Triggering information by context

With the increased availability of personal computers with attached sensors to capture their environment, there is a big opportunity for context-aware applications; these automatically provide information and/or take actions according to the user's present context, as detected by sensors. When wel l designed, these applications provide an opportunity to tailor the provision of information closely to the user's current needs. A sub-set of context-a ware applications are discrete applications, where discrete pieces of i nformation are attached to individual contexts, to be triggered when the user enters those contexts. The advantage of discrete applications is that authori ng them can be solely a creative process rather than a programming process: it can be a task akin to creating simple web pages. This paper looks at a general system that can be used in any discrete context- aware application. It propounds a general triggering rule, and investigates how this rule applies in practical applications

Exploiting Semi-Directional Transceivers for Localization in Communication Systems

Localization is the process of determining relative, as well as absolute, positions of communicating devices. Traditionally, the process is conducted using range or directional estimates. In contrast, this research uses weak information to form relatively tight bounds on possible locations of communicating devices. Under certain conditions, achieved location estimation results are strong. However, these results are highly sensitive to the operating conditions of the proposed networks. More significant results were obtained from specialized cases and that the application yields somewhat limited information for a general randomized network topology. Feasible localization results were found to be attainable but not necessarily practical for multiple experiments. This is due to the brute force nature of the implemented localization algorithm which experiences an exponential increase in runtime as the number of nodes increases

Self-* distributed query region covering in sensor networks

Wireless distributed sensor networks are used to monitor a multitude of environments for both civil and military applications. Sensors may be deployed to unreachable or inhospitable areas. Thus, they cannot be replaced easily. However, due to various factors, sensors\u27 internal memory, or the sensors themselves, can become corrupted. Hence, there is a need for more robust sensor networks. Sensors are most commonly densely deployed, but keeping all sensors continually active is not energy efficient. Our aim is to select the minimum number of sensors which can entirely cover a particular monitored area, while remaining strongly connected. This concept is called a Minimum Connected Cover of a query region in a sensor network. In this research, we have designed two fully distributed, robust, self-* solutions to the minimum connected cover of query regions that can cope with both transient faults and sensor crashes. We considered the most general case in which every sensor has a different sensing and communication radius. We have also designed extended versions of the algorithms that use multi-hop information to obtain better results utilizing small atomicity (i.e., each sensor reads only one of its neighbors\u27 variables at a time, instead of reading all neighbors\u27 variables). With this, we have proven self-* (self-configuration, self-stabilization, and self-healing) properties of our solutions, both analytically and experimentally. The simulation results show that our solutions provide better performance in terms of coverage than pre-existing self-stabilizing algorithms

Análise dos problemas de provisão de QoS em redes sem fio utilizando simulação

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Ciência da Computação

Context-aware Non-electronic Service Discovery and Composition

In today’s web, many web services are created and updated on the Internet. In many cases, a single service is not sufficient to respond to the user’s request and often services should be combined through service composition to fulfill business goals. Service discovery and service composition can be highly compatible with context, i.e., according to context information, e.g., location, budget and time, services are chosen and composed. Moreover, we include non-electronic services, e.g., restaurants, movie theaters shopping malls and so on, into service composition. Non-electronic services are rarely considered in existing service composition research, however are frequently used in people’s daily life. In this thesis, we provide an approach for using contexts to discover and compose non-electronic services. We present a new context model which is to make it more suitable for service composition. This model is also able to handle both low level sensor data and high level data in predicated logic. Our service composition algorithm uses soft constraints, dissatisfaction of which causes a penalty instead of the fail of planning. With this feature, the service composition algorithm can give the user several “good enough” solutions, instead of null solution. Additionally, a replanning module is developed to refine the solution according to user’s further adjustments of his or her requirements. As a motivating example, a web based Personal Entertainment Planner system is built

Extraktion von Kontextinformationen zur Analyse von Nutzerströmen

Kontextadaptive Dienste ermitteln auf Basis von Sensordaten die aktuelle Situation des Nutzers. Dabei zählt neben Zeit, Identität und Aktivität vor allem der Aufenthaltsort zu den primären Kontextinformationen. Gerade Gebäude- und Infrastrukturbetreiber haben höchstes Interesse an solchen Daten, bekommen jedoch nur selten Zugriff darauf. Eine vielversprechende Alternative stellt das Aufzeichnen und Analysieren von Bluetooth- bzw. WLAN-Signalen dar, welches sich auch ohne Einverständnis der Nutzer realisieren lässt. Einige Startup-Unternehmen bieten mit dieser Strategie bereits Kundenanalysen an, jedoch fehlen wissenschaftliche Studien über die tatsächliche Güte solcher Verfahren. Zudem stellt die Extraktion primärer Kontextinformationen eine bisher ungelöste Herausforderung dar, da die aufgezeichneten Daten ein hohes Rauschen und eine geringe Frequenz aufweisen. Die vorliegende Arbeit geht dieses Problem der Datenunsicherheit an. So wird im ersten Teil untersucht, wie und welche Informationen aus Kommunikationsdaten gewonnen werden können. Diese werden anschließend zur Berechnung von Nutzerströmen in einem realen Szenario verwendet. Mithilfe einer bekannten Grundwahrheit können erstmals belastbare Aussagen über die Güte der evaluierten Verfahren getroffen werden. Die Ergebnisse zeigen, dass sich gerade WLAN-Daten zur Nutzerstromanalyse eignen, weshalb anschließend Simulationsmodelle von WLAN-Beobachtungen entwickelt werden. Dabei wird erstmals neben der Zeit auch die Aktivität und das Endgerät berücksichtigt. Der zweite Teil beschäftigt sich mit der Extraktion der Ortsinformation aus WLAN-Daten, die von mehreren Messknoten aufgezeichnet werden. Hierbei werden zunächst geometrische Ansätze zur Platzierung solcher Knoten vorgestellt. Auf Basis der Ergebnisse werden Messknoten installiert, um Bewegungspfade mobiler Nutzer im Gebäude zu ermitteln. Es zeigt sich, dass deterministische Methoden nicht die nötige Genauigkeit liefern und probabilistische Verfahren andere Nachteile aufweisen. Deshalb wird der State-Partikel-Filter als neuartige hybride Variante vorgestellt, die im Rahmen der Evaluation bessere Ergebnisse in Bezug auf anerkannte Metriken erreicht. Im dritten Teil wird die Extraktion von Aktivitäts- und Identitätsinformationen untersucht. Hierzu wird ein modifiziertes Verfahren zur Bestimmung von Ruhe- und Bewegungsphasen vorgestellt, das im Vergleich zu verwandten Arbeiten genauer ist. Auf Basis aller verfügbaren Informationen wird schließlich zur Identitätserkennung eine Klassifizierung von Nutzerrollen durchgeführt. Anders als in bisherigen Arbeiten findet so eine komplette Extraktion primärer Kontextinformationen aus aufgezeichneten Kommunikationsdaten statt.Context-aware services mainly estimate a user's current situation using sensor data. The well-known primary types of context information are time, identity, activity, and above all, location. Building managers and infrastructure providers are particularly interested in such data. However, they hardly get access to it. A promising alternative way without requiring users' permission for data access is to observe and analyse Bluetooth as well as Wi-Fi signals. Some start-ups already apply this technique in order to offer retail analytics. However, scientific studies providing information about the real performance of such approaches are still missing. Furthermore, extracting all of the primary types of context information is still challenging, due to the fact that the recorded data suffers from high noise and low sampling rates. This work deals with the afore-mentioned problems. Hence, the first chapter investigates, how and which kind of information can be inferred from captured communication data. Subsequently, this information is used to estimate user flows in a realistic scenario. With access to a known ground truth it becomes possible for the first time to reveal the real performance of the evaluated approaches. The results indicate that Wi-Fi captures are suitable for user flow analysis. Hence, models for simulating Wi-Fi based observations are developed considering time and novel aspects such as the user's activity and the device. The second chapter deals with the extraction of location information from Wi-Fi data which is captured by several distributed monitoring units. As a first step, geometric approaches for the placement of such units are presented. Based on the achieved results, Wi-Fi monitors are deployed in order to track and estimate trajectories of mobile users. In this connection, it is shown that deterministic methods do not reach the required accuracy and probabilistic approaches suffer from different drawbacks. Therefore, the so-called State-Particle-Filter is introduced as a novel hybrid variant returning better results in terms of well-adopted metrics within the performed evaluation. In the third chapter, the extraction of activity and identity information is investigated. Therefore, a modified approach for recognition of dwell times and motion periods is introduced which is shown to be more accurate than existing techniques. Finally, on the basis of all the available information, a user role classification task is performed for identity discovery. Thus, in contrast to other works, a complete extraction of the well-known primary types of context information is realized using captured communication data and the proposed methods

An analysis of interaction in the context of wearable computers

The focus of this thesis is on the evaluation of input modalities for generic input tasks, such inputting text and pointer based interaction. In particular, input systems that can be used within a wearable computing system are examined in terms of human-wearable computer interaction. The literature identified a lack of empirical research into the use of input devices for text input and pointing, when used as part of a wearable computing system. The research carried out within this thesis took an approach that acknowledged the movement condition of the user of a wearable system, and evaluated the wearable input devices while the participants were mobile and stationary. Each experiment was based on the user's time on task, their accuracy, and a NASA TLX assessment which provided the participant's subjective workload. The input devices assessed were 'off the shelf' systems. These were chosen as they are readily available to a wider range of users than bespoke inpu~ systems. Text based input was examined first. The text input systems evaluated were: a keyboard,; an on-screen keyboard, a handwriting recognition system, a voice 'recognition system and a wrist- keyboard (sometimes known as a wrist-worn keyboard). It was found that the most appropriate text input system to use overall, was the handwriting recognition system, (This is forther explored in the discussion of Chapters three and seven.) The text input evaluations were followed by a series of four experiments that examined pointing devices, and assessed their appropriateness as part of a wearable computing system. The devices were; an off-table mouse, a speech recognition system, a stylus and a track-pad. These were assessed in relation to the following generic pointing tasks: target acquisition, dragging and dropping, and trajectory-based interaction. Overall the stylus was found to be the most appropriate input device for use with a wearable system, when used as a pointing device. (This isforther covered in Chapters four to six.) By completing this series of experiments, evidence has been scientifically established that can support both a wearable computer designer and a wearable user's choice of input device. These choices can be made in regard to generic interface task activities such as: inputting text, target acquisition, dragging and dropping and trajectory-based interaction.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

An Infrared Network for Mobile Computers

The PARCTAB infrared network provides a flexible infrastructure for research into wireless mobile computing. The network consists of a collection of room-sized cells each wired with a base station transceiver. Mobile computers communicate with transceivers through a carrier sense multiple access (CSMA) protocol and act as terminals for applications executing on remote hosts. Each mobile computer is represented by a proxy, or agent, accessible to applications at a fixed network address. In the PARCTAB system it is the agent that is responsible for delivering requests to its corresponding mobile computer, and tracking the mobile as it moves from cell to cell. 1 Introduction Personal digital assistants (PDAs) perform the function of paper organizers with the added benefits of digital control. Like paper organizers, PDAs fit in the palm of the hand and can be carried with you throughout the day. However, the true advantage of PDAs are realized by communication with networks of more..