Algorithms for Sensor Systems 7th International Symposium on Algorithms for Sensor Systems, Wireless Ad Hoc Networks and Autonomous Mobile Entities, ALGOSENSORS 2011, Saarbrücken, Germany, September 8-9, 2011, Revised Selected Papers - Erlebach, Thomas; Nikoletseas, Sotiris; Orponen, Pekka (Springer Berlin Heidelberg, 2012)