Quality Of Experience Model Research Articles

A Game Theoretic Framework for Quality of Experience Enhancement in Dense Stadia

In crowded venues, such as sports stadia, maintaining an acceptable network quality of experience (QoE) is hard to achieve. Installing small cells, distributed antenna systems or high-density WiFi in every stadium is too expensive for mobile network operators. Hence, we propose a novel distributed low-cost solution based on user coordination to improve the average QoE when the network capacity cannot be enhanced. Specifically, fans take turns in disabling their cellular connectivity, such that the connected users utilize the relaxed network to obtain then share common match data with the disconnected users via Peer-to-Peer (P2P) connectivity. To eliminate a free-riding behavior, a limited punishment strategy in a large repeated game is proposed and shown to yield an approximate subgame-perfect Nash equilibrium. In addition, we model human irrationality as game noise incorporated into the proposed equilibria. A proposed application-oriented QoE model is first obtained via SimuLTE, an extension of OMNET++, then used in MATLAB simulations to verify the proposed solution. The results show tangible gains realized by the proposed solution under realistic scenarios and parameters.

Quality of experience column

Research on Quality of Experience (QoE) has advanced significantly in recent years and attracts attention from various stakeholders. Different facets have been addressed by the research community like subjective user studies to identify QoE influence factors for particular applications like video streaming, QoE models to capture the effects of those influence factors on concrete applications, QoE monitoring approaches at the end user site but also within the network to assess QoE during service consumption and to provide means for QoE management for improved QoE. However, in order to progress in the area of QoE, new research directions have to be taken. The application of QoE in practice needs to consider the entire QoE eco-system and the stakeholders along the service delivery chain to the end user.

Active Learning for Crowdsourced QoE Modeling

Quality of experience (QoE) models predict the subjective quality of multimedia based on the relevant quality of service (QoS) factors. Due to the large space of QoS factors and the high costs of conducting subjective tests, efficient sampling strategies are required to determine which QoS configurations are to be queried, that is, evaluated by subjects. In this study, we extend the IQX model proposed by [M. Fiedler, T. Hosfeld, and P. Tran-Gia, “A generic quantitative relationship between quality of experience and quality of service,” IEEE Netw. , vol. 24, no. 2, pp. 36–41, Mar./Apr.2010.] toward a multidimensional QoS–QoE model (MIQX). To explore the complicated interaction between QoS factors more efficiently, we develop active learning algorithms for the multidimensional QoE model. Then, we conduct comprehensive experiments to compare the effectiveness of applying different sampling methods to crowdsourced video quality assessment tasks. In offline experiments that assume annotators give the same scores after changing the querying order, we demonstrate that active learning performs best and that a space-filling algorithm performs significantly better than random sampling. However, when we analyze the performance of the active sampling approaches more deeply using a novel field experiment, we observe that the active learning algorithms, which have been shown to be effective in the offline setting, can fail due to the habituation effect and individual differences of annotators. The active learning methods can also succeed when these issues are mitigated. These findings suggest that simply simulating the sample acquisition order, which is widely adopted in previous active learning literature [2] – [5] , is not sufficient for multimedia quality assessment tasks.

QoE-Driven Joint Optimization of Segment Adaptation and Resource Allocation for DASH Clients Over LTE Networks

In this paper, we focus on a comprehensive dynamic adaptive streaming over HTTP (DASH) framework, which consists of video content analysis at the HTTP adaptive streaming server, joint optimization of segment switch and resource allocation at eNodeB, and playback information extraction at the client, to improve the quality of experience (QoE) of the DASH clients over long-term evolution networks. We explore the unique characteristics of each segment by establishing the size-time and size-distortion models based on the video packet information extracted from the encoder rather than modeling the entire video sequence by a fixed function. Video quality, stability, and playback continuity can be predicted and reflected by these constructed models. Considering the above three factors, we develop an accumulative QoE model by calculating and predicting the QoE factors of each segment. Then, the entire framework is formulated as a mixed-integer non-linear programming mathematical model to maximize the total QoE of the DASH clients, where decisions on resource allocation and video segment switch are jointly optimized in a semi-synchronous centralized mode. Resource allocation consists of resource block assignment and modulation and coding scheme selection rather than only determining the resource utilization percentage. To perform the optimization, we develop a low-complexity heuristic algorithm that decomposes the original problem into multiple subproblems. The simulation results show that our proposed algorithms can efficiently improve the QoE level compared with other existing algorithms.

A Continuous QoE Evaluation Framework for Video Streaming Over HTTP

A continuous evaluation of the end user’s quality-of-experience (QoE) is essential for efficient video streaming. This is crucial for networks with constrained resources that offer time-varying channel quality to its users. In hypertext transfer protocol-based video streaming, the QoE is measured by quantifying the perceptual impact of distortions caused by rate adaptation or interruptions in playback due to rebuffering events. The resulting impact on the QoE due to these distortions has been studied individually in the literature. However, the QoE is determined by an interplay of these distortions, and therefore necessitates a combined study of them. To the best of our knowledge, there is no publicly available database that studies these distortions jointly on a continuous time basis. In this paper, our contributions are twofold. First, we present a database consisting of videos at full high definition and ultrahigh definition resolutions. We consider various levels of rate adaptation and rebuffering distortions together in these videos as experienced in a typical realistic setting. A subjective evaluation of these videos is conducted on a continuous time scale. Second, we present a QoE evaluation framework comprising a learning-based model during playback and an exponential model during rebuffering. Furthermore, we perform an objective evaluation of popular video quality assessment and continuous time QoE metrics over the constructed database. The objective evaluation study demonstrates that the performance of the proposed QoE model is superior to that of the objective metrics. The database is publicly available for download at http://www.iith.ac.in/~lfovia/downloads.html .

Enhancing QoE for Mobile Users by Environment-Aware HTTP Adaptive Streaming.

HTTP adaptive streaming (HAS) has become a dominated media streaming paradigm in today’s Internet, which enriches the user’s experience by matching the video quality with the dynamic network conditions. A range of HAS mechanisms have been proposed to enhance the Quality of Experience (QoE). However, existing mechanisms ignore the environmental impact in the QoE evaluation of mobile users, while the popularity of mobile video allows users to watch videos in diversified scenarios. In this paper, we propose an environment-aware HAS scheme that fully concentrates on the different criteria for evaluating video QoE under different environments. Using the advantage of the sensors in mobile phones, the scheme constructs and validates a video QoE model based on environment perception and then designs a model-driven, environment-aware HAS rate adaptation algorithm. We also evaluate the scheme with an environment-aware DASH (Dynamic Adaptive Streaming over HTTP) player in real mobile environments. Compared to the benchmark HAS mechanism, the experimental results demonstrate that our scheme can provide appropriate differentiated rate adaptation for different environments, resulting in a higher QoE.

An intelligent sampling framework for controlled experimentation and QoE modeling

For internet applications, measuring, modeling and predicting the quality experienced by end users as a function of network conditions is challenging. A common approach for building application specific Quality of Experience (QoE) models is to rely on controlled experimentation. For accurate QoE modeling, this approach can result in a large number of experiments to carry out because of the multiplicity of the network features, their large span (e.g., bandwidth, delay) and the time needed to setup the experiments themselves. However, most often, the space of network features in which experimentations are carried out shows a high degree of similarity in the training labels of QoE. This similarity, difficult to predict beforehand, amplifies the training cost with little or no improvement in QoE modeling accuracy. So, in this paper, we aim to exploit this similarity, and propose a methodology based on active learning, to sample the experimental space intelligently, so that the training cost of experimentation is reduced. We validate our approach for the case of YouTube video streaming QoE modeling from out-of-band network performance measurements, and perform a rigorous analysis of our approach to quantify the gain of active sampling over uniform sampling.

Two-phase rate adaptation strategy for improving real-time video QoE in mobile networks

With the popularity of smart handheld devices, mobile streaming video has multiplied the global network traffic in recent years. A huge concern of users' quality of experience (QoE) has made rate adaptation methods very attractive. In this paper, we propose a two-phase rate adaptation strategy to improve users' real-time video QoE. First, to measure and assess video QoE, we provide a continuous QoE prediction engine modeled by RNN recurrent neural network. Different from traditional QoE models which consider the QoE-aware factors separately or incompletely, our RNN-QoE model accounts for three descriptive factors (video quality, rebuffering, and rate change) and reflects the impact of cognitive memory and recency. Besides, the video playing is separated into the initial startup phase and the steady playback phase, and we takes different optimization goals for each phase: the former aims at shortening the startup delay while the latter ameliorates the video quality and the rebufferings. Simulation results have shown that RNN-QoE can follow the subjective QoE quite well, and the proposed strategy can effectively reduce the occurrence of rebufferings caused by the mismatch between the requested video rates and the fluctuated throughput and attains standout performance on real-time QoE compared with classical rate adaption methods.

Non-Cooperative Game Theory Based Rate Adaptation for Dynamic Video Streaming over HTTP

Dynamic Adaptive Streaming over HTTP (DASH) has demonstrated to be an emerging and promising multimedia streaming technique, owing to its capability of dealing with the variability of networks. Rate adaptation mechanism, a challenging and open issue, plays an important role in DASH based systems since it affects Quality of Experience (QoE) of users, network utilization, etc. In this paper, based on non-cooperative game theory, we propose a novel algorithm to optimally allocate the limited export bandwidth of the server to multi-users to maximize their QoE with fairness guaranteed. The proposed algorithm is proxy-free. Specifically, a novel user QoE model is derived by taking a variety of factors into account, like the received video quality, the reference buffer length, and user accumulated buffer lengths, etc. Then, the bandwidth competing problem is formulated as a non-cooperation game with the existence of Nash Equilibrium that is theoretically proven. Finally, a distributed iterative algorithm with stability analysis is proposed to find the Nash Equilibrium. Compared with state-of-the-art methods, extensive experimental results in terms of both simulated and realistic networking scenarios demonstrate that the proposed algorithm can produce higher QoE, and the actual buffer lengths of all users keep nearly optimal states, i.e., moving around the reference buffer all the time. Besides, the proposed algorithm produces no playback interruption.

QoE-driven big data management in pervasive edge computing environment

In the age of big data, services in the pervasive edge environment are expected to offer end-users better Quality-of-Experience (QoE) than that in a normal edge environment. However, the combined impact of the storage, delivery, and sensors used in various types of edge devices in this environment is producing volumes of high-dimensional big data that are increasingly pervasive and redundant. Therefore, enhancing the QoE has become a major challenge in high-dimensional big data in the pervasive edge computing environment. In this paper, to achieve high QoE, we propose a QoE model for evaluating the qualities of services in the pervasive edge computing environment. The QoE is related to the accuracy of high-dimensional big data and the transmission rate of this accurate data. To realize high accuracy of high-dimensional big data and the transmission of accurate data through out the pervasive edge computing environment, in this study we focused on the following two aspects. First, we formulate the issue as a high-dimensional big data management problem and test different transmission rates to acquire the best QoE. Then, with respect to accuracy, we propose a Tensor-Fast Convolutional Neural Network (TF-CNN) algorithm based on deep learning, which is suitable for high-dimensional big data analysis in the pervasive edge computing environment. Our simulation results reveal that our proposed algorithm can achieve high QoE performance.

User-centric QoE model of visual perception for mobile videos

It is crucial for service providers to improve user’s quality of visual perception for mobile users. Quality of experience (QoE) is an important perceptual visual metric. In this paper, we propose a user-centric QoE assessment model by joint considering technological-aware and psychology-aware parameters in the QoE communication ecosystem. For technological parameters, video encoding features are extracted from the video stream, and video content feature is estimated by video analysis. Moreover, user interests are also quantitatively collected as psychology parameters. Then, QoE model is developed by using support vector machine (SVM). Subjective tests have been performed. The collected data from subjective tests are used for training and validation of the proposed model. The experiment results show that the proposed user-centric QoE assessment model performs better in terms of high Pearson correlation coefficient (PCC) and low root-mean-square error (RMSE) compared with the conventional models.

Quality-of-Experience for Adaptive Streaming Videos: An Expectation Confirmation Theory Motivated Approach.

The dynamic adaptive streaming over HTTP (DASH) provides an inter-operable solution to overcome volatile network conditions, but how the human visual quality-ofexperience (QoE) changes with time-varying video quality is not well-understood. Here, we build a large-scale video database of time-varying quality and design a series of subjective experiments to investigate how humans respond to compression level, spatial and temporal resolution adaptations. Our path-analytic results show that quality adaptations influence the QoE by modifying the perceived quality of subsequent video segments. Specifically, the quality deviation introduced by quality adaptations is asymmetric with respect to the adaptation direction, which is further influenced by other factors such as compression level and content. Furthermore, we propose an objective QoE model by integrating the empirical findings from our subjective experiments and the expectation confirmation theory (ECT). Experimental results show that the proposed ECT-QoE model is in close agreement with subjective opinions and significantly outperforms existing QoE models. The video database together with the code are available online at https://ece.uwaterloo.ca/~zduanmu/tip2018ectqoe/.

A quantitative relationship between Application Performance Metrics and Quality of Experience for Over-The-Top video

Quality of Experience (QoE) is a measure of the overall level of customer satisfaction with a vendor. In telecommunications, consumer satisfaction is of great interest in the adoption of novel multimedia products and services. A number of factors can greatly influence the customer experience during a video session. Factors such as user perception, experience, and expectations are expressed by QoE while factors such as application and network performance are expressed by Quality of Service (QoS) parameters. This paper studies the relationship between QoS and QoE in a session-based mobile video streaming. Specific QoS Application Performance Metrics (APMs) are examined based on a QoE assessment database which is built for experimentation and contains 108 subjects. It is shown that these APMs are highly related to two QoE factors, Technical Quality (TQ) and Acceptability. Furthermore, Viewing Ration (VR) parameter and the corresponding Kendall correlation between VR and QoE factors proves that VR is a valuable metric for mapping QoS to QoE. We further generated the compacted decision tree to predict QoE factors through Rebuffering Ratio (RR), Non-interruption Content Viewing Ratio (VRc), and Non-interruption Viewing Ratio (VRs). Through extensive experimentation, a general relationship between APMs and QoE factors has been examined and a primary QoE model is proposed based on this relationship.

A Quality-of-Experience Database for Adaptive Video Streaming

The dynamic adaptive streaming over HTTP provides an inter-operable solution to overcome the volatile network conditions, but its complex characteristic brings new challenges to objective video quality-of-experience (QoE) measurement. To test the generalizability and to facilitate the wide usage of QoE measurement techniques in real-world applications, we establish a new database named Waterloo Streaming QoE Database III (SQoE-III). Unlike existing databases constructed with hand-crafted test sequences, the SQoE-III database, so far the largest and most realistic of its kind, consists of a total of 450 streaming videos created from diverse source content and diverse distortion patterns, with six adaptation algorithms of diverse characteristics under 13 representative network conditions. All streaming videos are assessed by 34 subjects, and a comprehensive evaluation is conducted on the performance of 15 objective QoE models from four categories with regards to their efficacy in predicting subjective QoE. Detailed correlation analysis and statistical hypothesis testing are carried out. The results of this paper shed light on the future development of adaptive bitrate streaming algorithm and video QoE monitoring system. The subjective database is available online at https://ece.uwaterloo.ca/~zduanmu/tbc2018qoe/ .

5G-QoE: QoE Modelling for Ultra-HD Video Streaming in 5G Networks

Traffic on future fifth-generation (5G) mobile networks is predicted to be dominated by challenging video applications such as mobile broadcasting, remote surgery and augmented reality, demanding real-time, and ultra-high quality delivery. Two of the main expectations of 5G networks are that they will be able to handle ultra-high-definition (UHD) video streaming and that they will deliver services that meet the requirements of the end user’s perceived quality by adopting quality of experience (QoE) aware network management approaches. This paper proposes a 5G-QoE framework to address the QoE modeling for UHD video flows in 5G networks. Particularly, it focuses on providing a QoE prediction model that is both sufficiently accurate and of low enough complexity to be employed as a continuous real-time indicator of the “health” of video application flows at the scale required in future 5G networks. The model has been developed and implemented as part of the EU 5G PPP SELFNET autonomic management framework, where it provides a primary indicator of the likely perceptual quality of UHD video application flows traversing a realistic multi-tenanted 5G mobile edge network testbed. The proposed 5G-QoE framework has been implemented in the 5G testbed, and the high accuracy of QoE prediction has been validated through comparing the predicted QoE values with not only subjective testing results but also empirical measurements in the testbed. As such, 5G-QoE would enable a holistic video flow self-optimisation system employing the cutting-edge Scalable H.265 video encoding to transmit UHD video applications in a QoE-aware manner.

Learning a Continuous-Time Streaming Video QoE Model

Over-the-top adaptive video streaming services are frequently impacted by fluctuating network conditions that can lead to rebuffering events (stalling events) and sudden bitrate changes. These events visually impact video consumers' quality of experience (QoE) and can lead to consumer churn. The development of models that can accurately predict viewers' instantaneous subjective QoE under such volatile network conditions could potentially enable the more efficient design of quality-control protocols for media-driven services, such as YouTube, Amazon, Netflix, and so on. However, most existing models only predict a single overall QoE score on a given video and are based on simple global video features, without accounting for relevant aspects of human perception and behavior. We have created a QoE evaluator, called the time-varying QoE Indexer, that accounts for interactions between stalling events, analyzes the spatial and temporal content of a video, predicts the perceptual video quality, models the state of the client-side data buffer, and consequently predicts continuous-time quality scores that agree quite well with human opinion scores. The new QoE predictor also embeds the impact of relevant human cognitive factors, such as memory and recency, and their complex interactions with the video content being viewed. We evaluated the proposed model on three different video databases and attained standout QoE prediction performance.

A Survey of Emerging Concepts and Challenges for QoE Management of Multimedia Services

Quality of Experience (QoE) has received much attention over the past years and has become a prominent issue for delivering services and applications. A significant amount of research has been devoted to understanding, measuring, and modelling QoE for a variety of media services. The next logical step is to actively exploit that accumulated knowledge to improve and manage the quality of multimedia services, while at the same time ensuring efficient and cost-effective network operations. Moreover, with many different players involved in the end-to-end service delivery chain, identifying the root causes of QoE impairments and finding effective solutions for meeting the end users’ requirements and expectations in terms of service quality is a challenging and complex problem. In this article, we survey state-of-the-art findings and present emerging concepts and challenges related to managing QoE for networked multimedia services. Going beyond a number of previously published survey articles addressing the topic of QoE management, we address QoE management in the context of ongoing developments, such as the move to softwarized networks, the exploitation of big data analytics and machine learning, and the steady rise of new and immersive services (e.g., augmented and virtual reality). We address the implications of such paradigm shifts in terms of new approaches in QoE modeling and the need for novel QoE monitoring and management infrastructures.

QoE-Aware OTT-ISP Collaboration in Service Management

It is a matter of fact that quality of experience (QoE) has become one of the key factors determining whether a new multimedia service will be successfully accepted by the final users. Accordingly, several QoE models have been developed with the aim of capturing the perception of the user by considering as many influencing factors as possible. However, when it comes to adopting these models in the management of the services and networks, it frequently happens that no single provider has access to all of the tools to either measure all influencing factors parameters or control over the delivered quality. In particular, it often happens to the over-the-top (OTT) and Internet service providers (ISPs), which act with complementary roles in the service delivery over the Internet. On the basis of this consideration, in this article we first highlight the importance of a possible OTT-ISP collaboration for a joint service management in terms of technical and economic aspects. Then we propose a general reference architecture for a possible collaboration and information exchange among them. Finally, we define three different approaches, namely joint venture, customer lifetime value based, and QoE fairness based. The first aims to maximize the revenue by providing better QoE to customers paying more. The second aims to maximize the profit by providing better QoE to the most profitable customers (MPCs). The third aims to maximize QoE fairness among all customers. Finally, we conduct simulations to compare the three approaches in terms of QoE provided to the users, profit generated for the providers, and QoE fairness.

A TOPSIS-based QoE model for adapted content selection of slide documents

In certain platforms, such as Google Docs, documents are adapted for specific mobile device types, and the installation of their applications is required. Although the documents can be accessed via Web browsers, their correctness is not guaranteed. In content selection, the document is adapted into various versions, from which the optimal one, based on a quality of experience (QoE) criterion, is delivered. Existing works evaluate the QoE of each content version using the user’s preferences and context parameters, such as device resolution and network bitrate. They ask the user to weight the context parameters, and then combine them using the simple-additive-weighting (SAW) method. However, not all users are familiar with the context parameters, and cannot understand their relationship with the requested content. Besides, not all parameters are compensatory to be summed up. In this paper, we propose a TOPSIS-based QoE model to address the two aforementioned drawbacks. We use the context parameters to define high-level functions understandable by all users, and combine them using the TOPSIS method. Experimental results show the convenience of our QoE model and its reliability over the SAW-based method, as well as the weighting-product (WP) method, which is used as an alternative to the SAW one.

Quality of experience enhancement of high efficiency video coding video streaming in wireless packet networks using multiple description coding

Recently, video streaming has attracted much attention and interest due to its capability to process and transmit large data. We propose a quality of experience (QoE) model relying on high efficiency video coding (HEVC) encoder adaptation scheme, in turn based on the multiple description coding (MDC) for video streaming. The main contributions of the paper are (1) a performance evaluation of the new and emerging video coding standard HEVC/H.265, which is based on the variation of quantization parameter (QP) values depending on different video contents to deduce their influence on the sequence to be transmitted, (2) QoE support multimedia applications in wireless networks are investigated, so we inspect the packet loss impact on the QoE of transmitted video sequences, (3) HEVC encoder parameter adaptation scheme based on MDC is modeled with the encoder parameter and objective QoE model. A comparative study revealed that the proposed MDC approach is effective for improving the transmission with a peak signal-to-noise ratio (PSNR) gain of about 2 to 3 dB. Results show that a good choice of QP value can compensate for transmission channel effects and improve received video quality, although HEVC/H.265 is also sensitive to packet loss. The obtained results show the efficiency of our proposed method in terms of PSNR and mean-opinion-score.