Only released in EOL distros:
The heatmap package allows you to create a WIFI-heatmap
This package allows you to automatically build visual WiFi heatmaps.
The heatmap package allows the user to select a previously recorded map (e.g. by gmapping) and define a measurement area on it. Then a coverage path gets planned and the robot takes Wifi signal strength samples while covering the area. These samples are visualized in RViz. On its way the robot uses the navigation_stack to avoid ostacles in the measuring area. When robot is done the package offers the possibility to do an interpolation to get a continuous heatmap from the scattered samples.
The only hardware requirements are a mobile robot platform supporting move_base and a WiFi device.