Wednesday, December 20, 2017

Access Point Mounting for Warehouses and Open Ceilings Part #1

It seems that I can’t go a week without running into a situation where mounting the AP isn’t straightforward or easy. Whether the installation is in a warehouse, or in a factory with tall ceilings, or in a new trendy office with open ceilings and exposed ductwork and conduit. Putting the AP close to the user and below obstructions can be difficult. In the past, organizations had to come up with custom mounting solutions. Some of which were better than others. Whereas others seemed to just make the matter worse. For some excellent examples of this, check out Eddie Forero’s Bad-Fi site ( However luckily there has been a movement by 3rd party mount companies to create solid mount platforms to properly install AP’s in these types of deployments. We'll get into those in the next installment of this post. But first, let’s take a look at these difficult areas, and what their individual issues might be.

Warehouses – Warehouses have been utilizing WiFi for a long time. However in the past many deployments were mostly for just bar code scanners. With speed and roaming being low-priority design considerations, if a design was done at all. Nowadays however warehouses are starting to take advantage of new applications that require a strong, consistent, and well-designed wireless network. Organizations can no longer have dead spots or sticky clients. They need to have wireless coverage equal to that of an office deployment. Unfortunately warehouses can be one of the more difficult places to design to that level of requirements for.
    Lets start off with what warehouses are designed and built to do. A warehouse by definition are buildings whose sole purpose is to store goods. To do this, they come in an incredible array of sizes and shapes. But their design aspects are mostly the same. They are normally huge cavernous buildings, many of which have hundreds of thousands of square feet. To put that in relation, an acre is only 43,560 square feet. So we have buildings whose footprints can be measured in acres. Warehouses also normally have very tall ceilings easily reaching 30ft or more. Which takes where Access Points most often are deployed (ceilings) and puts it that much further away from the client device. Also, these ceilings are supported by I-Beams or trusses, which are not the most ideal of mounting surfaces.
    Warehouses often store their goods on large metal racks. These racks often soar all the way to the incredibly tall ceilings we touched upon earlier. It's easy to think of these metal racks as walls when designing, especially when attempting to do a predictive design for a warehouse. However despite their size, they are open shelving. Meaning that some (much?) of the attenuation will come from what the actual inventory stored on them. This can offer issues of its own. One that I most recently saw was a beverage distribution company with aluminum cans on pallets being stored on the shelves. Now in addition to the multipath issues that the racking can cause, we have a true canyon (get it? CAN-yon?) of reflectors.
    As with any environment, we also have to consider the client devices and applications being utilized. The majority of devices that you will run into in a warehouse are bar code scanning guns that have minimal throughput requirements. The hardest part of these "legacy" devices were that they could be a bit "sticky." However as I alluded to in the beginning of the post, warehouses are starting to utilize new applications which require devices with more capabilities. Unfortunately these devices usually have less capable radios than their larger bar code scanner siblings. On top of all of that, VoWiFi has made its presence felt in the warehouse market. Putting stringent design requirements in place.
    So lets put it all together - We have incredibly large buildings, with soaring ceilings. That are filled with canyons whose walls are made up of metal shelving and inventory reaching from the floor to the ceiling. The client devices have become smaller, with weaker radios. But the design requirements have become more stringent.

Open Ceiling Office – It seems like more and more office spaces are going with what I think of as an “industrial” feel. Foregoing the traditional drop ceiling, and leaving the ceiling open, exposing all of the electrical conduit, HVAC, and ceiling/floor trusses. In many cases, these ceilings are not very tall. However many organizations will try and deploy their AP’s on the trusses or against the ceiling itself, above the conduit and HVAC runs. Meaning that there is a plethora of metal between the AP and the user. Again, Eddie’s Bad-Fi site is littered with examples of this. I have also encountered the same issue in re-purposed mill buildings. With tall open ceilings, and open HVAC, cable raceways, conduit, etc between the ceiling and user.

How can we overcome this? How can you mount an AP below all of the obstructions? Essentially that would require hanging an AP in midair. So, how do you mount an Access Point where no mounting surface exists? It's simple! You bring the mounting surface down to where the Access Point needs to be installed. We'll focus on the specialized mounts in the next post. In this post however we're going to go over some of the common materials used to actually hang the mount where it needs to be.

 Threaded Rod aka “All-Thread” – This is the most common material used to hang things from ceilings. It’s found almost everywhere. Look up next time you are in a space with a tall open ceiling like a supermarket or large box store and you are bound to find All-Thread used to hold up any number of things, from lighting to signage to sprinkler systems and everything in between. It’s most commonly found in a 3/8”diameter with a thread pattern of 16 per inch. It comes in a wide array of lengths and can be easily cut to whatever length is necessary. One advantage of threaded rod is that it's stiff. Many customers try and hang Access Points from wires or cables. However that requires multiple "strings" to properly hang the AP, and at that point the mount can still sway if a breeze was to catch them. Cable mounts can also be notoriously hard to make level, making the Access Point off kilter, and potentially providing uneven coverage.

Beam Clamp – These are used to hang threaded rod from an I-Beam or from a truss. You can find them in any number of throat sizes. They will come with a built-in bolt to use to tighten the clamp down on the surface, and then there is a nut to lock that bolt into place.

Ceiling Flange – These are very simple threaded rod hangers that can be mounted (screwed or bolted) directly to a flat surface. 

Hanger Bolts – I don’t know how these eluded me for so long. These are threaded rod hangers that have a threaded section on one end to hang the rod from, and then a lag screw section on the other end. These come in a number lag screw lengths, and can also have different hanger orientations. Whether they are holding the threaded rod perpendicular to the lag screw, or vertically in-line with the screw.

The great thing is that all of these things can be found at your local large box store. In fact I bought all of these things on a quick trip to Lowes. Also, none of these require specialized tools to work with. The threaded rod can be cut to size with a simple hacksaw, otherwise all you need is a wrench or a drill to get the others in place. 

This also isn't to say that threaded rod is the only way to hang AP mounts, because it certainly isn't! One of the mounts we will touch upon in the next post can hang from conduit. Which results in a fairly slick deployment, because your mounting hardware at that point also contains your cable management.

Hopefully this helps give you some ideas on some materials you can use to provide your Access Points the most ideal mounting location. In the next post we'll talk about some of the actual mounts that you can utilize to finish off your installation.


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