Philipp Blum

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In this chapter, we review time synchronization and calibration for wireless sensor networks. We will first consider time synchronization in Sections 1.1–1.6, before turning to calibration in Section 1.7. We will show that time synchronization can be considered as a calibration problem and many observations about time synchronization can be transferred to(More)
Interval-based synchronization provides the nodes of a distributed system with guaranteed bounds on a common time. This is a crucial piece of infrastructure in many distributed sensing and actuating systems. In this paper, we propose a modification to a known interval-based synchronization algorithm; our new algorithm obtains substantially better results in(More)
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(More)
NSO heterocycles (HET) are typical constituents of coal tars. However, HET are not yet routinely monitored, although HET are relatively toxic coal tar constituents. The main objectives of the study is therefore to review previous studies and to analyse HET at coal tar polluted sites in order to assess the relevance of HET as part of monitored natural(More)
Clock synchronization is a crucial basic service in typical sensor networks, since the observations of distributed sensors more often than not need to be ordered ("<i>a</i> happened before <i>b</i>") or otherwise related ("<i>a</i> and <i>b</i> happened within a time window of size <i>x</i>") in time. Ad-hoc networks may exhibit characteristics which make(More)
With the field of wireless sensor networks rapidly maturing, the focus shifts from “easy” deployments, like remote monitoring, to more difficult domains where applications impose strict, real-time constraints on performance. One such class of applications is safety critical systems, like fire and burglar alarms, where events detected by sensor nodes have to(More)
We present an evaluation strategy for clock synchronization algorithms. It is based on a combination of measured traces, which provide for realistic performance estimation, and of simulation, which guarantees repeatability. The evaluation strategy includes parameteroptimization to allow for a fair comparison of algorithms; a generalpurpose evolutionary(More)