An Energy Efficiency Scheme for Wireless Sensor Networks * Dimitrios J. Vergados 1,2 , Dimitrios D. Vergados 2 and Nikolaos Pantazis 2 1 School of Electrical and Computer Engineering National Technical University of Athens Iroon Polytexneiou 9, Zografou, Athens, Greece emal: djvergad@telecom.ntua.gr 2 Department of Information and Communication Systems Engineering University of the Aegean GR-83200 Karlovassi, Samos, Greece email: {vergados, npantazis}@aegean.gr Abstract. Wireless Sensor Networks (WSNs) facilitate, monitoring and controlling of physical environments from remote locations with better accuracy. Sensor networks are dense wireless networks consisting of groups of small, inexpensive nodes, which collect and disseminate critical data. Thus, sensor nodes have various energy and computational constraints, because of their inexpensive nature and ad hoc method of deployment. Considerable research has been focused at overcoming these deficiencies through low-energy consumption schemes. In this paper, we propose a Scheduling Scheme for Energy Efficiency in Wireless Sensor Networks. The basic concept of this scheme is to try to maximize the time each sensor node remains in SLEEP mode, and to minimize the time spent in IDLE mode, taking into account not only the consumed power, but also the end-to-end transmission delay. Key-Words Wireless Sensor Networks, Power Control, Low-energy Consumption 1 Introduction Wireless Sensor Networks (WSN) have been increased dramatically the recent years as they are used more and more in the daily life. Medical, Environmental and Military Sectors are some of the most important areas that the recent developments have been applied in. In order to guarantee the Wireless Sensor Networks survivability and increase network lifetime in such special purpose environments, various energy efficiency schemes have been proposed in the literature. In some cases, sensor networks are expected to be able to operate for a long period of time in standby, and transmit the gathered data when required, as soon as possible. Under theses assumptions, most of the time the network is not in operation, but the network nodes * This work has been supported by GSRT, Hellenic Ministry of Development, through the PENED 2003 Project: “Design and Development Models for QoS Provisioning in Wireless Broadband Networks”.