As you know, an alternative method to GPS location – LBS service – is a handy feature in Wialon system. When GPS satellites are not available, Wialon will automatically switch to LBS (cellular tower-based) location detection. LBS location feature is helpful for units tracking in container shipping, tracking in buildings and urban areas with poor GPS signal. Since the first launch of Wialon LBS Service we’ve essentially improved it and now it’s high time we gave you a complete overview of this useful function.
How it works?
Generally GPS tracker consists of a GPS/GLONASS receiver for location detection and a GSM module for data exchange with the server. Generally, GSM signal is much stronger than GPS: it’s hard to jam it and easy to catch it even in case of external antenna malfunction.
For data transmission GSM module is to be registered at a network provider cell base station, which in its turn transmits Cell ID and other parameters like lac, mnc, mcc. Some GPS tracker models can send Cell ID in the messages to the server.
To get the geographical location of many cell base stations, we can turn, for instance, to the Opencellid – the world’s largest collaborative community project that collects GPS positions of cell towers – which currently has about 8 million unique GSM Cell IDs.
But still it’s not full enough and there are much more cell base stations to be discovered. This is what Wialon LBS Service actually does and much more.
How we collect Cell IDs?
As you know, we have more than 400 000 units hosted in Wialon Data Center. A lot of them send to the server both GPS coordinates and Cell IDs of the base stations (cellid, lac, mnc, mcc) where units are registered at the moment. And most of these units are vehicles driving various roads.
Data handling allows for collecting location points bound to a base station Cell ID, but being closer to road infrastructure. Besides, these data help us register new cell base stations which have not been included in Opencellid database yet. This way we get our own unique database, relevant for our customers.
How Wialon LBS Service detects unit location?
In case a unit doesn’t send GPS coordinates to the server, Wialon system picks up the base station Cell ID and searches the coordinates in our own database. If the point is detected unit coordinates are sent with an allowance for previously accumulated data. If the point is not available in our proprietary database, the query is forwarded to Opencellid database. That way you get the coordinates of the base station where the unit is registered.
To make the process clear to you, we’ve carried out an experiment, testing Wialon LBS Service capabilities.
It’s well established that metro stations have no GPS coverage whereas GSM signal is caught pretty well at most of them. Therefore using the received Cell IDs we can locate a unit. We took a route across the Minsk metro line and got the following picture with LBS data (blue track):
It is assumed that subway stations use cell base transceivers to receive and transmit GSM signal from and to ground-based cell base stations. Therefore their coordinates don’t match with subway stations location.
To show you how Wialon LBS Service works, we specified the coordinates of the cell base stations in our proprietary database. It resulted in the following unit track:
Obviously, the quality of the track has been significantly changed for the better.
The same coordinates adjustment process now occurs in Wialon automatically: the more units send their coordinates together with Cell ID, the more accurate location will be defined in future in case of GPS signal loss.
*Yellow refers to the accumulated points of Wialon LBS service database, red refers to the Opencellid points. With account of points overlap.
LBS positioning is activated in the Advanced tab of the unit properties dialog (“Allow positioning by cellular base stations” check box). If ‘LBS detected’ data is more recent than GPS one, then it will be used for determining current unit’s location.
The messages with coordinates detected with LBS service are marked with (0) satellites captured.
Currently we have about 5 million points accumulated in our database, including more than one million points bound to the cell base stations not available in Opencellid. In 80% of queries Wialon LBS Service allows for precise unit location detection. Our database is updated and improved every second and it will definitely become a strong advantage for our partners businesses.