Defence of dissertation in the field of Network Economics, M.Sc. Lennart Schulte
The title of thesis is “Mobile network delay characteristics and interactions with the transport layer”
Mobile networks have become an integral part of everyday life with many users relying on its presence and performance. We can see this trend in the high growth of mobile subscriptions and data usage. In addition, there is a wide range of appli-cations being used, with very different requirements on the connectivity. A major part of the data volume being transmitted over mobile networks is trans-ferred as bulk, for example as app update or video download. The time for the video to start is critical, as user might abandon watching if loading times are too long, which in turn decreases revenue for content providers.
The protocol responsible for determining the sending rate is the Transmission Con-trol Protocol (TCP). As such, it is of major importance that mobile network and TCP work well together in order to provide optimal performance and user experience.
This dissertation highlights the interactions of TCP and mobile networks and inves-tigates bottlenecks and possible improvements. The study is based on a large amount of measurements from Finnish mobile networks performed by the users of Netradar/Nettitutka, a the crowd-sourced mobile measurement platform.
The results show that it is surprisingly common for TCP and the mobile network to interact badly, and that algorithms to handle certain problematic situations are hav-ing ill side effects. While the performance can be heavily increased by correctly configuring TCP, it shows that a closer interworking of protocols and new technolo-gies are needed for better interoperability and optimal performance.
Opponent: Professor Jussi Kangasharju, University of Helsinki, Finland.
Custos: Professor Jukka Manner, Aalto University School of Electrical Engineering, Department of Communications and Networking.