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It is now widely accepted that GPS meets, under ideal operational conditions, all attributes of a ubiquitous positioning system, i.e. accuracy, reliability and availability. However, its performance quickly deteriorates in certain environments, such as indoors or in urban canyons. In such environments, the demand for location based services (LBS) is growing(More)
The utility and adoption of indoor localization applications have been limited due to the complex nature of the physical environment combined with an increasing requirement for more robust localization performance. Existing solutions to this problem are either too expensive or too dependent on infrastructure such as Wi-Fi access points. To address this(More)
Recently new location technologies have emerged that can be employed in modern advanced navigation systems. They can be employed to augment common satellite positioning techniques (GNSS) and dead reckoning as they offer different levels of positioning accuracies and performance. An integration of other technologies is especially required in indoor and(More)
For an increasing number of applications, the performance characteristics of current generation Global Navigation Satellite Systems (GNSS) cannot meet full availability, accuracy, reliability, integrity and vulnerability requirements. It is anticipated however that around 2010 the next generation of GNSS will offer around one hundred satellites for(More)
This paper provides a decentralized and coordinate-free algorithm, called DGraF (decentralized gradient field) to identify critical points (peaks, pits, and passes) and the topological structure of the surface network connecting those critical points. Algorithms that can operate in the network without centralized control and without coordinates are(More)
For the majority of applications that use positioning information, solutions from Global Navigation Satellite Systems (GNSS) can easily meet the accuracy, availability and reliability required. This assumes that the GNSS receiver is always operating in an environment that offers clear sky visibility. However, for a growing number of location based services(More)
Real time kinematic (RTK) GPS techniques are now commonly adopted to achieve centimetric position accuracy requirements. The classical RTK methodology allows for an operational distance between the reference station and the user, within a range of 40-50 kilometres, due to the correlation of some GPS errors with distance. By adopting a Network RTK (NRTK)(More)