Modelling the GPS-receiver: a look from the LBS side

Within the research field of Location-based Services (LBS), a second generation is being prepared to be launched to the market. Besides the fact that the market is more mature (e.g. many mobile phones have a built-in GPS receiver), there are two novelties: a focus on proactive applications and multi-user applications. This is needed in order to support, by example, a Buddy Finder application. The main problems that these mobile terminals are facing are: the energy consumption of the GPS receiver (e.g. the capacity of a mobiles battery is limited, and can only support a GPS in tracking mode for a few hours), its startup time (i.e. cold, hot and warm start) and the unavailability of GPS in indoor environments and in urban canyons (e.g. the city centre). Though the next generation (Galileo, as from 2011, and GPS-III, as from 2013), will offer improved accuracy and coverage, the problem of indoor coverage and battery load largely remains. To overcome this, a multitechnology approach is needed at the positioning layer. This paper proposes a state model for a GPS-receiver that takes into account the different startup modes. This approach allows monitoring and even proactively dealing with the energy consumption and time to first fix, which can be used in an LBS application for supporting the positioning technology choices. The main novelty is that this model allows managing the GPS receiver based on typical requirements from proactive multi-target LBS.

Publication year:2008

Keywords:GPS, communication