Quality of Experience in Cloud services: Survey and measurements

Cloud-based systems are gaining enormous popularity due to a number of promised benefits, including ease of use in terms of deployment, administration and maintenance, high scalability as well as flexibility to create new services. However, as more personal and business applications migrate to the Cloud, the service quality becomes an important differentiator between providers, specially in the case of mobile operators. Quality of Experience (QoE) as perceived by the end-user has therefore the potential to become the guiding paradigm for managing quality provisioning and applications’ design in the Cloud. This paper presents the results of several Cloud QoE studies performed for different Cloud-based services, ranging from services with low requirements in terms of latency and interactivity (e.g., Cloud storage systems), multimedia On-Demand services (e.g., YouTube video streaming), communication and telepresence (e.g., Lync Online videoconferencing) to highly interactive services (e.g., Virtual Cloud Desktop). The results of these studies provide a ground truth basis for developing future Cloud services with QoE requirements, as well as for dimensioning the underlying network provisioning infrastructures, particularly with regard to mobile access technologies.     

Analysis of Skype VoIP traffic in UMTS: End-to-end QoS and QoE measurements

In the future Internet, multi-network services will follow a new paradigm in which the intelligence of the network control is gradually moved to the edge of the network. This impacts both the objective Quality of Service (QoS) of the end-to-end connection as well as the subjective Quality of Experience (QoE) as perceived by the end user. Skype already offers such a multi-network Voice-over-IP (VoIP) telephony service today. Due to its ease of use and a high sound quality, it becomes increasingly popular in the wired Internet.UMTS operators promise to offer large data rates which should suffice to support VoIP calls in a mobile environment. However, the success of those applications strongly depends on the corresponding QoE. In this work, we analyze the theoretically achievable as well as the actually achieved quality of IP-based voice calls using Skype. This is done performing measurements in both a real UMTS network and a testbed environment. The latter is used to emulate rate control mechanisms and changing system conditions of UMTS networks. The results show in how far Skype over UMTS is able to keep pace with existing mobile telephony systems and how it reacts to different network characteristics. The investigated performance measures comprise the QoE in terms of the MOS value and the QoS in terms of network-based factors like throughput, packet interarrival times, or packet loss.     

QoE assessment model for multimedia streaming services using QoS parameters

This paper proposes a video QoE (Quality of Experience) assessment model which can assess video quality of experience with only QoS (Quality of Service) parameters and their relative importance at network layer. Since network or service providers can forecast whether to provide multimedia services above a certain level of service quality using the proposed model, they can offer and maintain optimum network environment for multimedia service such as IPTV. Through an experiment of video quality comparison we show that our QoS/QoE correlation model is closely related with video quality degradation patterns to network environmental change.     

Adaptive IPTV services based on a novel IP Multimedia Subsystem

Heterogeneous communication devices are emerging and changing the way of communication. Innovative multimedia applications are now accessible through these embedded systems. The 3GPP IP Multimedia Subsystem (IMS) provides a basic architecture framework for the Next Generation Network (NGN) supporting the convergence platform for service provisioning in heterogeneous networks. ETSI TISPAN standardization effort focuses on delivering IPTV services on such platform. Nevertheless, IPTV on IMS standardization suffers from a lack of efficient user-centric network management mechanisms as the end-user may consume IPTV service from different access networks, on different mobile devices, at anytime. User’s Perceived Quality of Service (PQoS) or Quality of Experience (QoE) of IPTV service may also suffer from wireless access network impairments. This paper introduces new functionalities in IPTV over IMS architecture which optimize satisfaction of the end-user and resource utilization of the operator’s networks. A context-sensitive User Profile (UP) model is used to deliver IPTV streams adapted to the user’s environment. In order to optimize the operator network usage, the impact of spatiotemporal dynamics of the video content on the deduced perceptual quality is considered. A Multimedia Content Management System (MCMS) is proposed to perform dynamic cross-layer adaptation of the IPTV stream based on PQoS measurements at the end-user side.     

The relationship between quality of service perceived and delivered in mobile Internet communications

Today mobile network operators offer a wide variety of mobile Internet services to their customers including mobile email, banking, and news services. The acceptance of these services is heavily based on quality of service (QoS) experienced by the user. So far the discussion of QoS has been very network centric and the key to user satisfaction has been the network performance. In this paper we analyze the relationship between QoS perceived by the customer and network performance offered by the service provider. We conduct a lab experiment where network performance variables were controlled. Statistical analysis of the results indicates that there is no 1:1 correspondence or even truly linear relationship between network performance and perceived QoS as recommended by the International Telecommunications Union-Telecommunication (ITU-T). Instead the relationship varied from application to application. We examine several usability factors as potential reasons behind this phenomenon and make suggestions for future research.     

QoE management for video conferencing applications

We introduce a framework for managing the QoE of videos coded with the H.264 codec and transmitted by video conferencing applications through limited bandwidth networks. We focus our study on the medium-motion videos with QCIF, CIF, and VGA resolutions, the most pervasive video formats used by video conferencing applications across the Internet and cellular telephony systems. Using subjective tests for measuring the level of video quality perceived by end users, we expose the relation between the main influential video parameters and the quality experienced by end users. Furthermore, after investigating the effect of different frame rates and compression levels on video streaming bit rate, and consequently on QoE, we propose a QoE control mechanism for limited-bandwidth situations. A congestion control technique is also introduced in this paper and used in simulations for verifying the efficiency of the proposed QoE management algorithm and to implement this algorithm for practical applications.     

QoS Management by Means of Application Control

The complexity and sophistication of integratedbroadband networks call for a broad repertoire ofmanagement methods. Foreseen intensive competition ofthe communications market, and the upgrade ofend-customer's satisfaction as the focal point of anymanagement policy, raise a very important problem: howto utilize efficiently the resources of the networkwhile maintaining the Quality of Service (QoS) provided to end-users within a pre-negotiated range. Inthis paper, a QoS management architecture for multimediaapplications based on an application control scheme isproposed. Adhering to the Total Quality Management (TQM) paradigm, we let management span over theentire communication stack, the entire network(end-to-end) and the entire call duration. Applicationcontrol scheme aims to meet pre-specified QoS goals by adjusting the traffic produced by theend-user applications. The adjustment technique is basedon the notion that each multimedia session is allowed tooperate on a set of discrete application quality levels. A method for monitoring and assessingthe end-user perceived quality is presented. Themathematical problem of optimal resources allocation andan associated heuristic are specified. Finally, a specific instantiation of the introduced QoSmanagement architecture on a real testbed is describedand experimentation results are presented andevaluated.     

Location query based on moving behaviors

The importance of location prediction is rapidly increasing with the current trend of database applications in mobile computing environment. However, current personal communication services network could only provide currently maintained location information of non-idle mobile terminals. Pertinent researches predict the future location based on tangent velocity approaches, which require mobile terminals to spend lots of precious electronic power to sense and then measure a sequence of positions for predicting the future tangent velocity, and the prediction is effective only within a short range of time. In this study, we propose an approach to predict future locations of mobile terminals based on the moving behaviors mined from their long-term moving history. Location prediction based on moving behavior requires no power consumption for position measurement, and the prediction results are effective for a long time without requiring the queried clients to be non-idle. With the help of moving behavior, we propose several location prediction operators for location query. Finally, we demonstrate the accuracy of the location query operators through simulation statistics. The experimental results show that the predictions are accurate enough for regular moving mobile terminals.     

Implementation of 4kUHD HEVC-content transmission

The Internet of things (IoT) has received a great deal of attention in recent years, and is still being approached with a wide range of views. At the same time, video data now accounts for over half of the internet traffic. With the current availability of beyond high definition, it is worth understanding the performance effects, especially for real-time applications. High Efficiency Video Coding (HEVC) aims to provide reduction in bandwidth utilisation while maintaining perceived video quality in comparison with its predecessor codecs. Its adoption aims to provide for areas such as television broadcast, multimedia streaming/storage, and mobile communications with significant improvements. Although there have been attempts at HEVC streaming, the literature/implementations offered do not take into consideration changes in the HEVC specifications. Beyond this point, it seems little research exists on real-time HEVC coded content live streaming. Our contribution fills this current gap in enabling compliant and real-time networked HEVC visual applications. This is done implementing a technique for real-time HEVC encapsulation in MPEG-2 Transmission Stream (MPEG-2 TS) and HTTP Live Streaming (HLS), thereby removing the need for multi-platform clients to receive and decode HEVC streams. It is taken further by evaluating the transmission of 4k UHDTV HEVC-coded content in a typical wireless environment using both computers and mobile devices, while considering well-known factors such as obstruction, interference and other unseen factors that affect the network performance and video quality. Our results suggest that 4kUHD can be streamed at 13.5 Mb/s, and can be delivered to multiple devices without loss in perceived quality.

     

Qos-aware Middleware for Mobile Multimedia Communications

Next generation wireless communications system will be required to support the seamless delivery of voice, video and data with high quality. Delivering hard Quality of Service (QOS) assurances in the wireless domain is complex due to large-scale mobility requirements, limited radio resources and fluctuating network conditions. To address this challenge we are developing mobiware, a QOS-aware middleware platform that contains the complexity of supporting multimedia applications operating over wireless and mobile networks. Mobiware is a highly programmable software platform based on the latest distributed systems technology (viz. CORBA and Java). It is designed to operate between the application and radio-link layers of next generation wireless and mobile systems. Mobiware provides value-added QOS support by allowing mobile multimedia applications to operate transparently during handoff and periods of persistent QOS fluctuation.     

移动互联网视频传输优化的架构研究

随着3G移动互联网的快速发展,在手机等移动终端上看视频成为一种日常应用.但互联网上的大部分视频对于移动用户而言,其码率相对较大,而且移动用户的可用带宽受环境影响变化大,不稳定,影响了用户观看视频的体验.提出一种针对移动互联网的视频传输优化解决方案的系统架构,该架构从缓存和压缩两个方面入手,通过缓存缓解运营商的骨干网流量压力,通过视频压缩降低视频码率以满足用户的实际接入带宽.该架构既为运营商节约了带宽、降低了运营成本,同时也保证用户观看视频的连续性,提高用户体验.     

A Modular Approach to Mobile QoS Signaling— Motivation,Design & Implementation

In order to support mobile multimedia applications in next generation wireless IP-based networks, it is necessary to deliver seamless voice, video and data at high quality. Therefore, session mobility and Quality of Service (QoS) for mobile end systems are required. Within this article, the authors point out a new way to approach the problem. Instead of tightly coupling a modified QoS signaling mechanism with a certain mobility mechanism, a more generic and long-term solution is proposed and exemplified on the basis of existing IETF protocols. The connection-less IP network layer is enhanced by a lightweight and truly optional connection-oriented mobile network service, which offers the possibility to establish soft state unicast connections at the network layer. Hence, a connection-oriented network service is available within a radio access network (RAN) architecture to all end systems—mobile or fixed—independent of the application. Thereby, it is possible to integrate QoS and connectivity signaling for mobile end systems, as well as other connection-oriented services like explicit routing or load balancing.     

“I would like to see the subtitles and the face or at least hear the voice”: Effects of picture ratio and audio–video bitrate ratio on perception of quality in mobile television

In new mobile video applications, the subjectively perceived visual and audiovisual qualities are critical factors in the wide audience adoption of mass products. The critical factors in mobile video coding are related to low bitrates, framerates and screen size of the devices. The first part of this study examined the effects of codecs, bitrates and picture ratio on the perceived visual video quality. In the second study, effects of two audio–video bitrate ratios are presented as factors in the perceived audiovisual video quality and the results are compared to the previous study that showed the content dependency in the audio–video bitrate ratio comparisons. In the results of the visual quality study, H.264 was rated as the most satisfying, but the quality was still not enough for text legibility and perceiving important details of image due to the QCIF picture ratio. The codec XviD was in generally experienced as worse than the H.264, but with the screen size SIF-SP with XviD codec was rated better with several contents. In the audiovisual study, the results also showed that in the low total bitrates the significance of audio is increased. However, the higher and lower bitrates had similar content dependent effects.     

Measures of perceived end-user computing competency in an organizational computing environment

The proliferation of end-user computing has necessitated the development of reliable and valid instruments that can measure an end-user computing competency for improving an individual business performance. End-user computing competency influences how well an end-user can apply computing knowledge, applications, and computing systems to his or her tasks in an organizational computing environment. This study presents an instrument that can efficiently measure perceived end-user computing competency. Using a survey of 338 respondents, we conducted a correlation analysis between total scores and item scores and factor analysis, and proposed a 17-item instrument that measures the end-user computing competency. The validity and reliability of the instrument is presented, and the theoretical and practical application of this instrument is discussed.     

移动流媒体技术在视频监控中的应用

本文在介绍移动流媒体技术在视频监控中应用的系统结构基础上，着重阐述了在移动网络环境下，如何实现实时、可靠的流媒体传输。提出了码速控制技术、前向纠错技术、交织技术在无线传输中的应用。     

Improving application QoS with residential multihoming

An appealing solution for a networked end host to circumvent last mile congestion is to connect to multiple service providers simultaneously, which is known as multihoming. The differences in peering relationships among different service providers make it possible for multihomed hosts to use significantly different routes to the same destination. Therefore, multihoming can dynamically avoid points of congestion in the network by taking advantage of the choice among different routes available at any given time.In this paper, we evaluate the potential benefits of residential multihoming for different classes of applications. For Web access applications, we show that response times and download times can be significantly reduced by multihoming, and this is achievable by employing a simple measurement-based switching algorithm. For Voice-over-IP (VoIP) applications, we show via analysis and wide area experiments that perceived voice quality, as quantified by the Mean Opinion Score (MOS) metric, can be improved with a combination of multihoming and forward error correction coding. Finally, for video streaming applications, performance improvements can be realized by splitting video sessions over multiple physical links and migrating sessions to non-congested paths. Collectively, these results suggest that multihoming can be an effective solution to provide quality of service for diverse classes of Internet applications for residential users.     

移动流媒体技术在视频监控中的应用

本文在介绍移动流媒体技术在视频监控中应用的系统结构基础上,着重阐述了在移动网络环境下,如何实现实时、可靠的流媒体传输。提出了码速控制技术、前向纠错技术、交织技术在无线传输中的应用。     

Designing a collector overlay architecture for fault diagnosis in video networks

To prevent subscriber churn, network service providers of VoD, SDV and IPTV have a pressing need to pro-actively detect, isolate and fix outages within an access network. Network induced degradations prove to be detrimental for streaming applications. This typically leads to a poor quality of experience (QoE) for subscribers. By monitoring key functional points of the access network for traces of degradation, service providers can devise mechanisms to mitigate the problem.In this work we propose a hierarchy of exporters, collectors and ANCON (ANalysis and CONtrol) nodes that can semi-autonomously monitor, detect and isolate impairments within an access network. Exporters on the data plane gather and disseminate statistics for individual subnets, which are streamed onto “collector” nodes on an orthogonal plane. Collector nodes aggregate traffic from various exporters, and stream them onto the root of the tree (ANCON). With an even placement of exporters, root cause analysis can now take the granularity of loss rates or delay rates in individual segments or subnets of an access network. As an extension to our architecture, we show that the overlay can support instrumentations of quality evaluation for streaming video. As an example, we use a simple MOS plugin that is in part an extension of the ITU-T Erlang model to predict the quality of a video stream much before it reaches the end user. We show that our overlay can support a wide variety of quality evaluation metrics. Through extensive simulations and an implementation, we discuss issues of engineering such an overlay, isolating impairments in access networks, instrumenting MOS plugins and predicting video quality of multimedia streams in transit.     

信令网关仿真器的设计与实现

随着VoIP和第三代移动通信的发展，对信令网关的需求将会越来越多。因此，信令网关仿真器也有很大的发展前景。本文先后阐述了NO．7与IP的互通方式、信令网关仿真器的设计和实现。最后得出了实验结果。     

A survey of data-driven approach on multimedia QoE evaluation

With the development of mobile communication technology and the growth of mobile device, the requirements for user quality of experience (QoE) become higher and higher. Network operators and content providers are interested in QoE evaluation for improving users’ QoE. However, multimedia QoE evaluation faces severe challenges due to the subjective properties of the QoE. In this paper, we provide a survey of the state of the art about applying data-driven approach on QoE evaluation. Firstly, we describe the way to choose factors influencing QoE. Then we investigate and discuss the strengths and shortcomings of existing machine learning algorithms for modeling and predicting users’ QoE. Finally, we describe our research work on how to evaluate QoE in imbalanced dataset.