Wireless Sensor Networks (WSN) are often deployed to sample the desired environmental attributes and deliver the acquired samples to the sink for processing, analysis or simulations as per the application needs. Many applications stipulate high granularity and data accuracy that results in high data volumes. Sensor nodes are battery powered and sending the requested large amount of data rapidly depletes their energy. Fortunately, the environmental attributes (e.g., temperature, pressure) often exhibit spatial and temporal correlations. Moreover, a large class of applications such as scientific measurement and forensics tolerate high latencies for sensor data collection. Accordingly, we develop a fully distributed adaptive technique for spatial and temporal innetwork data compression with accuracy guarantees. We exploit the spatio-temporal correlation of sensor readings while benefiting from possible data delivery latency tolerance to further minimize the amount of data to be transported to the sink. Using real data, we demonstrate that our proposed scheme can provide significant communication/energy savings without sacrificing the accuracy of collected data. In our simulations, we achieved data compression of up to 95% on the raw data requiring around 5% of the original data to be transported to the sink.
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General TermsAlgorithms, Design, Measurement, Performance Keywords spatial and temporal correlations, hierarchical clustering, energy efficiency, modeling, approximation, accuracy * Research supported in part by HEC and DFG GRK 1362 (TUD GKMM).Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, to republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee.
THE PROBLEM AND THE APPROACHIn WSN deployments, sensor nodes are often distributed over the monitoring area for unattended environmental monitoring or for supervisory functions. The typical WSN functionality being (i) local event detection and reporting it to the sink, and (ii) continuous data collection by sampling the environment and sending the samples to the sink. In this paper, we deal with continuous data collection. Applications utilize continuously collected data for (a) real-time decision making, such as surveillance, or (b) delay-tolerant processing such as modeling, analysis [17] and inference [3]. In this work, we develop adaptive modeling algorithms that exploit the delay-tolerance of the data collection to maximize data compression. As examples, various scientific applications, such as, volcano monitoring [21] or eco-systems [17] [5], require detailed ambient data with high spatio-temporal sampling resolution for fine-granular understanding of the physical processes. For such applications, a WSN is essentially ...