Understanding and mitigating the impact of Internet demand in everyday life

Digital devices and online services are increasingly embedded within our everyday lives. The growth in usage of these technologies has implications for environmental sustainability due to the energy demand from the underlying Internet infrastructure (e.g. communication networks, data centres). Energy efficiencies in the infrastructure are important, but they are made inconsequential by the sheer growth in the demand for data. We need to transition users’ Internet-connected practices and adapt HumanComputer Interaction (HCI) design in less demanding and more sustainable directions. Yet it’s not clear what the most data demanding devices and online activities are in users’ lives, and how this demand can be intervened with most effectively through HCI design. In this thesis, the issue of Internet demand is explored—uncovering how it is embedded into digital devices, online services and users’ everyday practices. Specifically, I conduct a series of experiments to understand Internet demand on mobile devices and in the home, involving: a large-scale quantitative analysis of 398 mobile devices; and a mixed-methods study involving month-long home router logging and interviews with 20 participants (nine households). Through these studies, I provide an in-depth understanding of how digital activities in users’ lives augment Internet demand (particularly through the practice of watching), and outline the roles for the HCI community and broader stakeholders (policy makers, businesses) in curtailing this demand. I then juxtapose these formative studies with design workshops involving 13 participants; these discover how we can reduce Internet demand in ways that users may accept or even want. From this, I provide specific design recommendations for the HCI community aiming to alleviate the issue of Internet growth for concerns of sustainability, as well as holistically mitigate the negative impacts that digital devices and online services can create in users’ lives

Providing efficient services for smartphone applications

Mobile applications are becoming an indispensable part of people\u27s lives, as they allow access to a broad range of services when users are on the go. We present our efforts towards enabling efficient mobile applications in smartphones. Our goal is to improve efficiency of the underlying services, which provide essential functionality to smartphone applications. In particular, we are interested in three fundamental services in smartphones: wireless communication service, power management service, and location reporting service.;For the wireless communication service, we focus on improving spectrum utilization efficiency for cognitive radio communications. We propose ETCH, a set of channel hopping based MAC layer protocols for communication rendezvous in cognitive radio communications. ETCH can fully utilize spectrum diversity in communication rendezvous by allowing all the rendezvous channels to be utilized at the same time.;For the power management service, we improve its efficiency from three different angles. The first angle is to reduce energy consumption of WiFi communications. We propose HoWiES, a system-for WiFi energy saving by utilizing low-power ZigBee radio. The second angle is to reduce energy consumption of web based smartphone applications. We propose CacheKeeper, which is a system-wide web caching service to eliminate unnecessary energy consumption caused by imperfect web caching in many smartphone applications. The third angle is from the perspective of smartphone CPUs. We found that existing CPU power models are ill-suited for modern multicore smartphone CPUs. We present a new approach of CPU power modeling for smartphones. This approach takes CPU idle power states into consideration, and can significantly improve power estimation accuracy and stability for multicore smartphones.;For the location reporting service, we aim to design an efficient location proof solution for mobile location based applications. We propose VProof, a lightweight and privacy-preserving location proof scheme that allows users to construct location proofs by simply extracting unforgeable information from the received packets