Energy-aware Adaptations for End-to- End Video Streaming to Mobile Handheld Devices

Optimizing user experience for streaming video applications on handheld devices is a significant research challenge. In this chapter, we propose an integrated endto-end power management approach that unifies low level architectural optimizations(CPU, memory, registers), OS power-saving mechanisms(dynamic voltage scaling) and adaptive middleware techniques(admission control, transcoding, network traffic regulation). Specifically, we identify interaction parameters between the different levels and optimize them to reduce power consumption. With knowledge of device configurations, dynamic device parameters and changing system conditions, the middleware layer selects an appropriate video quality and fine tunes the architecture for optimized delivery of video. Performance results indicate that architectural optimizations that are cognizant of user level parameters(e.g. transcoded video quality) can provide energy gains as high as 57.5% for the CPU and memory, when compared to the baseline case that does not employ any energy optimization. Middleware adaptations to changing network noise levels can save as much as 70% of energy consumed by the wireless network interface. Our approach to multiple-level and end-to-end management of power/performance has been implemented in a framework, called FORGE. We show how FORGE can substantially enhance the user experience in a mobile multimedia application.