Design and implementation of low power techniques for android based phone

Android is the latest trend in mobile operating systems. Although several smartphones in the market feature Android, it is still in development stage and growing rapidly due to large open source developer community, supported by Google Inc. Even though Android provides a complete set of application, middleware and Linux kernel for the phone applications developer, it does not fully utilize several standard kernel features. Also the Android kernel does not focus on processor specific implementations. The Android kernel fails to integrate and utilize several hardware features offered by modern mobile applications processors such as OMAP, PXA or i. MX series. Hence a mobile phone running existing default Android largely remains unoptimized and inefficient. One of such features untouched by Android kernel is Power Management. Though Android offers basic API support for suspending the device to low power mode, it still neglects other power management features provided by processor as well as standard Linux kernel.

This paper attempts to address the limitations of Android specific to power management at kernel level and proposes possible solutions for active and static power management in Linux to overcome these limitations. The developed solutions for active power management include selection of suitable governor algorithm and modification of its parameters and implementation of a daemon process which performs voltage and frequency scaling. Application level low power techniques for Android are also proposed to help application developers to optimize their software. The objectives of the paper are realized by designing and implementing low power techniques for OMAP3530 based Beagleboard. The functionality of the implemented low power techniques is verified through several test cases using benchmarking applications such as 2D/3D rendering, playing a movie file and decompressing.

The benchmarking applications are capable of putting widely varying workload on the OMAP3530 processor which helps in determining the performance of governor algorithm and user-space daemon process with different parameter settings. The test execution results are presented in terms of performance, execution time, total current consumed, standby time and battery life. From these tests, it is concluded that through low power techniques it is possible to achieve up to 29% increase in battery life and up to 117% increase in standby time at no or very little performance degradation.