A Framework for Context Modeling in Adaptive Ubiquitous Systems
Paper Presenter & Author: Dassen Sathan, UoM
Context awareness is an important capability for mobile computing that can sense their physical environment, and adapt their behavior accordingly, thus allowing users to discover and communicate their positions in the physical world. Three important aspects of context are: where you are; who you are with; and what resources are nearby. The term Location/context-awareness in ubiquitous computing was introduced by Schilit (1994) [1] and have become one of the most exciting concepts in early 21st-century computing, fueled by recent developments in pervasive computing (i.e., mobile and ubiquitous computing) including new computers worn by users, embedded devices, smart appliances, and sensors surrounding users and varieties of wireless networking technology. Although location is a primary capability, location-aware does not necessarily capture things of interest that are mobile or changing. Devices may have information about the circumstances under which they are able to operate and based on rules, react accordingly and users are part of the process. Context-aware applications which use them to adapt interfaces, tailor the set of application-relevant data, increase the precision of information retrieval, discover services, make the user interaction implicit, or build smart environments. For example: A context aware mobile phone may know that it is currently in the meeting room, and that the user has sat down. The phone may conclude that the user is currently in a meeting and reject any unimportant calls.[3]
A number of research and commercial location aware systems have been built making use of sensing techniques such as proximity, time of flight, triangulation etc. [2] Each of the solutions that have been proposed till now, try to improve the accuracy and precision of previous location aware systems. Despite, the efforts of researchers in improving the accuracy, building and deploying location aware applications that are usable by a wide variety of people in everyday situations is unfortunately not easier today that it was few years back. There are two main factors hindering the widespread deployment of context-ware services. First, location aware system do not cover a have a wide coverage, that is current context-aware systems either can be used only outdoor or a building or campus, but nowadays users want to get access to the services when they are in a building or roaming on a campus, in simpler terms users want both indoor and outdoor coverage. Secondly, the technology has a high cost for both users and application developers. Because existing context-aware system make use of devices such as GPS beacons that are expensive and time-consuming to calibrate. [3]
This project aims at developing a framework for collecting, managing, processing and disseminating context information to users and constitutes an important enabler for realizing more comprehensive context-sensitive communications in ubiquitous system. The framework will allow laptops, PDAs and cell phones to estimate their position by listening for the cell IDs of fixed radio beacons, such as wireless access points, and referencing the beacons’ positions in a database. The database will store the unique ID of beacons and exact location. Clients such as laptop device can compute their own location by hearing one or more IDs, looking up the associated beacons’ positions in a locally cached map, and estimating their own position referenced to the beacons’ positions. The framework will consist of three main modules, a spotter module, a tracker module and a mapper module. The spotter module scans all of the wireless cards on the machine and returns the device ID of access points that it sees within the covered range. The mapper module will take the device ID and extract the device location from the database. The Tracker module use measurements from the spotter and mapper module to produce estimated locations by triangulation.The framework will address both factors that were hindering the progress of context-aware applications by making use wi-fi equipments that lowers the cost of entry to users and has high beacon coverage.
References
[1] B. Schilit, N. Adams, and R. Want. (1994). "Context-aware computing applications". IEEE Workshop on Mobile Computing Systems and Applications (WMCSA'94) .
[2] schilit, b., lamarca, a., borriello, g., griswold, w., mcdonald, d., lazowska, e., balachandran, a., hong, j. & iverson, v. Challenge: Ubiquitous Location-Aware Computing and the Place Lab Initiative Proceedings of the First ACM International Workshop on Wireless Mobile Applications and Services on WLAN (WMASH).(2003)
[3] Anthony LaMarca, Yatin Chawathe, Sunny Consolvo, Jeffrey Hightower, Ian Smith, James Scott, Timothy Sohn, James Howard, Jeff Hughes, Fred Potter, Jason Tabert, Pauline Powledge,and Bill Schilit.Place Lab: Device Positioning Using Radio Beacons in the Wild, In proceedings of Pervasive 2005, Munich, Germany