Perceived QoS

ABSTRACT
After several years of research towards sophisticated QoS measurement tools and methods, the results given to end-users by most commonly used on-line speed measurement tools are still far from being precise. In order to define a reliable Internet speed measurement methodology for end- users, the impact that the static and dynamic constraints of network nodes and TCP/IP implementations could impose must be first carefully analyzed. Such constraints will deter- mine the measurement methodology to be defined in terms of measurement periods, number of concurrent connections and convergence time by deployment of controlled simula- tion/emulation environments and real world comparisons. This paper presents a detailed description of the works and leaves hints to be followed, aiming to get a full understanding of cross-layer effects during a speed test targeting end-user.

ABSTRACT
The evolution of Internet access technologies, together with the wide diversity of customer devices, has led to a complex scenario where measuring basic metrics with accuracy has become a rather complicated task. Although nowadays there are a lot of tools to assess the rate of Internet speed, most of them share neither the methodology nor the infrastructure to produce comparable results.

In this regard, the development of a unified approach to measure the Internet speed would be beneficial for all ICT players. The establishment of such proposal would inspire better confidence in consumers through the provision of precise comparisons, and it would also be very useful to operators, regulators and providers. Towards this aim, the ITU-T has been working on the definition of a unified methodology and measurement framework to assess the rate of Internet speed.

This paper presents a detailed description of the work that is being done at present in the definition of the aforementioned framework.

ABSTRACT
The current financial situation, together with the new market conditions, has led to major changes in the ICT sector over the last few years. Many of the services that were once only offered by operators are now being provided by third parties through the cloud. This situation has promoted new business models against the traditional ones. Furthermore, these economic changes have conducted to socio-cultural transformations with great impact on the user's behaviors. In this paper a cloud platform for the measurement and evaluation of the Quality of Experience (QoE) is presented. The platform is based in a model (QoXphere) that ensures the user satisfaction in terms of Quality of Service (QoS) and the provider economic benefits, as demanded in current market situation. In addition, the proposed cloud architecture intends to aid to advance in the work item opened recently in ITU-T to establish an ITU recognition procedure of testing laboratories with competence in ITU-T Recommendations.

ABSTRACT
The telecommunications sector has experienced significant changes over the past few years. The advent and rise of new applications and services, together with a competitive market, has led to a complex scenario in which quality of service (QoS) plays a major role. Under this condition, novel QoS regulation and standardization initiatives are required. During the last few years new terms and concepts, such as Quality of Experience (QoE) or QoS Perceived (QoP), have been included in the updated and new QoS-related standards as to better integrate the user’s point of view, as opposed to only network performance parameters. The influence of the user’s satisfaction on the Quality of Business (QoBiz) has also been given increased attention in the regulation and standardization bodies recently. The result is a loose collection of metrics and models that are not standardized and do not integrate all aspects of quality. Such integration is necessary to assure the successful development of this sector. This paper presents a new and integrated QoS model (QoXphere) that is spherical, adaptive and multi-layered.

ABSTRACT
Global interoperability testing, as defined in ITU T Q.3909, leads to complex experiments involving many actors and variables to be controlled. The definition and deployment of these experimental scenarios together with the development of the testing methodology is a major challenge that is essential for studying the impact of new technologies and networks on future society. This contribution proposes a collaborative testing platform (LabQoS) that provides the capability to define and share experimental scenarios and to test results. The platform has been designed to determine, develop and reproduce extensive QoS experimental scenarios and to make them available to researchers or members of standardization organizations in a collaborative environment.

ABSTRACT
This paper proposes the deployment of a network software platform for experimentation called LabQoS that will allow the scientific community to establish scientific experiments relating to measure the performance of applications and services on the Internet and other network environments. Previous experiences have already deployed measurement systems, but they don’t incorporate the concept of control of the scenario to enable the performing of experiments. This LabQoS capacity makes it an innovative platform unique in its approach. A module called Test Environment Builder has been designed in order to monitor the operating parameters, and to propose adaptation strategies to handle the scenario control variables. We define an experimental data model that identifies the entities to be considered in the management of the platform. Assessment mechanisms are proposed to study the dynamic sensitivity of the control variables with respect to the parameters. LabQoS is based on QoSMETER architecture that addresses technological aspects such as user management, deployment tools, data collection, reporting, security, etc.

ABSTRACT
The aim of this paper is to assess the impact of devices on Quality of Experience (QoE) of the user. As the types of video content viewed over handheld devices increases e.g. streaming video, it is important to evaluate the impact of the end device on video quality assessment. In this paper subjective tests were conducted with QCIF (176x144) videos over two devices 6 Personal Computer (PC) and mobile handset with 90 test conditions. The dataset was generated with a combination of parameters associated with the access network (block error rates and mean burst lengths), H.264 codec related parameter (sender bitrates) and content types. Subjects favoured PC test over handset test in almost all test scenarios. It was found that as the content activity increases device matters. These studies should help in context-aware services in deciding the encoding parameters based on type of device being used to receive content.

ABSTRACT
This paper deals with the analysis of user perceived visual quality for broadcast mobile TV services, considering energy constraints of mobile devices. A new broadcast multilayering video transmission scheme is proposed to cope with the heterogeneity of mobile devices capabilities, which enables mobile devices to achieve energy savings in accordance to the received visual quality. This new scheme includes audio transmission and still guarantees an acceptable channel switching delay. From subjective tests results, the impact of different service parameters is inferred. As concluded, an approach based on the fine tuning of video layer number and spatial resolution provides the highest achievable QoE level. An advanced decision making process is required to combine both QoE–awareness and energy–awareness.

ABSTRACT
In this paper, we consider mobile multimedia services delivered over a UMTS network. In this convergent scenario, low level error recovery mechanisms of the access network entail that almost all packet losses are caused by frames arriving at the receiver later than the playout time. Our aim is to find a simplified yet realistic expression for the statistics of the end-to-end delay in order to characterize related application level losses and infer resulting Quality of Experience (QoE). We present a simple and easy to implement model based on empirically obtained parameters that quantitatively reflects the statistical properties of delay. We apply the model to estimate the behavior of application level losses and delay which are the key factors while forecasting QoE in VoIP. Obtained results prove the suitability of the model to be integrated in cross-layer adaptation mechanisms and its utility for dimensioning VoIP playout buffers is also tested.

ABSTRACT
This paper deals with the analysis of user perceived visual quality for mobile multimedia services. H.264/AVC is selected for low resolution video encoding, and 3G UMTS is considered for mobile data services. From subjective tests results, the combined impact of different service- and network-level parameters is inferred. As a result, different cross-layer adaptation alternatives are proposed to maximize the perceived quality level under different service conditions.

ABSTRACT
The evolution of current networks to Next Generation Networks (NGNs) constitutes arguably the most significant transformation in the Telecommunication sector in recent decades. Quality of Service (QoS) is one of the key aspects in this evolution. In the NGN environment, networks are designed to be multiservice, supporting a wide range of premium services. Each of these services may have different QoS requirements which should be established based on the overall end user's perception. In this emerging context, novel QoS policies are required to adapt the traditional QoS regulatory model to the new scenario. This paper presents an approach to identify key factors that contributes to the development of future Internet quality of service regulation. A case study on the application of our user-centric QoS model to the Internet QoS regulation in Spain is described. The results of the study demonstrate the need for adapting current regulatory frameworks in order to ensure competition, pluralism and diversity in the new network environment.

ABSTRACT
In Universal Mobile Telecommunication System (UMTS) Radio Link Control (RLC) losses severely affect the Quality of Service (QoS) due to high error probability. Therefore, for any video quality prediction model, it is important to model the radio-link loss behaviour. In this paper we evaluate the impact of the radio access network on the end-to-end QoS for H.264 encoded video. In order to characterize the QoS level, a learning model based on Adaptive Neural Fuzzy Inference System (ANFIS) is proposed that takes into account the RLC loss models to predict the video quality in terms of the Mean Opinion Score (MOS). The RLC loss models considered are 2-state Markov models with variable mean burst lengths. The aim of the paper is two-fold. First, to find the impact of QoS parameters in both the physical and application layer on end-to-end video quality. Second, to propose a prediction model based on ANFIS to predict video quality over UMTS networks. ANFIS is well suited for video quality prediction over error prone and bandwidth restricted UMTS as it combines the advantages of neural networks and fuzzy systems. The ANFIS model is trained with a combination of application and physical layer parameters. The performance of the proposed model is validated with unseen dataset. These studies should help in the understanding of the impact of both the application and physical layer parameters on end-to-end video quality and in QoS control methods and adaptation.

ABSTRACT
The Quality of Service (QoS) of Universal Mobile Telecommunication System (UMTS) is severely affected by the losses occurring in Radio Link Control (RLC) due to high error probability. Therefore, for any video quality prediction model, it is important to model the radio-link loss behaviour appropriately. In addition, video content has an impact on video quality under same network conditions. The aim of this paper is to present video quality prediction models for objective, non-intrusive prediction of H.264 encoded video for all content types combining parameters both in the physical and application layer over UMTS networks. In order to characterize the QoS level, a learning model based on Adaptive Neural Fuzzy Inference System (ANFIS) is proposed to predict the video quality in terms of the Mean Opinion Score (MOS). ANFIS is well suited for video quality prediction over error prone and bandwidth restricted UMTS as it combines the advantages of neural networks and fuzzy systems. The loss models considered are 2-state Markov models with variable Mean Burst Lengths (MBLs) depicting the various UMTS scenarios. The proposed model is trained with a combination of physical and application layer parameters and validated with unseen dataset. Preliminary results show that good prediction accuracy was obtained from the model. The work should help in the development of a reference-free video prediction model and Quality of Service (QoS) control methods for video over UMTS networks.

ABSTRACT
Universal Mobile Telecommunication System (UMTS) is a third generation mobile communication systems that supports wireless wideband multimedia applications. The objective of this paper is to present a new model for non-intrusive prediction of H.264 encoded video quality over UMTS networks and to illustrate their application to video quality monitoring and adaptation in mobile wireless streaming services. First, we present an efficient regression model for predicting video quality non-intrusively for all content types. The model is predicted from a combination of a set of objective parameters in the application and physical layer in terms of the Mean opinion Score (MOS). The application layer parameters considered are the content type, sender bitrate and frame rate and the physical layer parameters are the block error rate modeled with 2 state Markov model for a mean burst length of 1.75. The performance of the proposed metric is evaluated with unseen dataset with good prediction accuracy. Second, we illustrate the application of the model in mobile streaming services by presenting a new Sender Bitrate (SBR) adaptation scheme at pre-encoding stage that is Quality of Experience (QoE) driven. The scheme was tested and evaluated in the NS2 based UMTS simulation network. Extensive simulation results demonstrate the effectiveness of the proposed adaptation scheme in terms of the MOS and especially at the UMTS network bottleneck access where perceived video quality is most affected. The proposed scheme was responsive to available network bandwidth and congestion and adapted the SBR accordingly maintaining acceptable quality in terms of the MOS. The proposed scheme has applications in network planning and content provisioning for network/service providers.

ABSTRACT
The provision of video streaming services over mobile data accesses is emerging as a promising service for the current and future Internet. This paper focuses on the study of H.264- based video contents over a typical 3G UMTS connectivity. The performance of the service is finally determined by the combined effects of the encoding features and the radio access characteristics. Therefore, based on the UMTS channel modeling, this paper tries to find out the optimal encoding configuration that provides the best service performance, in terms of Quality of Experience. In addition to other well-known encoding parameters, such as the source target bitrate, frame rate or resolution, this paper studies the impact of the maximum video slice size as a critical parameter for the performance of the considered service.

ABSTRACT
Quality of service has become one of the most important factors among Internet service providers. The implementation of appropriate QoS policies is essential in order to maintain customer loyalty and fulfill regulators' requirements. ITU-T recommendation E.802 provides a framework for the identification of QoS criteria relevant to users and ISPs. This Recommendation also provides guidelines to derive measurable QoS parameters from identified criteria. This article presents a QoS management model and implementation methodology for ISPs. We ground our investigation on the E.802 framework, which ISPs may face when implementing ITU-T Recommendation G.1000. The proposed methodology is meaningful for users, vendors, and network operators. Furthermore, its conformance with the ITU-T standard makes it suitable and deployment-ready for both regulators and providers.

ABSTRACT
This paper evaluates the performance of VoIP services over mobile accesses, with special focus on currently deployed Best Effort UMTS networks. There are different configuration parameters that have a great impact on end users' perception of quality. This paper tries to help understanding the impact of those parameters, and how they can be tuned for a better VoIP experience.

ABSTRACT
User’s requirements have become a key factor for any Quality of Service (QoS) management model to succeed. The advent and rise of new broadband services and network architectures (Triple-Play-Services, NGN…) depends on the ability of providers to achieve user’s expectations in these scenarios. For that reason, the overall end user’s perception (Quality of Experience – QoE) must be audited, on a regular basis, to address changing user’s needs. This paper presents a general system developed to evaluate QoE on IP networks. The system architecture is designed to be capable of emulating multi agent networks and dynamically changing conditions. In addition, the results of a Web browsing QoE experiment, laid out within this emulation system, are described. The experiment was conducted on the basis of ITU-T Recommendation G.1030, and aimed to update the perceptual model, provided in this Recommendation, to today’s user requirements and technical improvements.

ABSTRACT
This paper shows the relevance of implementing a dynamic and real-time Voice over IP (VoIP) service adaptation mechanism in order to avoid Perceived Quality of Service (PQoS) degradations. We have studied the most relevant parameters affecting the PQoS experienced by end users in VoIP services over mobile accesses. We will describe the enhancements carried out in the implementation of the simulation model in order to assess VoIP PQoS based on ITU-T E-model and introduce a real-time service adaptation method. This adaptation method involves codec and packetization changes through SIP signalling, jointly to dejittering buffer management, and would be launched upon detection of PQoS degradation, in order to enhance end users' experience.

ABSTRACT
IMS entails novel business opportunities for pioneering and emerging multimedia services, such as IPTV and VoIP video call applications. However, this strong commercial interest on this promising convergent IMS environment is balanced by the lack of efficient user/customer-centric network management mechanisms. ADAMANTIUM proposes an IMS-compatible Multimedia Content Management System (MCMS) focused on performing dynamic cross layer adaptations for optimization of the user experience in terms of perceptual quality for media services. This multimodal management system will be applied in an integrated and coherent way along all the network layers and delivery-chain nodes based on a user/customer-centric approach rather than a typical engineering one.

ABSTRACT
Traditional QoS related studies handle technical KPI (key performance indicators) which are supposed to measure the quality of telecommunication services. However, while trying to select an ISP, most users are not able to choice the most suitable one for their needs. This papers presents the application of a perceived QoS based model as a tool for helping users in this kind of decisions. Our model represents the impact of each one of the objective performance indicators on the perception of quality for a particular user profile. Once the model is built common users will be able to identify the best combination of performance indicators for their pattern of use of the different Internet services. We have used velocimetro.org, a website that provides measurement services for common users, in order to feed the model with real world values and compare 4 different Spanish ISPs.

ABSTRACT
In last years there have been some governmental initiatives aimed at the regulation of quality of service evaluation in telecommunications services. However this has proven to be a complex task especially for Internet services, where it is difficult to objectively assess the quality of a service and to identify whether one or more of the provider agents are responsible of final dissatisfaction of users. This paper affords the cited problem and intends to provide a methodology to asses the quality of service as perceived by end users. The aims of the proposed model are twofold: the evaluation of perceived quality of service (PQoS) based on subjective and objective measurements and the identification of responsibilities of the different agents involved in a service provision.

ABSTRACT
This paper presents a comprehensive model intended to analyze quality of service in telecommunications services and its causes. Although many works have been published in this area, both from a technical viewpoint as well as taking into consideration subjective concerns, they have not resulted in a unique methodology to assess the experienced quality. While most of the studies consider the quality of service only from a technical and end-to-end point of view, we try to analyze quality of service as a general gauge of final users' satisfaction. The proposed model allows us to estimate the quality experienced by end users, while offering detailed results regarding the responsibility of the different agents involved in the service provision. Once we overview the most significant elements of the model, an in-depth analytical study is detailed. Finally, we illustrate a practical study for web browsing service in order to validate the theoretical model.

ABSTRACT
This paper presents a comprehensive model intended to analyse general quality in telecommunications services centred in end users’ perceived quality (PQoS). The proposed model allows us to estimate the quality experienced by end users, while offering detailed analyses regarding the responsibility of the different agents involved in the service provision. We overview the structure of the model, that resembles QFD general quality model. Then we describe a practical study where the variation of the global satisfaction of users is estimated. This approximation is carried out by means of the evaluation of a set of telecommunications services with diverse nature, such as web browsing, VoIP and even technical support. Finally, we use the multiple linear regression method for assessing different providers' contribution to the PQoS in every considered network state.

ABSTRACT
This paper presents an overview of the research activities accomplished in the 'Telematics Engineering Group' (UPV/EHU) in the area of perceived QoS. We go over the achieved works until the current day and we present as well the scheduled research tasks regarding the measurement of QoS from an end user perspective. The proposed theoretical model is intended to analyse the performance experimented in every agent involved in the provision o f Internet services. Furthermore, we state several in-progress enhancements to the model and introduce an approach to empirically validate the model.