The aim of this thesis is to investigate existing design patterns for WebRTC applications in order to achieve a scalable, performant and efficient WebRTC application that keeps streams unique. Further, this thesis shows how these can be implemented using JavaScript technologies. Through a literature study, we conclude that the design patterns full mesh using a signaling server and star topology with a media server that relays streams, called Selective Forwarding Unit (SFU). Both these design patterns have quality attributes that are desirable. We propose an approach of combining these patterns in the same application in order to achieve a scalable application that can fit a broad spectrum of use cases while being efficient. As full mesh is performant and cost-effective in comparison to an SFU but does not scale well with increasing number of participants, we investigate ways to optimize a full mesh session to use it as long as possible before converting a session to using an SFU. We came up with a way to optimize a full mesh session by limiting the bandwidth used for the media streams which reduces the CPU usage for the clients. The proposed approach of combining full mesh and an SFU is implemented based on a previous WebRTC application and a high-level description of how that was achieved is included in this thesis. We perform an experiment where we measure the client’s CPU usage using the above-mentioned approaches in order to reinforce our findings. The result show that limiting the bandwidth of media streams can increase the possible number of participants in a full mesh session and that it is possible to transfer an ongoing session from full mesh to an SFU and back again. We conclude that combining these patterns in the same application is a viable strategy when creating a WebRTC application.

<p>Many products are built from more or less independently developed subsystems. For instance, a car consists of subsystems for transmission, braking, suspension, etc. These subsystems are frequently controlled by an embedded computer system. In the automotive industry, as well as in other application domains, there is currently a trend from an approach where subsystems have dedicated computer hardware and other resources (a federated approach) to an approach where subsystems share hardware and other resources (an integrated approach). This is motivated by a strong pressure to reduce product cost, at the same time as an increasing number of subsystems are being introduced.</p><p>When integrating subsystems, it is desirable that guarantees valid before integration are also valid after integration, since this would eliminate the need for costly reverifications. The computer network is a resource that is typically shared among all subsystems. Hence, a central issue when integrating subsystems is to provide an efficient scheduling of message transmissions on the network. There are essentially three families of schedulers that can be used: priority-driven schedulers that assign priorities to messages, time-driven schedulers that assign specific time-slots for transmission of specific messages, and share-driven schedulers that assign shares of the available network capacity to groups of messages.</p><p>This thesis presents a framework for share-driven scheduling, to be implemented and used in embedded networks, with the aim to facilitate subsystem integration by reducing the risk of interference between subsystems. The framework is applied in the automotive domain.</p><p>The initial parts of the thesis give an overview of systems, subsystems and network technologies found and used in the automotive domain. Then, the share-driven scheduling framework is presented, analytically investigated and proven, as well as evaluated in a simulation study. Finally it is shown how the framework is to be configured and used in the context of subsystem integration. The results show that the framework allows for flexible and efficient scheduling of messages with real-time constraints, facilitating integration of subsystems from a network point of view.</p>

Internet Access logs in a local area network are the most prominent records when the source of an Internet event is traced back. Especially in a case where an illegal activity having originated from your local area network is of concern, it is highly desirable to provide healthy records to the court including the source user and machine identity of the log record in question. To establish the validity of user and machine identity in the log records is known as source authentication. In our study, after the problem of source authentication in each layer is discussed in detail, we argue that the only way to establish a secure source authentication is to implement a system model that unifies low level and upper level defense mechanisms. Hence, in this thesis we propose an Unauthorized Internet Access Blocking System validating the Source Information in Internet Access Logs. The first version of our proposed system, UNIDES, is a proxy based system incorporating advanced switches and mostly deals with the low level source authentication problems. In the second version, we extend our system with SIACS which is an Internet access control system that deals with the user level source authentication problems. By supplementing the classical username-password authentication mechanism with SSL client authentication, SIACS integrates a robust user level authentication scheme into the proposed solution.

Many products are built from more or less independently developed subsystems. For instance, a car consists of subsystems for transmission, braking, suspension, etc. These subsystems are frequently controlled by an embedded computer system. In the automotive industry, as well as in other application domains, there is currently a trend from an approach where subsystems have dedicated computer hardware and other resources (a federated approach) to an approach where subsystems share hardware and other resources (an integrated approach). This is motivated by a strong pressure to reduce product cost, at the same time as an increasing number of subsystems are being introduced. When integrating subsystems, it is desirable that guarantees valid before integration are also valid after integration, since this would eliminate the need for costly reverifications. The computer network is a resource that is typically shared among all subsystems. Hence, a central issue when integrating subsystems is to provide an efficient scheduling of message transmissions on the network. There are essentially three families of schedulers that can be used: priority-driven schedulers that assign priorities to messages, time-driven schedulers that assign specific time-slots for transmission of specific messages, and share-driven schedulers that assign shares of the available network capacity to groups of messages. This thesis presents a framework for share-driven scheduling, to be implemented and used in embedded networks, with the aim to facilitate subsystem integration by reducing the risk of interference between subsystems. The framework is applied in the automotive domain. The initial parts of the thesis give an overview of systems, subsystems and network technologies found and used in the automotive domain. Then, the share-driven scheduling framework is presented, analytically investigated and proven, as well as evaluated in a simulation study. Finally it is shown how the framework is to be configured and used in the context of subsystem integration. The results show that the framework allows for flexible and efficient scheduling of messages with real-time constraints, facilitating integration of subsystems from a network point of view.

This thesis seeks to discuss conducting technique in relation to real-time communication of Vamp, Safety-Bars and Lead-Ins through left-hand gestures within the context of opera and musical theatre. The research aims to develop a codified set of gestures suitable for the left-hand. It will explore and analyse left-hand gestures which are commonly used, but not yet codified, and the importance in which the preparatory beat plays a role in communicating the Vamp and Lead-In. This research also aims to establish a framework for conductors to create their own left-hand gestures and better understand musical structure used in Opera and Musical Theatre. The new gestures developed through research into visual and body languages (such as sign languages) as well as body movement (sound painting). The gestures will be tested through one artistic project, with three sections, then analysed using methods of qualitative inquiry. The paper is narrative based in its structure; with the reader guided through each topic by the last. The introduction sets up the main idea for this thesis, then each section is guided by these elements. The research questions and aims were formed because of the available literature; thus, they appear after the theory chapter.

The Technology today is changing at a fast pace. The growth of computers and telecommunications over the past three decades has been extraordinary. We today are at the point where all technologies related to communication and data transfer are submerging to a common platform. A number of different methods are available for data communication or data transfer. The important factor in all communication setups is to satisfy user demands with low cost and reliability. The area of interest for this thesis is future energy substations and wind mills. In order to make things more straight forward and see its different options and capabilities the focus is on designing and implementing a new energy protocol called Energy Real Time Protocol (eRTP) based on Iyad Real Time Protocol (iRTP) [2]. The protocol is designed to meet the requirements of power and energy networks in terms of sending the energy parameters with VoIP data (optional) among power stations at different locations. Keeping in mind the importance transferring energy parameters in real-time, the presented protocol has built upon small individual algorithms/modules designed for multi-core architecture. Each module is supposed to be processed by an individual core/processor in parallel.

Made available in DSpace on 2016-04-26T18:15:09Z (GMT). No. of bitstreams: 1 Angela Pintor dos Reis.pdf: 1296951 bytes, checksum: b382511cce6ae79eb1fd861bdd110ade (MD5) Previous issue date: 2015-06-22 / This research examines the ways in which the phenomena of communication and speed jointly instigate subtle forms of violence that ultimately thwart the recognition of experience in intersubjective relations (technologically articulated or not) in the advanced mediatic civilization. Consistent with this demarcation, the overall objective of the research was to investigate how these forms of violence are composed as capital assimilated by the individual and how they appear embedded in the dynamics of recognition, compromising its effectiveness in social life under dromocracized conditions (i.e., marked by acceleration in all the sectors of human activity). The relevance of this study lies in the treatment of the aforementioned communication logic as a habitus and therefore as a complex of mediations between individuals, in which certain forms of violence not commonly studied participate, affecting recognition as a constitutive experience of the individual. The main research problem consists in understanding specifically how the violence arising from real-time logic jeopardizes the conditions for recognition in this dromocratic context of intersubjective relationships. This problem implies the basic assumption that such subtle forms of violence are articulated in the life of an individual who self-elaborates upon processing symbolic representations of himself and of the other, irreversibly deepening the conditions of impracticability of recognition as an intersubjective experience. The theoretical framework is based on the following thematic research lines and authors: [1] socio-historical foundations of advanced mediatic civilization and of dromocracy, according to Trivinho and Virilio; [2] concepts of violence and its manifestations, outlined by Michaud, Dadoun, Crettiez, Pontara, Bourdieu and Passeron, and Trivinho; [3] definition of the individual in Lacan; and [4] principles of recognition in Honneth, Taylor, Levinas, Derrida and Lacan. Given the theoretical nature of this research, the bibliographic material is reflectively analyzed, focusing on practical and emblematic situations that underlie the materiality of violence inherent to the logic of real-time communication, which enhances the precariousness of recognition in accelerated social life. It is believed that the findings of this research constitute a proposed epistemological critique of the modus operandi of real time, considered in the Thesis as a problematizing sociocultural factor of relationships in which individual and alterity are irremediably involved / A presente pesquisa está dedicada às formas pelas quais os fenômenos da comunicação e da velocidade fomentam conjuntamente modalidades sutis de violência que acabam por inviabilizar a experiência do reconhecimento em relações intersubjetivas (articuladas ou não tecnologicamente) na civilização mediática avançada. Coerente com esse recorte, o objetivo geral da pesquisa foi o de investigar como essas formas de violência compõem-se como capital incorporado pelo sujeito e apresentam-se incrustadas na dinâmica do reconhecimento, comprometendo a sua efetivação na vida social sob condições dromocratizadas (isto é, marcadas pela aceleração em todos os setores de atuação humana). A relevância do estudo radica no tratamento da referida lógica comunicacional como habitus e, por essa razão, como complexo de mediações entre sujeitos, do qual participam configurações da violência não comumente estudadas, ressoantes no reconhecimento como experiência constitutiva do indivíduo. O principal problema de pesquisa consiste em saber, especificamente, como as violências dimanantes da lógica do tempo real comprometem as condições para o reconhecimento nesse contexto dromocrático de relações intersubjetivas. Esse problema implica a hipótese básica de que tais formas sutis de violência articulam-se no percurso de um sujeito que se autoelabora ao processar representações simbólicas de si e do outro, aprofundando irreversivelmente as condições de inviabilização do reconhecimento como experiência intersubjetiva. O quadro teórico de referência assenta-se nos seguintes eixos temáticos e respectivos autores: [1] fundamentos social-históricos da civilização mediática avançada e da dromocracia, conforme Trivinho e Virilio; [2] conceitos de violência e de suas formas de manifestação, concebidos por Michaud, Dadoun, Crettiez, Pontara, Bourdieu e Passeron, e Trivinho; [3] definição de sujeito em Lacan; e [4] princípios do reconhecimento em Honneth, Taylor, Lévinas, Derrida e Lacan. Em virtude do caráter teórico da pesquisa, projeta-se o tratamento reflexivo do material bibliográfico com remissão a situações práticas e emblemáticas que fundamentam a materialidade das violências imanentes à lógica da comunicação em tempo real, que intensificam a precariedade do reconhecimento na vida social acelerada. Estima-se que os resultados alcançados perfaçam uma proposta epistemológica crítica do modus operandi do tempo real, considerado na Tese como fator sociocultural problematizador das relações em que sujeito e alteridade encontram-se irremediavelmente envolvidos

Embedded applications have become more and more complex, increasing the demands on the communication network. For reasons such as safety and usability, there are real-time constraints that must be met. Also, to offer high performance, network protocols should offer efficient user services aimed at specific types of communication. At the same time, it is desirable to design and implement embedded networks with reduced cost and development time, which means using available hardware for standard networks. To that end, there is a trend towards using switched Ethernet for embedded systems because of its hight bit rate and low cost. Unfortunately, since switched Ethernet is not specifically designed for embedded systems, it has several limitations such as poor support for QoS because of FCFS queuing policy and high protocol overhead. This thesis contributes towards fulfilling these requirements by developing (i) real-time analytical frameworks for providing QoS guarantees in packet-switched networks and (II) packet-merging techniques to reduce the protocol overhead. We have developed two real-time analytical frameworks for networks with FCFS queuing in the switches, one for FCFS queuing in the source nodes and one for EDF queuing in the source nodes. The correctness and tightness of the real-time analytical frameworks for different network components in a singel-switch neetwork are given by strict theoretical proofs, and the performance of our end-to-end analyses is evaluated by simulations. In conjunction with this, we have compared our results to Network Calculus (NC), a commonly used analytical scheme for FCFS queuing. Our comparison study shows that our anlysis is more accurate than NC for singel-switch networks. To reduce the protocol overhead, we have proposed two active switched Ethernet approaches, one for real-time many-to-many communication and the other for the real-time short message traffic that is often present in embedded applications. A significant improvement in performance achieved by using our proposed active networks is demonstrated. Although our approaches are exemplified using switched Ethernet, the general approaches are not limited to switched Ethernet networks but can easily be moified to other similar packet-switched networks.

Time-Triggered Controller Area Network (TTCAN) is a hybrid communication paradigm with combining both time-triggered and event-triggered traffic scheduling. Different from the standard Controller Area Network (CAN), communication in TTCAN is performed according to a pre-computed, fixed (during system run) schedule that is called as TTCAN System Matrix. Thus, communication performance of TTCAN network is directly related to structure of the system matrix, which makes the design of system matrix a crucial process. The study in this thesis consists of the extended work on the development of a systematic approach for system matrix construction. Methods for periodic message scheduling and an approach for aperiodic message scheduling are proposed with the aim of constructing a feasible system matrix, combining three important aspects: message properties, protocol constraints and system performance requirements in terms of designated performance metrics. Also, system matrix design, analyses and performance evaluation are performed on example message sets with the help of two developed software tools.

The objective of this thesis is to improve the performance of real-time communication overa wireless channel, by means of specifically tailored channel coding. The deadlinedependent coding (DDC) communication protocol presented here lets the timeliness and thereliability of the delivered information constitute quality of service (QoS) parametersrequested by the application. The values of these QoS parameters are transformed intoactions taken by the link layer protocol in terms of adaptive coding strategies.Incremental redundancy hybrid automatic repeat request (IR-HARQ) schemes usingrate compatible punctured codes are appealing since no repetition of previously transmittedbits is made. Typically, IR-HARQ schemes treat the packet lengths as fixed and maximizethe throughput by optimizing the puncturing pattern, i.e. the order in which the coded bitsare transmitted. In contrast, we define an IR strategy as the maximum number of allowedtransmissions and the number of code bits to include in each transmission. An approach isthen suggested to find the optimal IR strategy that maximizes the average code rate, i.e., theoptimal partitioning of n-kparity bits over at most M transmissions, assuming a givenpuncturing pattern. Concatenated coding used in IR-HARQ schemes provides a new arrayof possibilities for adaptability in terms of decoding complexity and communication timeversus reliability. Hence, critical reliability and timing constraints can be readily evaluatedas a function of available system resources. This in turn enables quantifiable QoS and thusnegotiable QoS. Multiple concatenated single parity check codes are chosen as examplecodes due to their very low decoding complexity. Specific puncturing patterns for thesecomponent codes are obtained using union bounds based on uniform interleavers. Thepuncturing pattern that has the best performance in terms of frame error rate (FER) at a lowsignal-to-noise ratio (SNR) is chosen. Further, using extrinsic information transfer (EXIT)analysis, rate compatible puncturing ratios for the constituent component code are found.The puncturing ratios are chosen to minimize the SNR required for convergence.The applications targeted in this thesis are not necessarily replacement of cables inexisting wired systems. Instead the motivation lies in the new services that wireless real-time communication enables. Hence, communication within and between cooperatingembedded systems is typically the focus. The resulting IR-HARQ-DDC protocol presentedhere is an efficient and fault tolerant link layer protocol foundation using adaptiveconcatenated coding intended specifically for wireless real-time communications. / Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie, 2198, Technical report. D, 29,