Data acquisition in sensor networks with large memories

Wireless Sensor Networks will soon become ubiquitous, making them essential tools for monitoring the activity and evolution of our surrounding environment. However such environments are expected to generate vast amounts of temporal data that needs to be processed in a power-effective manner. To this date sensor nodes feature small amounts of memory which mostly limits their capabilities to queries that only refer to the current point in time. In this paper we initiate a study on the deployment of large memories at sensor nodes. Such an approach gives birth to an array of new temporal and top-k queries which have been extensively studied by the database community. Our discussion is in the context of the RISE (RIverside SEnsor) hardware platform, in which sensor nodes feature external flash card memories that provide them several Megabytes of storage. 1

Nodes: A novel system design for embedded sensor networks

Emerging technologies provide increasingly powerful, efficient, compact and economically viable capabilities like single chip solutions for wireless embedded sensor systems, and large capacity flash memories. In this paper we present the RISE (RIverside SEnsor) platform, a novel system design for embedded sensors built around a System-on-Chip device interfaced with a large external storage memory in the form of off-the-shelf SD (Secure Digital) Card. RISE supports a new paradigm of “sense and store ” as opposed to the prevalent “sense and send ” for sensor networks. We describe the hardware and software structure of RISE which supports the standard TinyOS and NesC environment. We demonstrate that significant energy savings together with the additional benefits of reduced complexity and increased ease of use are achieved by adopting the sense and store methodology in which we transmit only the data of interest. It has been determined that percentage energy savings per node for storing data as against transmitting over a single hop can be expressed as (92.2 – 105.9x), where x is the fraction of useful data that needs to be transmitted. Also investigated, is a number of applications that benefit from the extra degree of freedom afforded by a large storage media. 1