Networking -- Versatile Support for Efficient Neighborhood Data Sharing -- An Energy-Efficient K-Hop Clustering Framework for Wireless Sensor Networks -- Efficient Routing from Multiple Sources to Multiple Sinks in Wireless Sensor Networks -- Tracking -- inTrack: High Precision Tracking of Mobile Sensor Nodes -- Approximate Initialization of Camera Sensor Networks -- Trail: A Distance Sensitive WSN Service for Distributed Object Tracking -- Algorithms -- Towards Energy-Efficient Skyline Monitoring in Wireless Sensor Networks -- Secure Data Aggregation with Multiple Encryption -- RIDA: A Robust Information-Driven Data Compression Architecture for Irregular Wireless Sensor Networks -- Loss Tomography in Wireless Sensor Network Using Gibbs Sampling -- Applications and Support -- Fence Monitoring – Experimental Evaluation of a Use Case for Wireless Sensor Networks -- Development of a Wireless Sensor Network for Collaborative Agents to Treat Scale Formation in Oil Pipes -- Deployment Support Network -- Medium Access Control -- Energy Consumption of Minimum Energy Coding in CDMA Wireless Sensor Networks -- Crankshaft: An Energy-Efficient MAC-Protocol for Dense Wireless Sensor Networks -- Decentralized Scattering of Wake-Up Times in Wireless Sensor Networks -- OS and Tools -- Improving the Energy Efficiency of the MANTIS Kernel -- Model-Based Design Exploration of Wireless Sensor Node Lifetimes -- Multithreading Optimization Techniques for Sensor Network Operating Systems -- Localization -- An Empirical Study of Antenna Characteristics Toward RF-Based Localization for IEEE 802.15.4 Sensor Nodes -- Radio Propagation-Aware Distance Estimation Based on Neighborhood Comparison -- Removing Systematic Error in Node Localisation Using Scalable Data Fusion.

This book constitutes the refereed proceedings of the 4th European Workshop on Wireless Sensor Networks, EWSN 2007, held in Delft, The Netherlands in January 2007. The 22 revised full papers presented were carefully reviewed and selected from 164 submissions. The papers are organized in topical sections on networking, tracking, algorithms, applications and support, medium access control, os and tools, as well as localization.