from Part II - Energy management and conservation
Published online by Cambridge University Press: 05 August 2014
To develop energy-efficient techniques, the first step is to understand how energy is consumed on a mobile device. A mobile device consists of hardware components, such as microprocessors, wireless network interfaces, storage, cameras and a touchscreen, and software running on top of these hardware components. Lower-power serial buses facilitate the communication between the internal system components. These hardware components are the actual energy consumers.
Smartphone and mobile device power optimization happens on multiple levels:
• Silicon-level, in which the transistor capacitance and the chip design affect the energy efficiency. Higher capacitance requires the transistors to do more work.
• SoC-level, in which multiple power/voltage/clock domains can be used to support granular power management with the help of software. In addition, dynamic voltage and frequency scaling (DVFS) is used to dynamically adjust both the voltage and frequency to meet the given energy and performance level.
• Software-level, in which various power managers monitor and control the energy and power settings. A high-level framework is needed to perform system-wide tuning and optimization.
There are several choices that contribute critically to the overall efficiency of a mobile device, for instance from an energy-consumption viewpoint. They are the SoC including the CPU, display technology, communications technology, and the OS. The system-level power management is coordinated by the OS. In this chapter, we survey these crucial components and examine their energy consumption.
To save this book to your Kindle, first ensure [email protected] is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Find out more about the Kindle Personal Document Service.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.