Wireless Access

Good day. We are experiencing wireless client connectivity issues near the far end of the warehouse and I would appreciate any input that you may offer in regards to possibly receiving a stronger wireless signal. Attached is a diagram that would provide a better view of the wireless AP setup.

Nine directional Aruba 277 AP's, with a 80 degree beamwidth, are installed in a warehouse with a floor space roughly 400 feet by 85 feet. The AP's are mounted approximately 30 feet from the floor. Other than the two rows of concrete beams shown in my diagram, there are three rows of shelving that are approximately 15 feet high that run the full the length of the building. AP's 1-6 labeled in my diagram are mounted on the side walls in a staggard fashion concentrating the RF signal across from each other. AP's 7-9 are focusing the RF signal towards the far end of the warehouse. We already know this is not an ideal installation and the original intent was to install all nine AP's the full length of the warehouse on the side walls, five one one side and four on the other, to provide wireless service. Due to no communications rack with network services either in the middle or far-end of the warehouse, and distance limitations of Category 6 cable, all AP's are physically installed within the first half of the warehouse. A wireless survey and installation plan was completed about two years ago but was not followed due to lack of network services and infrastructure. Wireless connectivity on the first half of the warehouse is excellent, we have an issue on the far end where three AP's are focused to provide service and clients have very low signal (1-2 bars) and SNR values are very low (10-18). It is 110 paces from the far end of the warehouse to AP's 7-9, which is about 275 feet. Maybe 275  feet is just too far?

On the master controller, we've already tried an "AP Specific" configuration for AP's 7-9 where the 2.4 GHz radio transmit power was increased to 15 dB and the 5 GHz radio was increased to 21 dB, but there is not much positive change. Any recommendations that may help with the current situation? My initial thought is to recommend that a new communcations cabinet be installed on the far end of the warehouse and the second half of the building be run from that point, basically mimic how the first half if currently installed. A couple other warehouses in the vicinity have AP's installed the full lentgh of the building (5 AP's on one side and 4 on the other) and have much better wireless coverage. Just wondering if someone here has run into this situation before and can provide some advice. Thanks in advance.....

Attachment(s)

Drawing1.pdf   100 KB 1 version

You are correct.  You would probably need a design like below:

EDIT:  Just as a test, I would move a single AP to the middle and do a site survey around it with the transmit power on each band at 12 to see the coverage to model your predicted coverage.  I would also point the access point straight down when you move that AP to the middle.

Thanks for the reply cjoseph.  In regards to your recommendation for testing: I assume that testing one AP in the approximate area where you have AP 7 listed on the diagram?  And, just curious as to the reasoning for pointing the AP straight at the floor when performing a test?  These are Aruba model 277 AP's which are directional and have an approximate 80 degree beamwidth.  I am learning so just curious.  Thanks..

The strategy to pointing the AP-277 access point down is to understand the symetric coverage you can get from it while testing at that height.  You want to understand the symetric coverage before you start tilting that access point.  Every environment is specific and I do not know what usable coverage you can get with your specific clients on an AP-277 access point mounted 30 feet in the air.  My suggestion is a way to get that basic information, but it does not account for all your challenges.

Warehouses are some of the most challenging wireless designs, period. Instead of just offering you a single suggestion to get started,  I should  also point you to these slides on Warehouse design  here:  https://community.arubanetworks.com/aruba/attachments/aruba/WLAN-Professionals-Summit-2014/3/1/WLAN%20Design%20for%20Warehouses.pdf 

That would allow you to understand your general challenges in deploying a warehouse and to give you more ideas.  I would get direct advice from someone who has experience deploying wireless in warehouses  to assist you, because adding another closet and mounting access points 30 feet in the air is very expensive.

What is the transmit strength of your wireless clients? and are they B, A, G or N? 

We used to use a similar deployment and have since run the fiber to get to the far end of our warehouses, but were able to limp along by using 100mw radios in the affected warehouse, and moving our weaker clients to better covered buildings.