ABSTRACT
Taking a look over current mobile implementations, the overhead introduced by the uplink signaling can be prevented reducing the rate of Channel Quality Information reports sent from the mobile users to the channel-aware schedulers located at base stations. In this context, the main goal of the present work is to handle the problem of scheduling traffic flows in modern wireless downlink systems under partially observable channel feedback. With this objective, we focus on the design of an scheduler aimed at minimizing the mean flow delay. In this way, we model the optimization problem as a Partially Observable Markov Decision Process, which depends on the belief state of each users best channel condition. Due to the complexity of the model, we consider the Whittle index-based relaxation, and we derive an index rule which is easily implementable. Whittle indices are obtained offline by means of an algorithm called Adaptive Greedy. The proposed scheduling policy consists in giving priority to the users with the highest Whittle index value. The resulting scheduling solution is then evaluated in both single-class and multi-class scenarios, using real-world channel quality traces in the performed experiments. The obtained results show that the proposed scheduling index rule outperforms the well-known channel-aware disciplines.

ABSTRACT
In the context of cloud-enabled 5G radio access networks with network function virtualization capabilities, we focus on the virtual network function placement problem for a multi-tenant cluster of small cells that provide mobile edge computing services. Under an emerging distributed network architecture and hardware infrastructure, we employ cloud-enabled small cells that integrate micro servers for virtualization execution, equipped with additional hardware appliances. We develop an energy-aware placement solution using a robust optimization approach based on service demand uncertainty in order to minimize the power consumption in the system constrained by network service latency requirements and infrastructure terms. Then, we discuss the results of the proposed placement mechanism in 5G scenarios that combine several service flavours and robust protection values. Once the impact of the service flavour and robust protection on the global power consumption of the system is analyzed, numerical results indicate that our proposal successes to efficiently place the virtual network functions that compose the network services in the available hardware infrastructure while fulfilling service constraints.

ABSTRACT
This paper focuses on multi-tenant 5G networks with virtualization and mobile edge computing capabilities, in the scope of cloud-enabled small cell deployments. In this context, the work here presented deals with the service management and orchestration challenges that arise when handling service mapping on the multi-tenant distributed cloud-enabled radio access network architecture. For that aim, once analysed cloud edge services management and 5G network instantiation in the OpenStack platform, we modify the provided virtual infrastructure manager so as to incorporate virtual network function placement features of the SESAME environment. As main contributions, we adapt the OpenStack application instances to 5G Network Service instantiation, and we include an energy-aware and latency-constrained placement solution.

ABSTRACT
In the context of ultra-dense heterogeneous networks in 5G, we focus on the load balancing problem of elastic traffic in a single macrocell that is supported by a number of small cells. Each small cell is modeled by a single-class processor sharing queue, whereas the macrocell is modelled by a multi-class processor sharing queue. We assume that the macrocell is always consuming energy, while a small cell can be switched off when it is idle with the setup delay penalty. As the main contribution, aimed at minimizing the weighted sum of the mean delay and the mean power consumption in the system, we develop static and dynamic load balancing policies that take into account the setup delay. All the obtained results are analytically founded. The performance of the static policy is evaluated using the achieved analytical expressions which include the static optimal probabilities achieved before, whereas for the dynamic policy we need to carry out simulations using previously obtained numerical results from the first policy iteration procedure. As concluded, numerical results indicate that the dynamic policy outperforms the static policy under realistic settings.

ABSTRACT
Hurrengo belaunaldiko sareen kudeaketak eskakizun erronkariei aurre egin behar izango die birtualizazio, softwarizazio eta cloud computing bezalako teknologia gaitzaileen aplikazioaren bitartez. Horrelako kudeaketa egoera konplexuan, adimen artifizialaren erabilpena ziklo kognitibo gisa erreminta ezberdintzaile eta ahaltsua bilakatu daiteke sistemaren errendimendu orokorra hobetzeko. Lan honek cloud-ean oinarritutako maila-anitzeko ziklo kognitiboa aurkezten du, aurresandako printzipioak aprobetxatzen dituena, 5G arkitekturaren kontrol eta kudeaketa atazak bermatzeko. Eredu berriztatzaile honek eskema kognitibo zentralizatu eta banatuak konbinatzen ditu modulu erabakitzaileetan sare arkitekturaren maila ezberdinetan, ertza eta cloud ingurunearen arteko elkareragiketa sustatzeko.

ABSTRACT
Sare baliabideen esleipenean kalitate subjektiboaren maximizaziorako planifikazioaren garrantziaren eta beharraren aurrean, lan honetan erabiltzaileek hautemandako kalitatearen maximizazioa helburutzat duen sare baliabideen planifikaziorako scheduling algoritmoetan sakondu da. Ikerketa hau matematika arloan ekarpen handia duten Gittins zein Whittle metodoen bidez lortutako kalitate subjektiboaren maximizaziorako scheduling indize erregela motako soluzioen azterketan zentratu da. Modu honetan, lehenik eta behin, bi diziplina horiek aurkeztu dira, Gittins-ena sinpleagoa izanik. Ondoren, bi planifikazio politika horien errendimendua erkatu da, Whittle-en soluzioak emaitza nabarmenki hobeak erakusten dituelarik. Ondorio bezala, indizearen konplexutasunaren eta eskuratu nahi den kalitate subjektiboaren zehaztasunaren arabera, Gittins-en edo Whittle-n oinarritutako proposamena aukeratuko da.

ABSTRACT
One of the most challenging problems in mobile broadband networks is how to assign the available radio resources among the different mobile users. Traditionally, research proposals are either specific to some type of traffic or deal with computationally intensive algorithms aimed at optimizing the delivery of general purpose traffic. Consequently, commercial networks do not incorporate these mechanisms due to the limited hardware resources at the mobile edge. Emerging 5G architectures introduce cloud computing principles to add flexible computational resources to Radio Access Networks. This paper makes use of the Mobile Edge Computing concepts to introduce a new element, denoted as Mobile Edge Scheduler, aimed at minimizing the mean delay of general traffic flows in the LTE downlink. This element runs close to the eNodeB element and implements a novel flow-aware and channel-aware scheduling policy in order to accommodate the transmissions to the available channel quality of end users.

ABSTRACT
This paper presents a novel architecture for optimizing the HTTP-based multimedia delivery in multi-user mobile networks. This proposal combines the usual client-driven dynamic adaptation scheme DASH-3GPP with network-assisted adaptation capabilities, in order to maximize the overall Quality of Experience. The foundation of this combined adaptation scheme is based on two state of the art technologies. On one hand, adaptive HTTP streaming with multi-layer encoding allows efficient media delivery and improves the experienced media quality in highly dynamic channels. Additionally, it enables the possibility to implement network-level adaptations for better coping with multi-user scenarios. On the other hand, mobile edge computing facilitates the deployment of mobile services close to the user. This approach brings new possibilities in modern and future mobile networks, such as close to zero delays and awareness of the radio status. The proposal in this paper introduces a novel element, denoted as Mobile Edge-DASH Adaptation Function, which combines all these advantages to support efficient media delivery in mobile multi-user scenarios. Furthermore, we evaluate the performance enhancements of this content- and user context-aware scheme through simulations of a mobile multimedia scenario.

ABSTRACT
This paper deals with the classical problem of radio resource management in LTE MIMO, with special focus to the specific radio channel characteristics in commercial LTE networks. First, we provide some conclusions about the Channel Quality Information traces obtained through field testing. From this analysis, we perform a series of experiments by means of an LTE emulator in order to evaluate the accuracy of different fading models used in the 3GPP. As a first outcome of the paper, we infer several fine-grain channel characteristics useful to feed further research work in the area of LTE MIMO. As a second contribution of the paper, we analyze the performance of classical schedulers (i.e., Round Robin, Best CQI and Proportional Fair) under the obtained LTE MIMO channel conditions. Specifically, we analyze the impact of the channel feedback reporting rate in scenarios with multiple greedy sources.

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 services that in the past were only offered by operators are now held by third parties through the cloud, which has caused a shift towards new business models at the expense of a more traditional market. 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 help in the advance of the work item recently opened in ITU-T to establish an ITU recognition procedure of testing laboratories with competence in ITU-T Recommendations by providing a unified cloud environment in which to validate them.

ABSTRACT
This paper deals with the resource allocation problem aimed at maximizing users’ perception of quality in wireless channels with time-varying capacity. First of all, we model the ubjective quality-aware scheduling problem in the framework of Markovian decision processes. Then, given that the obtaining of the optimal solution of this model is unachievable, we propose a simple scheduling index rule with closed-form expression by using a methodology based on Whittle approach. Finally, we analyze the performance of the achieved scheduling proposal in several relevant scenarios, concluding that it outperforms the most popular existing resource allocation strategies.

ABSTRACT
In this paper we study how to design a scheduling strategy aimed at minimizing the average holding cost for flows with general size distribution when the feasible transmission rate of each user varies randomly over time. We employ a Whittle-index-based approach in order to achieve an opportunistic and non-anticipating size-aware scheduling index rule proposal. When the flow size distribution belongs to the Decreasing Hazard Rate class, we propose the so-called Attained Service Potential Improvement index rule, which consists in giving priority to the flows with the highest ratio between the current attained service-dependent completion probability and the expected potential improvement of this completion probability. We further analyze the performance of the proposed scheduler, concluding that it outperforms well-known opportunistic disciplines.

ABSTRACT
This paper deals with the analysis of mobile multimedia services, with special focus on current media resolutions for mobile handsets. Since variable network conditions entail variable quality levels, nowadays several applications implement some kind of dynamic service adaptation in order to mitigate these effects. This paper analyzes the service performance from an end-to-end perspective, taking into account the several agents involved in the service provision. From a detailed study, the different possible sources of degradations are identified as well as their impact into the expected quality as perceived by end users. Based on the obtained results, the possible effects of different adaptation capabilities are discussed. The identification of the main source of degradations at the destination endpoint improves the adaptation capabilities and enhances the service performance in terms of perceived quality.

ABSTRACT
Most multimedia applications implement some kind of packet losses analysis mechanism to trigger self–adaptation actions. However, error recovery mechanisms such as ARQ variants avoid packet losses at IP level. Then, there appears an impact into the delay that may indeed result on application–level losses due to samples arriving later than the scheduled playout time. In most cases such degradations are not detected until they are so severe than even losses at IP level appear. We propose a lightweight method that achieves a finer grain estimation. We prove mathematically the capability of modified versions of statistics of delay to predict the error ratio of the wireless link and the load of the wired backhaul. After deducing also simplified heuristics for proposed method, we analyze their estimation capabilities and provide guidance for selecting appropiate parameters.

ABSTRACT
This paper deals with the subjective quality maximization problem when scheduling multimedia traffic flows in a shared channel. In order to quantify such user satisfaction a utility function dependent on flow transfer delay is used. In this context, we formulate the Quality of Experience aware resource allocation optimization problem as a Markov Decision Process. This model is analytically unsolvable in general, and as an approximate solution we develop a simple and tractable index rule based on Gittins approach, originally aimed just at minimizing mean flow delay. As concluded from simulation results, when evaluating subjective quality performance this novel index rule proposal outperforms the most relevant existing scheduling disciplines.

ABSTRACT
A major issue in the application of ad hoc networking to Wireless Networked Robotics is the choice of the routing protocol that performs better in a given scenario. However, far too little attention has been paid to routing issues involving enhanced robotic nodes. In view of the lack of a significant and comprehensive analysis, this research work completes an in-depth performance comparison of mostly well-known ad hoc routing protocols under a wide variety of conditions and applies the obtained results to a case study with three examples of real-world Wireless Networked Robotics scenarios.

ABSTRACT
Scalable video coding allows an efficient provision of video services at different quality levels with different energy demands. In order to deal with the resulting trade-off we analyze the number of video layers that are worth to be received taking into account the energy constraints. On one hand, a single-objective optimization is proposed based on dynamically selecting the number of layers, which is able to minimize the energy consumption with the constraint of a minimal quality threshold to be reached. However, this approach cannot reflect the fact that the same increment of energy consumption may result on different increments of visual quality. Thus, a multi-objective optimization is proposed and a utility function defined in order to weight the energy consumption and the visual quality criteria. Finally, since the optimization solving mechanism is computationally expensive to be implemented in mobile devices, a heuristic algorithm is proposed. This way mobile operators and end users could significally reduce their energy consumption while keeping reasonable quality levels.

ABSTRACT
This paper deals with the problem of scheduling mobile Internet traffic over a single cell wireless downlink data channel. On the one hand, we compare the performance of different size-based or/and channel-aware scheduling disciplines in mean delay terms, concluding that an approach that combines both size- and channel-awareness is the best alternative, which guarantees acceptable uplink overhead due to channel information reports. On the other hand, we study the impact of different scheduling algorithms on user's satisfaction for web browsing service. As concluded, in order to achieve a trade-off between maximizing overall mean subjective quality and reducing uplink signaling overhead due to channel quality reports, a scheduling policy that benefits from opportunistic gains in combination with a size-aware tie-breaking rule gives the best results.

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 a mobile UMTS network is considered for the access to services. First, from subjective tests results, the combined impact of different service- and radio 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. Afterwards, the backhaul segment is considered taking into account possible congestion effects after the aggregation of multi-user media stream. The proposed dynamic adaptation process determines the best combination of media bitrates in order to optimise the overall quality, by making use of information related to network performance both at the radio and backhaul segments.

ABSTRACT
The main scope of the chapter is to present the overall QoE-driven IPTV architecture and the respective perceptual benchmarking of it via a subjective evaluation procedure. The chapter is organized as follows: Section 15.2 presents an overview of all the core components of the adaptive IPTV system (IMS, QoE, Perceptual Cross layer adaptation, network management, etc.). In Section 15.3, the user-centric IPTV architecture is presented, containing NQoS to PQoS mapping operations, the Multimedia Content Management System, the monitoring and adaptation modules presentation, the enhancements of the current IMS functions, and UMTS/ WiMAX technologies QoE/QoS mapping. Section 15.4 analyzes in depth the QoE model used for IPTV cross-layer adaptation. Section 15.5 concludes the benchmarking of the whole architecture, and finally Section 15.6 draws the conclusions.

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 inclusion of multimedia content in different web-based services has increased significantly. Through an extensive subjective testing campaign, we analyse the quality of experience concerning video transmissions associated to these types of services when accessed from mobile devices and mobile Internet connections. Contrary to traditional normalised quality assessment studies, we point out the service context as a key aspect in quality assessments. Specifically, we analyse the impact of the duration of the test material on quality assessments. We find out that tolerance to visual degradations is higher in the specific context of use compared to when using standardised methodologies for quality assessment, which has a significant impact in terms of commercial service acceptability.

ABSTRACT
This paper focuses on multi-tenant 5G networks with virtualization and mobile edge computing capabilities, in the scope of cloud-enabled small cell deployments. In this context, the work here presented deals with the service management and orchestration challenges that arise when handling service mapping on the multi-tenant distributed cloud-enabled radio access network architecture. For that aim, once analysed cloud edge services management and 5G network instantiation in the OpenStack platform, we modify the provided virtual infrastructure manager so as to incorporate virtual network function placement features of the SESAME environment. As main contributions, we adapt the OpenStack application instances to 5G Network Service instantiation, and we include an energy-aware and latency-constrained placement solution.

ABSTRACT
The Cloud Enabled Small Cell (CESC) concept proposed in EU funded project SESAME has emerged as a promising solution to form a multi-tenant, multi-service architecture at the network edge according to 5G needs. It allows several operators/service providers to engage in a sharing model of both radio access capacity and Mobile Edge Computing (MEC) capabilities. From a business perspective, the shared ecosystem guarantees benefits such as easy system upgrades and CAPEX/OPEX reduction. However, depending on the adapted model which is reflected at Service Level Agreement (SLA) between involved stakeholders, cost and benefit of each party are subject to change. This paper is an effort to identify and analyse different radio and cloud models and pricing schemes for the joint provisioning of radio access capacity and MEC services in a multi-tenant Radio Access Network (RAN).

ABSTRACT
Radio Resource Management (RRM) function is a critical element in multi-user mobile networks. Nowadays, RRM is implemented at the 4G radio edge in order to enhance channelawareness and thus to optimize the efficiency of radio resources, at the cost of high computational requirements at the radio nodes. Current trends towards Network Function Virtualization aim at enabling software-based networking capabilities at different locations of the radio network architecture. This paper analyzes the impact of moving RRM functions to different Radio Access Network locations and with different channel quality feedback periods. Based on simulation results, the paper analyzes the experienced performance of different channel-aware scheduling strategies in the context of multi-user mobile multimedia scenarios with different radio channel conditions.

ABSTRACT
Este artículo trata sobre los esquemas de distribución de contenido multimedia a través de Internet, con especial interés en Internet móvil. Tanto la variabilidad de la calidad de los accesos radio como el incremento del tráfico multimedia plantean nuevos retos en relación a la gestión dinámica de los servicios sobre recursos de red compartidos. En primer lugar, el artículo ofrece una revisión del estado de la tecnología relacionada con el transporte multimedia extremo a extremo. A continuación, el artículo se centra en analizar la evolución de los mecanismos de adaptación dinámica, incluyendo desde esquemas extremo a extremo hasta la gestión dinámica de los recursos de red. Se analizan las posibles ventajas asociadas a nuevas arquitecturas como la computación en la nube móvil y las futuras redes 5G. Finalmente, el artículo identifica una serie de retos y desafíos en la gestión adaptativa de los servicios multimedia en el futuro.

ABSTRACT
One of the most challenging problems in mobile broadband networks is how to assign the available radio resources among the different mobile users. Traditionally, research proposals are either specific to some type of traffic or deal with computationally intensive algorithms aimed at optimizing the delivery of general purpose traffic. Consequently, commercial networks do not incorporate these mechanisms due to the limited hardware resources at the mobile edge. Emerging 5G architectures introduce cloud computing principles to add flexible computational resources to Radio Access Networks. This paper makes use of the Mobile Edge Computing concepts to introduce a new element, denoted as Mobile Edge Scheduler, aimed at minimizing the mean delay of general traffic flows in the LTE downlink. This element runs close to the eNodeB element and implements a novel flow-aware and channel-aware scheduling policy in order to accommodate the transmissions to the available channel quality of end users.

ABSTRACT
This work deals with the problem of scheduling traffic flows in emerging wireless networks. In actual mobile implementations the channel state feedback from the users to the radio schedulers may be deployed based on periodic reports in order to avoid uplink signaling overhead. In this work, we study how to design schedulers under partially observable channels. For that aim, we employ the Whittle index approach using a Partially Observable Markov Decision Process. We further analyze the performance of the derived scheduling solution, both in single-class and multi-class scenarios. Real-world channel quality traces are employed in experiments. Finally, we conclude that the proposed scheduling index rule outperforms well-known channelaware disciplines.

ABSTRACT
This paper deals with the classical problem of radio resource management in LTE MIMO, with special focus to the specific radio channel characteristics in commercial LTE networks. First, we provide some conclusions about the Channel Quality Information traces obtained through field testing. From this analysis, we perform a series of experiments by means of an LTE emulator in order to evaluate the accuracy of different fading models used in the 3GPP. As a first outcome of the paper, we infer several fine-grain channel characteristics useful to feed further research work in the area of LTE MIMO. As a second contribution of the paper, we analyze the performance of classical schedulers (i.e., Round Robin, Best CQI and Proportional Fair) under the obtained LTE MIMO channel conditions. Specifically, we analyze the impact of the channel feedback reporting rate in scenarios with multiple greedy sources.

ABSTRACT
In this paper we study how to design a scheduling strategy aimed at minimizing the average holding cost for flows with general size distribution when the feasible transmission rate of each user varies randomly over time. We employ a Whittle-index-based approach in order to achieve an opportunistic and non-anticipating size-aware scheduling index rule proposal. When the flow size distribution belongs to the Decreasing Hazard Rate class, we propose the so-called Attained Service Potential Improvement index rule, which consists in giving priority to the flows with the highest ratio between the current attained service- dependent completion probability and the expected potential improvement of this completion probability. We further analyze the performance of the proposed scheduler, concluding that it outperforms well-known opportunistic disciplines.

ABSTRACT
In this paper we study how to design an opportunistic scheduler when flow sizes have a general service time distribution with the objective of minimizing the expected holding cost. We allow the channel condition to have two states which in particular covers the important special case of ON/OFF channels. We formulate the problem as a multi-armed restless bandit problem, a particular class of Markov decision processes. Since an exact solution is out of reach, we characterize in closed-form the Whittle index, which allows us to define a heuristic scheduling rule for the problem. We then particularize the index to the important subclass of distributions with a decreasing hazard rate. We finally evaluate the performance of the proposed Whittleindex based scheduler by simulation of a wireless network. The numerical results show that the performance of the proposed scheduler is very satisfactory.

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
This paper deals with the analysis of the impact of different scheduling algorithms on flow level mean delay performance of elastic traffic in a single cell wireless downlink data channel paradigm. An enhanced size-based and channelaware discipline is proposed, which is based on the sized-aware Gittins index approach applied to a time-varying channel context. In order to compare the proposed Opportunistic Gittins rule performance with well-known scheduling algorithms, several simulations have been performed for stochastically arriving flows with Pareto sizes under fading conditions, for different network loads and channel quality indicator reporting rates. As concluded, an approach that combines both flow size-awareness and channel awareness is the best option, which guarantees a trade–off between minimizing uplink overhead due to channel quality reports and improving scheduling performance aimed at reducing overall flow mean delay.

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
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 article tries to specify the basis of a project about a new system to control and manage an Internet quality test that measures the access speed of Internet users. We will explain the current situation of the service to look for the necessities, and then try to propose tools to solve those necessities. These tools must be integrated in a common interface to give the administrator of the service an easy-to-use environment as long as a powerful system to manage the quality test tool. To conclude, we will propose the necessary technologies to implement the different parts of the system.