Protecting portable devices is becoming more important, not only because of the value of the devices themselves, but for the value of the data in them and their capability for transactions, including m-commerce and m-banking. An unobtrusive and natural method for identifying the carrier of portable devices is presented. The method uses acceleration signals produced by sensors embedded in the portable device. When the user carries the device, the acceleration signal is compared with the stored template signal. The method consists of finding individual steps, normalizing and averaging them, aligning them with the template and computing cross-correlation, which is used as a measure of similarity. Equal Error Rate of 6.4% is achieved in tentative experiments with 36 test subjects.
The latest camera-equipped mobile terminals and fast cellular networks have increased the interest in mobile multimedia services. The growing amount of stored digital information presents new challenges for video retrieval and browsing. Mobile multimedia services can be accessed with a wide variety of mobile terminals. Content delivery through mobile networks and its presentation in user terminals with limited capabilities requires special attention. This paper suggests a system that allows the creation, storage and retrieval of home videos. The server uses a distributed database, adaptive user interface and adaptive video transmission techniques for access by diverse mobile terminals and minimizing the required data transfer. Manually and automatically created metadata about the video contents is also stored in the database and can be queried in an intelligent manner by means of domain ontology. The user is able to browse through the search results and choose a video to view in a Metaplayer, in which in-video browsing is facilitated by a metadata display. This helps the user to find the interesting points in the video without having to stream unnecessary parts, thus reducing network load. State-of-the-art terminal profiling techniques are used to adapt the user interfaces and presentation of search results according to the user's preferences and device capabilities.