A Novel Design of Adaptive Reconfigurable Multicell Battery for Power-Aware Embedded Networked Sensing Systems Song Ci, Jiucai Zhang, Hamid Sharif Department of CEEN University of Nebraska–Lincoln NE68182, USA Email: {sci2,jiucaizhang,hsharif}@unl.edu Mahmoud Alahmad Department of AE University of Nebraska–Lincoln NE68182, USA Email:malahmad@unl.edu Abstract— Battery-powered embedded networked sensing sys- tems become more and more pervasive with the fast-paced deployment of various remote sensing applications. How to prolong the battery operating time is one of the most challenging areas in the design and development of these sensing systems due to the fact that the battery operation is much more dynamic and complex than considered, which is derived from its application and its internal structure (multiple hardwired series/parallel cells) to produce a specific voltage and capacity. Current research on prolonging the battery operating time is mainly focusing on the low-power hardware and energy-efficient network protocol designs, and simply treats the battery as a passive two-terminal energy source. In this paper, we will propose a novel adap- tive, proactive, and reconfigurable multicell battery design for supporting power-aware hardware and energy-efficient network protocols for embedded networked systems, which provides a whole new perspective to look at the energy problems of battery- powered embedded networked sensing systems. A theoretical modeling of the proposed design is provided, and simulation results show that the proposed design can significantly enhance the energy performance, especially for low voltage and low discharge current scenarios. I. I NTRODUCTION With the rapid development of computing technologies, more and more embedded networked sensing systems have been developed for various future ubiquitous computing paradigms. When hundreds even thousands of such systems configured to communicate through sophisticated protocols, we have a very powerful platform with a huge potential to change the remote sensing applications. The power of ubiquitous embedded networked sensing systems lies in their ability to monitor the physical environment through ad-hoc de- ployment of numerous self-configured sensor nodes. Wireless sensor networks are useful in a wide spectrum of applications ranging from environmental and biological monitoring to military and homeland security. However, usually most of the embedded networked sensing systems are disposable, or at least not being able to change battery every often. Thus, the energy efficiency problem becomes most prominent. Battery operating time is among the most important per- formance parameters for the networked embedded systems such as wireless sensors, active RFID tags, and other battery powered devices. In some critical mission scenarios such as emergency rescue, law enforcement, fire fighting, and battle field, longer battery operating time could save more lives. Furthermore, each year tens of millions of dead rechargeable batteries are discarded, causing a daunting high cost to dispose them, and this has been becoming a serious environmental issue. It is known that battery lifespan is closely related to the number of charge /discharge cycles. Therefore, longer battery operating time means longer battery lifespan. However, enhancing the battery operating time is a big challenge due to 1) the behaviors of energy consumption of each system component is dynamically changing according to the time-varying nature of the computing environment such as applications, network load, and link quality; 2) the battery operating time is much more dynamic and complex than considered derived from its application and its internal design structure (multiple hardwired series or/and parallel cells) to produce a specific voltage and capacity [1]. In other words, maximizing the battery operating time is a very difficult problem due to the nonlinearity of the battery behavior and its dependence on the characteristics of the discharge profile [2]. Moreover, current research to prolong the battery life is mainly aiming at the low-power design and the development of energy-efficient algorithms, resulting in the treatment of the battery as a passive two-terminal energy source rather than a dynamic system. Ignoring the discharge balance of the whole battery pack will lead poor battery performance, since the battery configuration can significantly affect the battery performance. In this paper, we will propose a novel design for an adaptive, proactive and reconfigurable multicell battery pack which uti- lizes the power-aware system modules such as the widely-used dynamic voltage scaling (DVS) capability of CPU, memory controller, and network interface cards, leading to a unified design framework of power-aware embedded networked sys- tems. The proposed design will significantly improve both battery operating time and battery lifespan, which will greatly improve the energy saving performance of current embedded 1930-529X/07/$25.00 © 2007 IEEE This full text paper was peer reviewed at the direction of IEEE Communications Society subject matter experts for publication in the IEEE GLOBECOM 2007 proceedings. 1043 Authorized licensed use limited to: IEEE Xplore. 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