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Sensor Networks

Contact Prof. Dr. rer. nat. Volker Turau
Staff Tobias Lübkert
Ivonne Andrea Mantilla González
Florian Meyer
Christoph Weyer

Project Description

The rapid technological progress allows for the integration of sensors, processors, wireless communication units, and energy sources on extremely small space nowadays. Networks consisting of high numbers of such nodes deployed in situ, physically placed in the environment close to objects they are sensing or even moving around allow numerous novel applications in environments where a cabling is not feasible or too inflexible. From a scientific point of view, sensor networks differ substantially from classical networks and distributed systems, they pose unique challenges:

In this project, heterogeneous sensor networks consisting of a broad palette of different kinds of nodes, of highly primitive sensors with minimal energy supply, computing power, and communication bandwidth, passive RFID based devices, stationary sensors connected to a LAN up to nodes with resources for aggregation and processing of data are considered.

The focus of our research is currently on the following topics:

Subprojects

Publications

Maximilian Köstler and Florian Kauer. A Remote Interface for Live Interaction with OMNeT++ Simulations. In Proceedings of the 4th OMNeT++ Community Summit 2017, September 2017. Bremen, Germany.
@InProceedings{Telematik_OMNETPP_2017, author = {Maximilian Köstler and Florian Kauer}, title = {A Remote Interface for Live Interaction with OMNeT++ Simulations}, booktitle = {Proceedings of the 4th OMNeT++ Community Summit 2017}, number = {arXiv:1709.02822}, day = {07-08}, month = sep, year = 2017, location = {Bremen, Germany}, }
Abstract: Discrete event simulators, such as OMNeT++, provide fast and convenient methods for the assessment of algorithms and protocols, especially in the context of wired and wireless networks. Usually, simulation parameters such as topology and traffic patterns are predefined to observe the behaviour reproducibly. However, for learning about the dynamic behaviour of a system, a live interaction that allows changing parameters on the fly is very helpful. This is especially interesting for providing interactive demonstrations at conferences and fairs. In this paper, we present a remote interface to OMNeT++ simulations that can be used to control the simulations while visualising real-time data merged from multiple OMNeT++ instances. We explain the software architecture behind our framework and how it can be used to build demonstrations on the foundation of OMNeT++.
Florian Kauer, Florian Meyer and Volker Turau. A Holistic Solution for Reliable Over-the-Air Software Updates in Large Industrial Plants. In Proceedings of the 13th Workshop on Intelligent Solutions in Embedded Systems (WISES 2017), June 2017, pp. 29–34. Hamburg, Germany.
@InProceedings{Telematik_WISES_2017, author = {Florian Kauer and Florian Meyer and Volker Turau}, title = {A Holistic Solution for Reliable Over-the-Air Software Updates in Large Industrial Plants}, booktitle = {Proceedings of the 13th Workshop on Intelligent Solutions in Embedded Systems (WISES 2017)}, pages = {29-34}, day = {12-13}, month = jun, year = 2017, location = {Hamburg, Germany}, }
Abstract: In cyber-physical systems, such as modern industrial plants, complex software is an essential part that enables cost-effective and flexible operation. However, this complexity increases the probability of problems that only reveal themselves after the deployment. This is even more important if security aspects are involved. Therefore, providing the possibility for software updates is an important building block in the design of industrial plants. This paper presents a holistic concept for software updates in an industrial plant with thousands of wirelessly connected embedded devices. Using wireless technology imposes additional difficulties in terms of data rate, packet size and reliability that have to be addressed in particular. The contribution also includes an analytical model to estimate the time until a new firmware is distributed. Evaluations carried out on hardware as well as in the OMNeT++ simulator demonstrate the applicability and scalability of the proposed approach.
Florian Kauer, Maximilian Köstler, Tobias Lübkert and Volker Turau. OpenDSME - A Portable Framework for Reliable Wireless Sensor and Actuator Networks (Demonstration). In Proceedings of the 3rd International Conference on Networked Systems (NetSys 2017), March 2017, pp. 1–2. Göttingen, Germany.
@InProceedings{Telematik_Netsys_2017, author = {Florian Kauer and Maximilian Köstler and Tobias Lübkert and Volker Turau}, title = {OpenDSME - A Portable Framework for Reliable Wireless Sensor and Actuator Networks (Demonstration)}, booktitle = {Proceedings of the 3rd International Conference on Networked Systems (NetSys 2017)}, pages = {1-2}, day = {13-16}, month = mar, year = 2017, location = {Göttingen, Germany}, }
Abstract: The Deterministic and Synchronous Multi-Channel Extension (DSME) of the IEEE 802.15.4 standard provides a data link layer for time division multiple access in wireless mesh networks. The authors present openDSME, a portable implementation for hardware and simulators which promises reliable message transfer suitable for applications in demanding industrial environments. A demonstration has been developed to illustrate the performance of openDSME in a simulated network and to show its benefits over CSMA/CA.
Florian Kauer, Maximilian Köstler, Tobias Lübkert and Volker Turau. Formal Analysis and Verification of the IEEE 802.15.4 DSME Slot Allocation. In Proceedings of the 19th ACM International Conference on Modeling, Analysis and Simulation of Wireless and Mobile Systems, November 2016, pp. 140–147. Malta.
@InProceedings{Telematik_MSWIM_Formal_DSME, author = {Florian Kauer and Maximilian Köstler and Tobias Lübkert and Volker Turau}, title = {Formal Analysis and Verification of the IEEE 802.15.4 DSME Slot Allocation}, booktitle = {Proceedings of the 19th ACM International Conference on Modeling, Analysis and Simulation of Wireless and Mobile Systems}, pages = {140-147}, month = nov, year = 2016, location = {Malta}, }
Abstract: Providing dependability is still a major issue for wireless mesh networks, which restrains their application in industrial contexts. The widespread CSMA/CA medium access can provide high throughput and low latency, but can not prevent packet loss due to collisions, especially in very large and dense networks. Time slotted medium access techniques together with a distributed slot management, as proposed by the Distributed Synchronous Multi-channel Extension (DSME) of the IEEE 802.15.4 standard, are promising to provide low packet loss, high scalability and bounded end-to-end delays. However, our implementation, openDSME, exposed some weaknesses. While the allocated slots allow for reliable data transmission, the slot management itself is conducted via CSMA/CA and is thus vulnerable to packet loss, eventually leading to an inconsistent slot allocation. This paper uses the UPPAAL framework for formal analysis and verification of the slot management process. The analysis identifies weaknesses of the slot allocation process under communication and node failures. However, it is shown that inconsistencies are eventually resolved and improvements to the procedure are proposed that reduce the negative impact of failed slot allocation procedures significantly.
Maximilian Köstler, Florian Kauer, Tobias Lübkert and Volker Turau. Towards an Open Source Implementation of the IEEE 802.15.4 DSME Link Layer. In Proceedings of the 15. GI/ITG KuVS Fachgespräch Sensornetze, University of Applied Sciences Augsburg, Dept. of Computer Science, September 2016. Augsburg, Germany.
@InProceedings{Telematik_FGSN_openDSME, author = {Maximilian Köstler and Florian Kauer and Tobias Lübkert and Volker Turau}, editor = {Juergen Scholz and Alexander von Bodisco}, title = {Towards an Open Source Implementation of the IEEE 802.15.4 DSME Link Layer}, booktitle = {Proceedings of the 15. GI/ITG KuVS Fachgespräch Sensornetze}, pages = , publisher = {University of Applied Sciences Augsburg, Dept. of Computer Science}, day = {22-23}, month = sep, year = 2016, location = {Augsburg, Germany}, }
Abstract: Reliable wireless solutions for large-scale automation are a major challenge today. The IEEE 802.15.4 standard forms the basis for many open and proprietary implementations. To reflect current state-of-the-art techniques, the IEEE has amended standard 802.15.4 with new MAC-layers such as TSCH, which resembles WirelessHART, and the Deterministic and Synchronous Multi-Channel Extension (DSME). This paper introduces openDSME, our implementation of IEEE 802.15.4 DSME. DSME aims at preventing packet collisions through slot reservation in networks where conventional CSMA/CA is not reliable enough. In this document, we will outline core features of DSME and openDSME, and present details of our implementation. Additionally, current research efforts on connected topics will be highlighted.
Andreas Weigel and Volker Turau. Hardware-Assisted IEEE 802.15.4 Transmissions and Why to Avoid Them. In Conference proceedings of the 8th International Conference on Internet and Distributed Computer Systems, IDCS 2015, September 2015, pp. 223–234. Windsor, UK.
@InProceedings{Telematik_IDCS_2015_6LoWPAN, author = {Andreas Weigel and Volker Turau}, title = {Hardware-Assisted IEEE 802.15.4 Transmissions and Why to Avoid Them}, booktitle = {Conference proceedings of the 8th International Conference on Internet and Distributed Computer Systems, IDCS 2015}, pages = {223-234}, day = {2-4}, month = sep, year = 2015, location = {Windsor, UK}, }
Abstract: 6LoWPAN’s fragmentation mechanism enables transport of IPv6 datagrams with the required minimum MTU of 1280 bytes over IEEE 802.15.4-based networks. Testbed experiments showed disastrously bad datagram success rates for a collection traffic scenario with large, 6LoWPAN-fragmented datagrams, which significantly differed from the simulation results for a comparable scenario. In this paper we present an experimental setup that enables capturing the MAC and transceiver states of participating nodes in realtime. The results of our experiments show, that for the given fragmentation/collection scenario, the usage of the extended operating mode of the transceiver hardware, which provides CSMA/CA, ACKs and retransmissions in hardware, is responsible for nearly all datagram losses. Therefore, we strongly advise against using such hardware-assisted modes of operation in similar traffic scenarios.
Gerry Siegemund, Volker Turau and Christoph Weyer. A Dynamic Topology Control Algorithm for Wireless Sensor Networks. In Proceedings of the International Conference on Ad-hoc, Mobile and Wireless Networks, ADHOC-NOW 2015, June 2015, pp. 3–18. Athens, Greece.
@InProceedings{Telematik_Adhoc-Now_2015, author = {Gerry Siegemund and Volker Turau and Christoph Weyer}, title = {A Dynamic Topology Control Algorithm for Wireless Sensor Networks}, booktitle = {Proceedings of the International Conference on Ad-hoc, Mobile and Wireless Networks, ADHOC-NOW 2015}, pages = {3-18}, month = jun, year = 2015, location = {Athens, Greece}, }
Abstract: Topology control algorithms (TCAs) are used in wireless sensor networks to reduce interference by carefully choosing communication links. Since the quality of the wireless channel is subject to fluctuations over time TCAs must repeatedly recompute the topology. TCAs ensure quick adjustment to new or deteriorating links while preventing precipitant changes due to transient faults. This paper contributes a novel dynamic TCA that provides a compromise between agility and stability, and constructs connected topologies for low latency routing. Furthermore, it enforces memory restrictions and is of high practical relevance for real sensor network hardware.
Florian Meier and Volker Turau. An Analytical Model for Fast and Verifiable Assessment of Large Scale Wireless Mesh Networks. In Proceedings of the Design of Reliable Communication Networks (DRCN), March 2015, pp. 185–190. Kansas City, MO, USA.
@InProceedings{Telematik_DRCN_Model, author = {Florian Meier and Volker Turau}, title = {An Analytical Model for Fast and Verifiable Assessment of Large Scale Wireless Mesh Networks}, booktitle = {Proceedings of the Design of Reliable Communication Networks (DRCN)}, pages = {185-190}, month = mar, year = 2015, location = {Kansas City, MO, USA}, }
Abstract: Ensuring reliability is a key requirement for using wireless mesh networks in industrial applications. Analytical models provide a valuable support in the design of reliable networks, especially for large scale applications, where simulations do not provide the required scalability. This paper proposes an analytical model for multi-hop IEEE 802.15.4 networks that incorporates significant improvements compared to previous models. Comparisons of the model with simulations using the MiXiM framework for OMNeT++ exhibit a very good compliance. The analytical model is therefore adequate for assessment of very large wireless mesh networks. Additionally, the model yields new insights into the characteristics of IEEE 802.15.4 networks, regarding the impact of acknowledgment collisions and the influence of hidden nodes on retransmissions.
Florian Meier and Volker Turau. Analytical Model for IEEE 802.15.4 Multi-Hop Networks with Improved Handling of Acknowledgements and Retransmissions. Technical Report arXiv:1501.07594, arXiv.org e-prints, January 2015.
@TechReport{Telematik_ARXIV_Multihop_Networks, author = {Florian Meier and Volker Turau}, title = {Analytical Model for IEEE 802.15.4 Multi-Hop Networks with Improved Handling of Acknowledgements and Retransmissions}, number = {arXiv:1501.07594}, institution = {arXiv.org e-prints}, month = jan, year = 2015, }
Abstract: The IEEE 802.15.4 standard allows for the deployment of cost-effective and energy-efficient multi-hop networks. This document features an in-depth presentation of an analytical model for assessing the performance of such networks. It considers a generic, static topology with Poisson distributed data-collection as well as data-dissemination traffic. The unslotted CSMA/CA MAC layer of IEEE 802.15.4 is closely modeled as well as an enhanced model of the neighborhood allows for consideration of collisions of packets including interferences with acknowledgements. The hidden node problem is taken into account as well as a formerly disregarded effect of repeated collisions of retransmissions. The model has been shown to be suitable to estimate the capacity of large-scale multi-hop networks.
Andreas Weigel, Martin Ringwelski, Volker Turau and Andreas Timm-Giel. Route-over forwarding techniques in a 6LoWPAN. EAI Endorsed Transactions on Mobile Communications and Applications, 14(5), December 2014.
@Article{Telematik_EAI_6LowPAN_2014, author = {Andreas Weigel and Martin Ringwelski and Volker Turau and Andreas Timm-Giel}, title = {Route-over forwarding techniques in a 6LoWPAN}, journal = {EAI Endorsed Transactions on Mobile Communications and Applications}, volume = {14}, number = {5}, month = dec, year = 2014, }
Abstract: 6LoWPAN plays a major role within the protocol stack for the future Internet of Things. Its fragmentation mechanism enables transport of IPv6 datagrams with the required minimum MTU of 1280 bytes over 802.15.4-based networks. With the goal of a fully standardized WSN protocol stack currently necessitating a route-over approach, i.e., routing at the IP-layer, there are two main choices for any 6LoWPAN implementation with regard to datagram fragmentation: Hop-by-hop assembly or a cross-layered direct mode, which forwards individual 6LoWPAN fragments before the whole datagram has arrived. In addition to these two straightforward approaches, we propose enhancements based on adaptive rate-restriction for the direct forwarding and a retry control for both modes to reduce the number of losses of larger datagrams. An evaluation of these modes in a simulation environment and a hardware testbed indicate that the proposed enhancements can considerably improve PRR and latency within 6LoWPAN networks.
Andreas Pfahl, Michael Randt, Florian Meier, Martin Zaschke, C.P.W. Geurts and Michael Buselmeier. A Holistic Approach for Low Cost Heliostat Fields. In Proceedings of the SolarPACES 2014, September 2014. Beijing, China.
@InProceedings{Telematik_SolarPACES_HolisticHeliostatFields, author = {Andreas Pfahl and Michael Randt and Florian Meier and Martin Zaschke and C.P.W. Geurts and Michael Buselmeier}, title = {A Holistic Approach for Low Cost Heliostat Fields}, booktitle = {Proceedings of the SolarPACES 2014}, month = sep, year = 2014, location = {Beijing, China}, }
Abstract: The AutoR-project takes a holistic approach to reduce the cost of heliostat fields: Wireless control and energy supply enables to use smaller heliostats which need less steel per mirror area (but usually have high wiring cost). A low cost but high efficient drive system is chosen which reduces energy consumption to a minimum amount and leads to low cost for PV cell and energy storage. The usual boundary layer wind tunnels tests for heliostats are proven regarding energy spectra to avoid oversizing of steel structure and drives or failures because of underestimations of the loads. The concepts for wireless control and energy supply, the wind tunnel investigations and the first rim drive heliostat prototype are presented.
Shrirang Abhyankar, Jed Brown, Matthew Knepley, Florian Meier and Barry Smith. Poster Abstract: Abstractions for Expressing Network Problems in PETSc. In SIAM Workshop on Network Science, July 2014. Chicago, US.
@InProceedings{SIAM_PETSc, author = {Shrirang Abhyankar and Jed Brown and Matthew Knepley and Florian Meier and Barry Smith}, title = {Poster Abstract: Abstractions for Expressing Network Problems in PETSc}, booktitle = {SIAM Workshop on Network Science}, month = jul, year = 2014, location = {Chicago, US}, }
Abstract: Developing scalable software for large-scale applications, particularly for networks and circuits, is challenging due to the underlying unstructured and irregular geometry of the problem. We present a programming framework recently added to the PETSc library to easily express network problems, and thereby reduce the application development time. A brief overview of the framework is presented and two application examples, one from power grid and the other from radio networks, are discussed.
Martin Ringwelski, Christian Renner, Andreas Reinhardt, Andreas Weigel and Volker Turau. The Hitchhiker's Guide to Choosing the Compression Algorithm for Your Smart Meter Data. In Proceedings of the IEEE International Energy Conference and Exhibition (EnergyCon'12), September 2012. Florence, Italy.
@InProceedings{Telematik_RRWRT_2012_CompressionGuide, author = {Martin Ringwelski and Christian Renner and Andreas Reinhardt and Andreas Weigel and Volker Turau}, title = {The Hitchhiker's Guide to Choosing the Compression Algorithm for Your Smart Meter Data}, booktitle = {Proceedings of the IEEE International Energy Conference and Exhibition (EnergyCon'12)}, day = {9-12}, month = sep, year = 2012, location = {Florence, Italy}, }
Abstract: Smart meters are increasingly penetrating the market, resulting in enormous data volumes to be communicated. In many cases, embedded devices collect the metering data and transmit them wirelessly to achieve cheap and facile deployment. Bandwidth is yet scarce and transmission occupies the spectrum. Smart meter data should hence be compressed prior to transmission. Here, solutions for personal computers are not applicable, as they are too resource-demanding. In this paper, we propose four lossless compression algorithms for smart meters. We analyze processing time and compression gains and compare the results with five off-the-shelf compression algorithms. We show that excellent compression gains can be achieved when investing a moderate amount of memory. A discussion of the suitability of the algorithms for different kinds of metering data is presented.
Christian Renner and Volker Turau. State-of-Charge Assessment for Supercap-Powered Sensor Nodes: Keep it Simple Stupid!. In Proceedings of the International Workshop on Algorithms and Concepts for Networked Sensing Systems Powered by Energy Harvesters (EnHaNSS'12), June 2012. Antwerp, Belgium.
@InProceedings{Telematik_RT_2012_CapModels, author = {Christian Renner and Volker Turau}, title = {State-of-Charge Assessment for Supercap-Powered Sensor Nodes: Keep it Simple Stupid!}, booktitle = {Proceedings of the International Workshop on Algorithms and Concepts for Networked Sensing Systems Powered by Energy Harvesters (EnHaNSS'12)}, day = {11}, month = jun, year = 2012, location = {Antwerp, Belgium}, }
Abstract: Electric double-layer capacitors, also known as supercaps, have several advantages over traditional energy buffers: They do not require complex charging circuits, offer virtually unlimited charge-discharge cycles, and generally enable easy state-of-charge assessment. A closer look yet reveals that leakage and internal reorganization effects hamper state-of-charge assessment by means of terminal voltage, particularly after a charging cycle. Sophisticated models capture this effect at the cost of an increased calculation and parameter-estimation complexity. As this is hardly feasible on low-power, low-resource sensor nodes, we evaluate the performance of simple models on a real energy-harvesting sensor node platform. We show that model errors are as low as 1-2% on average and never exceed 5% in our experiments, supporting that there is no need to employ more complex models on common sensor node platforms, equipped with unreliable ADC readings and uncertain consumption due to hardware variation in the same order of magnitude.
Christian Renner, Florian Meier and Volker Turau. Holistic Online Energy Assessment: Feasibility and Practical Application. In Proceedings of the 9th IEEE International Conference on Networked Sensing Systems (INSS'12), June 2012. Antwerp, Belgium. Best Student Paper Award.
@InProceedings{Telematik_RT_2012_HolisticEnergyAssessment, author = {Christian Renner and Florian Meier and Volker Turau}, title = {Holistic Online Energy Assessment: Feasibility and Practical Application}, booktitle = {Proceedings of the 9th IEEE International Conference on Networked Sensing Systems (INSS'12)}, day = {11-14}, month = jun, year = 2012, location = {Antwerp, Belgium}, note = {Best Student Paper Award}, }
Abstract: Combining energy harvesting with energy-aware scheduling enables perpetually operating sensor networks. The practical realization of this goal yet requires reliable and precise holistic online energy assessment. While the building blocks--assessing residual energy, predicting energy intake, and tracing energy consumption--have been studied in detail, the analysis of their interaction on a real platform has been neglected. This paper answers the question, whether these techniques can be easily joined to give a precise and correct picture of a sensor node's energetic state and behavior. For this purpose, we model the energy flow of a prototype energy-harvesting sensor node and evaluate the joint performance of state-of-the-art energy assessment based on a field test. We verify the system model and show the feasibility of holistic energy assessment, which tolerates small configuration errors, achievable with a combination of generic configuration and online calibration. We also analyze the feasibility of forecasting a node's future energetic state, and find that the presented method gives sufficient results for uniformly distributed consumption profiles.
Stefan Unterschütz and Volker Turau. Fail-Safe Over-The-Air Programming and Error Recovery in Wireless Networks. In Proceedings of the 10th Workshop on Intelligent Solutions in Embedded Systems (WISES'12), June 2012. Klagenfurt, Austria.
@InProceedings{Telematik_UT_2012_OTAP, author = {Stefan Unterschütz and Volker Turau}, title = {Fail-Safe Over-The-Air Programming and Error Recovery in Wireless Networks}, booktitle = {Proceedings of the 10th Workshop on Intelligent Solutions in Embedded Systems (WISES'12)}, day = {5-6}, month = jun, year = 2012, location = {Klagenfurt, Austria}, }
Stefan Unterschütz, Andreas Weigel and Volker Turau. Cross-Platform Protocol Development Based on OMNeT++. In Proceedings of the 5th International Workshop on OMNeT++ (OMNeT++'12), March 2012. Desenzano, Italy.
@InProceedings{Telematik_UWT_2012_CometOS, author = {Stefan Unterschütz and Andreas Weigel and Volker Turau}, title = {Cross-Platform Protocol Development Based on OMNeT++}, booktitle = {Proceedings of the 5th International Workshop on OMNeT++ (OMNeT++'12)}, day = {23}, month = mar, year = 2012, location = {Desenzano, Italy}, }
Christian Renner, Florian Meier and Volker Turau. Policies for Predictive Energy Management with Supercapacitors. In Proceedings of the 8th IEEE International Workshop on Sensor Networks and Systems for Pervasive Computing (PerSeNS'12), March 2012. Lugano, Switzerland.
@InProceedings{Telematik_RT_2012_Epol, author = {Christian Renner and Florian Meier and Volker Turau}, title = {Policies for Predictive Energy Management with Supercapacitors}, booktitle = {Proceedings of the 8th IEEE International Workshop on Sensor Networks and Systems for Pervasive Computing (PerSeNS'12)}, day = {19-23}, month = mar, year = 2012, location = {Lugano, Switzerland}, }
Abstract: This paper presents an algorithm to dynamically determine the maximum supported uniform demand for energy of sensor nodes powered by energy harvesters using supercapacitors as energy buffers. Knowledge about the maximum uniform consumption is required to adapt the sensor node's duty cycle or task schedule to achieve uniform, utility-maximizing, and depletion-safe operation. Our algorithm makes use of a supercapacitors' relationship between state-of-charge and voltage, is particularly designed to handle the non-linear system model, and is lightweight enough to run on low-power sensor node hardware. We define three energy policies, evaluate their performance using a real-world solar-harvesting trace, and analyze the influence of the supercapacitor's capacity and errors of the energy forecast.
Christian Renner and Volker Turau. Adaptive Energy-Harvest Profiling to Enhance Depletion-Safe Operation and Efficient Task Scheduling. Sustainable Computing: Informatics and Systems, 2(1):43–56, March 2012.
@Article{Telematik_RT_2012_AdaptiveSlotting, author = {Christian Renner and Volker Turau}, title = {Adaptive Energy-Harvest Profiling to Enhance Depletion-Safe Operation and Efficient Task Scheduling}, pages = {43-56}, journal = {Sustainable Computing: Informatics and Systems}, volume = {2}, number = {1}, month = mar, year = 2012, issn = {2210-5379}, }
Abstract: Forecasting the expected energy harvest enables small-sized energy-harvesting sensor nodes to schedule tasks or adapt the radio duty cycle. This ability ensures depletion-safe and efficient operation. Most energy sources exhibit cyclic patterns of intensity, e.g., the sun. These patterns show periods with unequal--low versus high and stable versus varying--energy production and heavily depend on a node's location as well as seasonal and environmental changes. Existing forecast algorithms do not exploit these patterns, but create and update forecasts at static and arbitrary points in time, the main knob being the number of updates per cycle. We present a method enabling sensor nodes to adapt to harvesting patterns at runtime. It is designed for seamlessly replacing the static scheme to improve the accuracy of a wide range of existing forecast algorithms. In our evaluation, we show that (i) the adaptive method traces the energy pattern in real-world deployments accurately, (ii) reacts to seasonal and environmental changes, (iii) increases forecast accuracy, and (iv) reduces the number of prediction updates. These achievements enhance depletion-safe operation and efficient task scheduling with fewer recalculations and adjustments of the duty cycle. They also facilitate the exchange of harvesting forecasts for collaborative node tasks, since less information has to be shared.
Christian Renner, Florian Meier and Volker Turau. Poster Abstract: Energy Assessment in Praxis. In Adjunct Proceedings of the 9th European Conference on Wireless Sensor Networks (EWSN'12), February 2012. Trento, Italy.
@InProceedings{Telematik_RT_2012_EnergyAssessment, author = {Christian Renner and Florian Meier and Volker Turau}, title = {Poster Abstract: Energy Assessment in Praxis}, booktitle = {Adjunct Proceedings of the 9th European Conference on Wireless Sensor Networks (EWSN'12)}, day = {15-17}, month = feb, year = 2012, location = {Trento, Italy}, }
Abstract: Combining energy harvesting with energy-aware scheduling enables perpetually operating sensor networks. Practical realization yet requires precise holistic online energy assessment. The building blocks are available, but the analysis of their interaction has been neglected. To close the gap, we evaluate the joint performance of energy assessment components. Our experiments substantiate that holistic energy assessment is feasible and that small configuration errors are tolerable.
Stefan Unterschütz, Christian Renner and Volker Turau. Opportunistic, Receiver-Initiated Data-Collection Protocol. In Proceedings of the 9th European Conference on Wireless Sensor Networks (EWSN'12), February 2012. Trento, Italy.
@InProceedings{Telematik_URT_2012_Orinoco, author = {Stefan Unterschütz and Christian Renner and Volker Turau}, title = {Opportunistic, Receiver-Initiated Data-Collection Protocol}, booktitle = {Proceedings of the 9th European Conference on Wireless Sensor Networks (EWSN'12)}, day = {15-17}, month = feb, year = 2012, location = {Trento, Italy}, }
Abstract: This paper presents and evaluates ORiNoCo, a novel data-collection and event-reporting protocol for sensor networks. ORiNoCo is built upon the asynchronous duty-cycle protocol RI-MAC and breaks with the tradition of exchanging extensive neighborhood information, a cornerstone of many competing collection protocols and one of their major source of communication overhead and energy expenditure. The merit of this venture is an opportunistic, energy-efficient, latency-reducing, and self-stabilizing protocol. ORiNoCo comes at virtually no extra costs in terms of memory demand and communication overhead compared to RI-MAC. We derive theoretical boundaries for the improvements in radio efficiency, latency, and energy-consumption. ORiNoCo is verified with these findings via simulation and compared with CTP. ORiNoCo achieves lower energy-consumption while reducing end-to-end delays.
Christian Renner, Stefan Unterschütz and Volker Turau. Power Management for Wireless Sensor Networks Based on Energy Budgets. Technical Report urn:nbn:de:gbv:830-tubdok-11065, Hamburg University of Technology, Hamburg, Germany, July 2011.
@TechReport{Renner_Unterschuetz_PowerManagement-TechReport, author = {Christian Renner and Stefan Unterschütz and Volker Turau}, title = {Power Management for Wireless Sensor Networks Based on Energy Budgets}, number = {urn:nbn:de:gbv:830-tubdok-11065}, institution = {Hamburg University of Technology}, address = {Hamburg, Germany}, month = jul, year = 2011, }
Abstract: This paper proposes and assesses analytical tools for large-scale monitoring applications with wireless sensor networks powered by energy-harvesting supplies. We introduce the concept of an energy budget, the amount of energy available to a sensor node for a given period of time. The presented tools can be utilized to realize distributed algorithms that determine a schedule to perform the monitoring task and the inherent communication. Scheduling is based on the energy budgets of the nodes or on latency requirements. In this context, we derive theoretical results for the energy consumption of the individual nodes plus the latency of event-reporting. These results are verified by simulations and a real testbed implementation.
Christian Renner, Sebastian Ernst, Christoph Weyer and Volker Turau. Prediction Accuracy of Link-Quality Estimators. In Proceedings of the 8th European Conference on Wireless Sensor Networks (EWSN'11), February 2011. Bonn, Germany. Acceptance rate 20%.
@InProceedings{Telematik_REWT_HoPS, author = {Christian Renner and Sebastian Ernst and Christoph Weyer and Volker Turau}, title = {Prediction Accuracy of Link-Quality Estimators}, booktitle = {Proceedings of the 8th European Conference on Wireless Sensor Networks (EWSN'11)}, day = {23-25}, month = feb, year = 2011, location = {Bonn, Germany}, note = {Acceptance rate 20%}, }
Abstract: The accuracy of link-quality estimators (LQE) is mission-critical in many application scenarios in wireless sensor networks (WSN), since the link-quality metric is used for routing decisions or neighborhood formation. Link-quality estimation must offer validity for different timescales. Existing LQEs describe and approximate the current quality in a single value only. This method leads to a limited accuracy and expressiveness about the presumed future behavior of a link. The LQE developed in this paper incorporates four quality metrics that give a holistic assessment of the link and its dynamic behavior; therefore, this research is an important step to achieving a higher prediction accuracy including knowledge about the short- and long-term behavior.
Sebastian Ernst, Christian Renner, Christoph Weyer and Volker Turau. Holistic Packet Statistics for Neighborhood Management in Sensor Networks. In Proceedings of the 9th GI/ITG KuVS Fachgespräch "Drahtlose Sensornetze" (FGSN'10), September 2010, pp. 17–20. Würzburg, Germany.
@InProceedings{Telematik_ERWT_HoPS, author = {Sebastian Ernst and Christian Renner and Christoph Weyer and Volker Turau}, title = {Holistic Packet Statistics for Neighborhood Management in Sensor Networks}, booktitle = {Proceedings of the 9th GI/ITG KuVS Fachgespräch "Drahtlose Sensornetze" (FGSN'10)}, pages = {17-20}, day = {16-17}, month = sep, year = 2010, location = {Würzburg, Germany}, }
Abstract: Knowledge of neighboring nodes is a fundamental requirement of many algorithms in the field of wireless sensor networks. The neighborhood relation of nodes is defined by their ability to communicate directly and not by their proximity. Due to the temporal changes of the wireless channel, link qualities must be continuously estimated. In this paper a new approach based on holistic packet statistics is presented. Unlike existing estimation techniques it forswears from squeezing a link's characteristics into a single value. The benefit of this approach is substantiated by an evaluation utilizing real-world and synthetic data.
Christian Renner, Volker Turau and Christoph Weyer. Performance of Energy-Efficient TDMA Schemes in Data-Gathering Scenarios with Periodic Sources. In Proceedings of the 7th IEEE International Conference on Networked Sensing Systems (INSS'10), June 2010. Kassel, Germany. Acceptance rate 22%.
@InProceedings{Telematik_RTW_EnergyEfficientTDMA, author = {Christian Renner and Volker Turau and Christoph Weyer}, title = {Performance of Energy-Efficient TDMA Schemes in Data-Gathering Scenarios with Periodic Sources}, booktitle = {Proceedings of the 7th IEEE International Conference on Networked Sensing Systems (INSS'10)}, day = {15-18}, month = jun, year = 2010, location = {Kassel, Germany}, note = {Acceptance rate 22%}, }
Abstract: Energy-efficient transportation of periodical sensor readings towards a single sink in wireless sensor networks is a challenging task. In general, two data-gathering strategies exist: on-demand and bulk data forwarding. For both strategies, cross-layer techniques are a promising approach, where TDMA is tailored to the underlying routing tree. Therefore, different TDMA schemes are compared regarding achievable throughput, packet delay, and energy-efficiency for various sampling rates and scenarios. Existing schemes perform well in dedicated topologies only. The new and simple TDMA scheme presented in this paper outperforms its predecessors in all scenarios under consideration. These findings are substantiated by both theoretical analysis and extensive simulation.
Christian Renner and Volker Turau. CapLibrate: Self-Calibration of an Energy Harvesting Power Supply with Supercapacitors. In Proceedings of the GI/ITG Workshop on Energy-aware Systems and Methods, February 2010. Hannover, Germany.
@InProceedings{Telematik_RT_2010_CapLibrate, author = {Christian Renner and Volker Turau}, title = {CapLibrate: Self-Calibration of an Energy Harvesting Power Supply with Supercapacitors}, booktitle = {Proceedings of the GI/ITG Workshop on Energy-aware Systems and Methods}, day = {22-23}, month = feb, year = 2010, location = {Hannover, Germany}, }
Abstract: Achieving perpetual and self-sustaining operation of wireless sensor nodes is an important topic of current research in the field of energy harvesting. Closely related to this is the employment of energy budgeting, i.e., effective utilization of available and future energy resources without pushing a node towards the hazard of energy depletion. Therefore, reliable prediction of node lifetime in context of the available energy within a given time is required. This in turn requires self-calibration of the sensor nodes and their energy harvesting supply. In this paper, we explore and assess models for a supercapacitor-based harvesting supply. The parameters of the models are discussed and determined, so that fast, reliable, and energy-efficient calibration becomes possible. Moreover, measurement results for a specific hardware platform are discussed and a roadmap for a self-calibration algorithm is presented.
Matthias Witt and Volker Turau. Robust and Low-Communication Geographic Routing for Wireless Ad Hoc Networks. Wireless Communications and Mobile Computing, 10(4):486–510, 2010.
@Article{Telematik_TW_2009_GeographicRouting, author = {Matthias Witt and Volker Turau}, title = {Robust and Low-Communication Geographic Routing for Wireless Ad Hoc Networks}, pages = {486-510}, journal = {Wireless Communications and Mobile Computing}, volume = {10}, number = {4}, year = 2010, }
Abstract: A novel beacon-less algorithm called Blind Geographic Routing (BGR) is presented, which comes with an effective and robust recovery strategy to circumvent voids, and a new technique to avoid simultaneous forwarding by more than one node, features not included in other beacon-less algorithms. BGR is the first beacon-less algorithm that also works in 3D topologies. Additionally, BGR supports different delivery semantics, which specify how close a node must be to the destination location in order to receive the message, and how many nodes shall receive it. These semantics allow for routing not only to designated nodes with network-wide known locations such as sinks, but to arbitrary destinations within the network area. It is shown through extensive simulation that BGR performs well even in the case of mobility, radio irregularity, and location errors, while GPSR as a beacon-based algorithm suffers from severe problems in realistic scenarios that do not follow the unit disk graph model, even with recent enhancements of the original GPSR algorithm.
Christian Renner, Jürgen Jessen and Volker Turau. Poster: Energy Estimation for Harvesting Supplies with Supercaps. In Proceedings of the Workshop on Self-Organizing Wireless Sensor and Communication Networks, October 2009. Hamburg, Germany.
@InProceedings{Telematik_RJT_2009_EnergyEstimation, author = {Christian Renner and Jürgen Jessen and Volker Turau}, title = {Poster: Energy Estimation for Harvesting Supplies with Supercaps}, booktitle = {Proceedings of the Workshop on Self-Organizing Wireless Sensor and Communication Networks}, day = {8-9}, month = oct, year = 2009, location = {Hamburg, Germany}, }
Arne Bosien and Volker Turau. RFID for Mobile Applications. In Proceedings of the Workshop on Self-Organizing Wireless Sensor and Communication Networks, October 2009, pp. 27–33. Hamburg, Germany.
@InProceedings{Telematik_SOMSED_2009_MOBILE_RFID, author = {Arne Bosien and Volker Turau}, title = {RFID for Mobile Applications}, booktitle = {Proceedings of the Workshop on Self-Organizing Wireless Sensor and Communication Networks}, pages = {27-33}, day = {8-9}, month = oct, year = 2009, location = {Hamburg, Germany}, }
Abstract: The availability of fast anti-collision algorithms is crucial for most RFID applications. This paper aims to evaluate these algorithms for applications in which it is not intended to identify the entirety of moving objects but to detect as much tags as needed to allow orientation. The navigation of Automated Guided Vehicles (AGV) by distributed landmarks is an example which clarifies the discriminative requirements compared to supply chain tasks. For the former purpose redundant information can be gained from different tags. This requires the detection of an application dependent percentage of all tags. Because AGVs are moving, the detection and read and write operations have to be close together and very fast, since repetitive communication is not always possible.
Andreas Lagemann, Jörg Nolte, Christoph Weyer and Volker Turau. Mission Statement: Applying Self-Stabilization to Wireless Sensor Networks. In Proceedings of the 8th GI/ITG KuVS Fachgespräch "Drahtlose Sensornetze" (FGSN'09), August 2009, pp. 47–49. Hamburg, Germany.
@InProceedings{Telematik_LNWT_2009_SelfWISE, author = {Andreas Lagemann and Jörg Nolte and Christoph Weyer and Volker Turau}, title = {Mission Statement: Applying Self-Stabilization to Wireless Sensor Networks}, booktitle = {Proceedings of the 8th GI/ITG KuVS Fachgespräch "Drahtlose Sensornetze" (FGSN'09)}, pages = {47-49}, day = {13-14}, month = aug, year = 2009, location = {Hamburg, Germany}, }
Abstract: Long living and unattended deployments of wireless sensor networks requires fault-tolerant solutions. Self-stabilizing algorithms are providing these properties in an elegant and verifiable way. Recently, a lot of research has been performed to determine appropriate means to apply these promising technique to wireless sensor networks. In this paper the current state of the art in this field is given. Additionally, three major challenges are presented for achieving self-stabilizing sensor networks.
Christoph Weyer, Christian Renner, Volker Turau and Hannes Frey. A Roadmap for Hardware and Software Support for Developing Energy-Efficient Sensor Networks. In Proceedings of the 8th GI/ITG KuVS Fachgespräch "Drahtlose Sensornetze" (FGSN'09), August 2009, pp. 67–70. Hamburg, Germany.
@InProceedings{Telematik_WRTF_2009_Roadmap, author = {Christoph Weyer and Christian Renner and Volker Turau and Hannes Frey}, title = {A Roadmap for Hardware and Software Support for Developing Energy-Efficient Sensor Networks}, booktitle = {Proceedings of the 8th GI/ITG KuVS Fachgespräch "Drahtlose Sensornetze" (FGSN'09)}, pages = {67-70}, day = {13-14}, month = aug, year = 2009, location = {Hamburg, Germany}, }
Abstract: Support for developing energy-efficient applications for wireless sensor networks is still scarce. In this paper a roadmap of a combined hardware and software approach is presented. The main idea is to collect state information and trace energy consumption of an application running in a testbed of real sensor nodes.
Felix Hackbarth, Thomas Meyerhoff, Harald Sauff, Bryce T. Bradford, Luis Torres, Helge Klimek, Björn Gressmann, Christian Renner, Martin Stemick, Christoph Weyer and Sebastian Georgi. SomSed - The Evolution of an Experimental Wireless Sensor Network Towards a Research Platform. In Proceedings of the 8th GI/ITG KuVS Fachgespräch "Drahtlose Sensornetze" (FGSN'09), August 2009, pp. 27–30. Hamburg, Germany.
@InProceedings{Telematik_HMSB_2009_SomSeD, author = {Felix Hackbarth and Thomas Meyerhoff and Harald Sauff and Bryce T. Bradford and Luis Torres and Helge Klimek and Björn Gressmann and Christian Renner and Martin Stemick and Christoph Weyer and Sebastian Georgi}, title = {SomSed - The Evolution of an Experimental Wireless Sensor Network Towards a Research Platform}, booktitle = {Proceedings of the 8th GI/ITG KuVS Fachgespräch "Drahtlose Sensornetze" (FGSN'09)}, pages = {27-30}, day = {13-14}, month = aug, year = 2009, location = {Hamburg, Germany}, }
Abstract: The exploratory focus of the SomSed research field is the interdisciplinary research on self organizing mobile sensor and data networks. Since the founding of SomSed in 2007, great progress in scientific research has been achieved and much practical knowledge has been gathered using a prototype network permanently installed. This prototype network, from hereon referred to as CampusNet, is the basis for further investigations and offers the possibility to perform long term measurements in a large scale and real environment. The scope of this paper is to outline the current status of the SomSed research field and to briefly discuss future developments.
Torsten Stremlau, Christoph Weyer and Volker Turau. tinyMoBot: A Platform for Mobile Sensor Networks. In Proceedings of the 8th GI/ITG KuVS Fachgespräch "Drahtlose Sensornetze" (FGSN'09), August 2009, pp. 43–44. Hamburg, Germany.
@InProceedings{Telematik_SW_2009_LEGO, author = {Torsten Stremlau and Christoph Weyer and Volker Turau}, title = {tinyMoBot: A Platform for Mobile Sensor Networks}, booktitle = {Proceedings of the 8th GI/ITG KuVS Fachgespräch "Drahtlose Sensornetze" (FGSN'09)}, pages = {43-44}, day = {13-14}, month = aug, year = 2009, location = {Hamburg, Germany}, }
Abstract: In many application scenarios of wireless sensor networks parts or the whole network consist of mobile sensor nodes. Currently, no common platform is available. This paper describes a project that has developed a mobile sensor node, based on standard components: a Crossbow IRIS mote and LEGO MINDSTORMS NXT components, i.e., motors and sensors.
Lars Niemann, Marcus Venzke, Christian Renner and Volker Turau. Clock Synchronization of TinyOS-based Sensor Networks with DCF77. In Proceedings of the 8th GI/ITG KuVS Fachgespräch "Drahtlose Sensornetze" (FGSN'09), August 2009, pp. 45–46. Hamburg, Germany.
@InProceedings{Telematik_NVRT_2009_DCF77, author = {Lars Niemann and Marcus Venzke and Christian Renner and Volker Turau}, title = {Clock Synchronization of TinyOS-based Sensor Networks with DCF77}, booktitle = {Proceedings of the 8th GI/ITG KuVS Fachgespräch "Drahtlose Sensornetze" (FGSN'09)}, pages = {45-46}, day = {13-14}, month = aug, year = 2009, location = {Hamburg, Germany}, }
Abstract: The paper presents an approach of applying DCF77 time radio signals to provide a clock with global time in sensor networks based on TinyOS. Some nodes containing DCF77 receiver hardware reliably decode time signals even if these are distorted to some extent. The clock with global time is provided by compensating clock drift. Time is distributed in the network with a protocol generating timestamps on the MAC layer.
Christian Renner, Jürgen Jessen and Volker Turau. Lifetime Prediction for Supercapacitor-powered Wireless Sensor Nodes. In Proceedings of the 8th GI/ITG KuVS Fachgespräch "Drahtlose Sensornetze" (FGSN'09), August 2009, pp. 55–58. Hamburg, Germany.
@InProceedings{Telematik_RJT_2009_Supercap, author = {Christian Renner and Jürgen Jessen and Volker Turau}, title = {Lifetime Prediction for Supercapacitor-powered Wireless Sensor Nodes}, booktitle = {Proceedings of the 8th GI/ITG KuVS Fachgespräch "Drahtlose Sensornetze" (FGSN'09)}, pages = {55-58}, day = {13-14}, month = aug, year = 2009, location = {Hamburg, Germany}, }
Abstract: Energy-aware task scheduling is a novel research direction for wireless sensor networks. It depends on accurate models for lifetime prediction. In other terms, nodes must be aware of present and future energy resources. This paper addresses the first step towards reaching this goal: It explores discharging-characteristics of supercapacitors, discusses analytical discharging-models for lifetime prediction, and evaluates these models by comparing them with real discharging curves.
Christoph Weyer, Volker Turau, Andreas Lagemann and Jörg Nolte. Programming Wireless Sensor Networks in a Self-Stabilizing Style. In Proceedings of the Third International Conference on Sensor Technologies and Applications (SENSORCOMM'09), June 2009. Athens, Greece.
@InProceedings{Telematik_WLT_2009_SelfWISE, author = {Christoph Weyer and Volker Turau and Andreas Lagemann and Jörg Nolte}, title = {Programming Wireless Sensor Networks in a Self-Stabilizing Style}, booktitle = {Proceedings of the Third International Conference on Sensor Technologies and Applications (SENSORCOMM'09)}, day = {18-23}, month = jun, year = 2009, location = {Athens, Greece}, }
Abstract: Wireless Sensor Networks (WSNs) operate in an unstable environment and thus are subject to arbitrary transient faults. Self-stabilization is a promising technique to add tolerance against transient faults in a self-contained non-masking way. A core factor for the applicability of a given self-stabilizing algorithm is its convergence time. This paper analyses the average stabilization time of three algorithms commonly regarded as central building blocks for WSNs. The analysis is accomplished with SelfWISE, a framework providing programming abstractions for selfstabilizing algorithms. The performed analysis considers the target models as well as network size and density. This demonstrates the usability of SelfWISE for evaluating selfstabilizing algorithms under a wide range of models.
Christoph Weyer, Christian Renner, Volker Turau and Hannes Frey. TinyAID: Automated Instrumentation and Evaluation Support for TinyOS. In Proceedings of the Second International Workshop on Sensor Network Engineering (IWSNE'09), June 2009. Marina del Rey, CA, USA.
@InProceedings{Telematik_WRTF_2009_TinyAID, author = {Christoph Weyer and Christian Renner and Volker Turau and Hannes Frey}, title = {TinyAID: Automated Instrumentation and Evaluation Support for TinyOS}, booktitle = {Proceedings of the Second International Workshop on Sensor Network Engineering (IWSNE'09)}, day = {10}, month = jun, year = 2009, location = {Marina del Rey, CA, USA}, }
Abstract: TinyAID is a tool that supports automated instrumentation and evaluation of TinyOS-based distributed applications. Two types of instrumentations are provided: logging of call chains and message flows within the network. TinyAID assists the debugging process by post evaluation of the logged data. A main benefit is the visualization component for representing traces in their spatial and temporal order. The instrumentation and evaluation concepts are evaluated in two case studies: the SelfWISE framework and a selection of routing algorithms. Due to the automated process of TinyAID the evaluation could be performed without a deeper knowledge of the implementations under test. In the first case TinyAID revealed a weakness in the TOSSIM random number generator. The second case demonstrates the power of TinyAID to visualize the quality of protocols in a unified manner, without any manual changes to the specific source code.
Christoph Weyer and Volker Turau. SelfWISE: A Framework for Developing Self-Stabilizing Algorithms. In Proceedings of the 16th ITG/GI - Fachtagung Kommunikation in Verteilten Systemen (KiVS'09), March 2009, pp. 67–78. Kassel, Germany.
@InProceedings{Telematik_TW_2009_SelfWISE, author = {Christoph Weyer and Volker Turau}, title = {SelfWISE: A Framework for Developing Self-Stabilizing Algorithms}, booktitle = {Proceedings of the 16th ITG/GI - Fachtagung Kommunikation in Verteilten Systemen (KiVS'09)}, pages = {67-78}, day = {2-6}, month = mar, year = 2009, location = {Kassel, Germany}, }
Abstract: This paper introduces SelfWISE, a framework for enabling wireless sensor networks to be programmed in a self-stabilizing manner. The framework eases the formal specification of algorithms by abstracting from low-level details such as wireless channel and hardwarespecific characteristics. SelfWISE consists of a language for expressing self-stabilizing algorithms, a runtime environment for simulating algorithms in wireless sensor networks, and supporting tools. The hereby applied transformation of formally described algorithms into the simulation environment preserves the self-stabilizing properties. Development, evaluation, and debugging of self-stabilizing algorithms is considerably facilitated by utilizing SelfWISE.
Sebastian Georgi, Christoph Weyer, Martin Stemik, Christian Renner, Felix Hackbarth, Ulf Pilz, Jens Eichmann, Tobias Pilsak, Harald Sauff, Luis Torres, Klaus Dembowski and Fabian Wagner. SomSeD: An Interdisciplinary Approach for Developing Wireless Sensor Networks. In Proceedings of the 7th GI/ITG KuVS Fachgespräch "Drahtlose Sensornetze" (FGSN'08), September 2008. Berlin, Germany.
@InProceedings{Telematik_GWSR_2008_SOMSeD, author = {Sebastian Georgi and Christoph Weyer and Martin Stemik and Christian Renner and Felix Hackbarth and Ulf Pilz and Jens Eichmann and Tobias Pilsak and Harald Sauff and Luis Torres and Klaus Dembowski and Fabian Wagner}, title = {SomSeD: An Interdisciplinary Approach for Developing Wireless Sensor Networks}, booktitle = {Proceedings of the 7th GI/ITG KuVS Fachgespräch "Drahtlose Sensornetze" (FGSN'08)}, day = {25-26}, month = sep, year = 2008, location = {Berlin, Germany}, }
Abstract: The research field "Self organized mobile Sensor and Data-networks" (SomSeD) is introduced. Its purpose is the in- vestigation of Wireless Sensor Networks (WSN). It benefits from interdisciplinary exchange between various institutes of the Hamburg University of Technology (TUHH). Due to different design constraints (such as energy-efficiency and package size) compared to well known classical computer networks, all aspects of the development of WSNs must be reconsidered. This paper describes the advantage of having experts of various faculties both in computer science and electrical engineering in a single research field. In addition to the introduction of the participating institutes, the de- ployment of a WSN on the TUHH campus will be outlined.
Christoph Weyer, Stefan Unterschütz and Volker Turau. Connectivity-aware Neighborhood Management Protocol in Wireless Sensor Networks. In Proceedings of the 7th GI/ITG KuVS Fachgespräch "Drahtlose Sensornetze" (FGSN'08), September 2008. Berlin, Germany.
@InProceedings{Telematik_WUT_2008_Mahalle, author = {Christoph Weyer and Stefan Unterschütz and Volker Turau}, title = {Connectivity-aware Neighborhood Management Protocol in Wireless Sensor Networks}, booktitle = {Proceedings of the 7th GI/ITG KuVS Fachgespräch "Drahtlose Sensornetze" (FGSN'08)}, day = {25-26}, month = sep, year = 2008, location = {Berlin, Germany}, }
Abstract: Neighborhood relations are changing over time in wireless sensor networks due to different hardware or environmental effects. These effects and memory limitations require a balanced neighborhood management to ensure agility, stability, symmetry, and connectivity. The proposed neighborhood management protocol Mahalle is optimized with regard to these four criteria. Agility and stability are achieved by ALE, a new adaptive link estimator.
Kay Römer and Christian Renner. Aggregating Sensor Data from Overlapping Multi-Hop Network Neighborhoods: Push or Pull?. In Proceedings of the International Conference on Networked Sensing Systems (INSS'08), June 2008, pp. 107–110. Kanazawa, Japan.
@InProceedings{Telematik_RR_2008_PushOrPull, author = {Kay Römer and Christian Renner}, title = {Aggregating Sensor Data from Overlapping Multi-Hop Network Neighborhoods: Push or Pull?}, booktitle = {Proceedings of the International Conference on Networked Sensing Systems (INSS'08)}, pages = {107-110}, day = {17-19}, month = jun, year = 2008, location = {Kanazawa, Japan}, }
Abstract: Network neighborhoods are a key communication abstraction in sensor networks, allowing sensor nodes to collect and aggregate sensor data from nearby other nodes. In many applications, multi-hop neighborhoods of several nodes overlap, such that nodes participate in many neighborhoods, having to contribute their data items to all containing neighborhoods. We consider two orthogonal approaches to efficiently support this data aggregation problem. A push-based approach, where each node floods its data item in a multi-hop neighborhood, and a pull-based approach, where each node collects data from nodes in a multi-hop network neighborhood using a spanning tree. Our goal is to identify situations where one approach outperforms the other. For this, we implement these protocols in TOSSIM, study overhead and yield as a function of the fraction of nodes in the network that perform data aggregation over a multi-hop neighborhood, and report our findings.
Volker Turau, Christoph Weyer and Christian Renner. Efficient Slot Assignment for the Many-to-One Routing Pattern in Sensor Networks. In Proceedings of the First International Workshop on Sensor Network Engineering (IWSNE'08), June 2008. Santorini Island, Greece.
@InProceedings{Telematik_TWR_2008_SlotAssignmentManyOne, author = {Volker Turau and Christoph Weyer and Christian Renner}, title = {Efficient Slot Assignment for the Many-to-One Routing Pattern in Sensor Networks}, booktitle = {Proceedings of the First International Workshop on Sensor Network Engineering (IWSNE'08)}, day = {11}, month = jun, year = 2008, location = {Santorini Island, Greece}, }
Abstract: In this paper an efficient TDMA slot assignment for the many-to-one routing pattern in wireless sensor networks is presented and analyzed. This assignment scheme is based on a simple to implement heuristic, named spatial path-based reuse (SPR). By considering several metrics, the superiority of this heuristic with respect to energy consumption and runtime compared to proposals found in the literature is demonstrated.
Arne Bosien, Marcus Venzke and Volker Turau. A rewritable RFID environment for AGV navigation. In Proceedings of the 5th International Workshop on Intelligent Transportation (WIT'08), March 2008, pp. 87–92. Hamburg, Germany.
@InProceedings{Telematik_BVT_2008_AVG_RFID_Environment, author = {Arne Bosien and Marcus Venzke and Volker Turau}, title = {A rewritable RFID environment for AGV navigation}, booktitle = {Proceedings of the 5th International Workshop on Intelligent Transportation (WIT'08)}, pages = {87-92}, day = {18-19}, month = mar, year = 2008, location = {Hamburg, Germany}, }
Abstract: The paper analyses potentials, challenges, and applications of using rewritable, stationary RFID tags for marking routes for autonomous vehicles in manufacturing environments. This approach promises to be flexible, robust, and inexpensive. Two algorithms are proposed also considering additional sensors.
Norbert Luttenberger, Stefan Fischer, Erik Mähle, Dirk Timmermann and Volker Turau. Multi-hybride Sensornetze. PIK - Praxis der Informationsverarbeitung und Kommunikation, 31(3):141–145, 2008.
@Article{Telematik_LFMTT_2008_MultiHybrideSensornetze, author = {Norbert Luttenberger and Stefan Fischer and Erik Mähle and Dirk Timmermann and Volker Turau}, title = {Multi-hybride Sensornetze}, pages = {141-145}, journal = {PIK - Praxis der Informationsverarbeitung und Kommunikation}, volume = {31}, number = {3}, year = 2008, }
Matthias Witt. Robust and Low-Communication Geographic Routing for Wireless Ad Hoc Networks. PhD Thesis, Hamburg University of Technology, Hamburg, Germany, 2008.
@PhdThesis{Telematik_Witt_2008_Diss, author = {Matthias Witt}, title = {Robust and Low-Communication Geographic Routing for Wireless Ad Hoc Networks}, publisher = {Cuvillier Verlag, Göttingen, Germany}, school = {Hamburg University of Technology}, address = {Hamburg, Germany}, edition = {1st}, year = 2008, isbn = {978-3-86727-733-4}, }
Volker Turau and Christoph Weyer. TDMA-Schemes for Tree-Routing in Data Intensive Wireless Sensor Networks. In Proceedings of the First International Workshop on Protocols and Algorithms for Reliable and Data Intensive Sensor Networks (PARIS'07), October 2007. Pisa, Italy.
@InProceedings{Telematik_TW_2007_TDMASchemesTreeRouting, author = {Volker Turau and Christoph Weyer}, title = {TDMA-Schemes for Tree-Routing in Data Intensive Wireless Sensor Networks}, booktitle = {Proceedings of the First International Workshop on Protocols and Algorithms for Reliable and Data Intensive Sensor Networks (PARIS'07)}, day = {8}, month = oct, year = 2007, location = {Pisa, Italy}, }
Abstract: A particular class of data intensive wireless sensor networks are those networks where sensors periodically measure data with high rates. The focus of this work is on the efficient transport of high volumes of sampled data through a multi-hop network with limited resources using a routing tree. This paper analyzes TDMA schemes for this purpose with respect to buffer usage and energy consumption. In particular, it is shown, that classical TDMA schemes are not optimal for tree-routing in data-intensive sensor networks.
Matthias Witt and Volker Turau. Geographic Routing in 3D. In Proceedings of the 6th GI/ITG KuVS Fachgespräch "Drahtlose Sensornetze" (FGSN'07), July 2007, pp. 75–78. Aachen, Germany.
@InProceedings{Telematik_WT_2007_3DRouting, author = {Matthias Witt and Volker Turau}, title = {Geographic Routing in 3D}, booktitle = {Proceedings of the 6th GI/ITG KuVS Fachgespräch "Drahtlose Sensornetze" (FGSN'07)}, pages = {75-78}, day = {16-17}, month = jul, year = 2007, location = {Aachen, Germany}, }
Abstract: Existing geographic routing algorithms assume a two-dimensional topology. Dedicated wireless sensor network scenarios demand for algorithms that operate in three-dimensional environments. This paper discusses issues which arise when making the step from 2D to 3D. Simulation studies show that 3D routing is less efficient than its 2D counterpart when comparing topologies with the same average node degree.
Volker Turau and Christoph Weyer. Long-term Reliable Data Gathering Using Wireless Sensor Networks. In Proceedings of the Fourth International Conference on Networked Sensing Systems (INSS'07), June 2007, pp. 252–259. Braunschweig, Germany.
@InProceedings{Telematik_LVMHTM_2007_Long-termReliableDataGathering, author = {Volker Turau and Christoph Weyer}, title = {Long-term Reliable Data Gathering Using Wireless Sensor Networks}, booktitle = {Proceedings of the Fourth International Conference on Networked Sensing Systems (INSS'07)}, pages = {252-259}, day = {6-8}, month = jun, year = 2007, location = {Braunschweig, Germany}, }
Abstract: This paper presents the design of a long-term reliable data gathering service for many-to-one communication in wireless sensor networks: all nodes send periodically delaytolerant data to a single node. The service operates reliably despite strict resource constraints, poor link qualities, and frequent disconnects. This paper presents a novel protocol for gathering periodically measured data including a solution for the wearleveling problem of the EEPROM. Furthermore, theoretical limits of this approach based on available bandwidth and local memory are provided. Finally, preliminary results of an implementation of the service are presented. In particular a detailed analysis of the energy consumption during the different phases of this experiment is provided.
Volker Turau and Christoph Weyer. Scheduling Transmission of Bulk Data in Sensor Networks using a Dynamic TDMA Protocol. In Proceedings of the International Workshop on Data Intensive Sensor Networks (DISN'07), May 2007, pp. 321–325. Mannheim, Germany.
@InProceedings{Telematik_TW_2007_SchedulingBulkData, author = {Volker Turau and Christoph Weyer}, title = {Scheduling Transmission of Bulk Data in Sensor Networks using a Dynamic TDMA Protocol}, booktitle = {Proceedings of the International Workshop on Data Intensive Sensor Networks (DISN'07)}, pages = {321-325}, day = {1}, month = may, year = 2007, location = {Mannheim, Germany}, }
Abstract: Sensor networks are increasingly used for applications in which sensors periodically measure data with high sampling rates. The reliable transport of high volumes of sampled data through a multi-hop network with limited resources requires sophisticated algorithms. This paper presents a novel protocol for this task that uses minimal energy, provides high throughput, and requires only small amounts of additional buffer. The protocol is based on a dynamic TDMA scheme and is robust against omission failures.
Matthias Witt and Volker Turau. The Impact of Location Errors on Geographic Routing in Sensor Networks. In Proceedings of the Second International Conference on Wireless and Mobile Communications (ICWMC'06), July 2006, pp. 76. Bucharest, Romania.
@InProceedings{Telematik_WT_2006_LocationErrorRouting, author = {Matthias Witt and Volker Turau}, title = {The Impact of Location Errors on Geographic Routing in Sensor Networks}, booktitle = {Proceedings of the Second International Conference on Wireless and Mobile Communications (ICWMC'06)}, pages = 76, day = {29-31}, month = jul, year = 2006, location = {Bucharest, Romania}, }
Abstract: Geographic routing in wireless sensor networks is based on the prerequisite that every node has information about its current position, for instance via GPS or some localization algorithm. This location information has a certain degree of inaccuracy in real deployments. The majority of geographic routing algorithms, however, has been designed for nodes with exact position information. We show that location errors yield bad performance or even complete failures. Two elaborated geographic routing algorithms for sensor networks, GPSR and BGR, are evaluated with the nodes having inaccurate location information, varying the standard deviation of the position error between zero and the transmission range. Simulation studies show a vast decrease of the packet delivery ratio. To enhance both algorithms, fixes for them are presented to improve the delivery ratio and to save energy in case of location errors.
Volker Turau, Matthias Witt and Marcus Venzke. Field Trials with Wireless Sensor Networks: Issues and Remedies. In Proceedings of the Second International Conference on Wireless and Mobile Communications (ICWMC'06), July 2006, pp. 86. Bucharest, Romania.
@InProceedings{Telematik_TWV_2006_FieldTrialsWSN, author = {Volker Turau and Matthias Witt and Marcus Venzke}, title = {Field Trials with Wireless Sensor Networks: Issues and Remedies}, booktitle = {Proceedings of the Second International Conference on Wireless and Mobile Communications (ICWMC'06)}, pages = 86, day = {29-31}, month = jul, year = 2006, location = {Bucharest, Romania}, }
Abstract: Extensive field trials are essential to evaluate protocols and algorithms for wireless sensor networks. The high costs of such trials demand for a systematic approach. This paper discusses the issues of setting up a field trial such as packaging, logging, and deployment. Details about a concrete field trial to evaluate a topology discovery algorithm are presented.
Matthias Witt and Volker Turau. Delivery Semantics for Geographic Routing. In Proceedings of the 5th GI/ITG KuVS Fachgespräch "Drahtlose Sensornetze" (FGSN'06), July 2006. Stuttgart, Germany.
@InProceedings{Telematik_WT_2006_DeliverySemantics, author = {Matthias Witt and Volker Turau}, title = {Delivery Semantics for Geographic Routing}, booktitle = {Proceedings of the 5th GI/ITG KuVS Fachgespräch "Drahtlose Sensornetze" (FGSN'06)}, day = {17-18}, month = jul, year = 2006, location = {Stuttgart, Germany}, }
Abstract: Geographic routing algorithms use locations rather than node addresses as destinations. But since it is not always guaranteed that there is indeed a node exactly at the destination location, there must exist a description which nodes shall be allowed to consume a message. In some cases, the message must not be consumed by a node at another location (e. g., if the sink is the destination), whereas in other cases, nodes in the vicinity may also consume it. This has to be chosen by the application, so the routing protocol should support different delivery semantics. Another question is if only one node may consume the message, or if multiple destination nodes are allowed. This paper proposes three orthogonal delivery parameters: closeness, multiplicity, and accept-outside.
Volker Turau. Computing Bridges, Articulations, and 2-Connected Components in Wireless Sensor Networks. In Proceedings of the Second International Workshop on Algorithmic Aspects of Wireless Sensor Networks (ALGOSENSORS'06), July 2006, pp. 164–175. Venice, Italy.
@InProceedings{Telematik_TURAU_2006_ComputingBridgesUA, author = {Volker Turau}, title = {Computing Bridges, Articulations, and 2-Connected Components in Wireless Sensor Networks}, booktitle = {Proceedings of the Second International Workshop on Algorithmic Aspects of Wireless Sensor Networks (ALGOSENSORS'06)}, pages = {164-175}, day = {15}, month = jul, year = 2006, location = {Venice, Italy}, }
Abstract: This paper presents a simple distributed algorithm to determine the bridges, articulation points, and 2-connected components in asynchronous networks with an at least once message delivery semantics in time O(n) using O(lg n)-length messages. The algorithm does not assume a FIFO rule for message delivery. Previously known algorithms either use longer messages or need more time. The algorithm meets the requirements of wireless senor networks and can be applied in several areas relevant to this field such as topology control, clustering, localization and virtual backbone calculations.
Marcus Venzke, Peng Kong and Volker Turau. A Generic Java Interface for Vertical Integration of Wireless Sensor Networks. In Proceedings of the Fourth Workshop on Intelligent Solutions in Embedded Systems (WISES'06), June 2006. Vienna, Austria.
@InProceedings{Telematik_VKT_2006_VerticalIntegrationSensorNet, author = {Marcus Venzke and Peng Kong and Volker Turau}, title = {A Generic Java Interface for Vertical Integration of Wireless Sensor Networks}, booktitle = {Proceedings of the Fourth Workshop on Intelligent Solutions in Embedded Systems (WISES'06)}, day = {30}, month = jun, year = 2006, location = {Vienna, Austria}, }
Abstract: The paper presents a generic, high-level Java interface for the vertical integration of wireless sensor networks. The intuitive interfaces are implemented in a framework that is easy to use. The classes of the framework can be extended to meet the requirements of a wide range of applications. In particular, the framework supports sending packets to and receiving packets from nodes of the sensor network. Packet types are represented as Java classes generated from meta-data based on XML Schema. This approach fosters short development cycles and provides the productivity needed in vertical integration applications. The ScatterWeb platform is used as a sample platform for sensor networks.
Volker Turau, Matthias Witt and Christoph Weyer. Analysis of a Real Multi-hop Sensor Network Deployment: The Heathland Experiment. In Proceedings of the Third International Conference on Networked Sensing Systems (INSS'06), June 2006, pp. 6–13. Chicago, Illinois, USA.
@InProceedings{Telematik_TWW_2006_HeathlandDeployment, author = {Volker Turau and Matthias Witt and Christoph Weyer}, title = {Analysis of a Real Multi-hop Sensor Network Deployment: The Heathland Experiment}, booktitle = {Proceedings of the Third International Conference on Networked Sensing Systems (INSS'06)}, pages = {6-13}, month = jun, year = 2006, location = {Chicago, Illinois, USA}, }
Abstract: This paper reports on the results and experience gained during a real-world deployment of a sensor network based on the ESB platform in the heathlands of Northern Germany. The goal of the experiment was to gain a deeper insight into the problems of real deployments as opposed to simulated networks. The focus of the experiment was on the long- and short-term reliability of radio links, estimation of link qualities, the influence of the link quality on multi-hop routing, and on neighborhood exploration.
Volker Turau, Christian Renner, Marcus Venzke, Sebastian Waschik, Christoph Weyer and Matthias Witt. The Heathland Experiment: Results And Experiences. In Proceedings of the Workshop on Real-World Wireless Sensor Networks (REALWSN'05), June 2005. Stockholm, Sweden.
@InProceedings{Telematik_TRVWWW_2005_Heathland, author = {Volker Turau and Christian Renner and Marcus Venzke and Sebastian Waschik and Christoph Weyer and Matthias Witt}, title = {The Heathland Experiment: Results And Experiences}, booktitle = {Proceedings of the Workshop on Real-World Wireless Sensor Networks (REALWSN'05)}, day = {20-21}, month = jun, year = 2005, location = {Stockholm, Sweden}, }
Abstract: This paper reports on the experience gained during a real-world deployment of a sensor network based on the ESB platform in the heathlands of Northern Germany. The goal of the experiment was to gain a deeper insight into the problems of real deployments as opposed to simulated networks. The focus of this report is on the quality of radio links and the influence of the link quality on multi-hop routing.
Matthias Witt and Volker Turau. BGR: Blind Geographic Routing for Sensor Networks. In Proceedings of the Third Workshop on Intelligent Solutions in Embedded Systems (WISES'05), May 2005, pp. 51–61. Hamburg, Germany.
@InProceedings{Telematik_WT_2005_BGR, author = {Matthias Witt and Volker Turau}, title = {BGR: Blind Geographic Routing for Sensor Networks}, booktitle = {Proceedings of the Third Workshop on Intelligent Solutions in Embedded Systems (WISES'05)}, pages = {51-61}, day = {20}, month = may, year = 2005, location = {Hamburg, Germany}, }
Abstract: This paper introduces BGR, a new beacon-less geographic routing algorithm for wireless sensor networks. Data packets are forwarded toward the destination, and nodes which hear the packet compete for becoming the next hop. A recovery strategy is provided for the case of empty forwarding areas. The main innovation is a strategy to avoid simultaneous forwarding situations, which would otherwise cause packet failures. It is confirmed by simulation that BGR sends very few packets and is reliable in fields with sufficiently high node density. Furthermore, BGR is compared with similar algorithms after developing a general framework for beacon-less algorithms with an integrative terminology. Different kinds of forwarding areas are compared.
Volker Turau, Christoph Weyer and Matthias Witt. Ein robustes Datenmonitoring-Verfahren für Sensornetzwerke. it - Information Technology, 47(2):63–69, April 2005.
@Article{Telematik_TWW_2005_Datenmonitoring, author = {Volker Turau and Christoph Weyer and Matthias Witt}, editor = {Christian Becker and Pedro José Marrón}, title = {Ein robustes Datenmonitoring-Verfahren für Sensornetzwerke}, pages = {63-69}, journal = {it - Information Technology}, volume = {47}, number = {2}, month = apr, year = 2005, }
Abstract: A new data monitoring method for wireless sensor networks is introduced. The method combines geographic hash tables with in-network aggregation. Queries are processed in regions, whose sensor nodes collect their values in nodes close to a determinated location within the region, where they can easily be requested from outside. The method is robust against node failures and movements and generates very little network traffic. This is confirmed by various simulations.
Matthias Witt, Christoph Weyer and Volker Turau. Monitoring Energy Consumption In Wireless Sensor Networks. In Proceedings oth the Fourth GI/ITG KuVS Fachgespräch "Drahtlose Sensornetze" (FGSN'05), March 2005. Zürich, Switzerland.
@InProceedings{Telematik_WWT_2005_Monitoring, author = {Matthias Witt and Christoph Weyer and Volker Turau}, title = {Monitoring Energy Consumption In Wireless Sensor Networks}, booktitle = {Proceedings oth the Fourth GI/ITG KuVS Fachgespräch "Drahtlose Sensornetze" (FGSN'05)}, month = mar, year = 2005, location = {Zürich, Switzerland}, }
Abstract: This note introduces an approach to monitor the consumption of energy in wireless sensor networks based on video streams composed from sequences of temperature maps. It is used to compare and evaluate beacon-less geographic routing algorithms.
Volker Turau and Christoph Weyer. Location-aware In-Network Monitoring in Wireless Sensor Networks. In Proceedings of the 34th Jahrestagung der Gesellschaft für Informatik e.V. (INFORMATIK'04), Volume 2, Workshop Sensor Networks, September 2004, pp. 355–359. Ulm, Germany.
@InProceedings{Telematik_TW_2004_InNetworkMonitoring, author = {Volker Turau and Christoph Weyer}, title = {Location-aware In-Network Monitoring in Wireless Sensor Networks}, booktitle = {Proceedings of the 34th Jahrestagung der Gesellschaft für Informatik e.V. (INFORMATIK'04), Volume 2, Workshop Sensor Networks}, pages = {355-359}, day = {20-24}, month = sep, year = 2004, location = {Ulm, Germany}, }
Abstract: This paper presents a data-centric and location-aware procedure to perform in-network evaluation of queries in sensor networks. The algorithm is a hybrid of geographic hash tables and in-network aggregation. It increases data availability and accounts for topology changes and generates mostly local network traffic.

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