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The reduction of energy consumption in microprocessors can be accomplished without impacting the peak performance through the use of dynamic voltage scaling (DVS). This approach varies the processor voltage under software control to meet dynamically varying performance requirements. This paper presents a foundation for the simulation and analysis of DVS algorithms. These algorithms are applied to a benchmark suite specifically targeted for PDA devices. INTRODUCTIONDynamic Voltage Scaling (DVS) allows devices to dynamically change their speed and voltage, increasing the energy efficiency of their operation [2]. Implementing DVS for a general-purpose microprocessor requires substantial software support and new metrics to fully realize and understand the advantages of this capability.In order to reduce the energy/operation (E) of our system we can increase the delay (D), allowing an associated reduction in our current operating voltage (V) [2]. The approximate relationship between these variables for CMOS is given by:and Dynamic Voltage Scaling (DVS) allows a device to dynamically change its voltage while in operation and thus tradeoff energy for delay. This allows the processor to provide the minimum necessary clock frequency with the maximum possible energy efficiency.Taking advantage of DVS requires algorithms, termed voltage schedulers, to determine the operating speed of the processor at run-time. This paper evaluates some previously proposed algorithms in a simulation environment consisting of an energy-accurate cycle-level simulator.Designing a microprocessor for DVS also requires substantial optimization and redesign at the circuit level [2]. However, in this paper we focus on the evaluation of the algorithms for choosing the appropriate performance and voltage level only.We specifically target a PDA-class device with respect to system configuration, workloads, and metrics [9]. Our target platform is described in Section 7; our results, however, are applicable to other computing devices, such as laptop computers and embedded microprocessor systems. For our analysis, we use a benchmark suite consisting of applications appropriate for a portable microprocessor system. We have developed a clipped-delay metric which allows us to effectively interpret the results from our simulations. PREVIOUS WORKVoltage scaling has been previously investigated in the context of UNIX workstation systems [10] [6]. System traces of UNIX workloads were analyzed and evaluated with a simple energy/delay model. They considered the effectiveness of a number of DVS algorithms on system energy consumption. We will use these algorithms to demonstrate our evaluation approach.Voltage scheduling has also been applied to DSP applications (e.g. an IDCT algorithm required for MPEG decompression) [4]. DSP applications typically have predictable computational loads with a pre-determined upper limit on computation required to be performed in a given time interval. These characteristics allow relatively easy estimates of the potential benef...

The Personal Server is a mobile device that enables you to readily store and access the data and applications you carry with you through interfaces found in the local environment. Unlike conventional mobile computers with relatively poor user interfaces, it does not have a display at all, instead wirelessly utilizing displays, keyboards and other IO devices found nearby. By co-opting large screens such as those found on desktop PCs, public display monitors, information kiosks, and other computers, a Personal Server is more effective than relying on a small mobile screen. This model goes beyond the mobile context and has wider implications for how we think about computing in general. A prototype system, including applications, system infrastructure, and a mobile platform, has been built to fully explore this model. This prototype sheds light on the suitability of standard components to support such a computing model, and from this illuminates directions for the design of future ubiquitous computing systems.

Microprocessors represent a significant portion of the energy consumed in portable electronic devices. Dynamic Voltage Scaling (DVS) allows a device to reduce energy consumption by lowering its processor speed at run-time, allowing a corresponding reduction in processor voltage and energy. A voltage scheduler determines the appropriate operating voltage by analyzing application constraints and requirements. A complete software implementation, including both applications and the underlying operating system, shows that DVS is effective at reducing the energy consumed without requiring extensive software modification.

Sophisticated electronics are within reach of average users. Cooperation between wireless sensor networks and existing consumer electronic infrastructures can assist in the areas of health care and patient monitoring. This will improve the quality of life of patients, provide early detection for certain ailments, and improve doctor-patient efficiency. The goal of our work is to focus on health-related applications of wireless sensor networks. In this paper we detail our experiences building several prototypes and discuss the driving force behind home health monitoring and how current (and future) technologies will enable automated home health monitoring.