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Recent studies confirm the importance of satellite positioning in location-based services (LBS) development. A field study was conducted in suburban and rural areas near Zagreb, Croatia in order to examine the real-time data compliance with recently established positioning performance requirements for LBS quality of service (QoS). Data analysis was based on comparison between actual positioning performance and pre-specified positioning parameter values using defined comparative procedures. The results presented here confirm a good correlation between the actual and required positioning performance, even without implementation of any of augmentation or assistance positioning methods.1. satellite. 2. positioning. 3. performance. 4. LBS. I N T R O D U C T I O N.In the history of location-based services (LBS) development, satellite positioning has been presumed to be a foundation positioning method (Beatty, 2002). The importance of satellite positioning in LBS development was established using third-party simulations and local field trials described in references. In order to confirm this presumption, a Zagreb field trial was conducted on 12 June, 2003. Dynamical positioning performance of satellite navigation in semiurban and rural environments is analysed in this paper. Four basic LBS positioning performance parameters were pre-defined, and their definitions were applied on a set of data collected during the field trial. The paper concludes with the plan of future activities in relation to obtained results of the field trial data analysis. P R E V I O U S W O R K.Satellite positioning is the most promising positioning method for LBS currently available (Filjar et al, 2001). The positioning performance of satellite navigation systems, GPS in particular, is comprehensively described in the related specifications (Department of Defense, 2001) and thoroughly examined during numerous field trials worldwide. However, the implementation of satellite positioning as the foundation of the location-based services (LBS) has not, so far, been appropriately challenged. Special requirements for LBS development

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Recent studies show that basic satellite positioning is reaching its limits in terms of performance improvements. Further enhancements in positioning performance can be based almost entirely on augmentation and procedures supported by other systems. Considering the complexity of the interrelationship with additional systems, intrinsically different solutions are being developed to solve the positioning performance improvement problem. Here we present a new concept in positioning. Dubbed distributed positioning, it merges basic satellite positioning with advanced and assisted positioning procedures. The resulting complex synergy unavoidably includes the use of additional technologies in mobile communications, wireless Internet, and advanced computer systems. The real advantage from the introduction of distributed positioning lies in its capability to provide a significant improvement in overall positioning performance. Latest navigation status and up-to-date local environment models are much easier to apply on rover positioning, compared with classical assisted-GPS positioning procedures. Distributed positioning presents a completely different approach in positioning performance improvement, opening new prospects in research and development not only in the field of the satellite positioning, but also in telecommunications and computer engineering.

One common approach in dealing with increased number of elderly is provisioning of IT based applications that strive to prolong their independent life. However, development of such applications is cumbersome and expensive. In order to simplify and ease the development of such applications, MPOWER framework has been developed. The MPOWER framework provides service based architecture and a set of predefined services that can be assembled into applications for elderly. In this article we give a brief overview of the MPOWER framework and concentrate on the issue of providing usable interfaces for the elderly. Specifically, we compare two versions of an application for the elderly, one using a thin and other a fat client. We demonstrate that although thin clients are simpler to develop, in many situations fat clients should be used as they can provide interfaces that are better accustomed to the elderly.