Network Impact on Quality of Experience of Mobile Video

University dissertation from Karlskrona : Blekinge Institute of Technology

Abstract: To an end user, Quality of Experience (QoE) matters more than Quality of Service (QoS) because she is the owner of her experience, which is the result of her perception. In recent times, QoE got increasingly much attention from service providers, operators, manufacturers and researchers. Amongst others, they are interested to know how the users perceive the quality of multimedia streaming and how to predict the QoE by measuring network performance parameters. Below the network layer, different access networks can be used, but the internet and transport layers remain the same for everyone on best-effort internet. We highlight a set of possible factors that are contributing towards the QoE, from network via transport to application layer, including applications, codecs, middleware and devices. To investigate the relationship of QoS and QoE, emulation-based experiments were designed. For the purpose of emulation, different shapers are in use by the research community. We selected three popular shapers, NetEm, NISTnet and KauNet, and investigated their emulation capabilities with focus on delay, delay variation and bit rate in order to be able to select the best-suited shaper for future use. Then, we studied the effect of QoS parameters on mobile video QoE. To evaluate the video QoE, user tests were conducted. We observe a much larger sensitivity of users to freezes and their placement within the video than what is predicted by an objective video quality assessment tool that is recommended by the standardisation organization ITU. Furthermore, we investigated the role of codec and device on QoE in view of network-induced problems.