BET Estimation on Power Saving by Intermittent Disabling Network Interface on Android

Abstract

The large power consumption of smartphones is an important issue. Smartphone operating systems such as Android have a function that invokes an application without user's operation. That is, an application runs and may communicate using its network interface in the screen-off state without user's operation. This behavior consumes large batteries. Temporarily disabling its network interface is one of the promising methods for reducing power consumption in the screen-off state. Less power is consumed while its network interface is disabled, but processes of disabling and enabling its network interface consume battery. Therefore, it is necessary to keep the interface disabled for a sufficiently long period such that the power consumption decreased by disabling the network interface exceeds the power consumption increased by the transition process of disabling and enabling the interface. In this paper, we focus on a method of reducing power consumption in the screen-off state by repeating to disable and enable the network interface and discuss estimation of its Break-Even Time (BET) with which the sizes of increased and decreased power consumption are the same. We then propose two methods for estimating BET. One method estimates BET by integrating the electric current. The other method estimates it according to the average electric current. We evaluate the methods with practical applications and Android devices and show that the method based on the average electric current can estimate BET accurately. In the case of our experiments, the difference between the actual and estimated BETs was less than 16.4%.