February 13-15, 2006, ETH Zurich

Preliminary Program

Monday, February 13
8:00 - 9:00	Registration
9:00 - 10:30	Tutorial 1: Data Management in Sensor Networks Samuel Madden (MIT, US).	Tutorial 2: Algorithms for Wireless Sensor Networks Roger Wattenhofer (ETH Zurich, CH).
10:30 - 11:00	Break
11:00 - 12:30	Tutorial 1 contd.	Tutorial 2 contd.
12:30 - 14:00	Registration
14:00 - 14:15	Workshop Opening
14:15 - 15:00	Keynote (Chair: Friedemann Mattern, ETH Zurich) Unleashing the Power of Wireless Networks through Information Sharing in the Sensor Internet Karl Aberer (Director NCCR-MICS, EPFL, CH)
15:00 - 15:30	Break
15:30 - 17:00	Session 1: Query Systems (Chair: Wolfgang Kellerer, DoCoMo Eurolabs) Semantic Streams: a Framework for the Composable Semantic Interpretation of Sensor Data Kamin Whitehouse (UC Berkeley, US), Jie Liu, Feng Zhao (Microsoft Research, US). PAQ: Time Series Forecasting for Approximate Query Answering in Sensor Networks Daniela Tulone (University of Pisa, IT), Samuel Madden (MIT, US). Proactive Context-Aware Sensor Networks Sungjin Ahn, Daeyoung Kim (Information and Communications University, KR).
17:00 - 17:30	Break
17:30 - 19:00	Session 2: Sensor Network Services (Chair: Dirk Westhoff, NEC) Constraint-based Distance Estimation in Ad-hoc Wireless Sensor Networks Urs Bischoff, Martin Strohbach, Mike Hazas, Gerd Kortuem (Lancaster University, UK). Sensor Density for Complete Information Coverage in Wireless Sensor Networks Bang Wang, Chua Kee Chiang, Vikram Srinivasan, Wei Wang (National University of Singapore, SG). Hierarchical Grid-Based Pairwise Key Predistribution Scheme for Wireless Sensor Networks Abedelaziz Mohaisen, Daehun Nyang (Inha University, KR).
19:00 - 21:00	Poster/Demo Reception

Tuesday, February 14
9:00 - 10:30	Session 3: Routing (Chair: Torsten Braun, Univ. of Berne) Generic Routing Metric and Policies for WSNs Olga Saukh, Pedro Marron, Andreas Lachenmann, Matthias Gauger, Daniel Minder, Kurt Rothermel (University of Stuttgart, DE). On the Scalability of Routing Integrated Time Synchronization Janos Sallai, Branislav Kusy, Akos Ledeczi (Vanderbilt University, US), Prabal Dutta (UC Berkeley, US). Distributed Dynamic Shared Tree for Minimum Energy Data Aggregation of Multiple Mobile Sinks in Wireless Sensor Networks Kwang-il Hwang, Jeongsik In, Doo-seop Eom (Korea University, KR).
10:30 - 11:00	Break
11:00 - 12:30	Session 4: Localization (Chair: Paul Havinga, Univ. of Twente) Constrained Tracking on a Road Network Michal Piorkowski, Matthias Grossglauser (EPFL, CH). Range-Based Localization in Mobile Sensor Networks Bram Dil, Stefan Dulman, Paul Havinga (University of Twente, NL). Hierarchical Localization Algorithm based on Inverse Delaunay Tessellation Masayuki Saeki, Kok-Hou Khor, Tomohiro Kousaka, Junya Inoue, Hiroaki Honda, Kenji Oguni (University of Tokyo, JP).
12:30 - 14:00	Lunch
14:00 - 15:30	Session 5: Platforms and Development (Chair: Amy Murphy, Univ. of Lugano) Power Management for Bluetooth Sensor Networks Luca Negri (Politecnico di Milano, IT), Lothar Thiele (ETH Zurich, CH). FlexCup: A Flexible and Efficient Code Update Mechanism for Sensor Networks Pedro Marron, Matthias Gauger, Andreas Lachenmann, Daniel Minder, Olga Saukh, Kurt Rothermel (University of Stuttgart, DE). Transforming Protocol Specifications for Wireless Sensor Networks into Efficient Embedded System Implementations Gerald Wagenknecht, Daniel Dietterle, Jean-Pierre Ebert, Rolf Kraemer (IHP Microelectronics, DE).
15:30 - 16:00	Break
16:00 - 18:00	Special Session: European WSN Research Initiatives (Chairs: Rolf Riemenschneider, European Commission and Adam Wolisz, TU Berlin) Overview of WSN Research in FP6 and Perspectives in FP7 Rolf Riemenschneider (European Commission, BE). Collaborative Business Items - Integrating Wireless Sensor Networks into Business Environments Stephan Haller (SAP, Germany). FP6/BMBF: eCube/eGrain Juergen Wolf (Fraunhofer IZM, Germany). Compositional Wireless Sensor Networks Peter van der Stok (Philips Research, NL). Enhanced Design Solutions for Wireless Sensor Networks applied to Distributed Environmental Monitoring Gianfranco Manes (Univ. of Florence, IT). FP6: RUNES IP Petri Maehoenen (RWTH Aachen, DE). Introduction to FP6 Network of Excellence CRUISE - Creating Ubiquitous Intelligent Sensing Environments Ramjee Prasad (Aalborg Univ., DK). Introduction to FP6 Integrated Project e-SENSE: Capturing Ambient Intelligence for Mobile Communications through Wireless Sensor Networks Laurent Herault (CEA-LETI, FR).
18:00 - 19:30	Guided Tour through ETH
19:30 - 22:30	Workshop Dinner

Wednesday, February 15
9:00 - 10:30	Session 6: Medium Access Control (Chair: Koen Langendoen, TU Delft) Extending Network Lifetime Using an Automatically Tuned Energy-Aware MAC Protocol Rebecca Braynard, Adam Silberstein, Carla Ellis (Duke University, US). Sift: A MAC Protocol for Event-Driven Wireless Sensor Networks Kyle Jamieson, Hari Balakrishnan (MIT, US), Y. C. Tay (National Univ. of Singapore, SG). f-MAC: A Deterministic Media Access Control Protocol Without Time Synchronization Utz Roedig, Andre Barroso, Cormac Sreenan (University College Cork, IE).
10:30 - 11:00	Special Session: Sentient Future Competition (Chair: Adam Wolisz, TU Berlin) Introduction George Coulouris (Cambridge Univ., UK). Awards Heinrich Arnold, Christian Wolf (Deutsche Telekom T-Labs, DE). 1st Prize: Large Scale Body Sensing for Infectious Disease Control Markus Endler (PUC-Rio, BR). 2nd Prize: BIN IT! The Intelligent Waste Management System David Schoch (Univ. Zurich, CH), Matthias Sala (ETH Zurich, CH). 3rd Prize: Vision of Congestion-Free Road Traffic and Cooperating Objects Ricardo Morla (INESC Porto, PT).
11:00 - 11:30	Break and SFC Posters
11:30 - 13:00	Session 7: Measurements (Chair: Jean-Pierre Ebert, IHP Microelectronics) A Measurement-based Analysis of the Interaction between Network Layers in TinyOS Umberto Malesci (Fluidmesh Networks Inc., US), Samuel Madden (MIT, US). Results of Bit Error Measurements with Sensor Nodes and Casuistic Consequences for Design of Energy-Efficient Error Control Schemes Andreas Willig (TU Berlin, DE), Robert Mitschke (Hasso-Plattner-Institute, DE). An Empirical Characterization of Radio Signal Strength Variability in 3-D IEEE 802.15.4 Networks using Monopole Antennas Dimitrios Lymberopoulos, Quentin Linsey, Andreas Savvides (Yale University, US).
13:00	Workshop Closing
13:00 - 14:30	Lunch
Workshop End

Rooms

Registration desk, breaks, poster reception:	ETZ, E floor, foyer
Tutorial 1:	ETZ, lecture hall E6
Tutorial 2:	ETZ, lecture hall E8
Plenary sessions:	ETZ, lecture hall E1
Lunch:	ETZ, Gloria bar
Guided tour:	begin: ETZ E1, end: Dozentenfoyer
Workshop dinner:	main building, Dozentenfoyer ("J" floor)
Wisents meeting:	ETZ, room E81

Tutorials

Tutorial 1: Data Management in Sensor Networks
Samuel Madden
MIT, USA

Abstract. This tutorial will cover recent topics in data management for sensor networks, focusing in particular on high level systems and languages for querying stored and streaming data in such networks. We will begin with a survey of language proposals, including TinyDB, Cougar, Regions, and other more recent work, and will then examine a range of implementation issues that arise in such systems, including issues related to power efficiency, time synchronization, data collection and dissemination, fault-tolerance, and state management. After attending the tutorial, audience members should have a good understanding of the various systems in this space as well as an awareness of the technical issues that make building such systems difficult.

Tutorial 2: Algorithms for Wireless Sensor Networks
Roger Wattenhofer
ETH Zurich, Switzerland

Abstract. In recent years, there has been a growing interest by theoreticians in wireless multi-hop sensor networks. In this tutorial we discuss some of the latest pearls of algorithmic sensor networking research. In particular, we investigate the link layer (e.g., MAC, topology control, clustering), the network layer (e.g., data gathering, routing), and services for sensor networks (e.g., positioning, time synchronization). We put a special focus on distributed protocols with practical appeal and on theoretical (im)possibility results "every sensor network engineer should know."

Invited Talk

Unleashing the Power of Wireless Networks through Information Sharing in the Sensor Internet
Karl Aberer, Director of the National Competence Centre in Research for Mobile Information and Communication Systems (NCCR-MICS)
EPFL, Switzerland

Abstract. We provide in this presentation in a first part an overview of the research activities of the Swiss National Competence Centre in Research for Mobile Information and Communication Systems (NCCR-MICS) in the area of self-organizing, wireless networks. In the second part we present specific MICS research results from our research group on managing information generated in such networks using self-organizing, logical overlay networks.

Recent advances in wireless communication enable the embedding of sensing and actuation technology into our physical environment at an unprecedented large scale and fine granularity. We show exemplary, recent theoretical advances and systems developments on self-organizing, wireless sensor networks and mobile ad-hoc networks achieved in MICS. They provide evidence for the comprehensive scope and high degree of interdisciplinarity required in this area of research. We illustrate the deployment of the resulting technologies in real-world applications. An application class we focus in MICS in particular concerns the monitoring of various typical physical phenomena in the Swiss environment, such as watershed, permafrost and avalanches.

In the long term, the increasing deployment and application of wireless networks beyond specialized, isolated applications will lead to the production of massive amounts of sensor data requiring further processing support and proper interpretation of data. We argue that self-organizing, logical overlay networks for resource and information sharing will play an important role for achieving this task. Structured overlay networks will be used to support scalable processing of data streams. Semantic overlay networks will be used to overcome heterogeneity in information representation. Finally, social overlay networks will be used to form agreements on meaning and utility of data. We illustrate these developments from our ongoing research: Global Sensor Network, a light weight implementation of an overlay network for sensor data stream sharing, PicShark, a peer-to-peer image sharing system with support for automated generation and sharing of image annotations, and Semantic Gossiping, a social mechanism based on belief propagation to reconcile heterogeneous annotation schemes.

As a result of these developments we envision the Internet to develop into a Sensor Internet in which physical reality, information technology and human activity become increasingly intertwined into one common complex system for better understanding and more easily mastering the environment we live in.

European Projects Session

In this session, prominent European research initiatives related to wireless sensor networks will be introduced by project representatives and by the European Commission.

Overview of WSN Research in FP6 and Perspectives in FP7
Rolf Riemenschneider (European Commission, BE).

Abstract. Wireless sensor networks have become a hot issue in research, and significant progress has been achieved in the past few years. In particular in 2005, the topic gained lot of momentum and became increasingly attractive for industry paving the way for new applications of sensor networks which go well beyond traditional sensor applications.

The talk will focus on research initiatives and research projects recently launched in the 6th European Framework Programme for the Information Society of the European Commission. References will be made to Embedded Systems portfolio after Call 5 and to other related strategic objectives of the IST work programme 2005/2006. Special attention will be paid to the structural prospects of FP7 and perspectives of the research domain.

Collaborative Business Items - Integrating Wireless Sensor Networks into Business Environments
Stephan Haller (SAP, Germany).

Abstract. The CoBIs project aims to integrate wireless sensor network technology and enterprise applications. Executing business logic - for example, to monitor the environment - directly at sensor nodes attached to physical items provides many benefits. In particular, changes in the environment are detected immediately and local decision-making reduces reaction time significantly. Furthermore, the backend enterprise systems are only notified about exceptions which makes the whole solution more scalable. Distributing business logic to the network however raises other difficulties. The CoBIs project tackles these using a service-oriented architecture that allows deployment of business logic to sensor nodes as composable services. The technology developed will be trialed in real-world conditions at a BP chemical plant where the storage of hazardous chemicals is monitored.

FP6/BMBF: eCube/eGrain
Juergen Wolf (Fraunhofer IZM, Germany).

Abstract. TBA

Compositional Wireless Sensor Networks
Peter van der Stok (Philips Research, NL).

Abstract. Billions of tiny, networked, wireless sensors are expected to assist people during their social, private, and professional activities. At least multiple thousands of applications are expected to exist on top of the wireless sensor network. Providing a unique, new software infrastructure for each of these applications will make the deployment of the networks prohibitively expensive. One of the possibilities to reduce costs is the provision of composable off-the shelf hardware and software modules which cover a large part of the infrastructure needs. Much of this work is realized within the context of European and national projects.

Enhanced Design Solutions for Wireless Sensor Networks applied to Distributed Environmental Monitoring
Gianfranco Manes (Univ. of Florence, IT).

Abstract. In the recent years, the availability of on-field monitoring became a key issue for the assessment of environmental processes. The adoption of Wireless Sensor Networks (WSN) for wide area environmental monitoring is currently considered one of the most challenging application scenarios for this emerging technology. The application of WSN technology represents a significant advance over traditional invasive methods of monitoring: Equipping natural spaces with networked microsensors might enable long-term data collection with enhanced accurateness. Further, the communication capabilities allow nodes to cooperate in performing more complex tasks, like statistical sampling or data aggregation, not feasible with a point-to- point telemetry. Finally, the computing and networking capabilities permits both the reprogramming and even the self-reconfiguring of the whole system.

The talk will present an overall solution focusing both on node, network and remote user interface issues. The proposed platform is finally applied to a realistic user defined scenario oriented to agro-food production phase monitoring within GoodFood Integrated Project. The results of the validation phase presented highlight remarkable advantages both in terms of cost and complexity reduction and experienced QoS enhancement as well and, consequently, validating the WSN technology adoption.

FP6: RUNES IP
Petri Maehoenen (RWTH Aachen, DE).

Abstract. TBA

Introduction to FP6 Network of Excellence CRUISE - Creating Ubiquitous Intelligent Sensing Environments
Ramjee Prasad (Aalborg Univ., DK).

Abstract. The recent developments in the research and the technology have brought visibility for the wireless sensor networks as one of the key enabling technologies in the next 10 years. Ubiquitous Intelligent Sensing Environments have promising future in supporting the everyday life of the European citizens, bringing important social benefits for each person and for the society as a whole. Taking into account the current fragmentation in the research in this field, CRUISE NoE intends to be a focal point in the planning and coordination of research on communication and application aspects of wireless sensor networking in Europe. To make a significant contribution to coordination and effectiveness of research, the consortium will evaluate, update and communicate the State-of-the-Art in wireless sensor networking to the technical community. It will distil a path from current technological status to a long term vision by defining the intermediate steps in a vision-based roadmap. In the joint research work CRUISE partners will establish a framework of common tools and methodologies to accelerate the research process and build sustainable collaboration links. The project will organize and participate in events which create awareness of the immense benefits of WSN, promote research on sensor networking and the integration of different European research initiatives.

Introduction to FP6 Integrated Project e-SENSE: Capturing Ambient Intelligence for Mobile Communications through Wireless Sensor Networks
Laurant Herault (CEA-LETI, FR).

Abstract. This talk will introduce a new integrated project: e-SENSE. Its main objective is to contribute to the evolution and definition of the future Ambient Intelligent Mobile Systems beyond 3G by integrating ubiquitous Wireless Sensor Networks in B3G mobile systems. WSN will capture the ambient intelligence surrounding mobile users. Capturing, classifying, filtering and sensing situation and context through phenomena and signals from the physical environment will support and significantly enhance and enrich personal, family and community-focused mobile applications and services as well as wireless communication systems.

e-SENSE develops a system concept and architecture to collaboratively capture a user's context, pre-process it into meaningful data to be input to a user's (individual, family, community) profile to enable context-enabled applications and services to a user at the right time.

Sentient Future Competition

The Sentient Future Competition attempts to explore innovative applications of wireless sensor networks in ten years from now. In this session awards will be given to the winners by representatives of Deutsche Telekom T-Labs, the sponsor of the competiton. Also, the winners will shortly present their visions. In the break following the session, the winners and additional highly ranked submissions will be presented in a short poster session.

1st Prize: Large Scale Body Sensing for Infectious Disease Control
M. Endler (PUC-Rio, BR).

2nd Prize: BIN IT! The Intelligent Waste Management System
D. Schoch (Univ. Zurich, CH), M. Sala (ETH Zurich, CH).

3rd Prize: Vision of Congestion-Free Road Traffic and Cooperating Objects
R. Morla (INESC Porto, PT).

Ambient Intelligence by Collaborative Eye Tracking
E. Yoneki (Cambridge Univ., UK).

A Day in the Life of the not too Distant Future
P. R. De Caux (Xposition, UK).

Embedded WiSeNts & Agnostic Algorithms of Creation
P. Bairaktaris (City Univ., UK).

Father in Womb
T. Camilo, A. Rodrigues, J. Sa Silva, F. Boavida (University of Coimbra, PT), E. Sa (Superior Institute of Applied Psychology, PT).

LocuSent - Locust Control
M. Laven (ArtCore Stockholm, SE).

PerSens: Personality Sensors
Z. Benenson, M. Guenes, M. Wenig (RWTH Aachen, DE).

Sentient Guardian Angel
M. Christ, G. Eichler, K. Miethe, S. Richter, J. Schmidt, J. Wukasch (DE).

Technical Papers

Semantic Streams: a Framework for the Composable Semantic Interpretation of Sensor Data
Kamin Whitehouse (UC Berkeley, US), Jie Liu, Feng Zhao (Microsoft Research, US).

Abstract. We present a framework called Semantic Streams that allows users to pose declarative queries over semantic interpretations of sensor data. For example, instead of querying raw magnetometer data, the user queries whether vehicles are cars or trucks; the system decides which sensor data and which operations to use to infer the type of vehicle. The user can also place constraints on values such as the the amount of energy consumed or the confidence with which the vehicles are classified. We demonstrate how this system can be used on a network of video, magnetometer, and infrared break beam sensors deployed in a parking garage with three simultaneous and independent users.

PAQ: Time Series Forecasting for Approximate Query Answering in Sensor Networks
Daniela Tulone (University of Pisa, IT), Samuel Madden (MIT, US).

Abstract. In this paper, we present a method for approximating the values of sensors in a wireless sensor network based on time series forecasting. More specifically, our approach relies on autoregressive models built at each sensor to predict local readings. Nodes transmit these local models to a sink node, which uses them to predict sensor values without directly communicating with sensors. When needed, nodes send information about outlier readings and model updates to the sink. We show that this approach can dramatically reduce the amount of communication required to monitor the readings of all sensors in a network, and demonstrate that our approach provides provably-correct, user-controllable error bounds on the predicted values of each sensor.

Proactive Context-Aware Sensor Networks
Sungjin Ahn, Daeyoung Kim (Information and Communications University, KR).

Abstract. We propose a novel context detection mechanism in Wireless Sensor Networks, called PROCON. In PROCON, context decisions are made in a distributed way, by cooperation of nodes connected through a context overlay on the network. As a result, the sensor network can deliver context level information, not low level sensing data, directly to proper actuators. Moreover, PROCON achieves highly efficient energy consumption compared to the existing centralized context detection mechanism. The analysis and simulation results show that the proposed mechanism outperforms the existing centralized mechanism in average energy consumption, capability of mitigating congestion to a base station, context service lifetime, and reliability.

Constraint-based Distance Estimation in Ad-hoc Wireless Sensor Networks
Urs Bischoff, Martin Strohbach, Mike Hazas, Gerd Kortuem (Lancaster University, UK).

Abstract. We propose a lightweight localisation approach for supporting distance and range queries in ad hoc wireless sensor networks. In contrast to most previous localisation approaches we use a distance graph as spatial representation where edges between nodes are labelled with distance constraints. This approach has been carefully designed to satisfy the requirements of a concrete application scenario with respect to the spatial queries that need to be supported, the required accuracy of location information, and the capabilities of the target hardware. We show that this approach satisfies the accuracy requirements of the example application using simulations. We describe the implementation of the algorithms on wireless sensor nodes.

Sensor Density for Complete Information Coverage in Wireless Sensor Networks
Bang Wang, Chua Kee Chiang, Vikram Srinivasan, Wei Wang (National University of Singapore, SG).

Abstract. Coverage is a very important issue in wireless sensor networks. Current literature defines a point to be covered if it is within the sensing radius of at least one sensor. This is a conservative definition of coverage and we have previously proposed a new notion of information coverage. Compared with the conventional definition of coverage, a point can still be information covered even if it is not within the sensing disk of any sensor. The density requirements for complete information coverage of a field are analyzed and simulated for a random sensor deployment. Our results show that significant savings in terms of sensor density can be achieved with information coverage.

Hierarchical Grid-Based Pairwise Key Predistribution Scheme for Wireless Sensor Networks
Abedelaziz Mohaisen, Daehun Nyang (Inha University, KR).

Abstract. Wireless Sensor Network (WSN) consists of huge number of sensor nodes which are small and inexpensive with very limited resources. The public key cryptography is undesirable to be used in WSN because of the limitations of the resources. A key management and predistribution techniques are required to apply the symmetric key cryptography in such a big network. Many key predistribution techniques and approaches have been proposed, but few of them considered the real WSN assumptions. In this paper, we propose a security framework that is based on a hierarchical grid for WSN considering the proper assumptions of the communication traffic and required connectivity. We apply simple keying material distribution scheme to measure the value of our framework. Finally, we provide security analysis for possible security threats in WSN.

Generic Routing Metric and Policies for WSNs
Olga Saukh, Pedro Marron, Andreas Lachenmann, Matthias Gauger, Daniel Minder, Kurt Rothermel (University of Stuttgart, DE).

Abstract. Energy-aware algorithms have proven to be a crucial part of sensor network applications, especially if they are required to operate for extended periods of time. Among these, efficient routing algorithms are of utter importance since their effect can be experienced by all other layers. Thus, the optimization and accurate prediction of the lifetime of the system can only be performed in the presence of accurate execution models that take energy consumption into account. In this paper, we propose a generic routing metric and associated policies that encompass most other existing metrics in the literature and use this model for the optimal construction of a routing tree to the sink. We also provide experimental results that show the benefits of using our novel metric.

On the Scalability of Routing Integrated Time Synchronization
Janos Sallai, Branislav Kusy, Akos Ledeczi (Vanderbilt University, US), Prabal Dutta (UC Berkeley, US).

Abstract. Reactive time synchronization is becoming increasingly popular in the realm of wireless sensor networks. Unlike proactive protocols, traditionally implemented as a standalone middleware service that provides a virtual global time to the application layer, reactive techniques establish a common reference time base post facto, i.e. after an event of interest has occurred. In this paper, we present the formal error analysis of a representative reactive technique, the Routing Integrated Time Synchronization protocol (RITS). We show that in the general case, the presence of clock skews cause RITS to scale poorly with the size of the network. Then we identify a special class of sensor network applications that are resilient to this scalability limit. For applications outside this class, we propose an in-network skew compensation strategy that makes RITS scale well with both network size and node density. We provide experimental results using a 45-node network of Berkeley MICA2 motes.

Distributed Dynamic Shared Tree for Minimum Energy Data Aggregation of Multiple Mobile Sinks in Wireless Sensor Networks
Kwang-il Hwang, Jeongsik In, Doo-seop Eom (Korea University, KR).

Abstract. Sink mobility creates new challenges for several sensor network applications. In mobile sink environments, each sink must propagate its current location continuously, through a sensor field, in order to keep all sensor nodes updated with the direction of data forwarding. This method consumes large amounts of energy. Although several protocols, such as DD, TTDD, and SEAD, have been proposed, in order to solve mobile sink problems, no existing approaches provide both a low delay and energy-efficient solution to this mobile sink problem. In this paper, a distributed dynamic shared tree for minimum energy data aggregation with low delay in highly mobile sink environments, is proposed. In the proposed protocol, the tree is shared with the other slave sinks. Through simulations it is shown that the DST is an extremely energy-efficient, robust protocol with relatively low delay, when compared to DD, TTDD, and SEAD.

Constrained Tracking on a Road Network
Michal Piorkowski, Matthias Grossglauser (EPFL, CH).

Abstract. Many applications of wireless ad hoc sensor and actuator networks (WSANs) rely on the knowledge of node locations. These are challenging to obtain when nodes are mobile and are not equipped with any specific positioning hardware. In this paper, we are interested in scenarios where there are constraints on the movement of nodes, such as with cars on a road network. We develop and analyse a tracking algorithm called MOONwalk that explicitly takes such constraints into account in order to improve the tracking precision. Furthermore, MOONwalk does not require global knowledge of the network, and therefore lends itself well to large-scale and high-mobility applications. We evaluate the accuracy of MOONwalk by comparing it to the optimal maximum likelihood estimator, under different radio conditions and deployment scenarios. We find that MOONwalk performs well despite its localized operation.

Range-Based Localization in Mobile Sensor Networks
Bram Dil, Stefan Dulman, Paul Havinga (University of Twente, NL).

Abstract. Localization schemes for wireless sensor networks can be classified as range-based or range-free. They differ in the information used for localization. Range-based methods use range measurements, while range-free techniques only use the content of the messages. None of the existing algorithms evaluate both types of information. Most of the localization schemes do not consider mobility. In this paper, a Sequential Monte Carlo Localization Method is introduced that uses both types of information as well as mobility to obtain accurate position estimations, even when high range measurement errors are present in the network and unpredictable movements of the nodes occur. We test our algorithm in various environmental settings and compare it to other known localization algorithms. The simulations show that our algorithm outperforms these known range-oriented and range-free algorithms for both static and dynamic networks. Localization improvements range from 12% to 49% in a wide range of conditions.

Hierarchical Localization Algorithm based on Inverse Delaunay Tessellation
Masayuki Saeki, Kok-Hou Khor, Tomohiro Kousaka, Junya Inoue, Hiroaki Honda, Kenji Oguni (University of Tokyo, JP).

Abstract. This paper presents the hierarchical sensor network system for robust localization. This system consists of parent nodes with a low priced L1 GPS receiver and child nodes equipped with an acoustic ranging device. Relative positions between child nodes are estimated based on acoustic ranging through the inverse Delaunay algorithm. This algorithm localizes all the nodes simultaneously, thus, the accumulation of the error in the localization is suppressed. Relatively localized child sensor nodes are given global coordinates with the help of GPS on parent nodes. Field experiment was conducted with three GPS parent nodes and twenty-one child nodes (MOTE).

Power Management for Bluetooth Sensor Networks
Luca Negri (Politecnico di Milano, IT), Lothar Thiele (ETH Zurich, CH).

Abstract. Low power is a primary concern in the field of wireless sensor networks. Bluetooth has often been labeled as an inappropriate technology in this field due to its high power consumption. However, most Bluetooth studies employ rather over-simplified, fully theoretical, or inadequate power models. We present a power model of Bluetooth including scatternet configurations and low-power sniff mode and validate it experimentally on a real Bluetooth module. Based on this model, we introduce a power optimization framework employing MILP (Mixed-Integer Linear Programming) techniques, and devise optimal power management policies in the presence of end-to-end delay constraints. Our optimizations, if backed by power-aggressive hardware implementations, can make Bluetooth viable for a wider range of sensor networks.

FlexCup: A Flexible and Efficient Code Update Mechanism for Sensor Networks
Pedro Marron, Matthias Gauger, Andreas Lachenmann, Daniel Minder, Olga Saukh, Kurt Rothermel (University of Stuttgart, DE).

Abstract. The ability to update the program code installed on wireless sensor nodes plays an import role in the highly dynamic environments sensor networks are often deployed in. Such code update mechanisms should support flexible reconfiguration and adaptation of the sensor nodes but should also operate in an energy and time efficient manner. In this paper, we present FlexCup, a flexible code update mechanism that minimizes the energy consumed on each sensor node for the installation of arbitrary code changes. We describe two different versions of FlexCup and show, using a precise hardware emulator, that our mechanism is able to perform updates up to 8 times faster than related code update algorithms found in the literature, while consuming only an eighth of the energy.

Transforming Protocol Specifications for Wireless Sensor Networks into Efficient Embedded System Implementations
Gerald Wagenknecht, Daniel Dietterle, Jean-Pierre Ebert, Rolf Kraemer (IHP Microelectronics, DE).

Abstract. In this paper, we present an efficient way how protocols modelled in SDL (Specification and Description Language) can be transformed into efficient implementations for resource-constrained wireless sensor nodes. We will show how SDL concepts such as processes, timers, or signals can be mapped to operating system concepts provided by the Reflex operating system. Our approach is based on optimized, automatically generated C code derived from the Telelogic TAU SDL Suite that can be left as is. The overhead caused by our SDL run-time environment is minimal, thus making it applicable in embedded systems. By pre-allocating memory for SDL signals it is possible to completely avoid dynamic memory allocation. We will also highlight some SDL modelling guidelines that help to avoid common SDL implementation overhead.

Extending Network Lifetime Using an Automatically Tuned Energy-Aware MAC Protocol
Rebecca Braynard, Adam Silberstein, Carla Ellis (Duke University, US).

Abstract. Sensor network devices have limited battery resources primarily consumed by radio communication. Network nodes play different communication roles and consequently consume different amounts of energy. Nodes with heavier communication burdens prematurely deplete their batteries and potentially partition the network such that other nodes are unable to communicate despite having energy remaining. We have developed Seesaw, an asynchronous and asymmetric MAC protocol that balances the energy consumption among nodes with differing loads, and thus prolongs network lifetime. Balancing is possible through Seesaw mechanisms that allow heavily burdened nodes to shift some of the effort of maintaining communication to more lightly loaded neighboring nodes. We show how to exploit the flexibility of asynchrony and asymmetry to balance energy consumption across the network, and develop methods for automatically tuning each node to achieve this.

Sift: A MAC Protocol for Event-Driven Wireless Sensor Networks
Kyle Jamieson, Hari Balakrishnan (MIT, US), Y. C. Tay (National Univ. of Singapore, SG).

Abstract. Nodes in sensor networks often encounter spatially-correlated contention, where multiple nodes in the same neighborhood all sense an event they need to transmit information about. Furthermore, in many sensor network applications, it is sufficient if a subset of the nodes that observe the same event report it. We show that traditional carrier-sense multiple access (CSMA) protocols for sensor networks do not handle the first constraint adequately, and do not take advantage of the second property, leading to degraded latency as the network scales in size. We present Sift, a medium access control (MAC) protocol for wireless sensor networks designed with the above observations in mind. We show using simulations that as the size of the sensor network scales up to 500 nodes, Sift can offer up to a 7-fold latency reduction compared to other protocols, while maintaining competitive throughput.

f-MAC: A Deterministic Media Access Control Protocol Without Time Synchronization
Utz Roedig, Andre Barroso, Cormac Sreenan (University College Cork, IE).

Abstract. Nodes in a wireless network transmit messages through a shared medium. Thus, a Media Access Control (MAC) protocol is necessary to regulate and coordinate medium access. For some application areas it is necessary to have a deterministic MAC protocol which can give guarantees on message delay and channel throughput. Schedule based MAC protocols, based on time synchronization among nodes, are currently used to implement deterministic MAC protocols. Time synchronization is difficult and costly, especially in energy constrained sensor networks. In this paper the f-MAC protocol is presented which can give guarantees regarding message delay and channel throughput without the requirement of time synchronization among nodes. The various trade-offs of f-MAC are analysed and discussed and application areas that would benefit from f-MAC are presented.

A Measurement-based Analysis of the Interaction between Network Layers in TinyOS
Umberto Malesci (Fluidmesh Networks Inc., US), Samuel Madden (MIT, US).

Abstract. There have been a number of recent proposals for link and network-layer protocols in the sensor networking literature, each of which claims to be superior to other approaches. However, a proposal for a networking protocol at a given layer in the stack is typically evaluated in the context of a single set of carefully selected protocols at other layers. Because of the limited data available about interactions between different protocols at various layers of the stack, it is difficult for developers of sensor network applications to select from amongst the range of alternative sensor networking protocols. This paper evaluates the interaction between several protocols at the MAC and network layers measuring their performance in terms of end-to-end throughput and loss on a large testbed. We identify some common sources of poor performance; based on this experience, we propose a set of design principles for the designers of future interfaces.

Results of Bit Error Measurements with Sensor Nodes and Casuistic Consequences for Design of Energy-Efficient Error Control Schemes
Andreas Willig (TU Berlin, DE), Robert Mitschke (Hasso-Plattner-Institute, DE).

Abstract. For the proper design of energy-efficient error control schemes some insight into channel error patterns is needed. This paper presents bit error and packet loss measurements taken with sensor nodes running the popular RFM TR 1001 wireless transceiver. Some key facts from the measurements are presented and it is evaluated, how energy-efficient selected combined forward error correction (FEC) and automatic repeat request (ARQ) schemes would be over the measured channel. One interesting result is that FEC schemes are less energy-efficient than schemes without FEC, even when the additional energy required to decode a packet is not considered. On the other hand, the energy-efficiency can be improved when retransmissions are postponed for a short time.

An Empirical Characterization of Radio Signal Strength Variability in 3-D IEEE 802.15.4 Networks using Monopole Antennas
Dimitrios Lymberopoulos, Quentin Linsey, Andreas Savvides (Yale University, US).

Abstract. The wide availability of radio signal strength attenuation information on wireless radios has received considerable attention as a convenient means of deriving positioning information. Although some schemes have been shown to work in some scenarios, many agree that the robustness of such schemes can be easily compromised when low power IEEE 802.15.4 radios are used. Leveraging a recently installed sensor network testbed, we provide a detailed characterization of signal strength properties and link asymmetries for the CC2420 IEEE 802.15.4 compliant radio using a monopole antenna. To quantify the several factors of signal unpredictability due to the hardware, we have collected several thousands of measurements to study the antenna orientation and calibration effects. Our results show that the often overlooked antenna orientation effects are the dominant factor of the signal strength sensitivity, especially in the case of 3-D network deployments. This suggests that the antenna effects need to be carefully considered in signal strength schemes.

Posters and Demos

1. Concealed Data Aggregation for WSNs (DEMO)
J. Girao, D. Westhoff (NEC, DE)

2. Low-Power Multihop Sensor Networking using WiseMAC (DEMO)
A. El-Hoiydi, J.-D. Decotignie (CSEM, CH)

3. Bayesian Localization in Randomized Wireless Sensor Networks
H. Schioler, M. B. Hansen, H. P. Schwefel (Aalborg Univ., DK)

4. Building Adaptable Sensor Networks with Sensor Cubes (DEMO)
H. Diall, K. Raja, I. Daskalopoulos, S. Hailes (UCL, UK), T. Torfs, C. Van Hoof (IMEC, BE), G. Roussos (Birbeck College, UK)

5. An Embedded GPRS Gateway for Environmental Monitoring Wireless Sensor Networks
F. Chiti, M. Chiabatti, G. Collodi, D. Di Palma, A. Manes (Univ. Florence, IT)

6. Pilot Experiment of an Early Warning Fire Detection System
G. M. Goncalves, A. Sousa, J. Pinto, P. Lebres, J. Sousa (Univ. Porto, PT)

7. Sensor Fusion in Multirobot Workcell Using Sensor Networks
M. Sallinen (VTT, FI), T. Heikkilae (Univ. Oulu, FI)

8. Power-Efficient Distributed Support Vector Machines for Wireless Sensor Networks
K. Flouri (Univ. Crete, GR), B. Beferull-Lozano (Univ. Valencia, ES), P. Tsakalides (Univ. Crete, GR)

9. A Theoretical Analysis of Routing Protocols in Wireless Sensor Networks
J. J. Vinagre, A. J. Caamano, J. Ramos, E. M. Reyes (Univ. Madrid, ES)

10. Energy Management in Buildings with Sensor Networks (DEMO)
D. Garces (Particle Computer, DE), A. Krohn (TECO, DE), O. Schoch (ETH Zurich, CH)

11. Wireless Sensor Networks in Agricultural Applications
A. Coers, M. Holzapfel, H.-C. Mueller (Fraunhofer IMS, DE)

12. NemoTrack: A RF-Based Robot Tracking System in Wireless Sensor Networks (DEMO)
X. Shen, H. Li, J. Zhao, J. Chen, Z. Wang, Y. Sun (Zhejiang Univ., CN)

13. Introducing Logical Neighborhoods for Programming Wireless Sensor and Actor Networks
L. Mottola, G. P. Picco (Politecnico di Milano, IT)

14. Efficient Decision Fusion with Performance Guarantees in Sensor Networks
Z. Benenson, G. Fabeck (RWTH Aachen, DE)

15. A Lifetime-Efficient Forwarding Strategy for Wireless Sensor Networks
M. Busse, T. Haenselmann, W. Effelsberg (Univ. Mannheim, DE)

16. Sensor Network Maintenance Toolkit (DEMO)
J. Beutel, M. Dyer, K. Martin (ETH Zurich, CH)

17. Modular Communication Protocols for Sensor Networks
O. Landsiedel, J. A. Bitsch, K. Denkinger, K. Wehrle (Univ. Tuebingen, DE)

18. Monitoring Indoor Temperature and Humidity for Pig Stables
J. A. Hansen, T. D. Nielsen, H. Schioler (Aalborg Univ., DK)

19. A PIR based wireless sensor node prototype for surveillance applications
P. Zappi, E. Farella, L. Benini (Univ. Bologna, IT)

20. Sensor Networks for Corrosion Monitoring
A. Hozoi, Z. Papp, P. van der Mark (TNO, NL)

21. Security and Advanced Control Issues in a Robotic Platform for Monitoring and Relief
A. Danesi, I. M. Savino, R. Schiavi, A. Bicchi, G. Dini (Univ. Pisa, IT)

22. Experimental Localization Results in an Indoor Wireless Sensor Network Testbed
S. Blom, M. Andretto, A. Zanella, M. Zorzi, S. Friso, R. Crepaldi (Univ. Padova, IT)

23. A Complete Energy Model for Wireless Sensor Networks
L. Oeberg, Y. Xu (Joenkoeping Univ., SE)

24. Receiver Oriented Trajectory Based Forwarding
A. Capone, M. Cesana, I. Filippini, L. Fratta, L. Pizziniaco (Politecnico di Milano, IT)

25. Architecture of a scalable wireless sensor network for pollution monitoring
K. Baumgartner, S. Robert (Univ. Yverdon, CH)

26. Energy Efficient Area Coverage in Arbitrary Sensor Networks
M. Sigalas, G. Vouros (Univ. of the Aegean, GR)

27. Toward Adaptive Wireless Sensor Networks
S. Santini (ETH Zurich, CH)

28. BASUMA - A Body Sensor System for Telemedicine (DEMO)
J.-P. Ebert, D. Dietterle (IHP, DE), M. Lang (TES Electronic Solutions, DE), T. Falck, J. Espina (Philips, DE), F. Scheller (Univ. Potsdam, DE)

29. Interfacing the Real World with Ubiquitous Gateways
C. Frank, C. Roduner (ETH Zurich, CH), C. Noda, M. Sgroi, W. Kellerer (DoCoMo, DE)

30. Interactive In-Field Inspection of WSNs (DEMO)
M. Ringwald, M. Yuencel, K. Roemer (ETH Zurich, CH)