Wi-Fi coverage

Predicted Wi-Fi coverage on a floor plan: for each point of the floor, the best signal (RSSI) received from the access points that are up, band by band (2.4, 5 or 6 GHz), with a loss for each wall crossed. When an access point goes down, its coverage hole shows at the next refresh.

This is an estimate for dashboards and demonstrations, not a site survey: the log-distance model ignores reflections, neighbouring floors and people.

Data

The panel joins every series by the ap label and keeps the last value of each series, so instant and range queries both work, in time series or table format. Each metric is recognised by the end of its name (__name__), or by the query's refId when an aggregation drops the name.

Metric (name ends with)	Labels	Use
ap_info	ap, optional x, y, model, site, building, floor	The list of APs, and their position on the plan, x and y from 0 to 1, origin top left. Without it, every series with an ap label makes an AP.
ap_up	ap	0 takes the AP out of the computation. Optional, APs are up by default.
tx_power_dbm	ap, band	Transmit power of each radio. An AP without a radio on the band does not transmit on it.
radio_channel	ap, band	Shown on hover.
ap_clients	ap, band	Shown on hover.
noise_floor_dbm	ap, band	Shown on hover.

Bands are 2.4GHz, 5GHz and 6GHz.

APs without x and y labels can be placed by hand, see below.

Edit the plan

Users who can edit dashboards get an Edit plan button in the legend, in view as in edit mode; in the panel editor the toolbar is always there. It sits above the plan:

• Move APs: drag an access point; the map follows as you drag. Unplaced APs are listed to be put on the plan. Positions set this way are saved in the panel options and win over the data; Back to data position removes them.
• Draw walls: drag to draw a wall in the chosen material. Wall ends snap to other walls, nearly straight walls are straightened, Shift keeps them horizontal or vertical. Click a wall to select it, Ctrl+click (Cmd+click) to add or remove walls, Ctrl+A to select them all; then change their material or press Delete. A single selected wall can have its ends dragged.
• Rooms: drag a rectangle to add the four walls of a room at once, in the chosen material.
• Scale: draw a line over a length you know on the plan, such as a corridor, and type its real length: the floor size follows, keeping the plan's proportions.
• Floor plan: upload an SVG, PNG, JPEG or WebP plan for the shown floor and set its size in metres, keeping the image proportions. A panel has no file storage: the plan is stored in the dashboard, SVG as is, other images scaled down to 2000 px and converted to WebP. Prefer SVG, or a URL for heavy plans.
• Undo and Redo (Ctrl+Z, Ctrl+Shift+Z) go back over these changes; Discard drops them all.

Changes are saved with the dashboard: after Done, save the dashboard to keep them. Turn the button off with the Allow plan editing option. For a dashboard generated from an inventory, copy the geometry from the panel options back to the source.

What if

Outside the editor, What if in the legend lets anyone try changes and see the coverage follow: drag APs, add APs (with the median transmit power of the real ones), click an AP to switch it off. Nothing is saved; Done goes back to the data. Turn it off with the Allow what-if option.

Options

• Floor plan URL: SVG or PNG stretched to the floor's size, for example public/floorplans/${site}-f${floor}.svg for files served by Grafana, or any absolute URL. Variables allowed. Other relative paths resolve like the Canvas panel's images, from public/build/.

• Geometry: floor size in metres and walls, as JSON. Wall ends go from 0 to 1 like the APs.

  {
    "size_m": [62, 24],
    "walls": [{ "from": [0.22, 0], "to": [0.22, 1], "material": "glass" }]
  }
  

  For a dashboard with a floor variable, give every floor and set Floor to pick one, for example ${site}-f${floor}:

  { "floors": { "hq-f1": { "size_m": [62, 24], "walls": [] } } }
  

• Band: 2.4GHz, 5GHz, 6GHz, or a variable such as $band.

• View: signal (RSSI) or best AP, one colour per dominant access point.

• Thresholds: good -67 dBm (voice, video), fair -75 dBm (data), weak -82 dBm (connection possible), hidden below -90 dBm.

• Radio model: wall materials and band parameters, merged over the defaults below.

• AP positions: positions set in the editor, by AP name.

• Uploaded plans: plans uploaded in the editor, by floor, with their size and a button to remove them.

• Data links: links set in the field options open from each access point, with ${__field.labels.ap} for its name.

Model

RSSI = Ptx + Gap + Gclient - PL(1 m) - 10 n log10(d) - sum of wall losses, with PL(1 m) = 20 log10(f MHz) - 27.55 and d at least 1 m.

	2.4 GHz	5 GHz	6 GHz
Frequency (MHz)	2437	5500	6500
Exponent n	3.0	3.2	3.4
AP gain (dBi)	4	5	5
Glass, drywall (dB)	3	4	5
Brick (dB)	6	10	12
Concrete (dB)	12	15	18
Metal (dB)	25	30	30

These defaults are orders of magnitude, to be calibrated.