Voltage scaling for energy minimization with QoS constraints

We propose variable voltage scheduling algorithms that minimize energy while satisfying the quality of service (QoS) requirements. We consider the case when multiple applications are running on a single processor equipped with a limited sized buffer and each application has a different computational load and timing constraint. We use the Lagrange multiplier method to theoretically determine the relation between the application voltages such that the energy is minimum, and then develop iterative algorithms to satisfy the relation. The iterative algorithms find the minimum energy solution with polynomial time complexity for both the off-line case and the online case. We show the effect of buffer size and application deadline times on the ability of the system to reduce energy. Furthermore, we consider the effect of discharge current on battery life and show that the voltage assignment for maximum battery capacity is very similar to the voltage assignment for maximum energy