In this work, we design and implemented a Unified Sensing Coverage Architecture, called uSense, which features three novel ideas: Asymmetric Architecture, Generic Switching and Global Scheduling. uSense provides sensing coverage through a creative separation of scheduling from switching. We design and implement sophisticated scheduling algorithms externally and represent such intelligence with a lightweight generic switching algorithm running at resource-constrained sensor nodes. As an instance of these scheduling algorithms, we propose a novel two-level scheduling algorithm, called uScan. We evaluate our architecture with a network of 30 MicaZ motes, an extensive simulation with 10,000 nodes. The results indicate that uSense is a promising architecture to support flexible and efficient coverage in sensor networks.

The problem of localization of wireless sensor nodes has long been regarded as very difficult to solve, when considering the realities of real world environments. In this work, we formally describe, design, implement and evaluate a novel localization system, called Spotlight. Our system uses the spatio-temporal properties of well controlled events in the network (e.g., light), to obtain the locations of sensor nodes. We demonstrate that a high accuracy in localization can be achieved without the aid of expensive hardware on the sensor nodes, as required by other localization systems. Through performance evaluations of a real system deployed outdoors, we obtain a 20cm localization error. A sensor network, with any number of nodes, deployed in a 2500m2 area, can be localized in under 10 minutes, using a device that costs less than $1000. To the best of our knowledge, this is the first report of a sub-meter localization error, obtained in an outdoor environment, without equipping the wireless sensor nodes with specialized ranging hardware.

In mNets, we separate a dense network into several connected sparse sub-networks, which use different frequencies to support parallel data transmission through multiple sub-networks. We decouple the component into two sub-functions, frequency assignment and data forwarding. Using Asymmetric Function Placement, we implement a set of sophisticated algorithms to do near- optimal frequency assignment outside the networks, and a lightweight data forwarding mechanism at sensor nodes.