Guido Stromberg

Key generation based on acceleration data of shaking processes

Hard restrictions in computing power and energy consumption favour symmetric key methods to encrypt the communication in wireless body area networks which in term impose questions on effective and user-friendly unobtrusive ways for key distribution. In this paper, we present a novel approach to establish a secure connection between two devices by shaking them together. Instead of distributing or exchanging a key, the devices independently generate a key from the measured acceleration data by appropriate signal processing methods. Exhaustive practical experiments based on acceleration data gathered from real hardware prototypes have shown that in about 80% of the cases, a common key can be successfully generated. The average entropy of these generated keys exceed 13bits.

A service gateway for networked sensor systems

An emerging area in ubiquitous computing is networked sensor systems. The typical approach is to connect sensor-actuator devices using classic network infrastructures at a low level. These networks can serve as infrastructures to dynamically integrate, sensors and actuators into complex interactive systems while providing convenient services and interfaces to users. A prominent scenario for ubiquitous computing and ad hoc networking is an in-house environment using smart sensor system. Shaman, an extendable Java-based service gateway for networked sensor systems, integrates small network-attached sensor-actuator modules (SAMs) into heterogeneous, high-level networking communities. The system unburdens its connected SAMs by transferring functionality from the SAMs to the gateway.

Embedding Low-Cost Wireless Sensors into Universal Plug and Play Environments

Research on Ubiquitous Computing is conducted in two opposing directions: One focuses on the seamless interaction of high-performance end devices by defining semantic mechanisms for device discovery and control. Ubiquitous computing is however also understood as the massive, unobtrusive integration of small electronic devices, in particular of small sensors and actuators, into our environment. These nodes must be cheap and energy-efficient, but are thus less flexible.

Wake-up-frame scheme for ultra low power wireless transceivers

In wireless sensor networks and wireless personal area networks, power consumption is one of the most important design criteria for each small device. One of the biggest power consumers in such a device, the RF transceiver, should normally always be kept powered on for possible incoming packets; this is very power inefficient. The preamble sampling scheme was proposed to enable a receiver to sample the channel only periodically with a very low duty cycle by sending a long wake-up-preamble before the data frame; this dramatically reduces the power consumption of the receiver. The paper proposes to use a wake-up-frame instead of a wake-up-preamble to optimize further the preamble sampling scheme, achieving an additional battery lifetime gain in the order of tens to hundreds percent in different topologies and traffic loads.

Making Embedded Software Development More Efficient with SOA

SOA has been one of the most fascinating design paradigms for enterprise-level application software during the recent years. Key to its success has been the inherent support of reusability and scalability. This has brought forward significant advancements in the efficiency of SOA based software during development, deployment and runtime. As a result of the ongoing increase of computational power on embedded devices, and the ever-increasing connectivity of these, SOA has become relevant also for devices with medium computational capabilities like WiFi routers. Extrapolation suggests that SOA will soon be seen on typical embedded systems like sensors and actuators. In this paper we make a survey to outline the potential of SOA to become a key factor in embedded software development. We believe that by embracing this paradigm, current obstacles in the embedded development process can be addressed more effectively, leading to an efficient and less error prone design flow. Although some efforts in this direction have already been made, there are still areas open for research in order to optimize the development process for embedded SOA.

Reliable, real-time routing in wireless sensor and actuator networks

We present a novel Reliable, Real-time Routing protocol (3R) based on multipath routing for highly time-constrained Wireless Sensor and Actuator Networks (WSANs). The protocol consists of a newly designed routing metric and a routing algorithm utilizing this metric. Our routing metric enables strong Quality-of-Service (QoS) support based on parallel transmissions which significantly reduces transmission delays in WSANs. A routing algorithm utilizing this metric is presented based on Dijkstras shortest path. A novel Medium Access Control (MAC) layer that supports dynamical adjustments of retransmission limits, reduces traffic overhead in multipath routing protocols. Thorough simulations have been performed to evaluate the routing protocol, and the results show that real-time performance of WSANs can be vastly improved.

50.2: A Novel Fault‐Tolerant Architecture for Self‐Organizing Display and Sensor Arrays

Research on ‘electronic paper’ mainly focuses on novel electro-optical materials, while system aspects such as fault tolerance and signal processing have been largely disregarded so far. A network of regular primitive information processing elements is presented to be embedded into the display backplane. The architecture self-dependently detects the geometry of the display. Routing paths for the image data are established circumventing defective or missing regions. The concept and its relevance will be discussed on the basis of software simulations.

Innovative Key Generation Approach to Encrypt Wireless Communication in Personal Area Networks

In this paper we present a signal processing methodology for sharing symmetric keys in personal area networks. Symmetric encryption and decryption are commonly used because of limitations in computing power and energy consumption. However, key sharing still imposes challenges regarding usability, computational complexity of algebraic key exchange algorithms, and security. Our approach is that keys are generated locally on devices by shaking them, and that the keys are equal if and only if the devices are shaken together. Based on practical assessments, we show that the key generation algorithm is able to generate keys from acceleration data with an average entropy of 13bit/key in 70% of the cases.

Impact of link quality estimation errors on routing metrics for wireless sensor networks

Link quality-based routing protocols are often utilized in wireless sensor networks. Link quality estimation algorithms are used to retrieve information about the link quality, which is evaluated to choose the best available path. Concurrently, recent work has revealed severe inaccuracies in link quality estimations provided by modern short-range wireless devices. The sensitivity of routing protocols to such errors in the estimation of the link quality has not been considered so far. In this paper, we define two main classes of link quality-based routing metrics and examine these classes. We present a method to estimate the sensitivity of routing metrics to link quality estimation errors and confirm this method by simulations. Some routing metrics are surprisingly strong influenced by estimation errors. This finding questions the applicability of these protocols in large-scale networks and necessitates that the impact of link quality estimation errors is explicitly regarded in future developments of link-quality-based routing metrics to create more robust metrics. Our proposed method to estimate the sensitivity of routing metrics on link quality estimation errors shows to be helpful here.

Sindrion: a prototype system for low-power wireless control networks

We present a system architecture called Sindrion which allows us to create a cheap, energy-efficient, wireless control network to integrate small embedded sensors and actuators into one of the most established middleware platforms for distributed semantic services, namely universal plug and play (UPnP). To meet rigid constraints regarding cost and power consumption, complex data processing is sourced out from the sensor or actuator nodes to dedicated computing terminals, which establish a proxy in the UPnP network.