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EkaHOW? Ekahau 101: Setting Up a Site Survey

Ekahau is without a doubt one of the most powerful tools available to a wireless engineer. This program allows a user to map, plan, and measure the wireless environment of a given area so that designs can be created or improved as needed. There are two main uses for this program: Predictive Surveys, and Active Surveys. A predictive survey is what’s created prior to the implementation of a wireless network, and contains the architectural design of the building the network will be installed in. The Ekahau suite comes with pre-configured wall types, complete with attenuation values that help predict just how the wireless signal will propagate and attenuate, so that there are no surprises after wireless access points are installed.

An Active Survey takes a network that has already been designed, and by walking through the site with a device to measure signal, creates a “heatmap” (or coverage map) of the existing infrastructure. There are several methods of performing an active survey, such as with a Sidekick – Ekahau’s in-house wireless adapter with a full array of wireless antennas and spectrum analyzer – or by using a laptop or tablet’s integrated or external wireless adapters. After an active survey has been completed, the surveyor will be able to identify weak points in the design, like excessive or insufficient coverage, lack of secondary coverage, or co-channel interference. This can help resolve issues anywhere from basic connectivity to poor device roaming for mobile devices, and can even reduce the number of helpdesk tickets submitted when used in an enterprise environment by preventing issues from arising in the first place.

So, where do we begin? Generally, with a floorplan. I’ve use my house for this example, which unfortunately didn’t have an up-to-date design, so I created one of my own. Please forgive any structural inaccuraces; I am a wireless engineer, not a structural engineer. However, the floorplan created should be accurate enough for our purposes here.

Could use a banana for scale

So, with the floorplan created, the next step is to import the maps to Ekahau, set the scale and apply the appropriate wall types.

Arrow one designates where to add your map. To do this, take a screenshot of your PDF, or even better, import an AutoCAD .dwg file if one is available. These will often contain the wall types, and can save you a lot of work! To add a second floor, select the three dot icon next to the map drop down (where it says no maps in the screenshot) and simply import the next floor.

Arrow two designates the scale function. This allows you to set the scale so that the signal generated by an access point can be rendered and modeled properly, and is a critical component of the design. It is best practice to use the longest measurement you can acquire to ensure the design is scaled as accurately as possible. To accomplish this, I highly recommend getting a laser range finder (like this one) to save yourself some headache. They’re also extremely handy to have in the event that you need to create a floorplan from scratch. Since my floorplans have a scale included, I’ll be using that to set the scale for this design. To set the scale, click and drag along the designated reference wall, and release at the end of the wall. Then enter the wall length and hit enter.

Arrow three designates the wall type drop down menu, where you can select from a wide array of commonly used wall types, or create your own if you’re creating a design for something a little on the more custom side, such as a home theater with sound insulation, or the interior of a rocketship. (Dream big, right?) For this design, I’ve used drywall for the primary wall type, and a combination of hollow and pocket doors for the doorways. Additionally, for the basement exterior, I used concrete as the lower floor is an underground l̶a̶i̶r̶ space.

Once the floorplans and walls have been added and the scale has been set, you should have something similar to this:

Hopefully you haven’t hit a wall yet, unless it’s a part of the design. Then you’ll probably have several.

Since this design is for multiple floors, the next thing to do is set alignment points. This is crucial for predictive surveys, as this is what will allow the application to properly model AP coverage through floors- and yes! APs *can* and will transmit through flooring/ceiling. This can have a major impact on users if the access points are placed vertically on top of one another, so it’s always good to keep the design for the adjacent floors in mind when selecting a location for them.

To align the floors, select the floor alignment button (the icon with the crosshairs in the button bar) and place the points in locations which are constant throughout the design. Generally, this will be locations such as elevators, stairwells, or exterior corners if the building has the same layout on each floor. Each floor needs a minimum of 3 reference points, as modeling relies on triangulation to accurately render coverage.

Once the alignment points have been added, they should appear on the floorplan as such:

Don’t point fingers, use them for reference.

But wait, there’s more! Just because the points have been added, doesn’t mean they’re correlated and properly aligned yet. To complete the alignment process, you’ll need to navigate to the pane to the left of the floorplan and select the “Building” tab. It’s already been selected in the screenshot above. From there, click on “New Building, then select the floors you’d like to add (you can hold CTRL and import multiple floors at once.) Finally, hit “Add Floor(s)”

Once that has been done, and the distance between your alignment points has been validated, you should be at this point:

My alignment is chaotic good, for those wondering.

At this point, the base design is done, but we’ll toss in some other items since this is first and foremost about learning!

When creating a design, there will likely be areas that coverage won’t be needed in, areas that fall out of scope of your design, or areas of particularly high attenuation (aka the fancy word for signal loss.) Thankfully, Ekahau has factored for these areas, and given us tools to design accordingly. These functions are the Area Tool and Attenuation Area Tool.

We’ll start with the area tool, specifically the exclusion tool. Since I most likely won’t be hosting VoIP calls from my garage, we’ll exclude this area from the design. And should I ever decide that I would, in fact, like to host a podcast in the garage, all we’d need to do is remove the exclusion area, and Ekahau will automatically update the model accordingly.

First, select the Exclusion Tool in the button bar:

Then, simply create an enclosed area in the same way we did when creating walls, and right click to complete the area.

Once complete, you should see the new area outlined by grey dots. Additionally, if you’d like to create a note to explain why coverage is not needed in the given area, the Map Note tool in the button bar will allow you to convey that to anyone reviewing the design. This can also come in handy when performing an active survey and you encounter an area you don’t have access to, or to denote any oddities you might find- like a pipe organ in a house on the Historic Landmark register. Side note: if anyone has the attenuation value of brass pipes handy, I’ve got a new custom wall type (or maybe attenuation area…?) to create.

Which leads me to the next design element: Attenuation areas! Most commonly, these will be areas constructed with dense walls, such as elevator shafts, stairwells, firehalls, bank vaults, or FBI interrogation rooms. (Kidding on the last one… I think?) However, there are other environmental factors that can come into play here as well, like paper filing warehouses, or dense foliage when designing for outdoor coverage. Since I don’t keep a hard copy of every document I’ve ever received, or live in the forest, we’ll create an attenuation area for the stairwell. Granted, mine isn’t concrete like you’d encounter in commercial spaces, but either way, the signal will very likely have a hard time propagating. Since I know that my stairwell is composed of drywalls on each side, and drywall has an attenuation value of -3dB, we’ll create a -6dB attenuation area, since any signal transversing the material will need to pass through both walls to reach the other side. This will be done on both floors by selecting the following button:

And we’re climing the stairway… to attenuation.

ProTip: When creating a custom attenuation area, it’s critical to ensure the measured heights are correct. For instance, if adding something like a warehouse rack, the difference between a 4 foot shelf and a ceiling-height rack will have a substantial impact on the model. Plan accordingly!

The left field is where you enter your attenuation value, as indicated by the squiggly lines, or sine waves if you’re feeling fancy. The height is set in the middle fields- if the object spans vertically from the floor, use the left center field. If the object is ceiling mounted (like cabinetry) use the right center field. You can also select the color your area displays on the map using the color dropdown. Finally, name your masterpiece in the far right field.

And the final product should look something like this:

Congratulations! You’ve scaled the steps to successfully create your first map!

At this point, the floorplan is ready for your predictive design! And don’t worry: I know I mentioned creating boundaries using the area tool, but we’ll do that in the next section after illustrating *why* it’s best practice to do so.

Continue to Part 2 Here:

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