Location-Based Services : A Road Towards Situation Awareness Renato Filjar#, Gordan Jezic*, Maja Matijasevic* (# Ericsson Nikola Tesla, Zagreb; * University of Zagreb) (Email : renato.filjar@ericsson.com) With the widespread use of mobile devices and increased demand for mobile services, Location-Based Services (LBS) represent a promising addition to service offerings of net- work operators as well as third-party service providers. Based on long-term research in LBS, our group has proposed a generic Enhanced LBS Reference Model (ELRM), which de- scribes the concept, the architecture and the functionalities of the LBS. In addition, an evol- utionary information process has been identified within the LBS, that represents knowledge maturity from position awareness to situation awareness. Both the ELRM and the infor- mation evolution process in LBS are presented in this article and illustrated by a case study within the framework of the 3GPP-standardised IP Multimedia Subsystem (IMS). This case- study emphasises the opportunities for navigation- and LBS-related solutions development provided by modern telecommunication technologies. KEY WORDS 1. LBS model. 2. Location landscape. 3. Situation awareness. 4. Telecommunication network. 1. INTRODUCTION. The modern definition of location-based services (LBS) presents them as a group of emerging telecommunication services that successfully and purposefully merge ubiquitous position determination, mobile data communi- cations and position-related content, with a defined level of quality of service (QoS). A considerable development has been made in recent years with the aim to define the general LBS reference model that would be able to present all entities required for implementation of a location-based service, and their interrelations. Our group has developed the unique LBS reference model which successfully presents the process of obtaining the best positioning estimate and communicates it with the LBS appli- cations (Filjar et al, 2004). However, in search of a more general reference model of LBS as an information and telecommunication service, a considerable enhancement of this model was to be developed. As a result, the Enhanced LBS Reference Model (ELRM) has been identified (Filjar, Busˇic´, 2007). Further evaluation of the ELRM has led to identification of an evolutionary process through which the ‘‘ raw ’’ position estimate matures to location. This evolution paves the road towards practical im- plementation of situation awareness. This paper addresses improved ELRM concept, architecture, and functionalities, and describes location information evolutionary process. Practical implementation THE JOURNAL OF NAVIGATION (2008), 61, 573–589. f The Royal Institute of Navigation doi:10.1017/S0373463308004864 Printed in the United Kingdom