On Providing Energy-efficient Data Transmission to Mobile Devices

The transformation from telephony to mobile Internet has fundamentally changed the way we interact with the world by delivering ubiquitous Internet access and reasonable cost of connectivity. The mobile networks and Internet services are supportive of each other and together drive a fast development of new services and the whole ecosystem. As a result, the number of mobile subscribers has skyrocketed to a magnitude of billions, and the volume of mobile traffic has boomed up to a scale no-one has seen before with exponential growth predictions. However, the opportunities and problems are both rising. Therefore, to enable sustainable growth of the mobile Internet and continued mobile service adaption, this thesis proposes solutions to ensure that the reduction of overall environmental presence and the level of QoE are mutually addressed by providing energy-efficient data transmission to mobile devices. It is important to understand the characteristics of power consumption of mobile data transmission to find opportunities to balance the energy consumption and the growth of mobile services and the data volumes. This research started with power consumption measurements of various radio interfaces and investigations of the trade-off between computation and communication of modern mobile devices. Power consumption models, state machines and the conditions for energy-efficient mobile data transmission were proposed to guide the development of energy-saving solutions. This research has then employed the defined guideline to optimise data transmission for energy-efficient mobile web access. Proxy-based solutions are presented in this thesis, utilising several strategies: bundling-enabled traffic shaping to optimise TCP behaviour over congested wireless links and keep the radio interface in low power consumption states as much as possible, offloading HTTP-object fetching to shorten the time of DNS lookups and web content downloading, and applying selective compression on HTTP payload to further reduce energy consumption of mobile data transmission. As a result, the solutions dramatically reduce the energy consumption of mobile web access and download time, yet maintain or even increase user experience