System Energy Efficiency Lab
Home People Research Publications Sponsors Contacts
Current Project
Past Projects


Long-term science experiments that require high-resolution sensor data need platforms (e.g. buoys or towers), which are large enough to house large solar panels and bulky batteries. The current practice of using large form factor platforms poses significant functional, operational, financial, and policy challenges. For example, large solar panels and batteries cost more money and result in less portable platforms which are harder to deploy and maintain. In addition, policy decisions often regulate the form factor of buoys that can be deployed in public lakes, oceans, or forests (e.g., to preserve aesthetic value). Although scientists would like to go with miniaturized buoys, energy-constraints imposed by small solar panels and batteries limit their deployment duration. To that end, building on a well defined "sensor appliance" created using Sensor-Rocks, we will develop novel context-aware power management algorithms that will maximize the network lifetime and provide scientists unprecedented capability to conduct long-term experiments using miniaturized platforms.

An energy efficient ROUTING and SCHEDULING mechanism for ad-hoc wireless network

In large-scale ad hoc wireless networks data delivery is made challenging by the lack of a network infrastructure and limited energy resources. We propose a novel scheduling and routing strategy for ad hoc wireless networks to address these challenges. Our solution achieves large power savings (up to 60%) while delivering data efficiently. The scheduling algorithm switches off the wireless interface of a large number of nodes for a significant fraction of time thus achieving large energy savings. The algorithm runs above the MAC layer in a completely distributed manner. We test our ideas on a heterogeneous wireless sensor network we have deployed in southern California - HPWREN. Routing relies on a backbone of active nodes that dynamically change over time. The backbone nodes are responsible for delivering the packets to the proper locations. Those nodes that are not part of the backbone run our low-power scheduling algorithm

the SHiMmer project

SHiMmer is a wireless platform that combines active sensing and localized processing with energy harvesting to provide long-lived structural health monitoring. SHiMmer uses piezoelectric transducers (PZTs) to evaluate a portion of a structure to determine if damage exists. Unlike other sensor networks that periodically monitor a structure and route information to a base station, our device acquires data and processes it locally before communicating with an external device, such as a remote controlled helicopter. Because SHiMmer receives all its power from solar cells, energy neutrality is essential - the node should not use more energy than it can harvest. We develop algorithms for achieving high performance while maintaining energy neutrality.