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802.11-based indoor positioning systems have been under research for quite some time now. However, despite the large attention this topic has gained, most of the research focused on the calculation of position estimates. In this paper, we go a step further and investigate how the position error that is inherent to 802.11-based positioning systems can be estimated. Knowing the position error is crucial...
We present a novel system that allows small handheld devices to detect other devices in the local proximity and to exchange messages with them. The client devices use WLAN to access the system via a web interface and do not require additional software or modification of the device's operating system. The physical closeness of client devices is estimated based on their signal strengths measured by...
With the increasing proliferation of powerful mobile devices, the use of location-based services has gained noticeable momentum. However, new challenges arose with the higher user mobility. Especially in the context of location-based services, one of these challenges is the problem of selecting the most suitable positioning technology. This paper gives a brief overview of the three most common techniques...
At first glance, making electronic music seems to be a domain which is also well suited for people with limited eye-sight. However, a closer analysis reveals that standard software and hardware are both strongly dominated by graphical output. In order to close this gap for visually impaired musicians, we developed a MIDI (Musical Instrument Digital Interface) sequencer with audio-feedback and a new...
In this paper, we proposes a method to utilize the huge number of IEEE 802.11 access points in an inner city environment to distribute information such as local sensor values, votes or short text messages. Due to the overlapping channels on IEEE 802.11b/g it is possible to receive packets from neighboring channels by overhearing. This fact allows every access point to monitor a part of the frequency...
One of the drawbacks of location fingerprinting systems is the effort that is necessary to set up and update the fingerprint database. In this paper, we propose a novel approach to significantly reduce this effort. We split the area of operation into a grid of quadratic cells and then combine these cells into larger regions of similar signal properties using a clustering algorithm and a novel similarity...
We propose a system for acquiring, maintaining, and communicating Real-World Achievements. The concept is based on virtual world systems that are in common use in current Massively Multiplayer Online Games (MMOG) like World of Warcraft or Warhammer Online. The system design is centered around a global database of achievement definitions and individual progress.
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