Towards Energy Efficient Multimedia Streaming to Mobile Devices

In the last few years the mobile devices have been increasingly used as part of the people daily routines. The Android smartphones and tablets are responsible for a large part of this increase and are used around the clock, causing the energy consumption in these devices to be a concern. Since these devices are most of the time connected to the Internet, the energy consumed by the IEEE 802.11 interface is responsible for a fast drain in the battery lifetime, leading to the need of finding solutions to reduce the wireless interface energy consumption. Therefore, this work presents the state of the art concerning the IEEE 802.11 technology and a discussion of the most important energy consumption optimizations presented in the literature. To allow the study of the energy consumption in Android devices, a testbed setup is described and was used to perform a characterization of the IEEE 802.11 interface energy consumption in Android devices. The results showed that the implemented power saving techniques do not provide a proper trade-o↵ between the energy consumption and the end-user expectations in the presence of Continuous Media Applications. Since the Continuous Media Applications are expected to be responsible for the most part of the mobile tra c in a few years, proposing mechanisms that keep the end-user expectations while reducing the energy consumption becomes a challenge. With this challenge in mind, this work presents the EXPoSE framework which aims to extend the control of the IEEE 802.11 interface to the endusers, in Android devices. The validation of this framework in a real testbed showed energy savings between 5% and 54% while taking into account the end-user configurations. Furthermore, this work also proposes the enhanced Power save Algorithm for continuous Media Applications (OPAMA) lite mechanism for Android devices. The experimental evaluation in a real testbed showed a clear benefit of employing this mechanism in the presence of Continuous Media Applications, since, it is possible to reduce more than 55% of the energy consumption while keeping the end-user expectations, namely the maximum allowed delay.