Wireless Troubleshooting Tools

RF Graph analysis using WCAE Desktop and Gephi

RF Network visualization could be a very useful tool, to understand AP relationships, RRM behavior, or roaming issues, etc. or just because it is nice... outside the limiting factors of building, floors or other physical constructs

This process will show how to build a powerful RF analysis, using WCAE desktop 0.8.7 or higher, and Gephi 0.92

Content

Initial requirements

Install Gephi

https://gephi.org/users/download/

Open WCAE Desktop, select the file you want to analyze

Ensure "RRM NDP report" is selected
Click on "Process File"
The tool will generate a XLS report, and a new gexf file, in the same location as the input file
Open Gephi, and load the gefx file, click OK to import the file:

Initial Graph will be displayed almost impossible to evaluate, don't worry!. We will apply changes to make this a lot more readable

Creating a meaningful Topology

Using the Nearby distance as weight, the tool can spread the Aps depending on their RF relationship

In the Layout window, click the dropdown and select Force Atlas 2.

You can play with the different values, to adapt to different situations, but ensure you scroll down the options, and click on "Prevent Overlap". For the rest of values, let's use the defaults for initial evaluation, and click Run. Let the graph go over several iterations (10 to 20, depending on complexity), until you have the access points "spread" properly

Coloring Aps by RF cluster

It is easy to cluster the Aps on areas, grouping together Aps that have a stronger RF relationship. That is useful to visualize contiguous RF areas

In the right side, click on Modularity:

Leave defaults, press OK:

Click OK on next window with the analysis results
Go to the left, click on Appearance, Partition, and on the dropdown, select Modularity Class

Depending on the number of RF sectors (complex networks will have more) Click on the Palette.. and select "Generate", to apply a coloring rule matching the number of RF sectors
Ensure that the number displayed matches the number of values in the upper left corner

Now click Apply... the graph starts getting more interesting:

Changing AP node size to represent Neighbor count (RF visibility)

This can be very useful to see what are the Aps with largest impact on the network

Go to the Appearance area, and click on the size icon to the right of "Nodes" (looks like 3 concentric circles)

Click Ranking, and select Degree as attribute, you can select a minimum/maximum size, depending on the network density, using 5/10 can be a good range, you should test what makes sense to the AP count and density, click apply

The changes may or not be visible, depending on the size of the network. We will work on that later

Visualizing the signal power between Aps

By default, the edge weights represent the RF Nearby values between Aps, which translate to RSSI levels representing the distances between Aps. It is possible to apply coloring rules to visualize those relationships

On the Appearance window, select Edges, Ranking
From the drop down, select Weight
Click on the color, and let's select a palette that would be useful for the RF values or just what you would like, then click apply

Now we have a lot more details in the graph, but it could be "too far" to make sense depending on AP count

Zooming to see details

After doing the AP node, and edge changes, we may want to see more details, but on the default scale this could be difficult on large networks

Click on the lower right corner button in the graph window, it looks like a square with a triangle:

Now use the zoom slider to get closer
You can move the graph, using the right button on your mouse

Now, by default, the edge width may be too wide to visualize things properly. Use the slider next to the T to adjust to what fits the AP density of your network

Adding AP names

Now that RF relationships, and relative impact are visible, we can add AP names labels to the graph, to help on any further analysis

Click on the T, by default, most of the time the names will be too big to make any sense, except for small AP counts

Use the slider after the font name and size to adjust the labels to something readable

Now we have a proper RF representation, clearly showing which Aps have the largest impact, and what are the relationship between them

Visualizing relationship for single AP

To see the neighbors for a single AP, just move the mouse on top of one AP node. It will highlight all other nodes in relation to it

Final Comments

There is no easy way to predict what will be the best values to get a good visualization of your network. On this document we provided a set of good steps and recommendations, but do not hesitate to test other options that could create awesome representations for further RF analysis