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Interactive immersive media come with stringent network-level requirements such as high bandwidth (i.e., several Gbps) and low latency (i.e., five milliseconds). Today, most video-streaming applications leverage the transmission control protocol (TCP) for reliable end-to-end transmission. However, the reliability of TCP comes at the cost of additional delay due to factors such as connection establishment, head-of-line (HOL) blocking, and retransmissions under sub-optimal network conditions. Such behavior can lead to stalling events or freezes, which are highly detrimental to the user's Quality of Experience (QoE). Recently, QUIC has gained traction in the research community, as it promises to overcome the shortcomings of TCP without compromising on reliability. However, while QUIC vastly reduces the connection establishment time and HOL blocking, thus increasing interactivity, it still underperforms while delivering multimedia due to retransmissions under lossy conditions. To cope with these, QUIC offers the possibility to support unreliable delivery, like that of the user datagram protocol (UDP). While live-video streaming applications usually opt for completely unreliable protocols, such an approach is not optimal for immersive media delivery since it is not affordable to lose certain data that might affect the end user's QoE. In this paper, we propose a partially reliable QUIC-based data delivery mechanism that supports both reliable (streams) and unreliable (datagrams) delivery. To evaluate its performance, we have considered two immersive-video delivery use cases, namely tiled 360-degree video and volumetric point clouds. Our approach outperforms state-of-the-art protocols, especially in the presence of network losses and delay. Even at a packet loss ratio as high as 5%, the number of freezing events for a 120-second video is almost zero as against 120 for TCP.

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The rigidity of traditional network architectures, with tightly coupled control and data planes, impairs their ability to adapt to highly dynamic requirements of future application domains. While Software-Defined Networking (SDN) can provide the required dynamism, it suffers from scalability issues. Therefore, efforts have been made to propose alternative decentralized solutions, such as the flat distributed SDN architecture. Such alternatives address the scalability problem for mainly local flows, but are impaired by a substantial increase in the overhead for cross-domain flow setup. To manage the trade-off between scalability and overhead, there is a need for intermediate hierarchical solutions. However, these have not been explored to the complete potential so far. Furthermore, the Network Function Virtualization (NFV) paradigm complements SDN by offering computational and storage services in the form of Virtual Network Functions (VNFs). When integrated seamlessly, both SDN and NFV can offer solutions to the problems posed by highly dynamic application domains. Hence, this work proposes a scalable hierarchical SDN control plane architecture for SDN/NFV-based next-generation application domains such as immersive media delivery system. We have implemented the proposed architecture based on the well-known state-of-the-art ZeroSDN controller. To evaluate the performance of the architecture, we have implemented an on-demand immersive media (point cloud) streaming application and varied the load on the control plane using the background traffic. To benchmark our solution, we have evaluated its performance in comparison with the centralized and flat distributed architectures. We show that the proposed architecture performs better than the rest in terms of scalability, lost flows, and processing latency. Our study shows that the proposed architecture when distributed to three controllers, accepts 23% more flows with almost 70% reduced processing latency compared to the state-of-the-art ONOS controller.

Abstract-For a long time, the risk of customer churn, i.e. to leave an operator, has been used as argument in favor of Quality or Experience (QoE) research. However, the understanding of how churn behavior and QoE are related is still limited. This is problematic, as customer retention and churn prediction have grown in importance in face of ever-growing competition on the telecom market. The work presented in this paper aims to make a contribution in this respect, by exploring the relationships between QoE ratings, data volumes and churn risk through a longitudinal user study. Using an Experience Sampling Methodinspired approach we have been collecting weekly feedback on experienced quality, annoyance and intentions to churn from 22 users for up to eight weeks. Additionally, measurements of weekly used data volumes were collected. We observed churning behavior for 3 out of 22 participants and analyze the rating and data usage profiles of churners against non-churners. Furthermore, we investigate correlations of ratings and volumes, and find that "annoyed churners surf less". Our findings point out warning signals for potential user churn as well as promising directions for future studies.

Millimeter wave (mmWave) communication technology is expected to enable ultra-high speed and ultra-low latency communications owing to the availability of high-capacity bands at a frequency range of 30 GHz to 300 GHz. Despite its abundant resources, it is prone to signal attenuation due to blockage and mobility. So far, evaluations of first generation mmWave hardware are limited to lower-layer metrics. In this demonstrator, we propose to evaluate the multimedia application performance while using commercial off-the-shelf routers, using an 8K video streaming scenario. To achieve this, this paper introduces a mmWave testbed which incorporates mobility and blockage while streaming the video. In addition, it provides a detailed description of the steps involved in the deployment of experiments and analysis of the results.