Wireless Access

Dear Community,

I have to replace 6 ancient 802.11b-APs (each has 2 PCMCIA cards installed with an exterenal omnidirectional antenna with 7dBi gain) in a warehouse. 

The total space to cover is 150meter x 70meter. The external antennas are placed away from the access points at a distance between 4 and 15 meter. The APs are mounted at a hight of approx. 8 meters.

As the installation of new cable runs for more access points is quite time consuming and expensive and the warehouse is operated 24x7, I plan to just replace the old APs with new indoor IAPs. I have yet made any decision about the new AP modell, but we have plenty of IAP207 installed in our office spaces, but I am quite sure I can not use them there, right? As the old APs use external antennas, I assume that I need to do the same with the new antennas.

The clients are using 2.4 GHz handhelds for SAP transcation, so no demand high bandwidth / 5 GHz even in the future.

So could you please advice if you think such an approach (only replace APs and external antennas, leaf everything in place) sounds feasible (which AP and antenna should I use then). Or do you say this approach is doomed to fail and I have to make a full passive survey, RF planning, installation of new and more APs in different locations, etc.

Thank you for your time and advice,

Gerhard

Warehouses are the most challenging environment in which to deploy, because there can be many variables.  With that being said, all of Aruba's 802.11ac access points have a downtilt omnidirectional pattern that can provide coverage even if they are mounted 10 meters up, so you can avoid using external antennas.

The challenging point is understanding where you would place those access points at that height and the coverage they would provide.  You should use an IAP-207 to survey the coverage that it would provide in your warehouse to possibly understand what coverage you can acheive.  

Again, there can be quite a few variable providing coverage in a warehouse and you should be aware of how to deal with all of them befor e you deploy, or ask a professional who does..

Dear Colin,

thank you very much for this first feedback. I already thought that this environment will be a challenge.

I have attached a warehouse plan where one can see the placement of the APs and much they are apart and roughly where now the external antennas are placed.

So my second thought was to use an IAP with external antenna connectors and place those antennas at the same place where the old ones are right now.

Best Regards,

      Gerhard

Gerhard,

There are many variables in a warehouse and I cannot make a recommendation based on your diagram.  I can only tell you that you can use Aruba 802.11ac access points for high ceilings.  The coverage would vary based on your terrain, the clients that would need to connect and the applications that you are running.  Please take a look at the presentation here:  http://community.arubanetworks.com/t5/Airheads-Breakouts/Hostile-Environments-Wireless-LAN-Design-for-Warehouses/ta-p/247147 to understand what to look out for...

Dear Colin,

thanks for pointing me to this video. It helped me quite a lot to better understand the problems that I'll be facing.

Best Regards,

     Gerhard

To add, there's a good chance that the existing system is a legacy system and only uses one antenna per radio. In modern WLAN, with MIMO and 11ac APs, there are multiple antennas per radio, so you couldn't just replace the APs and use the old antennas, or performance could actually be worse than what you have now. Additionally, long antenna cable runs add tons of loss.

Far better to look at replacing the existing system with APs mounted to the ceiling and forgo using long antenna cable extensions. We have environmentally secure APs as well (for areas that may get cold or be extremely dirty) at a very competitive cost. 

There are multiple guides and web links on warehouse design guidelines, but as each warehouse has unique characteristics, getting an AP up there to survey/model with should be step 1 to make sure you are doing it correctly. If you cannot, due to cost or no impacts to production, then you would trade accuracy for overbuilding the WLAN to make sure you have complete coverage. 

Dear Howard,

yes, it is a legacy system which uses 2 PCMCIA cards per AP, but each card has only one radio and one antenna attached to it. I now checked some cable lengths from the AP to the antenna and they are indeed up to 15 feet long.

I had discussed this warehouse setup with an Wireless Engineer to get some basic recomendations which Aruba AP would be one to do AP-on-a-stick measurements (and which antennas to use for this). He recommended to start with either an IAP304 or better an IAP314 with AP-ANT-1W antennas. After comparing prices I ordered an IAP314 with 4 AP-ANT-1W antennas for the AP-on-a-stick measurement. So I try to see with AP-on-a-stick measurements if this AP mounted to the places of the original APs gives me enough coverage. If not, I know at least the places where I need to put more APs in.

Best Regards,

     Gerhard

802.11b is nearly 20 years old, which means the cabling could be of the same vintage. You might want to replace it or at the very least, get it certified by a cabling professional. Are the existing AP's powered over ethernet? 

You are right, APs and cables are of the same (stone) age. Yes they are powered over Ethernet.

Best Regards,

     Gerhard