Harilaos Koumaras

A Theoretical Framework for End-to-End Video Quality Prediction of MPEG-based Sequences

This paper presents a novel theoretical framework for end-to-end video quality prediction of MPEG-based video sequences. The proposed framework encloses two discrete models: (i) A model for predicting the video quality of an encoded signal at a pre-encoding stage and (ii) A model for mapping QoS-sensitive network parameters (i.e. packet loss) to video quality degradation. The efficiency of both the discrete models is experimentally validated, proving by this way the accuracy of the proposed framework.

Video Quality Prediction Models Based on Video Content Dynamics for H.264 Video over UMTS Networks

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 Universal Mobile Telecommunication Systems (UMTS) networks. In order to characterize the Quality of Service (QoS) level, a learning model based on Adaptive Neural Fuzzy Inference System (ANFIS) and a second model based on non-linear regression analysis is proposed to predict the video quality in terms of the Mean Opinion Score (MOS). The objective of the paper is two-fold. First, to find the impact of QoS parameters on end-to-end video quality for H.264 encoded video. Second, to develop learning models based on ANFIS and non-linear regression analysis to predict video quality over UMTS networks by considering the impact of radio link loss models. The loss models considered are 2-state Markov models. Both the models are 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 both the models. The work should help in the development of a reference-free video prediction model and QoS control methods for video over UMTS networks.

SDN/NFV-enabled satellite communications networks

In the context of next generation 5G networks, the satellite industry is clearly committed to revisit and revamp the role of satellite communications. As major drivers in the evolution of (terrestrial) fixed and mobile networks, Software Defined Networking (SDN) and Network Function Virtualisation (NFV) technologies are also being positioned as central technology enablers towards improved and more flexible integration of satellite and terrestrial segments, providing satellite network further service innovation and business agility by advanced network resources management techniques. Through the analysis of scenarios and use cases, this paper provides a description of the benefits that SDN/NFV technologies can bring into satellite communications towards 5G. Three scenarios are presented and analysed to delineate different potential improvement areas pursued through the introduction of SDN/NFV technologies in the satellite ground segment domain. Within each scenario, a number of use cases are developed to gain further insight into specific capabilities and to identify the technical challenges stemming from them.

A framework for end-to-end video quality prediction of MPEG video

This paper proposes, describes and evaluates a novel framework for video quality prediction of MPEG-based video services, considering the perceptual degradation that is introduced by the encoding process and the provision of the encoded signal over an error-prone wireless or wire-line network. The concept of video quality prediction is considered in this work, according to which the encoding parameters of the video service and the network QoS conditions are used for performing an estimation/prediction of the video quality level at the user side, without further processing of the actual encoded and transmitted video content. The proposed prediction framework consists of two discrete models: (i) a model for predicting the video quality of an encoded signal at a pre-encoding stage by correlating the spatiotemporal content dynamics to the bit rate that satisfies a specific level of user satisfaction; and (ii) a model that predicts primarily the undecodable frames (and subsequently the perceived quality degradation caused by them) based on the monitored averaged packet loss ratio of the network. The proposed framework is experimentally tested and validated with video signals encoded according to MPEG-4 standard.

Shot boundary detection without threshold parameters

Automatic shot boundary detection is a field, where many techniques and methods have been proposed and have claimed to perform reliably, especially for abrupt scene cut detection. However, all the proposed methods share a common drawback: the necessity of a threshold value, which is used as a reference for detecting scene changes. The determination of the appropriate value or the dynamic reestimation of this threshold parameter remains the most challenging issue for the existing shot boundary detection algo- rithms. We introduce a novel method for shot boundary detection of discrete cosine transform (DCT)-based and low-bit-rate encoded clips, which exploits the perceptual blockiness effect detection on each frame without using any threshold parameter, therefore mini- mizing the processing demands required for algorithm

QoE4CLOUD: A QoE-driven multidimensional framework for cloud environments

Cloud Operators, in order to respond effectively to the QoS requirements of cloud applications, are obliged to apply over-provisioning policies. In general, this tactic leads to severe waste of the available cloud computing resources. Similarly, both Service/Platform Providers and End-Users wish to avoid the extra cost of this over-provisioning tactic and pay only per use, without having to statically reserve extra resources in advance. As a consequence, the cloud community urgently asks for flexible and intelligent management solutions, towards enhanced and efficient utilization of the cloud. The ultimate target of any intelligent cloud management scheme should be the provision of a service at an adequate quality level, creating the need to introduce the notion of Quality of Experience (QoE). In this context, this paper proposes a unified QoE-aware management framework, directly targeting to cloud computing environments. The proposed management system suggests the optimization of cloud resources usage and offered services in terms of QoE, satisfying the different service and resource requirements of all the involved cloud entities. In addition, the proposed novel approach merges together various QoS aspects in a multidimensional framework, referred to as QoE4CLOUD, which considers the perceived quality as the key metric for the management and performance optimization of the cloud environment.

Unidirectional lightweight encapsulation: performance evaluation and application perspectives

Multi Protocol Encapsulation (MPE) is today the dominant method for encapsulating IP data into the MPEG-2 Transport Stream so they can be conveyed over digital television platforms (DVB or ATSC). Unidirectional Lightweight Encapsulation (ULE) is a new alternative to MPE, providing simplicity, efficiency and configurability. This paper presents the principle and benefits of ULE, approaches the issues associated with its adoption and compares it against MPE through extensive performance measurements in a fully functional testbed under IPv4 and IPv6 load. It also proposes, implements and demonstrates the combination of MPEG-4/H.264, IPv6 and ULE as the most efficient and flexible protocol stack for next-generation transmission of digital video over Digital Television networks

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.

ADAMANTIUM project: Enhancing IMS with a PQoS-aware multimedia content management system

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.

Survey of cross-layer proposals for video streaming over Mobile Ad hoc Networks (MANETs)

Efforts to realize video streaming over Mobile Ad hoc Networks (MANETs) meet many challenges, which are addressed by different techniques. In the highly dynamic and unpredictable environment of MANETs, cross-layer mechanisms seem to be the most suitable for optimising video streaming. This paper presents a survey of 44 studied papers on the area, comparing tools, parameters and metrics used for their evaluation. It also indicatively describes in more detail some of these proposals.