Matthias Berning

Using a 2DST waveguide for usable, physically constrained out-of-band Wi-Fi authentication

This paper proposes using a 2D waveguide for a novel means of authentication in public Wi-Fi infrastructures. The design of the system is presented, and its practicability and usability is comparatively discussed with that of five other tag and context based authentication schemes, two of which have not been previously realized. In accordance with the presented application scenarios, all of the schemes were implemented in a platform-independent fashion built on web technology.

Error correction in single-hop wireless sensor networks: a case study

Energy efficient communication is a key issue in wireless sensor networks. Common belief is that a multi-hop configuration is the only viable energy efficient technique. In this paper we show that the use of forward error correction techniques in combination with ARQ is a promising alternative. Exploiting the asymmetry between lightweight sensor nodes and a more powerful base station even advanced techniques known from cellular networks can be efficiently applied to sensor networks. Our investigations are based on realistic power models and real measurements and, thus, consider all side-effects. This is to the best of our knowledge the first investigation of advanced forward error correction techniques in sensor networks which is based on real experiments.

ProximityHat: a head-worn system for subtle sensory augmentation with tactile stimulation

In this paper we present the iterative design process of our wearable sensory substitution system ProximityHat, which uses pressure actuators around the head to convey spatial information. It was already shown that the sense of touch can be used to augment our perception of reality. Existing systems focus on vibration signals for information transfer, but this is unsuitable for constant stimulation in everyday use. Our system determines the distance to surrounding objects with ultrasonic sensors and maps this information to an inward pressure. It was evaluated in a study with 13 blindfolded subjects in orientation and navigation tasks. The users were able to discern at least three different absolute pressure levels with high certainty. Combined with the sensors, they could also use continuous values to navigate hallways and find doors. Most users had only a few collisions, but a small group of three individuals struggled more. We attribute this to the latency and resolution of the final prototype, which led to slow walking speed and will be addressed in future work.

The TECO Envboard: A mobile sensor platform for accurate urban sensing — And more

Participatory Urban Sensing scenarios have increasingly been studied in the past years. At the same time, societys concern about the effects of pollutants on peoples personal health as well as on the environment grew. This, in conjunction with studies that helped to give a better understanding of those effects, lead to new and stricter regulations and standards set up by governments. Such standards define limits for concentrations which should or may not be exceeded. There are usually several of such maximum permissible values for different pollutants, and they may differ from country to country. As a result, we see the need for ways to take accurate, fine-grained and mobile measurements, e.g in order to identify hot spots or monitor people at risk. Standard fixed measuring methods are not suitable for such scenarios. This demo presents a generic platform for such measurements - the TECO Envboard.

Point & control -- interaction in smart environments: you only click twice

This work presents a system that makes use of the Microsoft Kinect to enable Point&Click interaction for the control of appliances in smart environments. A backend server determines through collision detection which device the user is pointing at and sends the respective control interface to the users smartphone. Any commands the user issues are then sent back to the server which in turn controls the appliance. New devices can either be registered manually or using markers such as QR codes to identify them and get their position at the same time. The video demonstrates the interaction concept and our technical implementation.

pARnorama: 360 degree interactive video for augmented reality prototyping

Designing novel and meaningful interactions in the domain of Augmented Reality (AR) requires an efficient and appropriate methodology. A user centered design process requires the construction and evaluation of several prototypes with increasing technical fidelity. Although the main content of the application can already be conveyed with prerendered video, one of the main interactions in AR - the user-selected viewpoint - is only available in a very late stage. We propose the use of panoramic 360° video for scenario based user evaluation, where the user can select his point of view during playback. Initial users report a high degree of immersion in the constructed scenario, even for handheld AR.

A study of depth perception in hand-held augmented reality using autostereoscopic displays

Displaying three-dimensional content on a flat display is bound to reduce the impression of depth, particularly for mobile video see-trough augmented reality. Several applications in this domain can benefit from accurate depth perception, especially if there are contradictory depth cues, like occlusion in a x-ray visualization. The use of stereoscopy for this effect is already prevalent in head-mounted displays, but there is little research on the applicability for hand-held augmented reality. We have implemented such a prototype using an off-the-shelf smartphone equipped with a stereo camera and an autostereoscopic display. We designed and conducted an extensive user study to explore the effects of stereoscopic hand-held augmented reality on depth perception. The results show that in this scenario depth judgment is mostly influenced by monoscopic depth cues, but our system can improve positioning accuracy in challenging scenes.

jNode: A sensor network platform that supports distributed inertial kinematic monitoring

Because of the intrinsic advantages of wireless inertial motion tracking, standalone devices that integrate inertial motion units with wireless networking capabilities have gained much interest in recent years. Several platforms, both commercially available and academic, have been proposed to balance the challenges of a small form-factor, power consumption, accuracy and processing speed. Applications include ambulatory monitoring to support healthcare, sport activity analysis, recognizing human group behaviour, navigation support for humans, robots and unmanned vehicles, but also in structural monitoring of large buildings. This paper provides an analysis of the current state-of-the-art platforms in wireless inertial motion tracking and presents a novel open-source and open-hardware hybrid tracking platform that is extensible, low-power, flexible enough to be used for both short- and long-term monitoring and based on a firmware that allows it to be easily adapted after being deployed.

Augmented service in the factory of the future

Servicing the factory of the future raises challenges for the service teams and organizations. The industrial plant environment is changing rapidly due to the impact of the market and new autonomously operating information technologies such as on site information and communication services, an Internet of Things (IoT), smart sensors and intelligent automation devices as well as progress in conventional machines and technologies.

WoR-MAC: Combining Wake-on-Radio with Quality-of-Service for intelligent environments

Intelligent environments (IE) leverage embedded processing and wireless communication to assist users in a variety of ways. Applications rely on low power consumption for longer lifetimes, though different applications require different Quality-of-Service (QoS) requirements from the MAC layer. Until now, low power has come at the cost of other QoS parameters such as latency or packet loss. This paper presents WoR-MAC, a wireless MAC protocol which allows pre-existing protocols to be combined with remote multi-node wake-ups. The protocols are embedded into Wake-on-Radio (WoR) frames, allowing nodes to sleep during periods of low activity and be woken asynchronously with a single short RF signal. After waking, nodes begin communication using the embedded MAC protocol. Once the nodes have been woken, they maintain the QoS of the original MAC, with greatly reduced power consumption. The results indicate that WoR-MAC maintains packet loss characteristics of CSMA-CA and TDMA, as well as latency after accounting for the duty cycle and collaborative parameter estimation, while reducing power consumption by up to 49%.