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TWIST: a scalable and reconfigurable testbed for wireless indoor experiments with sensor networks

We present TWIST, a scalable and exible testbed architecture for indoor deployment of wireless sensor networks. The design of TWIST is based on an analysis of typical and desirable use-cases. It provides basic services like node configuration, network-wide programming, out-of-band extraction of debug data and gathering of application data, and also introduces several novel features.Firstly, TWIST supports experiments with heterogeneous node platforms. Secondly, it supports active power supply control of the nodes. This enables easy transition between USB-powered and battery-powered experiments, dynamic selection of topologies as well as controlled injection of node failures into the system. Thirdly, TWIST supports creation of both at and hierarchical sensor networks. For this we introduce a layer of "super nodes" that on one hand form a part of the testbed infrastructure but can also play a role as elements of the sensor network.The self-configuration capability, the use of hardware with standardized interfaces and open-source software makes the TWIST architecture scalable, affordable, and easily repli-cable. To demonstrate its usefulness, we present our experiences with building and using a specific realization of TWIST that spans three floors of our office building and supports over one hundred sensor nodes.