Geobeacon localization

Insights on how Sensolus trackers use Bluetooth geobeacon technology for localization.

Geobeacon localization is a BLE localization technology based on the detection of transmitted signals from known geobeacons that are installed at fixed locations. The IDs and locations of the geobeacons are entered in the Sensolus platform.

The geobeacon periodically sends a BLE signal containing its ID. When a tracker is in the vicinity of the geobeacon, the ID is registered and sent to the Sensolus platform by the tracker . The platform can resolve the geobeacon ID to the configured location.

Different localization technologies have different characteristics. Localization using geobeacons is particularly useful in indoor situations where GPS localization doesn't work. Although, there are also very good reasons to use geobeacons outdoors as well:

  • Localization using geobeacons is 5 times more energy efficient than GNSS localization.
  • Geobeacons can result in an higher location accuracy compared to GNSS or Wi-Fi localization.

Functioning of Sensolus geobeacons

When a tracker performs a geobeacon localization, it will scan for nearby Sensolus geobeacons and report the IDs of the geobeacons to Sensolus platform.

This works as following: the locally installed geobeacon periodically emits a BLE signal which contains a unique number (UID) and which is registered by the tracker. This geobeacon UID is then sent over the LPWAN network to the Sensolus platform where it is resolved to a location. For this to work properly, the location of each geobeacon must have been correctly entered in the platform.



Figure 1. Functioning of the geobeacons

Sensolus geobeacons

Sensolus currently offers two geobeacon models:
  • GB 3000: a stand alone geobeacon.
  • GB 3100: a geobeacon that is remotely manageable.

Geobeacon transmission power

The average broadcast range from a geobeacon to a tracker is between 2 and 100 meter. Sensolus provides 8 adjustable transmission power levels to broaden or limit the average broadcast range:
  • range 0: -40dBm / 2 meter
  • range 1: -20dBm / 7 meter
  • range 2: -16dBm / 10 meter
  • range 3: -12dBm / 15 meter
  • range 4: -8dBm / 22 meter
  • range 5: -4dBm / 27 meter
  • range 6: 0dBm / 50 meter
  • range 7: +4dBm / 100 meter
Note: The distance given is in open air and can vary a lot depending the environment. For instance, metallic constructions or walls can significantly reduce BLE signal transmission.
Note: It is recommended to use the same transmission power on all geobeacons installed in the same building. Else, the tracker might report a wrong position.

Geobeacon location capture

When a location capture is triggered, the tracker will scan for nearby geobeacons for a predetermined duration. When it finds at least one beacon, the tracker will send a location message with information for up to two detected beacons.



Figure 2. Geobeacon location capture diagram

Geobeacon usage and installation

Geobeacons are typically used indoors where detecting GNSS signals is difficult. Hence, in combination with GNSS a tracker can cover both indoor and outdoor use cases. Correct installation of the geobeacons requires careful planning. When multiple geobeacons are within range, the tracker will send the identifiers of the two geobeacons with the highest signal strength to the platform .
Note: A geobeacon roll-out requires careful planning where to put the geobeacons.

The diagram below shows two options for an given area. The geobeacon can be placed in the middle (For example: on the ceiling) or two geobeacons could be placed on the edges.



Figure 3. Geobeacon placement in a single room

If there are no other geobeacons nearby, the left option is recommended. If there would be other neighboring zones nearby, the right option is better because it 'offers' 2 correct geobeacons to detect. There are also a few strategies that can be leveraged to control how far the signal of the geobeacons reaches. The signal strength of the geobeacons can be configured, which can be used as a mechanism to control how 'snappy' a location is.

Depending on the configured signal strength and the presence of physical obstructions around the geobeacon, the signal reach of a geobeacon can vary between 2 and 100 meters. The material on which the geobeacon is mounted, as well as its orientation, are important too. Mounting a geobeacon on a metal surface facing inwards will significantly reduce the signal towards the backside. The picture blow shows this effect:



Figure 4. Geobeacon mounted on a metal surface

A suggested geobeacon installation diagram for a larger area (for example: an industrial hall) is shown in the figure below:



Figure 5. Geobeacon placement in an industrial environment.

In this example, the hall has 4 zones of interest which are each covered with sufficient geobeacons.

Note: If the zones were to be tightly adjacent, there would always be an error margin on the location mapping, as radio signals do not define strict borders.

Trackers with geobeacon localization functionality

On the list with Sensolus trackers you can see which tracking devices contain the geobeacon localization functionality.