Allison Kealy

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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)
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)
Cooperative positioning (CP) is an approach for positioning and/or positioning enhancement among a number of participants, which communicate and fuse their position-related information. Due to the shortcomings of Global Navigation Satellite Systems (GNSSs), modern CP approaches are considered for improving vehicular positioning where the GNSS cannot address(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)
The recognition of locomotion activities (e.g., walking, running, still) is important for a wide range of applications like indoor positioning, navigation, location-based services, and health monitoring. Recently, there has been a growing interest in activity recognition using accelerometer data. However, when utilizing only acceleration-based features, it(More)