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Andreas Hasler, Stephan Gruber, and Jan Beutel [HaslerGB:10] [published]
High-resolution rock dilatation measurements from steep bedrock permafrost and implications for rock fall release mechanisms
European Geosciences Union General Assembly 2010, Vienna, 2-7 May 10
In fractured bedrock of steep alpine permafrost rock faces, cleft dynamics, creep and stability of rock masses is influenced by the thermal conditions within and around discontinuities. An increasing number of documented rock falls from periglacial environments in the last decade raise the question, how and where this thermal influence becomes a controlling factor of rock fall activity. The mechanics of permafrost bedrock containing ice-filled clefts has rarely been investigated and only qualitative understanding of the processes interlinking temperature and stability in these situations exist. Here we present temperature, dilatation and translation measurements with high temporal resolution from six clefts at Matterhorn- Hörnligrat (3500m a.s.l.; Swiss Alps). Cleft opening / closing is recorded during cooling / warming at subzero temperatures in the upper cleft. This reversible dilatation is commonly explained by segregation ice formation within the cleft (cryogenic opening). Once temperatures reach the melting point (indicated by a zero curtain in cleft temperature records) an accelerated opening or shearing (depending on the geometrical setting) of the cleft takes place. We attribute this second slow mass movement to a sliding at a basal fracture plane of the rock mass that is introduced by melting conditions. We suspect this sliding mechanism to potentially culminate in the triggering of rock fall or rock avalanches. The response time of the cleft movements to temperature changes is on the order of some hours for both cases (cryogenic opening and sliding). This is surprisingly short for the dimensions of the surveyed rock masses and can not be explained by conductive heat transport between the rock surface and the ice-rock interface within the cleft. Dilatation-temperature plots with the lower cleft temperatures show even a time lag of the cleft temperature in comparison to the movement. This finding is little understood at present but indicates the possible importance of rock hydrology (pore water pressure/expulsion and advective heat transport) as a coupling mechanism between the meteorological conditions and the mechanics of the fractures.
Joel Fiddes, Stefanie Gubler, Stephan Gruber, Guido Hungerbühler, Oliver Knecht, Suhel Sheikh, Matthias Keller, and Jan Beutel [FiddesGGHKSKB:10] [published]
The investigation of ground temperatures in high mountain areas using IButtons
European Geosciences Union General Assembly 2010, Vienna, 2-7 May 10
Mountain areas are characterized by extreme variability in elevation, exposure to solar radiation and ground material. Many physical processes, that control ground temperatures and thereby permafrost, are highly affected by this variability. An improved understanding of permafrost and related processes in mountain areas therefore requires investigation at high spatial resolutions. The aim of this project is to investigate ground surface temperatures in high mountain areas. We focus on the effects of topography and local ground properties on surface temperatures at high spatial and temporal resolutions. We distributed 390 mini temperature logger IButtons (www.maxim-ic.com) at Corvatsch in the Upper Engadin (Switzerland) logging surface temperatures at a 3 hour time step. This distributed network of temperature loggers is planned to operate for 3 years. The programming, distribution and recovery of many IButton devices in high mountain areas is very timeconsuming. It requires a systematic recording and storage of relevant metadata such as the geographic coordinates of each IButton as well as other topographic characteristics. To easily handle these requirements and to stream-line field work, we developed an effective working procedure and supporting software to program and read-out IButtons (precision, time resolution, etc.) and to store the temperature measurements in a database together with the relevant metadata. The possibility to connect a GPS device and digital camera to this system makes the recording of meta-data and the reclamation of loggers very efficient. We present the project together with the main tools of the developed software.
Jan Beutel, Roman Lim, Andreas Meier, Lothar Thiele, Christoph Walser, Matthias Woehrle, Mustafa Yuecel [BeutelLMTWWY:09] [published]
Poster abstract: The FlockLab Testbed Architecture
7th ACM Conf. Embedded Networked Sensor Systems (SenSys 2009), Berkeley, 4-6 Nov 09
A vital factor for a successful deployment of sensor nodes is testing of all system aspects in a realistic setup. This work presents a testbed architecture which allows for detailed monitoring and stimulation of a wireless sensor node. In particular, time-accurate state extraction and power measurements are provided in a distributed, yet synchronized context. The FlockLab testbed architecture provides a distributed lab instrument, where detailed observations of every sensor node enable thorough testing. Software services allow for formulating testcases and reliable test data collection.
Matthias Keller, Jan Beutel, Andreas Meier, Roman Lim, Lothar Thiele [KellerBMLT:09b] [published]
Poster Abstract: Learning from Sensor Network Data
7th ACM Conf. Embedded Networked Sensor Systems (SenSys 2009), Berkeley, 4-6 Nov 09
Within the PermaSense project, two wireless sensor networks have been deployed for a long-term operation in the Swiss Alps. For enabling state-of-the-art permafrost research based on the collected data, highest possible data quality and yield have to be ensured. But, the operation of wireless sensors networks remains a hard research problem. Firstly, deployed wireless sensors networks are subject to continuous changes. Second, there are scenarios that can only be tested in the field as the capabilities of testbeds are too limited. Basically, it is not possible to test for many months before deploying in the field. In this poster, we present an analysis of our data that has been collected over nine months. In addition to describing our system design and methods, we also share our experiences from discovered severe incidences.
A. Meier, M. Woehrle, M. Weise, J. Beutel, L. Thiele [MeierWWBT:09] [published]
NoSE: Efficient Maintenance and Initialization of Wireless Sensor Networks
Sixth Annual IEEE Communications Society Conference on Sensor, Mesh, and Ad Hoc Communications and Networks (SECON 2009), Rome, 22-26 June 09
Wireless sensor networks (WSNs) are used for long-term observation and monitoring. Such long-lasting deployments require different maintenance tasks, such as the replacement of nodes and the most critical initial installation of the sensor nodes. During maintenance, the actual node placement is modified resulting in temporary topology fluctuations, which are very expensive in terms of energy. We propose the NoSE protocol stack enhancement for WSNs to target maintenance tasks. NoSE provides the functionality for switching the network between an operational state and a deep sleep state. The deep sleep state allows for switching the network to energy savings, while performing maintenance. The network may be woken up at any given time. During the time bounded start up, a comprehensive neighborhood assessment provides a solid basis for the subsequent network topology set up. Thus the success of a maintenance task, e.g., the initial deployment of the nodes, can be instantly validated. We present NoSE on a case study focusing on the initialization of a fire-detector WSN validated on a testbed and in simulation. [pdf]
Jan Beutel, Kay Roemer, Matthias Ringwald and Matthias Woehrle [BeutelRRW:09] [published]
Deployment Techniques for Sensor Networks
Sensor Networks - Where Theory Meets Practice, Springer, 2009
Jan Beutel, Stephan Gruber, Andreas Hasler, Roman Lim, Andreas Meier, Christian Plessl, Igor Talzi, Lothar Thiele, Christian Tschudin, Matthias Woehrle, Mustafa Yuecel [BeutelLMTWYGHPTT:09] [published]
PermaDAQ: A Scientific Instrument for Precision Sensing and Data Recovery under Extreme Conditions
8th ACM/IEEE International Conference on Information Processing in Sensor Networks (IPSN/SPOTS 2009), San Francisco, 13-16 Apr 09
The PermaSense project has set the ambitious goal of gathering real-time environmental data for high-mountain permafrost in unattended operation over multiple years. This paper discusses the specialized sensing and data recovery architecture tailored to meet the precision, reliability and durability requirements of scientists utilizing the data for model validation. We present a custom sensor interface board including specialized sensors and redundancy features for end-to-end data validation. Aspects of high-quality data acquisition, design for reliability by strict separation of operating phases and analysis of energy efficiency are discussed. The system integration using the Dozer protocol scheme achieves a best-in-class average power consumption of 148µA considerably exceeding the lifetime requirement. [pdf]
Jan Beutel, Stephan Gruber, Andreas Hasler, Roman Lim, Andreas Meier, Christian Plessl, Igor Talzi, Lothar Thiele, Christian Tschudin, Matthias Woehrle, Mustafa Yuecel [BeutelLMTWYGHPTT:09b] [published]
Demo Abstract: Operating a Sensor Network at 3500 m Above Sea Level
8th ACM/IEEE International Conference on Information Processing in Sensor Networks (IPSN/SPOTS 2009), San Francisco, 13-16 Apr 09
Sensor networks deployed in remote locations require easy to use but also extremely expressive tools for reliable operation. The PermaSense project has developed a platform based on a number of proven COTS components and integrated with the GSN based data backend. All tools are accessible from a single location in a web browser. This demo will present the monitoring and control tools in live operation with deployments on real field sites in the Swiss Alps. [pdf]
Roman Lim, Matthias Woehrle, Andreas Meier, Jan Beutel [LimWMB:09] [published]
Poster Abstract: Harvester - Energy Savings Through Synchronized Low-power Listening
The 6th European Conference on Wireless Sensor Networks (EWSN 2009); Cork, Ireland, February 11-13, 2009
Long-term data gathering with Wireless Sensor Networks (WSNs) systems requires drastic optimization of power consumption to provide a long system lifetime of the network of battery operated motes. In this work, we discuss Harvester, a low power data collection application which uses our enhancements on standard MAC and network layer components provided by the TinyOS operating system. We present considerable savings in energy through synchronization. [pdf] [ps]
Matthias Keller, Jan Beutel, Lothar Thiele [KellerBT:09] [published]
Demo Abstract: Mountainview - Precision Image Sensing on High-Alpine Locations
6th European Workshop on Sensor Networks (EWSN 2009), Cork, 11-13 Feb 09
We describe a novel optical sensor system designed for high-fidelity image acquisition in wireless sensor networks. The system uses precision optical equipment as well as a highresolution imager yielding accurate observations - a prerequisite for many image processing techniques. In order to deliver the lifetime and durability required by long-term environmental monitoring campaigns we present a custom solution that is optimized to integrate seamlessly into a power efficient wireless sensor network. The imaging system presented is based on a state-of-the-art wireless digital SLR camera, that has been packaged, augmented with the necessary power supply, heater, system supervision and control to operate reliably under the most hostile and extreme environmental conditions. [pdf]
A. Meier, M. Weise, J. Beutel, L. Thiele [MeierWBT:08] [published]
Poster Abstract: NoSE: Neighbor Search and Link Estimation for a Fast and Energy Efficient Initialization of WSNs
6th ACM Conf. Embedded Networked Sensor Systems (SenSys 2008), Raleigh, 5-7 Nov 2008
There are numerous possibilities to assemble a very resource-efficient and power-aware distributed sensor network tailored to a specific application. However, the task of initializing the network has not yet attracted much attention. This paper presents the NoSE (Neighbor Search and link Estimation) initialization scheme. NoSE provides an exhaustive neighbor search including a thorough link assessment, leveraging both high reactivity and greatly minimized energy consumption. Based on the information obtained in the initial link assessment phase, a routing protocol can subsequently set up and use an optimized network topology. [pdf]
A. Hasler, I. Talzi, J. Beutel, C. Tschudin and S. Gruber [HaslerTBTG:08] [published]
Wireless Sensor Networks in Permafrost Research – Concept, Requirements, Implementation and Challenges
9th Int'l Conf. on Permafrost (NICOP), Fairbanks, 29.6-3.7.08
Andreas Meier, Tobias Rein, Jan Beutel, Lothar Thiele [MeierRBT:08] [published]
Coping with Unreliable Channels: Efficient Link Estimation for Low-Power Wireless Sensor Networks
5th Intl Conf. Networked Sensing Systems (INSS 2008), Kanazawa, 17-19 June 08
The dynamic nature of wireless communication and the stringent energy constraints are major challenges for the design of low-power wireless sensor network applications. The link quality of a wireless link is known for its great variability, dependent on the distance between nodes, the antenna's radiation characteristic, multipath, diffraction, scattering and many more. Especially for indoor and urban deployments, there are numerous factors impacting the wireless channel. In an extensive experimental study contained in the first part of this paper, we show the magnitude of this problem for current Wireless Sensor Networks (WSNs) and that based on the overall connectivity graph of a typical multihop WSN, a large portion of the links actually exhibit very poor characteristics. We present a pattern based estimation technique that allows assessing the quality of a link at startup and as a result to construct an optimal neighbor table right at the beginning using a minimum of resources only. Our estimation technique is superior compared to other approaches where protocols continue to decide on the fly which links to use expending valuable energy both for unnecessary retransmissions and recursive link estimation. [pdf]
M. Woehrle and J. Beutel and R. Lim and M. Yuecel and L. Thiele [WoehrleBLYT:08] [published]
Power monitoring and testing in Wireless Sensor Network Development
Workshop on Energy in Wireless Sensor Networks (WEWSN2008), Santorini Island, 14 June 08
Abstract—Wireless Sensor Networks (WSNs) are becoming widely used in scientific applications as they allow for instrumenting the environment in previously impossible ways revealing unprecedented insight and detailed data. Long term monitoring of environmental processes and the harsh reality of remote and inaccessible terrain demand longevity from such WSN deployments. While functional correctness is typically the developers prime concern, unattended operation without the possibility to scavenge energy nor to exchange batteries demand applications to be significantly optimized for power consumption. Thus, power consumption of the application becomes a chief concern of system design where development necessitates appropriate means for monitoring, profiling and analysis. We propose the monitoring and testing of power consumption in an integrated testing infrastructure. We additionally present a novel methodology for automatic power profile testing for embedded systems in the context of WSNs.
Matthias Woehrle, Christian Plessl, Roman Lim, Jan Beutel, Lothar Thiele [WoehrlePLBT:08] [published]
EvAnT: Analysis and Checking of event traces for Wireless Sensor Networks
IEEE SUTC'08, Taichung, 11-13 June 08
Testing and veriﬁcation methodologies for Wireless Sensor Networks (WSN) systems in pre-deployment are vital for a successful deployment. Increased visibility of the internal state of a WSN application is established by instrumenting the application for logging execution traces at runtime. While the interpretation of the event traces is application-speciﬁc, a common method for analysis can be devised. This method should allow for a concise formula- tion of explorative queries to determine the occurrence and the cause of functional or performance problems. The contribution of this paper is an event analysis methodology that is implemented in the EvAnT framework. EvAnT allows for specifying queries that are executed on the collected traces. EvAnT is speciﬁcally tailored to WSN testing and debugging. We demonstrate the applicability of EvAnT by a case study in a building monitoring project.
Christian Frank, Philipp Bolliger, Friedemann Mattern, Wolfgang Kellerer [FrankBMK:08] [published]
The Sensor Internet at Work: Locating Everyday Items Using Mobile Phones
Pervasive and Mobile Computing Journal (in press), June 2008
We present a system for monitoring and locating everyday items based on users' mobile phones that are augmented with the capability of detecting near-by objects which are electronically tagged. It includes different usage scenarios from storing the context in which an item has left the sensing range of the local device to allowing object owners to search for objects using the infrastructure of mobile phones carried by other users. Next to describing the design of our object monitoring system, we provide an algorithm which can be used to search for a lost or misplaced item efficiently. Furthermore, we demonstrate the practicability of such wide-area search by means of user-carried sensors in a series of simulations complemented by a real-world experiment. [pdf]
Matthias Woehrle, Jan Beutel, Mustafa Yuecel, Lothar Thiele [WoehrleBYT:08] [published]
Approaching Wireless Sensor Networks Using Systematic Testing Strategies
ETHZ-TIK Report Nr. 284
Wireless Sensor Network (WSN) applications today are hard to develop, often resulting in fragile systems with meager performance. We contribute to the coordinated development of WSN applications through the presentation of test and validation methods that allow for gradual reﬁnement throughout the whole development ﬂow. The methods described allow to systematically develop an application or part thereof while continuously and systematically integrating and testing the system under develop- ment. This approach is based on continuous integration with a special focus on networked embedded systems and their speciﬁc requirements concerning the testing architecture. Additionally a set of advanced metrics for the assessment of power traces are presented. The applicability of the tools and strategy presented is demonstrated using the showcase of a challenging environmental monitoring application. [pdf]
Matthias Woehrle, Jan Beutel, Lothar Thiele [WoehrleBT:08b] [published]
The System Development Lifecycle – Learning from a Sensornet Review
ETHZ-TIK Report Nr. 283
Wireless Sensor Networks (WSNs) have been promised a bright future and economic potential. Since the vision of ’Smart Dust’, the ﬁeld has largely progressed: Miniaturization, integration and advances in MEMS technology have signiﬁcantly stimulated research efforts. While there has been a lot of progress in theoretical work and system optimizations, actual deployments have been non- or underperforming. The realism of the deployments has exposed substantial and serious barriers to initial application ideas, to interdisciplinary research and thus to the adoption of WSN systems. By reviewing the past and present of WSN systems and their development, signiﬁcant conclusions can be drawn. This work presents a review starting from the ’Smart Dust’ vi- sion, describing WSN platforms and components. While assessing the current state of the WSN system development lifecycle, novel ideas for WSN research are discussed. The ideas and suggestions presented in this work serve as a basis for future discussions and support the advancement of WSNs. [pdf]
M. Woehrle, J. Beutel and L. Thiele [WoehrleBT:08] [published]
Wireless Sensor Networks Test and Validation
Chapter in Handbook of Networked Embedded Systems. CRC Press/Taylor & Francis
K. Aberer, G. Alonso, G. Barrenetxea, J. Beutel, J. Bovay, H. Dubois-Ferrière, D. Kossmann, M. Parlange, L. Thiele, M. Vetterli [AbererABBBDKPTV:07b] [published]
Notre environnement devient intelligent
Bulletin electrosuisse, 21/2007, Nov 07
M. Woehrle, C. Plessl, J. Beutel and L. Thiele [WoehrlePBT:07] [published]
Increasing the Reliability of Wireless Sensor Networks with a Distributed Testing Framework
4th Workshop on Embedded Networked Sensors (EmNets 2007), Cork, 25-26 June 07
Designing Wireless Sensor Networks (WSNs) has proven to be a slow, tedious and error-prone process due to the inherent intricacies of designing a distributed, wireless, and embedded system. Failed projects indicate that a systematic design approach accompanied by a test methodology is needed to develop WSN software conforming to all design requirements including robustness and reliability. In this paper, we propose the fundamentals of such a test methodology. We present essential features of a framework for testing a broad range of WSN applications. We demonstrate with a case study that our test methodology is a feasible approach by integrating a number of available design-tools for the TinyOS operating system. While we target TinyOS in the case study due to its widespread use in WSN applications, the proposed test methodology is general and not tailored to a single WSN platform or operating system. [pdf]
Andreas Meier, Jan Beutel, Roman Lim and Lothar Thiele [MeierBLT:07] [published]
Design of a High-Reliability Low Power Status Monitoring Protocol
4th International Conference on Networked Sensing Systems (INSS 2007), Braunschweig, 6-8 June 07
J. Beutel, M. Dyer, R. Lim, C. Plessl, M. Woehrle, M. Yücel and L. Thiele [BeutelDLPWYT:07] [published]
Automated Wireless Sensor Network Testing
4th International Conference on Networked Sensing Systems (INSS 2007), Braunschweig, 6-8 June 07
The design of distributed, wireless, and embedded system is a tedious and error-prone process. Experiences from previous real-world Wireless Sensor Network (WSN) deployments strongly indicate that it is vital to follow a systematic design approach to satisfy all design requirements including robustness and reliability. Such a design methodology needs to include an end-to-end testing methodology. The proposed framework for WSN testing allows to apply distributed unit testing concepts in the development process. The toolflow decreases test time and allows for monitoring the correctness of the implementation throughout the development process. [pdf]
Matthias Dyer, Jan Beutel, Lothar Thiele [DyerBT:07] [published]
S-XTC: A Signal-Strength Based Topology Control Algorithm for Sensor Networks
2nd International Workshop on Ad Hoc, Sensor and P2P Networks (AHSP2007), Sedona, 21-23 Mar 07
We present S-XTC, a topology control algorithm that uses the received signal strength indicator (RSSI) of the radio on wireless sensor nodes. The algorithm is based on XTC, a practical topology control algorithm that constructs a relative neighborhood graph. In contrast to the pure XTC our extensions add to the robustness and resilience against fluctuation in the RSSI values. While guaranteeing connectivity and a bounded node degree, network topologies are able to adapt to gradual changes in the network and it's environment. In this paper, we discuss the shortcomings of the previous algorithm and evaluate S-XTC by analytical proofs and simulation results. Furthermore, we have successfully implemented and tested S-XTC on the BTnode platform of which we discuss a case study and performance evaluation. [pdf]
Aberer, Karl; Alonso, Gustavo; Barrenetxea, Guillermo; Beutel, Jan; Bovay, Jacques; Dubois-Ferrière, Henri; Kossmann, Donald; Parlange, Marc; Thiele, Lothar; Vetterli, Martin [AbererABBBDKPTV:07] [published]
Infrastructures for a Smart Earth - The Swiss NCCR-MICS initiative
PIK - Praxis der Informationsverarbeitung und Kommunikation, vol. 30. Jahrgang, no Heft 1, p. 20-25
The Swiss National Competence Center for Research in Mobile Information and Communication Systems (NCCR MICS or MICS) is a research initiative sponsored by the Swiss National Science Foundation to promote long term research projects in areas of vital strategic importance for Switzerland. The NCCR MICS covers a wide spectrum of topics in the area of mobile information and communication systems, ranging from information theory related to ad-hoc sensor networks to business models for pervasive computing, including network and routing issues, software and application development, and actual deployments of sensor networks. In this paper, we briefly present MICS as a whole, describe a major application in the area of environmental monitoring and discuss in some detail the hardware and software platforms developed in the Center.
Matthias Dyer, Jan Beutel, Lothar Thiele, Thomas Kalt, Patrice Oehen, Kevin Martin, Philipp Blum [DyerBTKOMB:07] [published]
Deployment Support Network - A Toolkit for the Development of WSNs
4th European Conference on Wireless Sensor Networks (EWSN'07), Delft, 29-31 Jan 07
In this paper, we present the Deployment Support Network (DSN), a new methodology for developing and testing wireless sensor networks (WSN) in a realistic environment. With an additional wireless backbone network a deployed WSN can be observed, controlled, and reprogrammed completely over the air. The DSN provides visibility and control in a similar way as existing emulation testbeds, but overcomes the limitations of wired infrastructures. As a result, development and experiments can be conducted with realistic in- and outdoor deployments. The paper describes the new concept and methodology. Additionally, an architecture-independent implementation of the toolkit is presented, which has been used in an industrial case-study. [pdf]
Jan Beutel, Matthias Dyer, Mustafa Yuecel, Lothar Thiele [BeutelDYT:07] [published]
Development and Test with the Deployment-Support Network (poster/demo)
4th European Conference on Wireless Sensor Networks (EWSN'07), Delft, 29-31 Jan 07
The Deployment-Support Network (DSN) is a new, minimal invasive methodology for developing and testing wireless sensor networks (WSN) in a realistic environment. A device under test, e.g. a target sensor network is augmented with a redundant wireless backbone network and a second set of nodes to carry out the testing logic. Enabling a developer to test a live application scenario on the actual target hardware on-site in an actual deployment while maintaining correct operation of the system enables the coordinated development as well as reproducible and realistic profiling of the behavior of sensor network nodes. [pdf]
Jan Beutel [Beutel:06b] [published]
Metrics for Sensor Network Platforms
ACM Workshop on Real-World Wireless Sensor Networks (REALWSN'06), Uppsala, 19 June 06
Today, practically every research group and every larger sensor network project is using a platform for implementation work spanning a great variety of approaches and hardware architectures. This is primarily due to the large application space with differing requirements on resources and architectures each on the one hand and the goal to minimize the overhead on the other hand. With this large application domain for sensor networks, it is unclear how to match differing application requirements and platform characteristics to achieve optimal resource usage. This work establishes a methodology for the classification and interpretation of sensor network platforms and develops a set of metrics that can be used to compare and analyse the characteristics of different platforms. This is applied in a case study analyzing some state of the art sensor network platforms of the recent years. With this set of metrics and methodology we provide an intuitive and easy to use visual tool for sensor network system designers. [pdf]
J. Beutel [Beutel:06] [published]
Fast-Prototyping Using the BTnode Platform
Design, Automation and Test in Europe (DATE 2006), Munich, 6-10 Mar 2006
The BTnode platform is a versatile and flexible platform for functional prototyping of ad hoc and sensor networks. Based on an Atmel microcontroller, a Bluetooth radio and a low-power ISM band radio it offers ample resources to implement and test a broad range of algorithms and applications ranging from pure technology studies to complete application demonstrators. Accompanying the hardware is a suite of system software, application examples and tutorials as well as support for debugging, test, deployment and validation of wireless sensor network applications. We discuss aspects of system design, development and deployment based on our experience with real wireless sensor network experiments. We further discuss our approach of a deployment-support network that tries to close the gap between current proof-of-concept experiments to sustainable real-world sensor network solutions. [pdf]
Kay Römer, Holger Karl, Friedemann Mattern (Eds.) [RoemerKM:06] [published]
Wireless Sensor Networks (Proceedings of EWSN 2006, Third European Workshop on Wireless Sensor Networks)
LNCS No. 3868, Springer-Verlag, ISBN 3-540-32158-6, Zurich, 13-15 Feb 2006
This volume contains the proceedings of EWSN 2006, the third in a series of European workshops on Wireless Sensor Networks. The workshop took place at ETH Zurich from February 13 to 15, 2006. Its objective was to present, discuss, and explore the latest technical developments in the field of wireless sensor networks, as well as potential future directions. Wireless Sensor Networks has become an active and popular research area, which is witnessed by the 133 submissions we received from authors all over the world. The program committee chose 21 papers for inclusion in the workshop. It was a difficult choice, based on several hundred reviews produced by the program committee and many outside referees, where each paper was typically reviewed by three reviewers. [pdf]
Kay Römer, Holger Karl, Friedemann Mattern (Eds.) [RoemerKF:06b] [published]
Wireless Sensor Networks
Adjunct Proceedings of EWSN 2006, Third European Workshop on Wireless Sensor Networks, ETH Zurich / Dept. of Computer Science No. 507, 13 Feb 06
This volume contains the adjunct proceedings of EWSN 2006, the third in a series of European workshops on wireless sensor networks. The workshop took place at ETH Zurich from February 13 to 15, 2006. Its objective was to present, discuss, and explore the latest technical developments in the field of wireless sensor networks, as well as potential future directions. In addition to the demonstration and poster abstracts, this volume also contains the winning submissions of the Sentient Future Competitions and a set of highly commened submissions to this competition. [pdf]
L. Negri, J. Beutel and M. Dyer [NegriBD:06] [published]
The Power Consumption of Bluetooth Scatternets
IEEE Consumer Communications and Networking Conference (CCNC 2006), Las Vegas, 8-10 Jan 06
Jan Beutel [Beutel:05] [published]
Design and Deployment of Wireless Networked Embedded Systems
PhD Thesis, ETH Zurich, August 2005. (Prof L. Thiele)
The recent rise and widespread adoption of wireless networking technologies for mobile communication applications has sparked numerous visions of an ever more networked and interactive world. One such vision proposed in the late nineties are wireless sensor networks, where wireless communication and computing elements are combined with integrated sensors to enable tightly coupled interaction with the physical world. As a new application domain for wireless technology, key challenges here are (i) the limited resources of the highly integrated nodes that are to be leveraged by the amount of devices deployed and the collaboration between them, (ii) the tight coupling of application, nodes and the environment and (iii) the broad usage profile by systemsexperts and nonexpert users alike.
First mediumscale experiments and fieldtrials have reported that it is increasingly hard to design, develop, deploy, test and validate systems consisting of more than a handfull of nodes, especially when situated in a realworld environment. Prototypical applications are scarce, seldomly consisting of more than a few tens to a hundred nodes. Setting up large, heterogeneous, interactive and functional systems as forecast in the visions is no small task; currently more an art than a systematic engineering effort. Coordinated methods and tools for the design and deployment of wireless networked embedded systems are missing today.
With this work, we to contribute to the design and development of wireless networked embedded systems. The specific contributions are presented and discussed in the context of a vertical slice of the design space concerned and the relevant questions encountered:
• Functional and qualitative requirements of a location management service for wireless sensor networks based on measurements and simulation have been developed. We present one of the earliest algorithms for the distributed computation of node location.
• A novel platform for fastprototyping of wireless sensor networks has been developed. This platform has successfully served numerous researchers, among ourselves, as an underlying infrastructure for experimentation and education.
• The BTnode platform has been used to develop multihop networks and topology control mechanisms for Bluetooth scatternets. To our knowledge the experiments presented are the largest connected Bluetooth scatternets reported to date.
• The concept of a deploymentsupport network as a powerful tool for the development, deployment, test and validation of wireless sensor networks is presented in conjunction with experimental evidence on the feasibility of the approach.
[pdf]
Kay Römer, Friedemann Mattern [RoemerM:05] [published]
Towards a unified view on space and time in sensor networks
Computer Communications (Elsevier), Volume 28, Issue 13, 2 August 2005
Luca Negri, Jan Beutel, Matthias Dyer [NegriBD:05] [published]
The Power Consumption of Bluetooth Scatternets
TIK Report No. 220, ETH Zurich
Low power has become a primary concern in the field of ad hoc and personal area networks. As manufacturers start endowing their designs with scatternet support, Bluetooth is emerging as a key enabling technology. Although this is driving research on Bluetooth power optimization, most proposals in the literature are based on either over simplified, fully theoretical, or old and inadequate power models. We present a real world power model of a Bluetooth device supporting scatternets and sniff mode, and validate it experimentally for the BTnode, an ad hoc and sensor network prototyping platform developed at ETH Zurich. Whilst guaranteeing a low computational complexity, the model achieves a 4% RMS error. [pdf]
Jan Beutel, Philipp Blum, Matthias Dyer, Clemens Moser [BeutelBDM:05] [published]
BTnode Programming - An introduction to BTnut Applications
Manual, TIK, ETH Zurich, 13 May 05
[pdf]
Jan Beutel [Beutel:05b] [published]
Robust Topology Formation using BTnodes
Computer Communications, Elsevier B.V., Amsterdam, The Netherlands, pages 1523-1530, vol. 28, no. 13, August 2005.
Research of the past years has brought about many new developments and proposals for wireless sensor networks, mostly in the areas of algorithms and theory, backed up by extensive simulation work. In order to fully understand the complexity of these issues from a system perspective we will highlight the idiosyncracies of multi-hop networking implemented on real devices. The BTnode is an autonomous wireless communication and computing platform based on a Bluetooth radio and a microcontroller aimed at fast prototyping and research in mobile computing. The TreeNet example implements a self-healing, distributed Bluetooth Scatternet formation on the BTnode platform.We will discuss our example implementation including devices used, prerequisites, limitations, algorithmic ideas and implementation results.
Jan Beutel, Matthias Dyer, Lennart Meier, Lothar Thiele [BeutelDMT:05] [published]
Scalable Topology Control for Deployment-Support Networks
4th International Conference on Information Processing in Sensor Networks (IPSN'05), UCLA, 25-27 Apr 05
Deployment-support networks (DSNs) have been proposed as a novel tool for the development, test, deployment, and validation of wireless sensor networks. They are expected to enhance scalability and flexibility in deployment by eliminating cable connections. In this paper, we describe our implementation of a DSN, giving details on the algorithms for topology control and maintenance. We provide various measurements in DSNs spanning up to 71 BTnode~rev3 devices, featuring the largest Bluetooth scatternet reported to date. We also discuss our experience gained in the development and experimentation. Our results strongly suggest that our implementation scales well to a large number of nodes. [pdf]
Matthias Dyer, Jan Beutel, Lennart Meier [DyerBM:05] [published]
Deployment Support for Wireless Sensor Networks (short paper)
4. GI/ITG KuVS Fachgespräch "Drahtlose Sensornetze", Zürich, 23-24 Mar 2005
We present the concept of Deployment-Support Networks(DSN), a tool for the coordinated deployment of distributed sensor networks. A DSN supports the development, debugging, monitoring, and testing of sensor–network algorithms and applications. With our implementation of the DSN on the BTnode rev3 platform, we have proven that the concept scales well to a large number of nodes. [pdf]
Jan Beutel, Attila Dogan [BeutelD:05] [published]
Using TinyOS on BTnodes
4. GI/ITG KuVS Fachgespräch "Drahtlose Sensornetze", Zürich, 23-24 Mar 2005
TinyOS has been very popular for wireless sensor network applications and is a de facto standard today. This study compares the architectural differences between the BTnode and Mote platforms and explains how to implement TinyOS applications on the BTnodes. In addition this enables to interface between networks of Mote and BTnode devices. [pdf]
Kay Römer, Friedemann Mattern [RoemerM:04] [published]
The Design Space of Wireless Sensor Networks
IEEE Wireless Communications, Vol. 11, No. 6, pages 54-61, Dec 2004
In the recent past, wireless sensor networks have found their way into a wide variety of applications and systems with vastly varying requirements and characteristics. As a consequence, it is becoming increasingly difficult to discuss typical requirements regarding hardware issues and software support. This is particularly problematic in a multidisciplinary research area such as wireless sensor networks, where close collaboration between users, application domain experts, hardware designers, and software developers is needed to implement efficient systems. In this paper we discuss the consequences of this fact with regard to the design space of wireless sensor networks by considering its various dimensions. We justify our view by demonstrating that specific existing applications occupy different points in the design space. [pdf]
Jan Beutel, Matthias Dyer, Martin Hinz, Lennart Meier, Matthias Ringwald [BeutelDHMR:04] [published]
Next-Generation Prototyping of Sensor Networks (short paper)
Second International Conference on Embedded Networked Sensor Systems (Sensys 2004), Baltimore, 3-5 Nov 04
Large-scale deployment of sensor networks is more and more becoming an issue to researchers and industry alike. The recently revised BTnode architecture provides two wireless radios and facilitates the interconnection of heterogeneous devices. Apart from offering interesting new opportunities in using multi-frontend devices in sensor-network research, this architecture is optimally suited for deployment-support networks as introduced in the following. [pdf]
Jan Beutel, Matthias Dyer, Lennart Meier, Matthias Ringwald, Lothar Thiele [BeutelDMRT:04] [published]
Next-Generation Deployment Support for Sensor Networks
TIK Report No. 207, ETH Zurich
We present a new methodology for the development, test, deployment, and validation of wireless sensor networks. Our approach is a robust, wireless cable replacement offering reliable and transparent connections to arbitrary WSN target devices. Compared to traditional serial-cable approaches, this results in enhanced scalability and flexibility with respect to node location, density, and mobility. This makes the coordinated deployment of WSNs possible. We describe the operation of this novel tool and discuss an exemplary implementation on the BTnode platform. [pdf]
Jan Beutel, Matthias Dyer, Lennart Meier, Lothar Thiele [BeutelDMT:04] [published]
Scalable Topology Control for Deployment-Support Networks
TIK Report No. 208, ETH Zurich
Deployment-support networks (DSNs) have been proposed as a novel tool for the development, test, deployment, and validation of wireless sensor networks. They are expected to enhance scalability and flexibility in deployment by eliminating cable connections. In this paper, we describe our implementation of a DSN, giving details on the algorithms for topology control and maintenance. We provide various measurements in DSNs spanning up to 71 BTnode~rev3 devices, featuring the largest Bluetooth scatternet reported to date. We also discuss our experience gained in the development and experimentation. Our results strongly suggest that our implementation scales well to a large number of nodes. [pdf]
Kay Römer, Thomas Schoch, Friedemann Mattern, Thomas Dübendorfer [RoemerSMD:04] [published]
Smart identification frameworks for ubiquitous computing applications
Wireless Networks (Springer), Vol. 10, Issue 6, Nov 04
We present our results of the conceptual design and the implementation of ubiquitous computing applications using smart identification technologies. First, we describe such technologies and their potential application areas, then give an overview of some of the applications we have developed. Based on the experience we have gained from developing these systems, we point out design concepts that we have found useful for structuring and implementing such applications. Building upon these concepts, we have created two frameworks based on Jini (i.e., distributed Java objects) and Web Services to support the development of ubiquitous computing applications that make use of smart identification technology. We describe our prototype frameworks, discuss the underlying concepts and present some lessons learned. [pdf]
Urs Anliker, Jan Beutel, Matthias Dyer, Rolf Enzler, Paul Lukowicz, Lothar Thiele, Gerhard Tröster [AnlikerBDELTT:04] [published]
A Systematic Approach to the Design of Distributed Wearable Systems
IEEE Transactions on Computers, Volume: 53, Issue: 8, pages 1017-1033, Aug 2004
Wearable computing has recently gained much popularity as an ambitious vision for future mobile systems. It targets intelligent, environment aware systems unobtrusively embedded into the mobile environments of the human body. With the combination of complex processing requirements, the necessity of placing sensors and input/output modules at different locations on the users body, and stringent limits on size, weight and battery capacity the design of such systems is an inherently difficult problem.
This paper targets methods for the systematic design and quantitative analysis of wearable architectures. It focuses on the tradeoffs between different assignments of computation and communication resources to individual modules. We first present a model that combines the various factors influencing the design of a wearable system into formal cost metrics. In particular, we show how to consistently incorporate specific wearable factors such as device placement requirements, ergonomics, and dynamic load profiles into the model. We then present efficient and precise estimation algorithms for the evaluation of different architectures with respect to our cost metrics. These algorithms are integrated into an automatic design space exploration environment that evolves a set of Pareto-optimal wearable architectures. Finally, we describe first quantitative results showing the tradeoffs between different architectures for a given wearable scenario. [pdf]
Jan Beutel [Beutel:04] [published]
Location Management in Wireless Sensor Networks
In Handbook of Sensor Networks: Compact Wireless and Wired Sensing Systems, CRC Press, July 2004.
Starting out from Weisers visionary standpoint in 1991 many technologies in the mobile and ad hoc arena have evolved over the past years. Advances in wireless communications and micro systems integration are enabling ever tighter and finer grained integration of electronic communication devices into the physical world. Wireless Sensor Networks (WSNs) are at one extreme of the design space, embracing such paradigm as immense scale, self-containment, selforganization, deep embedment and therefore also limited access of and to the devices involved. In this new regime Moores Law is paving way for two directions of thrust, (i) the traditional view where devices are getting ever more powerful while maintaining their size and (ii) an unprecedented possibility to shrink whole functional systems into tiny scales never anticipated before, like e. g. Smart-Dust.
Under the main prerequisite of WSNs, namely their stringent energy budget, the first classical WSN approaches have focused on efficient, symmetrical ad hoc network configurations, meaning that the devices at both ends of a communication channel were essentially of the same architecture. These early prototypical sensor nodes are now constantly maturing and shift the focus from the fabrication of the single device towards the management of large, heterogeneous systems and architectures and the services embedded into these. This shift in paradigm brings about a second requirement; robustness. In order to be able to scale to large networks consisting of the most heterogeneous clustered devices, mechanisms and services need to be tailored specifically for interoperability and the optimal management of the limited resources available in such nodes.
Location both in time and space has been identified as a key technology for the successful deployment and operation of context-aware sensor network services.
The benefit of location technology isn t limited to the subscriber of a network or to network operations like geographic routing but will enable every wireless enabled device to become a meaningful instrumentation probe. Today, technicians gather distributed environmental infor-mation by driving to specific sample sites and making measurements, a time-consuming and inefficient solution or by installing costly fixed infrastructure in often inaccessible target areas. Sensor data without a complete set of coordinates (this is a time stamp t, and (x; y; z) location) is next to useless. While the Global Positioning System (GPS) offers a solution for localization in an outdoor environment, no such option exists for an indoor setting.
In this chapter we want to give an overview of the issues connected with location management in WSNs. Apart from some general observations applicable to many wireless communication systems we are interested in the peculiarities of the WSN case, simplicity, robustness and energy awareness.
Jan Beutel, Oliver Kasten, Friedemann Mattern, Kay Römer, Frank Siegemund, Lothar Thiele [BeutelKMRST:04] [published]
Prototyping Wireless Sensor Network Applications with BTnodes
1st IEEE European Workshop on Wireless Sensor Networks (EWSN 2004), Berlin, 19-21 Jan 2004
We present a hardware and software platform for rapid prototyping of augmented sensor network systems, which may be temporarily connected to a backend infrastructure for data storage and user interaction, and which may also make use of actuators or devices with rich computing resources that perform complex signal processing tasks. The use of Bluetooth as the wireless networking technology provides us with a rich palette of Bluetooth-enabled commodity devices, which can be used as actuators, infrastructure gateways, or user interfaces. Our platform consists of a Bluetooth-based sensor node hardware (the BTnode), a portable operating system component, and a set of system services. This paper gives a detailed motivation of our platform and a description of the platform components. Though using Bluetooth in wireless sensor networks may seem counterintuitive at first, we argue that the BTnode platform is indeed well suited for prototyping applications in this domain. As a proof of concept, we describe two prototype applications that have been realized using the BTnodes. [pdf]
Jan Beutel, Oliver Kasten, Matthias Ringwald [BeutelKR:03] [published]
BTnodes - A Distributed Platform for Sensor Nodes
ACM SenSys, Los Angeles, 5-7 Nov 2003
We motivate a prototyping platform for ad hoc networking research showing some requirements and constraints. The architecture of the BTnodes, each of which can store information, compute and communicate, is explained in conjunction with some demo applications that have been implemented. Important requirements and design trade-offs to be able to support multiple, compatible communication interfaces, to handle limited resources, for power-aware operation and for efficient testbed deployment are discussed. [pdf]
Christian Plessl, Rolf Enzler, Herbert Walder, Jan Beutel, Marco Platzner, Lothar Thiele, Gerhard Tröster [PlesslEWBPTT:03] [published]
The Case for Reconfigurable Hardware in Wearable Computing
Personal and Ubiquitous Computing, Springer-Verlag, Vol. 7, No. 5, pages 299-308, Oct 2003
Wearable computers are embedded into the mobile environment of their users. A design challenge for wearable systems is to combine the high performance required for tasks such as video decoding with the low energy consumption required to maximise battery runtimes and the flexibility demanded by the dynamics of the environment and the applications. In this paper, we demonstrate that reconfigurable hardware technology is able to answer this challenge. We present the concept and the prototype implementation of an autonomous wearable unit with reconfigurable modules (WURM). We discuss experiments that show the uses of reconfigurable hardware in WURM: ASICs-on-demand and adaptive interfaces. Finally, we present an experiment with an operating system layer for WURM. [pdf]
Jan Beutel, Oliver Kasten, Matthias Ringwald [BeutelKR:03b] [published]
BTnode - Applications and Architecture Compared
TKN Technical Report TKN-03-012, 1. GI/ITG KuVS Fachgespraech Sensornetze, TU Berlin, July 2003
We motivate a prototyping platform for ad-hoc networking research showing some requirements and constraints. The architecture of the BTnodes, each of which can store information, compute and communicate, is explained in conjunction with some demo applications that have been implemented. Important requirements and design trade-offs to be able to support multiple, compatible communication interfaces, to handle limited resources, for power-aware operation and for e cient testbed deployment are discussed. [pdf]
Jan Beutel, Oliver Kasten, Matthias Ringwald, Frank Siegemund, Lothar Thiele [BeutelKRST:03] [published]
Bluetooth Smart Nodes for Ad-hoc Networks
TIK Report Nr. 167, ETHZ, 2003
In this paper, we describe the deployment of large mobile ad-hoc networks using standard components. The design, implementation and operation of distributed, self-organized, large scale, mobile communication and information systems poses many interesting research problems. While a lot of questions devoted to algorithmic and architectural aspects are already being pursued, few have actually deployed such systems to the extents envisioned. We present Bluetooth Smart Nodes, each of which can store information, compute and communicate using standard wireless interfaces on a limited resource platform. These wireless enabled small devices can interact in a heterogeneous environment consisting of different types of networking nodes as well as with other wireless enabled appliances. Important requirements and design trade-offs to be able to support multiple communication interfaces, handle limited resources, power aware operation and efficient testbed deployment are discussed. The BTnodes are integrated into our MANET application and networking framework. Demo applications give an insight into usage scenarios envisioned for future architectural explorations. [pdf]
Kay Römer, Friedemann Mattern, Thomas Dübendorfer, Jürg Senn [RoemerMDS:03] [published]
Smart Identification Frameworks for Ubiquitous Computing Applications
PerCom 2003 (IEEE International Conference on Pervasive Computing and Communications), March 2003
In this paper, we present our results in the conceptual design and the implementation of ubiquitous computing applications using smart identification technologies. First, we describe such technologies and their potential application areas, followed by an overview of some applications we have developed. Based on the experiences we gained from the development of these systems, we point out design concepts that we find useful for structuring and implementing such applications. Building upon these concepts, we have created two frameworks based on distributed Java objects and Web Services to support the development of ubiquitous computing applications that make use of smart identification technology. We describe our prototype frameworks, discuss the underlying concepts and present some lessons learned. [pdf]
Friedemann Mattern, Peter Sturm [MatternS:03] [published]
From Distributed Systems to Ubiquitous Computing - The State of the Art, Trends, and Prospects of Future Networked Systems
KIVS 2003 (Kommunikation in Verteilten Systemen), Leipzig, 26-28 Feb 2003
We summarize trends in communication paradigms for networked systems, mention well-established as well as innovative software infrastructures for distributed systems (such as COM+, CORBA, .NET and Jini), and give an overview of application domains such as grid computing, peer-to-peer computing, and mobile agents. We then discuss issues in spontaneous networking, and we explain the vision of Ubiquitous Computing and its intriguing prospects. [pdf]
Kay Römer, Oliver Kasten, Friedemann Mattern [RoemerKM:02] [published]
Middleware Challenges for Wireless Sensor Networks
ACM SIGMOBILE Mobile Computing and Communication Review (MC2R), Vol. 6, Issue 4 (Oct 2002)
Middleware for sensor networks aims to support the development of applications for large populations of wirelessly connected nodes capable of computation, communication, and sensing. We examine the purpose, functionality, and characteristics of such middleware. [pdf]
Christian Plessl, Rolf Enzler, Herbert Walder, Jan Beutel, Marco Platzner, Lothar Thiele [PlesslEWBPT:02] [published]
Reconfigurable Hardware in Wearable Computing Nodes
IEEE 6th International Symposium on Wearable Computers (ISWC2002) (Seattle, 9-12 June 2002)
Wearable computers are embedded into the mobile environment of the human body. A design challenge for wearable systems is to combine the high performance required for tasks such as video decoding with low energy consumption required to maximize battery runtimes and the flexibility demanded by the dynamics of the environment and the applications.
In this paper, we demonstrate that reconfigurable hardware technology is able to answer this challenge. We present the concept and the prototype implementation of an autonomous wearable unit with reconfigurable modules (WURM). We discuss two experiments that show the uses of reconfigurable hardware in WURM: ASICs-on-demand and adaptive interfaces. Finally, we develop and evaluate task placement techniques used in the operating system layer of WURM. [pdf]
Kay Römer, Friedemann Mattern, Thomas Dübendorfer, Jürg Senn [RoemerMDS:02] [published]
Infrastructure for Virtual Counterparts of Real World Objects
Technical Report ETHZ, 2002
Based on our experience with a collection of prototypical ubiquitous computing applications, we have identified a number of common basic tasks which led to the design of some simple mechanisms that we have found useful for structuring and implementing such applications. Building upon these mechanisms, we have created a software infrastructure to support the development of tag-based ubiquitous computing applications. Our framework is targeted at applications where objects are tagged with Radio Frequency Identification tags (RFIDs), a simple but powerful means of bridging the gap between the physical and the virtual world. A central feature of our infrastructure are virtual counterparts. They form augmented representations of real world objects and encapsulate their state and behavior. This paper presents the rationale, design, and implementation of our prototype infrastructure. [pdf]

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