SDP-Based Quality Adaptation and Performance Prediction in Adaptive Streaming of VBR Videos

Recently, various adaptation methods have been proposed to cope with throughput fluctuations in HTTP adaptive streaming (HAS). However, these methods have mostly focused on constant bitrate (CBR) videos. Moreover, most of them are qualitative in the sense that performance metrics could only be obtained after a streaming session. In this paper, we propose a new adaptation method for streaming variable bitrate (VBR) videos using stochastic dynamic programming (SDP). With this approach, the system should have a probabilistic characterization along with the definition of a cost function that is minimized by a control strategy. Our solution is based on a new statistical model where the future streaming performance is directly related to the past bandwidth statistics. We develop mathematical models to predict and develop simulation models to measure the average performance of the adaptation policy. The experimental results show that the prediction models can provide accurate performance prediction which is useful in planning adaptation policy and that our proposed adaptation method outperforms the existing ones in terms of average quality and average quality switch

New interaction models for 360º video

Esta dissertação tem como principal objectivo a incorporação de um mecanismo de buffering num sistema de multimídia, capaz de oferecer experiências multivista adaptáveis. A incorporação deste mecanismo vem provocar melhorias na qualidade de serviço e na qualidade de experiência. O sistema recorre ao protocolo MPEG-DASH e a uma câmara convencional para detecção dos movimentos da cabeça do utilizador. O sistema incorpora ainda um mecanismo de adaptação automática da qualidade, ajustável às condições da rede. O mecanismo desenvolvido é composto por um proxy e tem o objectivo de minimizar o atraso existente na transição de vistas. O proxy será capaz de enviar três vistas em simultâneo, duas em baixa qualidade, enquanto a vista principal será enviada e apresenta ao utilizador em alta qualidade.Sempre que existe um novo pedido por parte do utilizador, o mecanismo irá comutar entre as vistas enviadas até receber a resposta por parte do servidor. Deste modo, esta dissertação pretende identificar as dificuldades que se colocam relativamente à disponibilização e transmissão eficiente deste tipo de conteúdos, assim como os compromissos necessários ao nível da qualidade de experiência do utilizador.Today, the fast technological evolution and the significant increase in the demand for multimedia content has boosted the development of the transmission mechanisms used for this purpose.This development had repercussions in several areas, such as the immersive experiences that include the 360º contents. Whether through live streaming or using on demand services, the quality of service and experience have become two points whose development has assumed high importance. The capture and reproduction of 360º content allows transmitting an immersive view of reality at a given moment. With this approach, the industry intends to provide a product with better audiovisual quality, more comfortable for the user and that allows a better interaction with the same. An example of this is the choice of the view that most appeals to us in a given event (for example, football matches or concerts). This dissertation has as main objective the incorporation of a buffering mechanism in a multimedia system, able to offer adaptive multivista experiments. The system uses the MPEG-DASH protocol for efficient use of network resources and a conventional camera for detecting the movements of the user's head, selecting the points of view that one wishes to visualize in real time. The system also incorporates an automatic quality adjustment mechanism, adjustable to the network conditions. The buffering mechanism is intended to increase the quality of experience and the quality of service, minimizing the delay in the transition of views. The mechanism will consist of a proxy capable of sending three views simultaneously. Of these views, two will be sent in low quality, while the main view will be sent and presented to the user in high quality. Whenever there is a new request from the user, the mechanism will switch between sent views until it receives the response from the server. Based on these assumptions, the dissertation intends to identify the challenges that are posed regarding the availability and efficient transmission of 360º content, as well as the necessary commitments regarding the quality of user experience. This last point is particularly significant, taking into account the network requirements and the volume of data presented by the transmissions of this type of content

Implementation of live HTTP Adaptive Video Streaming over Mininet

Η μετάδοση βίντεο εξελίσσεται σε μια διαδεδομένη τεχνολογία για τη μετάδοση δεδομένων μέσω του Διαδικτύου. Η τεχνολογία Dynamic Adaptive Streaming over HTTP (DASH) επιτρέπει τη μετάδοση ροών δεδομένων σε ένα χρήστη με το μεγαλύτερο εφικτό ρυθμό δεδομένων κάτω από διαφορετικά εύρη ζώνης, κάτι ιδιαίτερα σημαντικό για τα ασύρματα δίκτυα. Σκοπός αυτής της διπλωματικής εργασίας είναι η ανάλυση της τεχνολογίας DASH όσον αφορά την ζωντανή μετάδοση βίντεο, καθώς και την εξέταση της ποιότητας εμπειρίας σε SDN δίκτυα από την πλευρά του χρήστη. Γι’ αυτό τον σκοπό αναπτύχθηκε ένα εικονικό SDN δίκτυο στο περιβάλλον Mininet, ούτως ώστε να προσομοιωθεί η τεχνολογία DASH. Σε κάθε πείραμα, ένας server μετέδιδε ζωντανά ένα βίντεο σε έναν client, ενώ την ίδια στιγμή μεταβαλλόταν το throughput που απολάμβαναν και οι δύο, προσθέτοντας επιπλέον δικτυακή κίνηση στο δίκτυο. Ταυτόχρονα, η εφαρμογή Wireshark παρακολουθούσε τα πακέτα που μεταδίδονταν από τον server στον client, αποθηκεύοντας διάφορες παραμέτρους του δικτύου, βάση των οποίων υπολογίστηκε η ποιότητα εμπειρίας του χρήστη. Συγκεκριμένα, εξετάστηκε η επιρροή που είχε το μέγεθος της προστιθέμενης δικτυακής κίνησης στην ποιότητα του μεταδιδόμενου βίντεο κι ως αποτέλεσμα στην ποιότητα εμπειρίας του χρήστη. Συμπεράναμε ότι τα μεταδιδόμενα δεδομένα είναι εξολοκλήρου συνδεδεμένα με την δικτυακή κίνηση του δικτύου και μάλιστα πιο συγκεκριμένα, όσο μεγαλύτερη είναι η δικτυακή κίνηση, τόσο χειρότερη είναι η ποιότητα αναπαραγωγής του video. Παρόλα αυτά, παρατηρήσαμε ότι η ποιότητα του μεταδιδόμενου βίντεο δεν άλλαζε πάντα άμεσα, λόγω της ύπαρξης του buffer του βίντεο του τελικού χρήστη. Η δομή της παρούσας διπλωματικής εργασίας είναι η εξής: Στο κεφάλαιο 1 παρουσιάζεται αναλυτικά η εξέλιξη των κινητών δικτύων από την πρώτη γενιά έως και την πέμπτη. Στη συνέχεια, στο κεφάλαιο 2 περιγράφεται αναλυτικά η τεχνολογία HTTP Adaptive Streaming (HAS) ως προς την αρχιτεκτονική, τα πλεονεκτήματα και τα μειονεκτήματά της. Επίσης περιγράφεται η αρχιτεκτονική της τεχνολογίας DASH, η εφαρμογή της και τα επιπλέον πλεονεκτήματα που προσφέρει. Το κεφάλαιο 3 αφορά την έννοια της ποιότητας εμπειρίας του χρήστη, τον τρόπο υπολογισμού της μέσω μοντέλων υπολογισμού καθώς και την επιρροή που έχει στην τεχνολογία HTTP video streaming. Όλα τα απαραίτητα προγράμματα για την διεξαγωγή των πειραμάτων που παρουσιάζονται στην παρούσα εργασία, όπως και οι ρυθμίσεις αυτών μπορούν να βρεθούν στο κεφάλαιο 4. Το κεφάλαιο 5 αναλύει σε βάθος τις σχεδιαστικές προδιαγραφές των πειραμάτων, κατά την διάρκεια των οποίων παρατηρήθηκε μείωση της ποιότητας εμπειρίας του χρήστη, ενώ παρουσιάζει και τα αποτελέσματα που προέκυψαν. Τέλος, το κεφάλαιο 6 συνοψίζει τα συμπεράσματα της παρούσας διπλωματικής εργασίας και αναφέρει επιγραμματικά ανοιχτά θέματα για μελλοντική έρευνα.Video streaming is growing into a well-known technology for media transmission over the Internet. Dynamic Adaptive Streaming over HTTP (DASH) permits transmitting data streams to a user with the largest feasible bit rate in different bandwidth situations which is especially important for wireless networks. The purpose of this thesis is to analyze DASH technology as far as live video streaming is concerned, as well as to examine the Quality of Experience (QoE) on SDN networks, namely to understand the user’s perspective. Thus, in this thesis, a virtual SDN network was developed in the Mininet environment to simulate DASH technology. In each experiment, one server transmitted a video live to a client while the throughput was changing by adding extra traffic to the network. At the same time, the Wireshark application was monitoring the transmitted packets from the server to the client, storing various parameters related to the network, based on which the user’s QoE was calculated. Specifically, the impact of the added traffic on the quality of the broadcast video was examined, and as a result the impact in terms of QoE was measured. We concluded that the transmitted data is entirely connected with the existing traffic in the network and in particular the higher the traffic, the poorer the selected resolution. However, we observed that the resolution of the broadcast video would not always change immediately, as a result of the existence of the buffer at the video client. The structure of this thesis is the following: Chapter 1 provides a detailed overview of the mobile networks’ evolution from the first generation to the fifth one. Chapter 2 describes in detail the HTTP Adaptive Streaming (HAS) technology in terms of its architecture, its advantages and disadvantages. It also describes the architecture of DASH technology, its implementation and the additional advantages it offers. Chapter 3 is about QoE, the way in which it is calculated through specific models, and its influence on HTTP video streaming technology. All the necessary programs in order to conduct the experiments presented in this thesis, as well as any necessary settings, can be found in Chapter 4. Chapter 5 provides an in-depth analysis of the design of the experiments, during which a decrease in the quality of the user’s experience was observed. It also presents the obtained results. Finally, Chapter 6 summarizes the conclusions of this thesis and discusses future work topics

An energy efficient http adaptive streaming protocol design for mobile hand-held devices

Internet traffic generated from mobile devices has experienced a huge growth in the last few years. With the increasing popularity of streaming applications in mobile devices, video traffic generated from mobile devices is also increasing. One of the big challenges of streaming applications on mobile devices is the energy intensive behaviour of such applications. Energy management has always been a critical issue for mobile devices. A wireless network interface consumes a significant portion of the total system energy while active. During video streaming, the network interface is kept awake for a long period of time. This causes a large energy drain. There are several research works focused on reducing energy consumption during video streaming on mobile devices. HTTP adaptive streaming is gaining popularity as a method of video delivery because of its significant advantages in terms of both user-perceived quality and resource utilization. By using rate adaptation via changes in the requested video version, it adapts to varying network available capacity. There are several research work that aim to increase the performance of rate adaptation. None of the previous works have focused on reducing energy consumption during HTTP adaptive streaming. In this thesis, an energy efficient HTTP adaptive streaming protocol is designed. The new protocol uses an efficient buffer management approach and a three step bitrate selection mechanism. The proposed protocol is implemented by modifying the Adobe OSMF player version 1.6. Performance evaluation of the new protocol is carried out by running a number of experiments in both a lab environment and three real world environments. The experimental results show that the proposed protocol is able to achieve high amounts of sleep time (by more than an estimated 70% for WiFi and more than 35% for 3G/EDGE) and reduce energy consumption during data transfer. It can also reduce data wastage by 80% in case of playback interruption in the video playback

Efficient Passive Clustering and Gateways selection MANETs

Passive clustering does not employ control packets to collect topological information in ad hoc networks. In our proposal, we avoid making frequent changes in cluster architecture due to repeated election and re-election of cluster heads and gateways. Our primary objective has been to make Passive Clustering more practical by employing optimal number of gateways and reduce the number of rebroadcast packets

Genetic and chemical perturbation of amino acid sensing by the GCN1-GCN2 pathway

Amino acid stress activates the GCN2-regulated branch of the integrated stress response (ISR). This ancient pro-survival signaling network is conserved across eukaryotes to react to cellular stress by controlling proteostasis. Mechanistically, GCN2 blocks translation by phosphorylating the initiation factor eIF2α and simultaneously activating an ATF4-dependent transcriptional program for stress adaptation. The amino acid response was initially discovered in Saccharomyces cerevisiae, where the HEAT-repeat protein GCN1 was suggested to regulate the GCN2 activation at the ribosomal machinery. The master regulator of cell growth, mTORC1, is another amino acid sensing hub, which also modulates translation. However, the molecular and mechanistic events that lead to the mammalian GCN2-ISR activation, its connection to the mTORC1 pathway and the outcomes in terms of cell state adaptation remain elusive. In this PhD thesis, I investigated the GCN2-ISR by genetic and chemical perturbation in diverse murine cell systems. My major focus was to dissect the interplay of GCN1, GCN2 and mTORC1 upon amino acid stress. Using CRISPR/Cas9-genetically modified cell lines, I found that GCN1 acts upstream of GCN2 to regulate its autophosphorylation and ultimately the ATF4-induced transcriptional response in an eIF2α independent way. Using a multi-omics approach, I show that GCN1 and GCN2 are isogenic in regulating the ISR in response to leucine stress by controlling transcriptome and proteome changes over time. Processes involved in mitochondrial 1C- metabolism, amino acid uptake, tRNA synthetases and glutamine metabolism are modulated at the gene and protein level in a GCN1 and/or GCN2 dependent way. Furthermore, I provide evidence that both proteins have a distinct bioenergetic profile – already at steady-state. I also show that GCN1 can be involved in the DNA damage response by physically interacting with the MRN complex in a transient way. I also highlight that the ISR can play a role in ferroptosis regulation in an ATF4-SLC7A11-dependent manner. Moreover, this thesis suggests that a direct interaction of GCN1 with GCN2 and the ribosome is unlikely. In a 3,876 compound GCN2 inhibitor screen, I discovered that dual mTOR inhibitors concurrently block the mTORC1 and the GCN2 branches of amino acid sensing upon amino acid stress. This effect was not mediated by direct GCN2-binding and independent of PERK and eIF2α. Instead, these results suggest a role of mTOR in modulating the activation of GCN2 upon prolonged leucine stress. Finally, I provide new insights on the involvement of GCN1 in the mammalian ISR and potential GCN2- and amino acid stress-independent functions. Moreover, I discovered an unexpected interplay of the GCN1-GCN2 and the mTORC1 amino acid sensing pathways, which is of high importance for understanding how these complex multiprotein kinases integrate nutrient sensing. This finding paves a new frontier for mTOR and GCN2 anti-neoplastic drug development for the selective targeting of amino acid-dependent cell protection pathways in cancer

Journal of Telecommunications and Information Technology, 2018, nr 2

kwartalni

Immunogenetics

This open access book explores techniques for working in the field of immunogenetics, i.e. fundamental and translational research into the adaptive immune receptor repertoire. Many chapters are dedicated to lab protocols, bioinformatics, and immunoinformatics analysis of high-resolution immunome analysis, exemplified by numerous applications. Additionally, the newest technological variations on these protocols are discussed, including non-amplicon, single-cell, and cell-free strategies. Written for the highly successful Methods in Molecular Biology series, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible laboratory protocols, and tips on troubleshooting and avoiding known pitfalls. Authoritative and practical, Immunogenetics: Methods and Protocols covers a broad spectrum of methodologies for applications in research and clinical diagnostics to illustrate the impact that immunogenetics has achieved and will further expand in all fields of medicine, from infection and (auto)immunity, to vaccination, to lymphoid malignancy and tumor immunity