While there are lots of different aspects to WLANs such as security, different standards, etc, one area that I think can be very beneficial to students is understanding how radio signals propagate and how objects interfere with those radio signals, and how to plan for the proper resource allocation of Wireless Access Points (WAPs).
But how do you decide where to place devices? You can "guestimate" or simply place your WAP wherever is convenient but unless you are working in a small space, you are likely to have dead spots. You can try the traditional approach which is often completed by doing a site survey. This is where you go and physically visit a proposed site. You temporarily place a WAP and walk around with a signal strength reader or laptop, recording the signal strength in various locations. You then move the WAP to a new location and repeat the process until you feel like you have found the ideal location for the WAP to give you the best coverage. This approach does work. But, it can be tedious and is an after the fact solution. As you can imagine, this can be time consuming and an expensive endeavor, ranging from $2500-$10,000 per building or more depending on the size of the building, the number of locations, and various other factors.
For an arguably better approach, you can actually determine the number of WAPs and their approximate location BEFORE you go to the trouble of purchasing and setting up all of your equipment by completing a Predictive Site Survey. While I am sure there are several ways to do this, the tool that I am familiar with is a tool provided by a company named Aerohive. Aerohive is a manufacturer of commercial Wireless Access Points and pushes for web based management of those WAPs. Pretty cool stuff. But, they also have what they call, a WiFi Planner tool. This tool allows you to enter the address of your facility using Google Maps and then draw your floor plan directly on their web page or to upload a PNG of your floor plan and then, based on the walls and wireless standard, it can automatically determine the number and location your WAPs need to be located on the plan, providing a heat map to illustrate coverage. Is that cool or what? You can also manually place WAPs and see the effect that it has on your coverage as well.
So, how do you use this? Well, you can register for a trial account for free at: https://www.aerohive.com/planner/.
If you select Try HiveManager NG, it will take you to the bottom of the page where you can register. Once registered and you have confirmed your account through the email they send you, return to https://www.aerohive.com/planner/ to login with the account information that you setup.
Once you do that, you will be presented with their dashboard. Impressive isn't it? Remember, this is a dashboard for managing your wireless network through the cloud. If this were a live network, you could keep an eye on your various WAPs, their performance, clients, etc. Again, very cool stuff. But, we are only interested in their planner tool, so select Plan in the navigation bar at the top.
Add Location brings up the dialog box we have below. You've got several different options to choose from. First, you need to create a Location, followed by creating a Building followed by creating a Floor. Type in whatever you want; I used Schuessler Sounds, Service, and 1st Floor respectively for each name. You can also type in your specific address or simply type in your city and state and click Save for each one.
With that done, select the name you gave for the floor you are working on in the navigation bar on the left. For me again, the name I gave it was 1st Floor. Once you select it, your screen should look similar to the one below.
Now you are ready to upload your floor plan. Click on Upload Floor Plan to see the dialog box below.
Click on Upload New From Computer to open the file upload dialog box below.
Click Choose and then navigate to wherever you save your Visio image of your floor plan. Note: you must save your Visio floor plan as a PNG file to upload it here.
Once you have selected the image file of your floor plan, click Upload and you will be presented with the dialog box below.
This basically wants to know how much of the image is your building versus how much is "extra". You can actually tweak the scale later so I recommend simply expanding the selection bars all the way to the corners to capture the entire image. Once you do, click Save All. Once I did that, I was presented with the following screen.
First click on Size the Plan and then select the Size Manually Check Box. Once you do, you should see something similar to the dialog box below. Notice the oval around the two red plus marks. This is how you are going to add scale to your drawing so that Aerohive knows how long your various walls are.
On my drawing, I drug the left red plus mark down so it was below the dialog box. Then, I drug the right red plus mark to the right wall. I then entered the distance between those two red plus marks to add scale to the drawing. In my case, that distance was 53 feet (I rounded up). Then click Apply to set the scale.
Now, you are pretty much done. The only thing left to do is actually generate the heat male. Do this by clicking on Plan Devices on the navigation bar at the top.
In the Auto Plan For group, select the More drop down box to select things like 2.4 GHz or 5 GHz, Channel Width, Device Type, Signal Strength, and/or Power. Keep in mind, this is for Aerohive products. But, this is still very useful. I would focus on the device Type and the specific standard you are looking to implement. In my case, I selected a device that said it was compliant with 802.11ac and then I clicked Auto Place. Just for giggles, play around with the 2.4 GHz and the 5 GHz ranges. How does this affect your coverage? How does it affect your speed? Neither choice is "right". It just depends on what you are trying to do. If you want to restrict your devices to the 802.11ac standard to get the benefit of speed, recognize that by operating at 5 GHz, you will not get the same range that you would get if your were operating at 2.4 GHz and thus, might need more WAPs for adequate coverage.
With that done, you end up with this:
Stunning, isn't it? OK, well, not really. It does at least indicate the approximate location in the building that the WAP should be located. It also tells me that I only need one WAP. That's cool to know isn't it? But, what else can I get out of this?
Well, click on View Heat Map in the navigation bar at the top. Just below the navigation bar, there are also several options. In the Show On Heatmap group, click RSSI.
MUCH cooler, eh? Now, you can play around a bit. Select the 2.4 GHz range under Radio to see how your heatmap changes. Does this make you want to reconsider changing wireless standards? Will you only allow 2.4 or 5 GHz devices? These are some of the decisions you will have to make.
Now, the above example is for illustration purposes only. In this floor plan, there is one crucial aspect missing: internal walls. Internal walls will have a huge effect on how the radio wave propagate throughout the building. You should not see concentric circle propagating around the WAP as you do in the above image. Rather, you should see concentric circle up until the radio signal impact a surface such as a wall. If Aerohive does not detect the walls in your diagram, you can go back and manually add them. Be sure to specify the materials they are made of as this will impact the signal propagation as well. The more accurate your floor plan, the more accurate your heatmap is going to be.
Ideally, you would start with this approach and then go back to do a modified site survey, where you are simply confirming successful wireless coverage in your building.
Hopefully you found this useful. If you have any questions, comments, or suggestions, please feel free to let me know.
