Wilfried Elmenreich

A universal smart transducer interface: TTP/A

The primary goal of a universal smart transducer interface is the provision of a framework that helps to reduce the complexity of large distributed real-time systems by introducing precisely specified (in the value domain and in the temporal domain) and small interfaces between smart transducers and their users. This paper presents a universal smart transducer interface that can be implemented on top of different real-time communication systems. It integrates a time-triggered communication protocol with an interface file system that provides the sources and sinks for the exchanged information. The final section discusses an implementation of this interface on a low cost (less than 1

PALDi: Online Load Disaggregation via Particle Filtering

) commercial off the shelf microcontroller.

GREEND: An energy consumption dataset of households in Italy and Austria

Smart metering and fine-grained energy data are one of the major enablers for future smart grid and improved energy efficiency in smart homes. Using the information provided by smart meter power draw, valuable information can be extracted as disaggregated appliance power draws by non-intrusive load monitoring (NILM). NILM allows to identify appliances according to their power characteristics in the total power consumption of a household, measured by one sensor, the smart meter. In this paper, we present an NILM approach, where the appliance states are estimated by particle filtering (PF). PF is used for nonlinear and non-Gaussian disturbed problems and is suitable to estimate the appliance state. ON/OFF appliances, multistate appliances, or combinations of them are modeled by hidden Markov models, and their combinations result in a factorial hidden Markov model modeling the household power demand. We evaluate the PF-based NILM approach on synthetic and on real data from a well-known dataset to show that our approach achieves an accuracy of 90% on real household power draws.

A Scalable and Efficient Approach for Obtaining Measurements in CAN-Based Control Systems

Home energy management systems can be used to monitor and optimize consumption and local production from renewable energy. To assess solutions before their deployment, researchers and designers of those systems demand for energy consumption datasets. In this paper, we present the GREEND dataset, containing detailed power usage information obtained through a measurement campaign in households in Austria and Italy. We provide a description of consumption scenarios and discuss design choices for the sensing infrastructure. Finally, we benchmark the dataset with state-of-the-art techniques in load disaggregation, occupancy detection and appliance usage mining.

Firefly clock synchronization in an 802.15.4 wireless network

The availability of small inexpensive sensor elements enables the employment of large wired or wireless sensor networks for feeding control systems. Unfortunately, the need to transmit a large number of sensor measurements over a network negatively affects the timing parameters of the control loop. This paper presents a solution to this problem by representing sensor measurements with an approximate representation-an interpolation of sensor measurements as a function of space coordinates. A priority-based medium access control (MAC) protocol is used to select the sensor messages with high information content. Thus, the information from a large number of sensor measurements is conveyed within a few messages. This approach greatly reduces the time for obtaining a snapshot of the environment state and therefore supports the real-time requirements of feedback control loops.

CoRe-MAC: A MAC-Protocol for Cooperative Relaying in Wireless Networks

This paper describes the design and implementation of a distributed self-stabilizing clock synchronization algorithm based on the biological example of Asian Fireflies. Huge swarms of these fireflies use the principle of pulse coupled oscillators in order to synchronously emit light flashes to attract mating partners. When applying this algorithm to real sensor networks, typically, nodes cannot receive messages while transmitting, which prevents the networked nodes from reaching synchronization. In order to counteract this deafness problem, we adopt a variant of the Reachback Firefly Algorithm to distribute the timing of light flashes in a given time window without affecting the quality of the synchronization. A case study implemented on 802.15.4 Zigbee nodes presents the application of this approach for a time-triggered communication scheduling and coordinated duty cycling in order to enhance the battery lifetime of the nodes.

A review on system architectures for sensor fusion applications

Cooperative relaying methods can improve wireless links, but introduce overhead due to relay selection and resource reservation compared to non-cooperative transmission. In order to be competitive, a cooperative relaying protocol must avoid or compensate for this overhead. In this paper, we present a MAC protocol for relay selection and cooperative communication as an extension to CSMA/CA which addresses resource reservation, relay selection, and cooperative transmission while keeping the overhead in terms of time and energy low. We discuss the efficiency of this protocol for packet error rate, throughput, and message delay in a multi-hop network. Simulation results show that the protocol performs similar and without noticeable overhead compared to standard CSMA/CA for good SNR while it is able to significantly improve throughput and reliability at larger distances.

Building blocks of cooperative relaying in wireless systems

In the literature there exist many proposed architectures for sensor fusion applications. This paper briefly reviews some of the most common approaches, i. e., the JDL fusion architecture, the Waterfall model, the Intelligence cycle, the Boyd loop, the LAAS architecture, the Omnibus model, Mr. Fusion, the DFuse framework, and the Time-Triggered Sensor Fusion Model, and categorizes them into abstract models, generic and rigid architectures. While an abstract model does not guide the designer in the concrete implementation, the generic architectures provide a generic design but leave open several design decisions regarding operating system, hardware, communication system, or database system. Rigid architectures specify at least some of these aspects and therefore provide existing hardware designs, tools, and source code at the cost of flexibility.

A comparison of LIN and TTP/A

SummaryThe concept of cooperative relaying promises gains in robustness and energy efficiency in wireless networks. This survey gives an introduction and overview of promising methods that can be used for cooperative relaying: relay selection protocols, cooperative channel and network coding, and physical layer aspects such as cooperative modulation. The particular methods can be seen as building blocks that can be configured and optionally used for designing a system. They offer a large number of design options for relaying systems. Based on available hardware features, expected environment, and required services an efficient system needs to be tailored using the right subset of available methods.ZusammenfassungDas Konzept des kooperativen Weiterleitens von Nachrichten ermöglicht eine Verbesserung der Robustheit und Energieeffizienz von drahtlosen Netzwerken. Dieser Artikel stellt einige vielversprechende Methoden für Netzwerke mit kooperativem Relaying vor. Im Speziellen werden Protokolle zur Relayauswahl, Kanalcodierung, Network Coding sowie kooperative Modulationstechniken behandelt. Die vorgestellten Methoden sind als Bausteine für ein Netzwerk mit kooperativem Relaying zu verstehen. Jede einzelne Methode kann optional und gemeinsam mit anderen verwendet werden und in den meisten Fällen zusätzlich noch dem Zweck entsprechend konfiguriert werden. Somit ergibt sich eine hohe Anzahl von Möglichkeiten, ein System mit kooperativem Relaying zu entwerfen. Das tatsächliche Design hängt letztendlich von Parametern wie der zur Verfügung stehenden Hardware, den Annahmen über die Zielumgebung sowie den Anforderungen der Applikation ab.

Evolving non-intrusive load monitoring

The paper compares two novel field-bus protocols for low-cost single-chip smart sensor and actuator nodes, LIN and TTP/A. Both protocols are central-master UART protocols, where the master with its precise oscillator establishes the stable time-base required by the slaves to synchronize their imprecise on-chip oscillators. While LIN provides the basic services needed for real-time communication, the TTP/A standard additionally specifies an interface-file system to perform on-line configuration, diagnostics and maintenance of smart sensor nodes. With TTP/A it is thus possible to produce preprogrammed simple transducer nodes or generic smart transducer nodes that can be configured dynamically to the given application requirements.