Location-based services are mobile network applications of growing importance and variability.
The space of location technologies and applications has not yet been fully explored, perhaps
omitting some important practical uses. In this work we present the SS7Tracker,an active, nonintrusive,
GSM Cell-ID-based solution to network-based location tracking. We demonstrate the
usability of the solution on practical tests carried out in a live GSM network.
In principle two tracking methods are used. Active tracking is based on periodic questioning
of the network about the location of tracked devices. Conversely passive tracking methods use
location information generated during communication between a mobile phone and the GSM
network. The advantage of active tracking is that it can track passive subscribers who are not using
the mobile phone at the moment. We present the SS7Tracker – a feasible approach to mobile
phone localization and tracking implemented within a live GSM network. For the mobile phone
localization we use Cell-ID positioning based purely on signaling messages of the Mobile Application
Part (MAP) protocol from the standard SS7 protocol. This determines the main features of
theSS7Tracker: It is non-intrusive to the existing signaling network equipment in the sense that it
does not demand any software or hardware changes neither in the network core elements nor in
the localized mobile phones. The platform is able to localize any subscriber of the GSM network,
no matter if his or her mobile phone is equipped with
GPS or if the subscriber is passive. It provides real-time localization with only small delay caused
by propagation of messages in the network, and the location accuracy depends on the size of network
cells. The localization is ensured by queries hidden to the localized subscriber and does not
require subscriber cooperation.
The architecture of the platform is client-server oriented. The server side is equipped with SS7
signaling board which acts as a GSM network signaling point via TDM and Ethernet card which
acts a GSM network signaling point via SIGTRAN (IP). The server side is connected to a live signaling
network in order to communicate with mobile network nodes to ensure the location retrieval.
Results of the tracking are visualized in a client side front end application GUI or map.
The following features are provided by our solution:
– The system supports simultaneous operation with up to 4 mobile operators (one SS7 link per
– SS7Tracker allows the end user to detect CGI of subscriber of the home network.
Optionally, the solution can support
real location detection of the roaming
subscriber in any country of the world and
for any serving mobile operator network.
SS7 Tracker solution has a possibility
to connect to any known type of known
nodes of CS Core.
Accuracy of MS location detection
– from 300 to 500 meters in urban conditions
and about 1500 – 5000 meters
outside the city. Accuracy depends from
density of radio covering the mobile operator’s
network in selected area.