Battery Aware Hierarchical Wireless Sensor Network for Distributed Data Collection

Project Summary: Wireless sensor networks (WSN) have gained considerable attention in applications where spatially distributed events are to be monitored. Recent technological advances have led to the emergence of small battery-powered sensors with considerable processing and communication capabilities. We consider a distributed, hierarchical wireless sensor network of energy-constrained nodes. Each node in this network has limited computation and storage resources, wireless communication capability, and a limited energy source in the form of a battery. This network of autonomous nodes performs collaborative problem solving, such as providing situational and tactical awareness to the first respondents in an emergency situation, carrying out automatic intrusion detection/deterrence, or object recognition and tracking. The problem of interest is maximizing the network lifetime while providing a minimum quality of service requirement subject to some performance constraints (e.g., the response time.) Energy is considered as a key network resource that must be allocated and dispensed properly to maximize the network lifetime. We analyze network and wireless link properties and develop protocols that compensate/account for effects of extreme variations in wireless link dependability, many-to-one nature of the communication in a mixed multi-tier WSN, local high-contention nodes in the network, and relatively high cost of maintenance. This research addresses battery awareness of a monitoring sensor network as an intrinsic aspect of the distributed data collection task. This project will produce battery-aware algorithms and techniques for wireless sensor network design and deployment as the key enabler for cost-effective realization of many applications. The broader impact of this project will be to assist in the critical ongoing efforts to deploy networks of energy-constrained sensors and distribution/collection nodes for environmental, medical and security applications.

Lifetime-Aware Hierarchical Wireless Sensor Network Architecture with Mobile Overlays — With power efficiency and lifetime awareness becoming critical design concerns, we focus on energy-aware design of different layers of the WSN protocol stack. In a RAW-07 conference paper, we presented and analyzed a hierarchical wireless sensor network with mobile overlays, along with a mobility-aware multi-hop routing scheme, in order to optimize the network lifetime, delay, and local storage size. Furthermore, we show how certain physical layer attributes may affect the overall network lifetime. More specifically, we have investigated how certain adaptive modulation schemes may affect overall energy balancing in the network and hence its lifetime. Finally, we investigate new lifetime models which can be used to obtain more practical design criteria for energy-aware system design.