such as smartphones with multiple wireless interfaces. However, the high energy consumption of Wi-Fi interfaces, especially when a device is idle, presents a significant barrier to the widespread adoption of VoIP over Wi-Fi. To address this issue, we present Cell2Notify, a practical and deployable energy management

such as smartphones with multiple wire-less interfaces. However, the high energy consumption of Wi-Fi interfaces, especially when a device is idle, presents a significant barrier to the widespread adoption of VoIP over Wi-Fi. To address this issue, we present Cell2Notify, a practical and deployable en-ergy management

si-multaneously utilizes two communication channels: cellular links carrying streaming content from the media Cloud to smartphones and WiFi links enabling cooperation among smartphones. There are three key contributions. First, the system copes with the variable loss rate and bandwidth fluctuation

a massive deployment of wireless networks, often in the form of WiFi hotspots, more and more attention is expected to be devoted to the energy-efficient management of wireless access infrastructure. These networks tend to be dense and over– provisioned, which in time leads to significant energy

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I first thank my thesis advisors Thiemo Voigt and Adam Dunkels for being my excellent advisors, and also for being the great colleagues you still are. Thiemo and Adam have complemented each other superbly, giving me feedback, perspectives, insights, and having made every single new venture truly fun. My deepest thanks also go to my professor Per Gunningberg, Uppsala University. Per has in a seemingly easy way spotted erroneous assumptions, has valued my research contributions, and has connected my own work with another broader world of research. I want to thank all colleagues in the Networked Embedded Systems group:

1. Networking trends 2. QoS over data networks 3. Label switching 4. Gigabit, 10 Gb Ethernet, RPR 5. Storage area networks 6. IP over DWDM 7. Wireless 8. Voice over IP

Vast majority of wireless appliances used in household, industry and medical field share the ISM frequency band. These devices need to coexist and thus are challenged to tolerate their mutual interference. One way of dealing with this is by using frequency hopping; where the device changes its

Digitising statistics handling through

the desperation of users. To establish a secure basis for Internet communication, we propose SafeSlinger, a system leveraging the proliferation of smartphones to enable people to securely and privately exchange their public keys. Through the exchanged authentic public key, SafeSlinger establishes a secure channel