Periodic Reporting for period 1 - VSDN (Video streaming services with Software-Defined Networking)
Reporting period: 2018-01-01 to 2019-12-31
VSDN developed a cross-layer QoE-aware media delivery platform of video streaming services and propose a network architecture, which combines service negotiation at the application level, with the concept of SDN, leading to optimal (in a QoE sense) path assignment. Specifically, the research objective of VSDN was to develop a novel SDN-based network architecture for network control and optimal resource allocation for video streaming: the aim was to investigate SDN principles to perform optimized path assignment while achieving the desired level of QoE. This includes the specification of the SDN controller functions which allocates resources to the network elements and configures the routing mechanisms. Moreover, the objective was to develop an end-to-end QoE-aware video streaming platform that adapts content delivery, considering their individual network conditions of each user and the overall topology and resources of the network in order to maximize the end-user QoE.
Moreover, we developed a QoE Monitoring Framework using SDN, in order to detect when the network conditions, such as packet loss and delay affect the video streaming and we developed a methodology to preserve the QoE in video applications. This is achieved by using an SDN Controller and implementing extra functionality on top of it in order to change the traffic’s transmission path to an alternative one, when QoE falls below a specified threshold. Also, we evaluated the proposed approach in a variety of network conditions to demonstrate the validity of the proposed methods.
The subjective tests have been contributed to ITU-T Study Group 12 Question 14, which provides recommendations on “Performance, Quality of Services and Quality of Experience” for multimedia services over networks. The fellow participated in several physical meetings of Question 14 of SG12 during the fellowship and contributed towards the standardization of the newly developed standard “Development of parametric models and tools for multimedia quality assessment”, and the outcome of the project will be directly applied to the new work item in Q.14 on adaptive streaming, named P.NATS which was standardized in December 2019 as ITU-T Rec. P.1204.
The main focus of research in this area so far is on the rate adaptation algorithms and an evaluation in mobile heterogeneous environments . However, the evaluation in these works primarily focuses on objective quality indicators (e.g. stalling/re-buffering events, number of quality switches) without assessing their synergistic impact on the actual QoE . Indeed, MPEG-DASH and its relationship to QoE are not yet well researched; first ideas on this topic are based on objective metrics not exactly reflecting QoE. According to its definition, QoE is influenced by user expectations, context, and personal preferences. Therefore, capturing and understanding end-users’ QoE goes beyond purely measuring video quality . To the best our knowledge, there are no studies to study the cross-layer synergistic cooperation and optimisation between the network architecture, the network virtualisation controls and functions, and the optimal streaming client adaptation to optimize the overall QoE of the end-users.