This paper presents practical protocols for authenticating the parameters that characterise a principal's context. Context features in what are known as mobile, ubiquitous, pervasive and nomadic computing systems. Location, in particular, is a highly significant contextual parameter. We present a model of context authentication based on the characteristics of communication channels. Then we present protocols for location authentication that are based on physical channel characteristics, including a protocol that we have implemented over HTTP for use from any Web browser. We conclude with a summary and discussion of the work.

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People are increasingly using personal digital assistants (PDAs) and cellphones in their daily lives. The primary advantage of these devices is that they are mobile. They allow people to perform tasks requiring computation and communication without tying them to specific locations. Despite the popularity of these devices, they do have drawbacks. Most significantly, they impose a trade-off between luggability and capability. To get smaller and lighter

The Intelligent Environment consists of ubiquitous connectivity in sensor rich environments coupled with adaptive technologies that allow access from multiple devices with varying capabilities. Context information is drawn from what the Intelligent Environment can sense about its current physical and computational environments. This context information relates to aspects of the environment which include, who is in the environment, what they are doing, what they have done, and what their actions are. Multi-granularity context description provides a mechanism to describe, at increasingly more abstract levels, such context information gleaned from the Intelligent Environment. The proposed architecture for the Intelligent Environment is central to determining methods for capturing such information at the lowest level, interpreting by historical reference, and aggregating into increasingly more abstract forms.

Designers of mobile, social systems must carefully think about how to help their users manage spatial, semantic, and social modes of navigation. Here, we describe our deployment of MobiTags, a system to help museum visitors interact with a collection of “open storage ” exhibits, those where the museum provides little curatorial information. MobiTags integrates social tagging, art information, and a map to support navigation and collaborative curation of these open storage collections. We studied 23 people’s use of MobiTags in a local museum, combining interview data with device use logs and tracking of people’s movements to understand how MobiTags affected their navigation and experience in the museum. Despite a lack of social cues, people feel a strong sense of social presence—and social pressure—through seeing others ’ tags. The tight coupling of tags, item information, and map features also supported a rich set of practices around these modes of navigation. Author Keywords Mobile tagging, museum, experience, presence, navigation

This Editorial lead paper for the Journal of Location Based Services surveys this complex and multi-disciplinary field and identifies the key research issues. Although this field has produced early commercial disappointments, the inevitability that pervasive location-aware services on mobile devices will emerge means that much research is needed to inform these developments. The paper reviews firstly: the science and technology of positioning, geographic information science, mobile cartography, spatial cognition and interfaces, information science, ubiquitous computing; and secondly the business, content and legal, social and ethics aspects, before synthesising the key issues for this new field.

This article is based on a shortened and adapted translation of the paper "Ubiquitous Computing: Szenarien einer informatisierten Welt" [6], some parts have also been taken from the paper "From Distributed Systems to Ubiquitous Computing -- The State of the Art, Trends, and Prospects of Future Networked Systems" [7]

The enabling of data produced by product embedded sensor devices for use in product development could greatly benefit manufactures, while opening up new business opportunities. Currently products such as cars already have embedded sensor devices, but the data is usually not available for analysis in real-time. We propose that a world-wide, inter-organizational network for product data gathering should be created. The network should be based on open standards so that it can be widely adopted. It is important that a common, interoperable solution is accepted by all companies, big or small, to enable innovative new services to be developed. In this paper, the concept of the Internet of Things (IoT) is described. The PROMISE project is presented, and a distributed messaging system for product data gathering developed within the project is introduced. Practical experiences related to the implementation of the messaging system in a real application scenario are discussed. 1

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Researchers and designers are increasingly making use of geographic location in designing context-aware computer systems. However, there has been little conceptual work on how geography interacts with technology. In this paper, we use the concepts of "place and space" to explore how technologies are used geographically and how they impact on, and are used in, the physical environment. Fieldwork with tourists using maps and guide books shows how technology brings space and place together in activity. This discussion is used to look at how technologies might better span place and space.