Signal issues in a warehouse

[Manish Mathur]

Hi Guys,

We are facing an issue in a warehouse deployment. We have deployed around 40 3702e series APs and the RRM is making the Aps transmit at very low power (index 8). However , the clients beneath the antennas are complaining of very low signal causing frequent disconnections. It appears that the APs are able to hear each other so well that they are lowering down the power. Whereas the signal is not able to make to the ground properly. The antenna models are AIR-ANT2566P4W-R=  which are mounted on ceiling joists.

What does this indicate and what can be done to rectify this ? Did we miss something during the site survey ? The site survey was done when the warehouse was being built. Hence, was empty.

Thanks,

Manish

[Leo Laohoo]

The antenna is a patch antenna and should be installed on the wall.  Just how are the APs/Antennas installed?

Are the problem evident with 802.11a or 802.11b radio?

[Manish Mathur]

Hi Leo,

Sorry for the late response. The issue is still there but I was out of town and thus could not respond. :)  .... Most of the bar code scanners are on 802.11g. I have attached some pictures of the warehouse with the antenna deployment. The patch antenna is ANT2566P4W-R=  and the other antenna type is AIR-ANT2544V4M-R .

Thanks ,

Manish 

[Leo Laohoo]

Look at the last picture (warehouse.jpg).  

The APs are installed way above the height of the shelves.  This means the APs can "see" (or "hear") each other instead of the shelvings (and the contents of the shelves) providing attenuation to the signal propagation.  

Might want to test by lowering the antennas down to the level so that the antenna is surrounded by SOMETHING instead of nothing. 

[jblake00111]

Hi Manish,

I appreciate this is 6 months after the question, and you have probably fixed the problem by now, but just in case you are still experiencing "challenges", take a look at http://www.cisco.com/c/en/us/td/docs/wireless/controller/technotes/8-3/b_RRM_White_Paper/b_RRM_White_Paper_chapter_0101.pdf which describes how to tweak RRM and transmit powers to get over the problem of APs that can hear each other better than the clients can hear them.

I've attached what I think is the most relevant chapter, but the whole book is useful.

Good Luck!

Jim

[lallimander]

Hi Jim,

Very good information in that TPC chapter. Can you please share what is book name and who is the author?

regards,

Kamal

[t_pesta]

Here's the URL to the complete book:
https://www.cisco.com/c/en/us/td/docs/wireless/controller/technotes/8-3/b_RRM_White_Paper.html
You can also download in PDF from there.