The Power Management Model for Hitachi 32-bit CPU Based Handheld PC "Himalia"

Abstract

This paper proposes a state transition model for the power consumption estimation of the handheld computer “Himalia”, which can receive information from networks sporadically. To process intermittently arriving information under a certain throughput, we need a power management mechanism that can control some modules of handheld computers on and off to save power consumption. The power saving is possible due to the existence of the “sleep” and “suspend” states of handheld computers. From the state probability transition of the state transition diagram for a tri-state power managed mechanism of the platform “Himalia”, we obtain the state probabilities of “sleep” and “suspend” and “normal””states”, respectively, and obtain the average power consumption which is lower than the same platform without power management mechanism. We also provide an estimate bound for the power consumption based on the tri-state power managed mechanism. The estimation also shows that the tri-state design can save 50% of power consumption at the homogeneous machine state probability