print page

Publications

Books | Journal Articles | Conference Contributions | PhD Theses | Technical Reports | Students' Theses

Books

Bernd-Christian Renner. Steffen Hölldobler et al. (Hrsg.), editor. GI-Edition Ausgezeichnete Informatikdissertationen 2013. Gesellschaft für Informatik (GI), 2014.
@Book{Telematik_Renner_GI_2013, author = {Bernd-Christian Renner}, editor = {Steffen H{\"o}lldobler et al. (Hrsg.)}, title = {GI-Edition Ausgezeichnete Informatikdissertationen 2013}, pages = {191-200}, series = {Gesellschaft f{\"u}r Informatik (GI)}, volume = {D-14}, publisher = {Gesellschaft f{\"u}r Informatik (GI)}, year = 2014, isbn = {978-3-88579-418-9}, }

Journal Articles

Christian Renner, Stefan Unterschütz, Volker Turau and Kay Römer. Perpetual Data Collection with Energy-Harvesting Sensor Networks. ACM Transactions on Sensor Networks, 11(12):1–12, November 2014.
@Article{Telematik_RUTR_2013_SCIS, author = {Christian Renner and Stefan Untersch{\"u}tz and Volker Turau and Kay R{\"o}mer}, title = {Perpetual Data Collection with Energy-Harvesting Sensor Networks}, pages = {1-12}, journal = {ACM Transactions on Sensor Networks}, volume = {11}, number = {12}, month = nov, year = 2014, }
Abstract: A sustainable, uniform, and utility-maximizing operation of energy-harvesting sensor networks requires methods for aligning consumption with harvest. This article presents a lightweight algorithm for online load adaptation of energy-harvesting sensor nodes using supercapacitors as energy buffers. The algorithm capitalizes on the elementary relationship between state of charge and voltage that is characteristic for supercapacitors. It is particularly designed to handle the nonlinear system model, and it is lightweight enough to run on low-power sensor node hardware. We define two energy policies, evaluate their performance using real-world solar-harvesting traces, and analyze the influence of the supercapacitor’s capacity and imprecisions in harvest forecasts. To show the practical merit of our algorithm, we devise a load adaptation scheme for multihop data collection sensor networks and run a 4-week field test. The results show that (i) choosing a duty cycle a priori is infeasible, (ii) our algorithm increases the achievable work load of a node when using forecasts, (iii) uniform and steady operation is achieved, and (iv) depletion can be prevented in most cases.
Christian Renner, Volker Turau and Kay Römer. Online Energy Assessment with Supercapacitors and Energy Harvesters. Sustainable Computing, Informatics and Systems, 4(1):10–23, March 2014.
@Article{Telematik_RTR_2013_SCIS, author = {Christian Renner and Volker Turau and Kay R{\"o}mer}, title = {Online Energy Assessment with Supercapacitors and Energy Harvesters}, pages = {10-23}, journal = {Sustainable Computing, Informatics and Systems}, volume = {4}, number = {1}, month = mar, year = 2014, issn = {2210-5379}, }
Abstract: Combining energy harvesting with energy-aware load adaptation and scheduling enables perpetually operating sensor networks. The practical realization of this goal yet requires methods for 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 and supercapacitor-powered sensor node. We show that in a real deployment simple supercapacitor models suffice for energy assessment, while capacity calibration is mandatory yet practicable. We evaluate the joint performance of state-of-the-art energy assessment based on an outdoor field test. We verify the system model and show the feasibility of holistic online energy assessment, which tolerates small configuration errors, achievable with a combination of generic configuration and online calibration. We analyze the feasibility of forecasting a node's future energy reserve and find that the presented method produces accurate results for uniformly distributed consumption profiles.
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.
Thomas Czerwionka, Corinna Peters and Christian Renner. ePortfolios an der TUHH. Konzeption und aktueller Stand im ELCH-Projekt "studIPort 2.0". Hamburger eLearning Magazin, 2:35–36, 2009.
@Article{Peters_EL2009, author = {Thomas Czerwionka and Corinna Peters and Christian Renner}, title = {ePortfolios an der TUHH. Konzeption und aktueller Stand im ELCH-Projekt "studIPort 2.0"}, pages = {35-36}, journal = {Hamburger eLearning Magazin}, volume = {2}, year = 2009, }

Conference Contributions

Andreas Weigel, Christian Renner, Volker Turau and Holger Ernst. Wireless Sensor Networks for Smart Metering. In Energy Conference and Exhibition (ENERGYCON), 2014 IEEE International, May 2014, pp. 722–729. Dubrovnik, Croatia.
@InProceedings{Telematik_EnergyCon_2014_SmartMetering, author = {Andreas Weigel and Christian Renner and Volker Turau and Holger Ernst}, title = {Wireless Sensor Networks for Smart Metering}, booktitle = {Energy Conference and Exhibition (ENERGYCON), 2014 IEEE International}, pages = {722-729}, day = {13-16}, month = may, year = 2014, location = {Dubrovnik, Croatia}, }
Abstract: Smart metering will change the way we assess and control energy consumption. The necessary two-way communication between energy utilities and smart meters yet requires further research. In par- ticular, cheap, low-maintenance, and reliable alterna- tives to existing approaches must be analyzed. We believe that self-organizing wireless sensor networks are a promising candidate. In this paper, we perform a requirement analysis for smart metering using wireless sensor network technology; we propose an architecture including a set of protocols; and we conduct a real-world evaluation with a testbed of 64 smart meters. With regard to latency and network formation time, the sys- tem was able to fulfill the identified requirements. The results show that the attained reliability for some traffic patterns is low. Further analysis revealed the use of link-layer broadcasts for one-to-many communication as a cause
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.
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, 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 Untersch{\"u}tz 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, 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.
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.
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 J{\"u}rgen 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}, }
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.
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 R{\"o}mer 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.
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.

PhD Theses

Bernd-Christian Renner. Sustained Operation of Sensor Nodes with Energy Harvesters and Supercapacitors. PhD Thesis, Hamburg University of Technology, Hamburg, Germany, 2013.
@PhdThesis{Telematik_Renner_2013_Diss, author = {Bernd-Christian Renner}, title = {Sustained Operation of Sensor Nodes with Energy Harvesters and Supercapacitors}, publisher = {Books on Demand GmbH, Norderstedt, Germany}, school = {Hamburg University of Technology}, address = {Hamburg, Germany}, edition = {1st}, year = 2013, isbn = {978-3-7322-3319-9}, }
Abstract: Sensor nodes powered by energy harvesters and supercapacitors open the door to unlimited and uninterrupted operation. This dissertation closes the persistent gap of system integration w.r.t. holistic online energy assessment, develops a new concept for harvest forecasting while assessing the behavior and quality of known approaches, and proposes a novel load adaptation scheme to achieve sustained and uniform sensor node operation with low complexity and computational overhead. For this purpose, a prototype of an energy harvester with a supercapacitor for off-the-shelf sensor nodes is developed and used for practical evaluation.

Technical Reports

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 Untersch{\"u}tz 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.
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 Fachgespr{\"a}ch "Drahtlose Sensornetze" (FGSN'10)}, pages = {17-20}, day = {16-17}, month = sep, year = 2010, location = {W{\"u}rzburg, 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.
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 Fachgespr{\"a}ch "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 Bj{\"o}rn Gre{\ss}mann 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 Fachgespr{\"a}ch "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.
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 Fachgespr{\"a}ch "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 J{\"u}rgen Jessen and Volker Turau}, title = {Lifetime Prediction for Supercapacitor-powered Wireless Sensor Nodes}, booktitle = {Proceedings of the 8th GI/ITG KuVS Fachgespr{\"a}ch "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.
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 Fachgespr{\"a}ch "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.

Students' Theses

Christian Renner. Energy-Efficient TDMA Schedules for Data-Gathering in Wireless Sensor Networks. Diploma Thesis, Hamburg University of Technology, Hamburg, Germany, June 2008.
@MastersThesis{Renner_2008_DiplomaThesis, author = {Christian Renner}, type = {Diploma Thesis}, title = {Energy-Efficient TDMA Schedules for Data-Gathering in Wireless Sensor Networks}, school = {Hamburg University of Technology}, address = {Hamburg, Germany}, month = jun, year = 2008, }