hi all

I have a large warehouse with 10 autonomous 1240 ap's they are running 802.11g. Thye sometimes complain of lost signal even though we had a survey done, the ap's are all along the back wall. what settings should I put on them, it seems that most of them are on full power, is this right? what tweaks can I do on them or checks ?


cheers


Carl

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scottmac Sun, 05/31/2009 - 05:15
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What have you tried so far?


carl_townshend Sun, 05/31/2009 - 14:37
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hi

i have tried changing channel setting to least congestion frequency, and turning noew signal, no joy.


any other ideas ?

Leo Laohoo Sun, 05/31/2009 - 19:05
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They sometimes complain of lost signal even though we had a survey done.


Was there a Survey done after the implementation?


What type of warehouse is it?


It's good that a survey was conducted before the implementation, however, warehouse being a warehouse the internal "structure" sometimes changes after the implementation. An example like changes to rows of pallets in a large storage warehouse. One minute there are rows of storage and another minute it's gone.


When staffs are complaining that they have no signal coverage, do they have line-of-sight to the AP?

rduke Mon, 06/01/2009 - 06:13
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It is kind of difficult to determine the problem without a lot of digging. One bit of advise. Do not assume the problem is the infrastructure. Test everything - including roaming. I had a similar complaint where I used to work and found the problem to be the roam setting was left blank in the image

on the wireless terminals (Techlogix). Roaming was so bad I lost connections for 30 seconds at a time. I got it down to about one or two missed pings by changing the setting to medium AP density. I monitored one of the

wireless clients with continuous pings. This is a good check to do because you can compare before and after you make adjustments. In my case the device did not want to roam at all. It would

hang on to the associated AP - even when it should not have to the point it was unusable.


Randy

kheentech Sun, 06/21/2009 - 03:24
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Hi Carl,


Common problem is AP's not patch in. Try pinging each AP via a patched in desktop PC within the same subnet. Alterntively, perform a continuos ping to the gateway while roaming to all AP. The purpose of the exercise is, if an AP is active and broadcasting RF and not patched in, guessed what, It'll act as a trap to the wireless client. The client will associate to that AP and latched on, due to the better signal rule but will appear as hanged or locked up until it disassociates and re-associates to a working AP.


Try this before anything.

mat.edwards Sun, 06/28/2009 - 01:25
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Hi Carl.


Warehouse environments can be extremely difficult for RF depending on what is stored.


I would first advise that you do not use least congested channel and do a static 1,6,11 channel plan. Also match the power of the AP to the clients, if the AP is set too high you will have one way communication whereby the client can hear the AP but not vice versa.


Depending on what applications are being used, it might be worth disabling the g rates if you do not require high throughput to ensure a more reliable connection.


There are many variables in a warehouse WLAN that can effect performance, you need to answer the following to identify the root cause:


What kind of antennas are you using on the APs? If you have them against the wall I would advise diversity patch with at leat one metre clearence of metal obstructions such as pillars and stock.


What do you keep in the warehouse? What clients are using? Handguns or Forklift trucks? What kind of application are you running? Have you verfied that it is the signal that is dropping as clients have a tendancy to blame the signal whenever they experience wireless problems? Does it happen in any particular area/time? Have you visually checked each AP for correct installation? How high are the APs? Do the client devices support diversity and is this enabled through the antenna installation/configuration?


If you want more help please answer the above questions plus might be useful to post the warehouse plan and AP locations.


Cheers


Mat




mat.edwards Sun, 06/28/2009 - 01:27
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Another good one I have had before is the installers plug the antennas into the 5GHz connections on the 1242's ! Certainly will get signal problems then...

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