Optimal service level allocation in environmentally powered embedded systems

ABSTRACT

Energy management is a critical concern in the design of embedded systems to prolong the lifetime or to maximize the performance under energy constraints. In particular, the emerging embedded systems with renewable energy sources rise new problems and trigger the revision of conventional energy management. If, e.g., the size of a solar cell limits the available power/energy of an electronic device, decisions like when to provide which service have to be made in order to satisfy the needs of the user as well as possible. In this paper, we explore how to maximize the system reward of diverse applications for an energy harvesting system. By utilizing the notion of rewards to express the different priorities of services, we answer the fundamental question of how to optimize the use of energy provided by a scarce and time-varying environmental source. For this purpose, we provide algorithms to optimally adjust service parameters dynamically. Our work is supported by simulation results which are based on long-term measurements of the power generated by real solar cells. Furthermore, we demonstrate how to dimension the embedded system, e.g., the battery capacity and elaborate on implementation details which are of practical importance.

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INDEX TERMS

Primary Classification:
  D. Software
  D.4 OPERATING SYSTEMS
      D.4.1 Process Management

General Terms:
Algorithms, Design

Keywords:
embedded systems, energy harvesting systems, reward maximization, solar cells