Towards Ubiquitous Positioning (UbiPos): A GNSS perspective

Ubiquitous computing or UbiComp represents the third wave in computing which has evolved from mainframe (one computer was shared by many users) and personal computing (one person uses one computer) eras. This so called "calm technology" encompasses many background supporting disciplines such as distributed computing, mobile computing, telecommunications, sensor networks, human-computer interaction, location sensing and artificial intelligence, just to name a few. As a most important element of UbiComp, Ubiquitous Positioning or UbiPos, particularly Global Navigation Satellite System (GNSS) positioning or augmented GNSS based UbiPos has not yet been well studied which is impeding the development and applications of UbiComp. There are currently two different and even conflicting general perspectives about the roles of GNSS or integrated GNSS for Ubiquitous Positioning under the context of UbiComp: either GNSS positioning, notably GPS positioning, is a mature technology which can deliver about 10 m positioning accuracy or GNSS is not appropriate technology at all for UbiComp because it has poor reliability when used indoors or under obscured environments where a mass market exists. The latter reputation comes from positioning trials in city centres which have often ended with lack of signals due to obstructions by the surroundings. People with this latter perspective try to avoid using GPS. The authors attempt to address from the GNSS researchers' perspective what available location sensing technologies could be employed for UbiComp, what are the major barriers which hamper the further exploitation of UbiComp, and how different positioning technologies and advanced computing could be integrated seamlessly to provide guaranteed positioning solutions at expected accuracy for different levels of UbiComp applications; from mm level accuracy for intelligent structural monitoring to tens of meter accuracy for cargo tracking. To support UbiPos and other research initiatives, a network Real-Time Kinematic (RTK) GPS testbed has been jointly established by the University of Nottingham and Leica Geosystems, which covers about 20,000 square kilometres in the centre of the United Kingdom and consists of 16 state of the art geodetic grade GPS reference stations. As the first step for the further exploitation of this established network RTK GPS facility for future UbiPos tests, the authors investigate the achievable positioning quality and the signal coverage of network RTK corrections through GPRS connection and the preliminary results are introduced in this paper.