Philipp Bolliger

Redpin - adaptive, zero-configuration indoor localization through user collaboration

Redpin is a fingerprint-based indoor localization system designed and built to run on mobile phones. The basic principles of our system are based on known systems like Place Lab or Radar. However, with Redpin it is possible to consider the signal-strength of GSM, Bluetooth, and WiFi access points on a mobile phone. Moreover, we devised methods to omit the time-consuming training phase and instead incorporate a folksonomy-like approach where the users train the system while using it. Finally, this approach also enables the system to expeditiously adapt to changes in the environment, caused for example by replaced access points.

The sensor internet at work: Locating everyday items using mobile phones

We present a system for monitoring and locating everyday items using mobile phones. The system is based on phones which are enhanced with the capability to detect electronically tagged objects in their vicinity. It supports various functionalities: On the one hand, phones can store the context in which users leave registered items and thus help to locate them later on. On the other hand, object owners can search for their objects using the infrastructure of mobile phones carried by other users. We describe the design of our object location system and provide an algorithm which can be used to search for lost or misplaced items efficiently by selecting the most suitable sensors based on arbitrary domain knowledge. Furthermore, we demonstrate the practicability of such wide-area searching by means of user-held sensors in a series of simulations complemented by a real-world experiment.

Objects calling home: locating objects using mobile phones

Locating physical items is a highly relevant application addressed by numerous systems. Many of these systems share the drawback that costly infrastructure must be installed before a significant physical area can be covered, that is, before these systems may be used in practice. In this paper, we build on the ubiquitous infrastructure provided by the mobile phone network to design a wide-area system for locating objects. Sensor-equipped mobile phones, naturally omnipresent in populated environments, are the main elements of our system. They are used to distribute search queries and to report an objects location. We present the design of our object search system together with a set of simple heuristics which can be used for efficient object search. Moreover, such a system can only be successfully deployed if environment conditions (such as the participant density and their mobility) and system settings (such as number of queried sensors) allow to find an object quickly and efficiently. We therefore demonstrate the practicability of our system and obtain suitable system parameters for its execution in a series of simulations. Further, we use a real-world experiment to validate the obtained simulation results.

Facet: towards a smart camera network of mobile phones

Smart camera networks provide the opportunity to detect, classify, and trace visual events by means of a wireless network of embedded computing devices equipped with camera sensors. Previous research in this area has largely focused on custom hardware solutions. In contrast, we propose to use mobile phones as a portable and low-cost platform to implement smart camera networks. Due to mass production, the price of mobile phones is constantly dropping while additional functionality is being added. In particular, the addition of cameras and ad hoc networking enable the use of mobile phones for smart camera networks. Also, software developed for mobile phones is highly portable due to standardized programming environments and APIs. In this paper, we present Facet, a self-organizing network of smart cameras and its software architecture, which addresses the specific challenges of the mobile phone platform. An initial prototype of Facet has been developed and is used to obtain first performance results in an office setting.

Creating Location-Based Services by Utilising a Web of Places

We present an open, decentralized, participatory system which realizes location-based services by gently extending the existing World Wide Web. Utilizing a geospatial search engine for such a Web of Places, users are able to consume location-based services generated by arbitrary parties using their mobile phones. Special care has been taken in order to foster the creation of places and services and their mobile usage by users. We further discuss that by using ranking algorithms based on place and service definitions, finding services relevant to the current location by searching only by geographic position might be feasible even in case of large numbers of relevant places.