Dinh-Xuan, L., Popp, C., Burger, V., Wamser, F., Hoßfeld, T.: Impact of VNF Placements on QoE Monitoring in the Cloud.International Journal of Network Management. (2018).
Wamser, F., Lombardo, C., Vassilakis, C., Dinh-Xuan, L., Lago, P., Bruschi, R., Tran-Gia, P.: Orchestration and Monitoring in Fog Computing for Personal Edge Cloud Service Support.2018 IEEE International Symposium on Local and Metropolitan Area Networks (LANMAN) (2018).
Loh, F., Wamser, F., Hoßfeld, T., Tran-Gia, P.: Quality of Service Assessment of Live Video Streaming with a Remote-Controlled Drone.IEEE Conference on Network Softwarization. , Montreal, Canada (2018).
Today's networks require a deep understanding of applications to optimize networks, efficiently design networks, and meet traffic demands, application heterogeneity, and application requirements. Current application areas include live video streaming and real-time applications, such as those that are named in 5G use cases with automation, disaster recovery, gaming, and Industry 4.0. In this work, we examine an application scenario with live video streaming and parallel real-time requirements in the uplink for disaster recovery. We study the quality of service (QoS) features of a remote-controlled drone. The drone is controlled via a tablet or smartphone while the video from the camera is transmitted from the drone to the user. There are high demands in both the uplink and downlink direction. The contribution of the work is the measurement of the QoS and application parameters for this scenario and the definition of influencing parameters for the application-layer.
Seufert, M., Zach, O., Slanina, M., Tran-Gia, P.: Unperturbed Video Streaming QoE Under Web Page Related Context Factors.9th International Conference on Quality of Multimedia Experience (QoMEX). , Erfurt, Germany (2017).
Quality of Experience (QoE) of Internet services is affected by human, system, and context influence factors. While most QoE studies so far are focused on system factors only, this work will assess the impact of context factors of video streaming on QoE. As video streaming is mostly consumed from web pages, such as video portals, the investigated test conditions are applied to the web page, which embeds the video player. Therefore, the study of context factors is implicitly conducted within a crowdsourced QoE study. The test conditions considered different page load times, poster image qualities, and displayed advertisements on the web page, which are typical context factors when consuming a video streaming service. The results of the study show that the modification of the context factors on the streaming web page leaves the users' QoE rating unperturbed, which suggests that the investigated context factors have a negligible impact on video streaming QoE, or that the rating task of the subjective QoE study superimposed the context factors.
Dinh-Xuan, L., Seufert, M., Wamser, F., Tran-Gia, P.: Study on the Accuracy of QoE Monitoring for HTTP Adaptive Video Streaming Using VNF.1st IFIP/IEEE International Workshop on Quality of Experience Management (QoE-Management). , Lisbon, Portugal (2017).
The fast growth of HTTP video streaming is responsible for a huge amount of traffic over the past few years. Due to the variety and popularity of video content, more and more people are watching videos on the smart TV or on mobile devices. As a result, a potential market is emerging for video providers, which can significantly increase their revenues. In order to offer users a good experience, adaptive video streaming has been introduced to adapt the video quality to the network conditions. Nevertheless, it is still difficult for the network operators to assess the actual video quality on the device of the users and therefore they can not react to improve the service on the network. In this work, we propose a Virtual Network Function (VNF) to monitor the Quality of Experience (QoE) for online video service in the network. To conduct the study, on the one hand, we design a VNF monitoring to measure the video quality and estimate the QoE at the client machine. Our function is placed in two locations nearby and far away from the user to analyze the impact of geographical placement of the VNF on its performance. On the other hand, we set up a local testbed to examine the functional operation and measure the actual video buffer from a client web browser directly to validate the accuracy of the function. Our findings show that with respect to function placement, the VNF has high accuracy in estimating the QoE if it is deployed at the edge network close to the user. However, the VNF does not perform well when it operates far away from the users, e.g., at data centers. These insights help network vendors to more closely monitor the quality of the videos streamed to their customers.
Seufert, M., Wehner, N., Wamser, F., Casas, P., D'Alconzo, A., Tran-Gia, P.: Unsupervised QoE Field Study for Mobile YouTube Video Streaming with YoMoApp.9th International Conference on Quality of Multimedia Experience (QoMEX). , Erfurt, Germany (2017).
YoMoApp (YouTube Monitoring App) is an Android app to monitor mobile YouTube video streaming on both application- and network-layer. Additionally, it allows to collect subjective Quality of Experience (QoE) feedback of end users. During the development of the app, the stable versions of YoMoApp were already available in the Google Play Store, and the app was downloaded, installed, and used on many devices to monitor streaming sessions. As the app was not advertised in special campaigns or used for dedicated QoE studies, the monitored streaming sessions of this period compose the data set of a large unsupervised field study. The collected data set is evaluated to characterize current mobile YouTube streaming on both application and network layers. Furthermore, the problems and methodology to obtain QoE results from such unsupervised field study are discussed together with the actual QoE results. Correlations between QoE factors are investigated, and the QoE of clusters of similar streaming sessions is analyzed.
Wamser, F., Loh, F., Bruschi, R., Lago, P., Seufert, M., Tran-Gia, P.: Dynamic Cloud Service Placement for Live Video Streaming with a Remote-Controlled Drone, (2017).
The continuous growth of Internet content, applications and services has led to ever more demanding requirements in the networks. To meet this, there have been significant developments in the migration of applications and services towards the cloud. The cloud not only provides applications, but also offers dynamic adaptability, scalability, and optimization with respect to the location of the application by migrating storage and application containers. In particular, cloud services can typically be placed and orchestrated at a variety of locations in the cloud. This demonstration shows a dynamic placement of a cloud service with video streaming and real-time control commands for a remote-controlled drone. We control a drone with the help of a cloud service which, in addition to the control commands, also returns a camera image to the operator. The requirements of this cloud application are groundbreaking. The camera requires high data rates from the drone to the cloud and from the cloud to the operator, so that the image can be transmitted in acceptable quality. For the control of the drone, a short delay must also be given in the direction of the drone so that the control can be carried out in real time.
Seufert, M., Kamneng Kwam, B., Wamser, F., Tran-Gia, P.: EdgeNetworkCloudSim: Placement of Service Chains in Edge Clouds Using NetworkCloudSim.1st IEEE International Workshop on Network Programmability - From the Data Center to the Ground (NetFoG). , Bologna, Italy (2017).
Edge cloud computing is a trending paradigm, which extends cloud computing by additionally utilizing computing resources at the network edge, e.g., at mobile base stations. Especially personalized services can be instantiated or migrated close to end users, which improves the latency and supports user mobility. However, the placement of the service chains is crucial for the performance of the services and the energy consumption of the edge cloud platform, and appropriate algorithms have to be designed. To support the simulative performance evaluation of such algorithms, EdgeNetworkCloudSim was developed. It is an extension of NetworkCloudSim, and allows to simulate and evaluate the orchestration and consolidation of service chains in an edge network cloud.
Wamser, F., Höfner, S., Seufert, M., Tran-Gia, P.: Server and Content Selection for MPEG DASH Video Streaming with Client Information.ACM SIGCOMM Workshop on QoE-based Analysis and Management of Data Communication Networks (Internet-QoE). , Los Angeles, CA, USA (2017).
In HTTP adaptive streaming (HAS), such as MPEG DASH, the video is split into chunks and is available in different quality levels. If the video chunks are stored or cached on different servers to deal with the high load in the network and the Quality of Experience (QoE) requirements of the users, the problem of content selection arises. In this paper, we evaluate client-side algorithms for dynamically selecting an appropriate content server during DASH video streaming. We present three algorithms with which the DASH client itself can determine the most appropriate server based on client-specific metrics, like actual latency or bandwidth to the content servers. We evaluate and discuss the proposed algorithms with respect to the resulting DASH streaming behavior in terms of buffer levels and quality level selection.
Loh, F., Burger, V., Wamser, F., Tran-Gia, P., Schembra, G., Rametta, C.: Performance Evaluation of Video Streaming Service Chains in Softwarized 5G Networks with Task Graph Reduction.29th International Teletraffic Congress (ITC) (2017).
Iffländer, L., Wamser, F., Metter, C., Tran-Gia, P., Kounev, S.: Performance Assessment of Cloud Migrations from Network and Application Point of View.Proceedings of 9th EAI International Conference on Mobile Networks and Management (MONAMI 2017). , Melbourne, Australia (2017).
Dinh-Xuan, L., Seufert, M., Wamser, F., Tran-Gia, P.: QoE Aware Placement of Content in Edge Networks on the Example of a Photo Album Cloud Service.IEEE 6th International Conference on Communications and Electronics (ICCE). , Ha Long, Vietnam (2016).
The paradigm of Software as a Service has gained great achievements in the last decade. By transferring computation and storage to the cloud and migrating services to the edge network, users benefit from using demanding services on lightweight devices. However, the user perceived quality of experience (QoE) for these services is facing the challenges of network impairments and the accessibility of users. Unlike a typical PC-based software, the cloud provides users a location-aware, flexible placement of resource for a cost effective service. The geographical placement of content is therefore one of the key factors that affects the user's satisfaction. The closer the content to the user geographically is, the faster it will be delivered to the user that will also increase the user perceived QoE. In this work, we estimate more precisely the QoE for photo loading time in a particular usage of a photo album cloud service with regard to the influence of various parameters. Firstly, we validate a TCP throughput model and use it to calculate the photo loading time from a given photo size and network QoS. Thereafter, we formulate a mapping function to calculate the MOS value from a QoE model adding the output of the TCP model. From this mapping function, we can estimate QoE for photo loading time from a given photo size, its placement and network QoS. Our main contribution is to determine the trade-off between the size of photo and its placement to acquire a high QoE for photo loading time, which is important for the development of a photo album cloud service.
Wamser, F., Casas, P., Seufert, M., Moldovan, C., Tran-Gia, P., Hoßfeld, T.: Modeling the YouTube Stack: from Packets to Quality of Experience.Computer Networks.109,211-224 (2016).
YouTube is one of the most popular and volume-dominant services in today’s Internet, and has changed the Web for ever. Consequently, network operators are forced to consider it in the design, deployment, and optimization of their networks. Taming YouTube requires a good understanding of the complete YouTube stack, from the network streaming service to the application itself. Understanding the interplays between individual YouTube functionalities and their implications for traffic and user Quality of Experience (QoE) becomes paramount nowadays. In this paper we characterize and model the YouTube stack at different layers, going from the generated network traffic to the QoE perceived by the users watching YouTube videos. Firstly, we present a network traffic model for the YouTube flow control mechanism, which permits to understand how YouTube provisions video traffic flows to users. Secondly, we investigate how traffic is consumed at the client side, deriving a simple model for the YouTube application. Thirdly, we analyze the implications for the end user, and present a model for the quality as perceived by them. This model is finally integrated into a system for real time QoE-based YouTube monitoring, highly useful to operators to assess the performance of their networks for provisioning YouTube videos. The central parameter for all the presented models is the buffer level at the YouTube application layer. This paper provides an extensive compendium of objective tools and models for network operators to better understand the YouTube traffic in their networks, to predict the playback behavior of the video player, and to assess how well they do it in the practice with the satisfaction of their customers watching YouTube.
Wamser, F., Seufert, M., Höfner, S., Tran-Gia, P.: Concept for Client-initiated Selection of Cloud Instances for Improving QoE of Distributed Cloud Services.ACM SIGCOMM Workshop on QoE-based Analysis and Management of Data Communication Networks (Internet-QoE). , Florianópolis, Brazil (2016).
We introduce a concept for client-initiated selection of service location and service quality for improving the Quality of Experience (QoE) of general cloud services. It is loosely based on the HTTP adaptive streaming approach (e.g., MPEG DASH). A manifest file compiled by the cloud service provider specifies the available service locations and qualities, from which the user selects the optimal service instance based on contextual information obtained from client measurements and user preferences. The proposed concept is defined and is implemented in two client-based decision algorithms for improving the QoE of a simple picture gallery cloud service. These decision algorithms are evaluated and their impact on the service delivery is discussed. The evaluation shows that it is possible to improve the service location and quality selection by light-weight client-based algorithms.
Seufert, M., Casas, P., Wamser, F., Wehner, N., Schatz, R., Tran-Gia, P.: Application-Layer Monitoring of QoE Parameters for Mobile YouTube Video Streaming in the Field.IEEE 6th International Conference on Communications and Electronics (ICCE). , Ha Long, Vietnam (2016).
YouTube video streaming is one of the most popular and most demanding services in cellular networks. Thus, operators are concerned about the quality of the streaming delivered by their networks and would like to monitor the Quality of Experience (QoE) of the end users. In this work, we conduct a field study of mobile YouTube video streaming, in which both network flow parameters and application-layer streaming parameters were monitored, and present the characteristics of current mobile YouTube streaming. The impact of both approaches is investigated showing that monitoring network parameters is not sufficient to directly infer the resulting QoE. In contrast, the streaming parameters, which can be obtained from application-layer monitoring, show high correlations to the subjectively experienced quality, and thus, are better suited for QoE monitoring.
Burger, V., Frances Pajo, J., Sanchez, O.R., Seufert, M., Schwartz, C., Wamser, F., Davoli, F., Tran-Gia, P.: Load Dynamics of a Multiplayer Online Battle Area and Simulative Assessment of Edge Server Placements.ACM Multimedia Systems Conference (MMSys). , Klagenfurt, Austria (2016).
Free-to-play models, streaming of games and eSports are reasons for online gaming to grow in popularity recently. On the forefront are multiplayer online battle arenas, which gain high popularity by introducing a competitive format that is easy to access and requires cooperation and team play. These games highly rely on fast reaction of the players, which makes latency the key performance indicator of such applications. To obtain low latency, this paper proposes moving game servers close to players towards the edge of the network. The performance of such mechanism highly depends on the geographic distribution of players. By analyzing match histories and statistics, we develop models for the arrival process and location of game requests. This allows us to evaluate the performance of edge server resource migration policies in an event based simulation. Our results show that a high number of edge servers is preferable compared to few larger edge servers to reduce the latency of players. This supports approaches that allow deploying virtual server instances in the back-haul.
Burger, V., Darzanos, G., Papafili, I., Seufert, M.: Trade-Off between QoE and Operational Cost in Edge Resource Supported Video Streaming.10th International Conference on P2P, Parallel, Grid, Cloud and Internet Computing (3PGCIC). , Krakow, Poland (2015).
The largest share of today`s consumer Internet traffic is video streaming and its demand on content delivery networks is continuously growing. To cope with the increasing demand of video streaming, recent work proposes mitigating end-user equipment to support content delivery at the edge of the network. The throughput of end-user equipment supporting content delivery is limited by the uplink of the users Internet connection.Especially for video streaming insufficient throughput causes the video to stall and affects the Quality of Experience (QoE) of end-users.To prevent video streams from stalling, we consider a tiered caching architecture, which requests higher tier caches to support content delivery, if the uplink throughput drops below a certain threshold. We conduct a simulative performance evaluation of the mechanism to investigate its impact on the QoE of end-users. Our results show that especially if the upload bandwidth of end-user equipment is low the setting of the threshold has a high impact. This can be used by operators to achieve the desired trade-off between QoE and operational cost for cache resources.
Seufert, M., Burger, V., Wamser, F., Tran-Gia, P., Moldovan, C., Hoßfeld, T.: Utilizing Home Router Caches to Augment CDNs towards Information-Centric Networking.European Conference on Networks and Communications (EuCNC). , Paris, France (2015).
To implement improved Quality of Service (QoS) and Quality of Experience (QoE) management for content-heavy services like video streaming, content has to be moved closer to the edge. The concept of information-centric networking (ICN) would be a prospective enabler but is currently not practically feasible yet. We propose a hierarchical caching architecture utilizing caches on home routers to augment existing content delivery network (CDN) infrastructure. This approach can be implemented via Software-defined Networking (SDN) and brings current CDNs closer towards ICN. Based on a simulation study, we confirm that our approach is able to serve content more locally, which results in QoS and QoE benefits for end users as well as inter-domain traffic savings for network operators.