Graceful Performance Modulation for Power-Neutral Transient Computing Systems

Abstract

Abstract-Transient computing systems do not have energy storage, and operate directly from energy harvesting. These systems are often faced with the inherent challenge of low-current or transient power supply. In this paper, we propose "powerneutral" operation, a new paradigm for such systems, whereby the instantaneous power consumption of the system must match the instantaneous harvested power. Power neutrality is achieved using a control algorithm for dynamic frequency scaling (DFS), modulating system performance gracefully in response to the incoming power. Detailed system model is used to determine design parameters for selecting the system voltage thresholds where the operating frequency will be raised or lowered, or the system will be hibernated. The proposed control algorithm for power-neutral operation is experimentally validated using a microcontroller incorporating voltage threshold-based interrupts for frequency scaling. The microcontroller is powered directly from real energy harvesters; results demonstrate that a powerneutral system sustains operation for 4-88% longer with up to 21% speedup in application execution.

Energy-driven computing: Rethinking the design of energy harvesting systems

“…8. Example of power-neutral operation [14], where a microcontroller dynamically adapts its core frequency to modulate its power consumption in response to the half-wave rectified signal from a micro wind turbine.…”

“…However, when the system is operating, its performance (hence power consumption) is static; this is likely to either waste power or draw too much (causing the supply to drop and operation be interrupted). To alleviate this and improve performance, the principles of power-neutral operation can be used to adjust the clock frequency (DFS) to modulate power consumption to match harvested power [14]. This approach is the hibernus-PN point on Fig.…”

Wearable and autonomous computing for future smart cities: Open challenges

“…This requires the re-engineering of applications and systems, as the system's operation is not only driven by the application requirements (which are often temporally driven) but becomes dependent on power availability (which dictates operational times). For example, energydriven systems should consider the possibility of adjusting system's performance (and hence the power consumption) dynamically such that it matches the harvested power [9].…”

Power neutral performance scaling for energy harvesting MP-SoCs

“…The power neutral operating paradigm [11], where a device's performance is dynamically modulated such that instantaneous power consumption matches the instantaneous harvested power, negates the need for energy storage. The authors demonstrate a practical implementation on an ultralow power single-core MCU where power consumption is controlled through dynamic frequency scaling (DFS).…”