NMS-ADV with V2110 WiFi: Triangulation requirements

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Hi,
we use NMS-ADV which provides advanced wifi map features with V2110 V10.31.04 (large).

I deployed three APs at the lab broadcasting a wifi and placed APs at a map. " Enable location-based service " is enabled at all three APs. But the map shows not the triangulated position. Instead the position of the client is marked at the AP to  which it is connected.

Is it possible to triangulate the position of a wifi device without using a third party Location Service like Aeroscout, Centrak or Ekahau (these are the selectable options at Wifi-Controller / Services / Location-based Service)?
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htw

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Posted 12 months ago

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Daniel Flouret, Employee

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HTW,

Triangulation requires at least three AP's seeing the connected user. but those three AP's must be in the same channel.

If you only have three AP's , they will be in different channels (or you would have co-channel interference) and will not meet that requirement. Since only one AP is reporting that user, EMC will highlight that AP and not a trinagulated location.

To do triangulation, you will need to install, at least, two sensors. The sensors continuously scan all channels in both 2.4 GHz and 5 GHz. That way, you will have your three devices on the same channel the user is connected to, and reporting information to allow EMC to estimate the probable location of the user.
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Daniel Flouret, Employee

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Ron Dvorak pointed out in a private message that my response was not entirely correct. And he's right.

Mobile units (smartphones, tablets, or anything else that connects to a wireless network) send probes to all allowed channels, looking for access points. This behavior is supposed to continue after the MU has selected one SSID and connected to it. But that's not always the case, and depends on the MU.

If you have MU's that frequently send probes in all channels, even when connected to an SSID, then locationing may be able to triangulate the position of the MU. But if it does not (many MU's, when connected to an SSID stop sending probes to save battery, unless something happens, like a fading connection), then you will not be able to triangulate. Unless tou have additional APs acting as sensors.

So, if locationing is important for you, and you want to make sure it works, no matter what, the recommendation is to add a couple of sensors.

The topology of your deployment is also important, so EMC includes a Heat Map that shows how well prepared is your network for locationing.



Bear in mind that, since location is calculated, it is VERY important to correctly scale the map and to mark all walls, doors, windows and other obstacles to the signal, with their correct construction materials. EMC will take all that into account to calculate the atenuation suffered by each AP's signal when traversing those obstacles, and better estimate the distance between the AP and the MU.
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Pala, Zdenek, Employee

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On the EWC, check the radar menu. Check if the triangulation/ location services are enabled and if APs are assigned.

Z.