Outdoor Location of Mobile Devices Using Trilateration Algorithms for Emergency Services

With the rise of mobile technologies, it seeks to solve a large number of needs that users have, for example locating people for emergency services. At present, there are a large number of applications dedicated to providing service of positioning through mobile devices, with the global positioning system (GPS) which is the main positioning technology used. However, other technologies exist that using the correct algorithms can give the position of a target with good precision; one of these technologies is the global system for mobile communications (GSM). The most popular positioning methods include the angle of arrival (AoA), time of arrival (ToA), triangulation, time difference of arrival (TDoA), and trilateration. At the beginning, the GSM service was simply a means of transmitting voice and short messages, with the passage of time the technologies evolved and expanded their characteristics, providing values that can be used to locate a person based on the signal strength received by a person, device, and in the known position of three or more reference nodes. When an emergency occurs, the current communication services (3G or 4G) are insufficient due to the high concentration of mobile subscribers in a single place that exceeds the capacity of an antenna. This means that calls to emergency services are not completed, which makes it difficult to rescue people in danger. Although GSM does not have a technology dedicated to positioning, it can provide valuable data for location by using dedicated algorithms, such as trilateration, with which the coordinates of the target device can be processed by the coordinates of three or more reference nodes.