Mpeg-Dash Users' Qoe: The Segment Duration Effect

MPEG-DASH has become one of the mainstream methods for streaming video over unmanaged networks, as it enables users to receive this video at the best possible QoE level the network capacity and the users' terminals capabilities allow. However, it has been observed that when MPEG-DASH users, sharing the same access network, request, in parallel, the offered video content, QoE unfairness occurs: some users receive video content that corresponds to a high QoE level whereas all others do not. As a reason for this result, literature points out the inter-dynamics between TCP's congestion avoidance mechanism and the on-off operational pattern of MPEG-DASH switching logic. In this paper, we try to shed some more light on this QoE unfairness issue by investigating how the segment duration of the video content can effect the MPEG-DASH users' QoE level. Towards this, we designed a number of experiments where two identical users request, concurrently, the same video service, but utilising a different segment duration. As this work is part of a larger effort regarding MPEG-DASH, QoE and interactive digital broadcasting, we conducted our experiments over an interactive DVB-T testbed. The experimental results show a strong correlation between the video's segment duration and the MPEG-DASH users QoE level: the user utilising a longer segment duration achieves a higher QoE level than the one utilising a shorter segment duration.