Mobile Station Location in GSM Cellular Network

Abstract

The Mobile Station Location (MSL) problem is the problem of physically locating a user of a cellular phone. One important application of a MSL would be emergency call centers, where the call center operator could see the location of the caller on a computerized map. MSL has not yet been implemented due to high costs. This thesis presents an approach on how to implement Mobile Station Location in GSM networks using existing GSM system entities and protocols. It is proposed to place the location calculation in a new entity in the GSM network, communicating with the other entities using protocols specified in the GSM system. The communication between the entity performing the MSL, and the rest of the GSM network is studied in detail, using SOL (Specification and Description Language). Schemes for performing the location calculation are presented, and a system for specifying location areas is proposed. An outline of how the position information can be presented to the emergency call center operator is also given. The method of placing the MSL in a separate entity and gathering position information from the GSM network using existing GSM protocols, should greatly simplify the implementation of MSL. Thus, it is possible to implement MSL in GSM at relatively small costs.