Server-based architectures have recently generated more interests and are currently considered for usage for communication in networks. In parallel, switched Ethernet technology has been widely adopted and used in lots of networked systems. Current requirements of networks for supporting real-time guarantees while being flexible at the same time have made the network designers to consider addition of some features to common switches. The FTT-Enabled Ethernet switch is a switch that has been developed to support the FTT (Flexible Time Triggered) paradigm. Recently, servers have been added in these types of switches in order to efficiently manage their allocated bandwidth to different types of messages. A hierarchical network of Ethernet switches might be designed in different ways according to the overall goals and properties of the network. In this thesis, after a study on different design solutions, an architecture has been proposed based on FTT-enabled switches, motivated by their support of real-time constraints and server-based communication features. After having created the architecture, a protocol for bandwidth reservation for this hierarchically composed Ethernet switch architecture is developed. Behavior of the designed protocol is described in detail and it has been modeled using Uppaal. Moreover, the temporal behavior (timing) of the network is presented.

Switched Ethernet is an Ethernet LAN that uses switches to connect individual nodes. This is popular because of its effective and convenient way of extending the bandwidth of existing Ethernets. Switched Ethernet is being considered by the industry community because of its open standardization, cost effectiveness, and the support for higher data rates up to 10Gbps. Even though many special-purposed solutions were proposed to support time constrained communication over Switched Ethernet, still there were some doubts about the real time handling capability of Switched Ethernet. To achieve reliable transmission guarantees for real time traffic over Switched Ethernet, it is important to measure the performance of Switched Ethernet networks for real time communication. In this thesis work we have observed the average end-to-end packet delay for real time traffic over a Switched Ethernet by simulation, which is very much essential for real time communication in industrial applications, where the communication is time-deterministic. In our thesis we used FCFS priority queuing in both the source nodes and switch. In this thesis we also discussed about the feasibility analysis for fixed sized frames and some traffic handling methods. We used 100mbp/s single full duplex Ethernet switch for our simulation. Finally simulation analysis and simulation results are discussed. Our purpose of simulation of Switched Ethernet networks is of good importance for the real time industrial applications.

Interaction is very important to all kind of education, including traditional face-to-face classroom lecture and e-Learning. Numerous attempts have been made by researchers to propose some asynchronous interaction methods. Only few studies have so far been made at synchronous ones. Synchronous Office Hour has recently brought to light by some researches. But so far the study of the know-how to conduct it effectively for teachers and students has never been examined. The aim of this paper is to explore the know-how. This research adopts Case Study to collect and analyze representative unique case from NSYSU Cyber University. The case is representative because of the sophisticated teacher, diverse interaction model and enthusiastic discussion. Data collection includes participant observation, deep open interviews, text records, video records, asynchronous board and electronic documents. Data analysis is based on three steps, including pick up key words from different data sources, reorganize the relation of key words and coding. We not only build initial Office Hour framework but also formula the environment setting, execution procedure and interaction model for conducting effective online Office Hour. The most important addition to be made is the value of Synchronous Office Hour to teachers and students.

Dynamic Distributed Dependable Real-time Industrial communication Protocol family (D3RIP), has been proposed in the literature considering the periodic or event-based traffic characteristics of the industrial communication networks. D3RIP framework consists of two protocol families: Interface Layer (IL) protocol family, which is responsible for providing the accurate time-division multiple access (TDMA) on top of a shared-medium broadcast channel, and Coordination Layer (CL), which is defined to fulfill the external requirements of IL. In this thesis, the hardware adaptations of the two protocols, Real-time Access Interface Layer (RAIL) and Time-slotted Interface Layer (TSIL), of the IL protocol family, are implemented. Their performance on both personal computers (PC) and development kits (DK) are observed.

The timely delivery of inter-task real-time messages over a communication network is the key to successfully developing distributed real-time computer systems. These systems are rapidly developed and increasingly used in many areas such as automation industry. This work concentrates on the timed-token Medium Access Control (MAC) protocol, which is one of the most suitable candidates to support real-time communication due to its inherent timing property of bounded medium access time. The support of real-time communication with the timed-token MAC protocol has been studied using a rigorous mathematical analysis. Specifically, to guarantee the deadlines of synchronous messages (real-time messages defined in the timed-token MAC protocol), a novel and practical approach is developed for allocating synchronous bandwidth to a general message set with the minimum deadline (Dmin) larger than the Target Token Rotation Time (TTRT). Synchronous bandwidth is defined as the maximum time for which a node can transmit its synchronous messages every time it receives the token. It is a sensitive paramater in the control of synchronous message transmission and must be properly allocated to individual nodes to guarantee deadlines of real-time messages. Other issues related to the schedulability test, including the required buffer size and the Worst Case Achievable Utilisation (WCAU) of the proposed approach, are then discussed. Simulations and numerical examples demonstrate that this novel approach performs better than any previously published local synchronous bandwidth allocation (SBA) schemes, in terms of its ability to guarantee the real-time traffic. A proper selection of the TTRT, which can maximise the WCAU of the proposed SBA scheme, is addressed. The work presented in this thesis is compatible with any network standard where timed-token MAC protocol is employed and therefore can be applied by engineers building real-time systems using these standards.

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / The present research aims to compare the different technologies that allow real-time communication between Android and iOS devices. We conducted a measurement-driven experiment to test the performance of each technology under different scenarios. We determine their functionality according to the environment for which they have been developed, showing competent information about their capabilities based on the communication channel they use, and their performance measured in milliseconds. The final results allow mobile application developers to determine which technologies suits them the best, based on the specific context of their projects. / Revisión por pares

Smart Cyber-Physical Systems (sCPS) are complex systems performing smart coordination that often require decentralized and network resilient operation. New development in the fields of the robotic systems, Industry 4.0 and autonomous vehicular system brings challenges that can be tackled with deployment of ensemble based sCPS, but require further refinement in terms of network resilience and data propagation. This thesis maps the use cases of the sCPS in the aforementioned domains, discusses requirements on the ensemble based architecture in terms of network properties, and proposes recommendations and technical means that help to design network aware ensemble based sCPS. The proposed solutions are evaluated by the means of target systems simulation using state of the art realistic network and vehicular simulators.

In recent years, mobile devices have become an integral part of our everyday life in various fields. The technology that powers them is used in various devices, such as smartphones, tablets, and PDAs. These devices hold extensive computation capabilities, along with advanced communication abilities, which are supported by an internet connection and diverse types of motion and location sensors. Mobile devices have changed the way people communicate with each other, for example by providing options to send instant text messages, perform live video calls with others in addition to voice conversations. These capabilities have encouraged educators to exploit mobile technology and promote new types of learning options. There are several new learning possibilities based on tools such as mobile dedicated applications, location-based learning activities, and interactive social related tasks. These new uses require adjustments to educational programs to allow support for this type of learning. The uniqueness of mobile learning, in contrast with the classic learning paradigm, is the ability to connect the learner through enhanced learning materials to the outside environment. This breaks the physical borders that exist in the traditional classroom and creates new learning possibilities, but it has its drawbacks. One of the difficulties that arise from this type of learning is the loss of contact in real time between teacher and student, especially when performing outdoor activities. The Treasure-HIT platform was conceived to create outdoor Treasure Hunt-based games, mainly for educational purposes, by introducing an authoring web platform and a supporting mobile application. The platform includes communication capabilities based on social interactions and cooperative learning with the integration of social networks, and yet real-time educator and student communication is still lacking. Adding real-time communication features provides a way to better support ongoing learning activities, and can take pressure off the learning process for the students, by providing them with a more personal experience and immediate support when needed. This thesis follows the process of addressing this concern in TreasureHIT, including the rationale, the background, the possible options and gradual development of a prototype solution to the problem under the existing Treasure-HIT infrastructure. In the thesis, the advantages of two features are explored: (1) the Realtime Group Tracking Map, which provides a way to monitor the movement and action of groups of players during game time, and (2) Instant Text Messaging service, which allows the game instructor to send custom text messages to the different game groups. The research findings indicate that the new monitoring options provide a solid tool for real-time analysis of the progress of the game and the ability to inform about various issues and solve them in real time. ii Furthermore, the instant message service feature received positive responses from the game-manager and players alike, on the grounds of major improvements to the general game flow and problem solving in real-time.

Background:  Cloud computing technology has come a long way with various technological advancements in the past few years. It has been accelerated with the evolution of various virtualization technologies. Currently almost every social platform and small-scale applications look towards cloud to deploy their services successfully and provide maximum satisfaction to their end-user. Thus, virtualizing their services becomes utmost important to deploy and develop their applications. This alone emphasizes the importance of Docker containers in the development world. Docker containers right now are playing a very important role in the field of cloud computing. Since Multimedia plays a huge role in our day to day lives and most people crave for faster and efficient responses, it is essential to develop our applications with better Real time communication capabilities. Thus, we are determining which container orchestration tool serves best for Real time communication applications.  A multimedia application is developed and deployed using WebRTC based Kurento media server and the performance of the server is measured when the application is deployed. We have chosen Kubernetes and Docker Swarm as container platforms for this thesis. The Servers and Clients are virtualized and metrics such as CPU Utilization, Network Traffic, Container overhead, Memory Utilization are measured. These metrics provide the performance overhead in different scenarios for each orchestration technology. This will be helpful to analyze and understand the effect of Kurento server on these technologies. Thus, the results are expected to determine which orchestration technology serves best for RTC applications. Objectives: The objectives of this project are:  • To implement WebRTC based Kurento server in a container orchestrated environment.  • To extract performance metrics such as Network Traffic, CPU and Memory Utilization while server is running.  • To compare WebRTC based Kurento server in Kubernetes and Docker Swarm.   Method: Kubernetes and Docker Swarm environments are setup and then docker images with video conferencing application(One-to-One call and One-to-Many call) using Kurento media server is deployed in them. Once either of the applications is running, experiments are performed for analyzing performance metrics like CPU Utilization, Memory Utilization, Network Traffic and overhead using monitoring tool, Prometheus. Along with Kubernetes and Docker Swarm, Kurento server is also deployed on a stand-alone container to estimate the performance overhead. Later, statistical analysis(ANOVA and differences of Standard error) is done over these metrics and conclusions are drawn.  Results: Based on the performed experiments and the extracted metrics, for One-to-One call application, Kubernetes showed better resource utilization for CPU and Network Traffic while it consumed more memory over Docker Swarm. Similar behaviour is observed for One-to-Many application. When application is scaled, the percent of resource utilization increase in Kubernetes is higher when compared to Docker Swarm, but overall resource utilization of Kubernetes is much lower than that of Docker Swarm.  Conclusions: WebRTC based Kurento media server is investigated in  Kubernetes and Docker Swarm. From the detailed analysis there is significant overhead in Docker Swarm than in Kubernetes for CPU Utilization and Network Traffic. For Memory Utilization, this is opposite. Packet Loss resulted in 0 percent as network transfer is within the same network . By considering all the metrics and providing evidence that numbers obtained in this thesis are statistically significant and not by fluctuations(ANOVA and post-hoc analysis), we can better recommend Kubernetes over Docker Swarm for Web based Real Time Communication.   However, not all applications need the complex deployment, scheduling, and scaling services (or the overhead) that Kubernetes offers. But to meet the increasing demand for seamless Real time communications, and to suffice user requirements, the overheard offered by it is acceptable.

In the field of industrial automation there is a huge demand for real time communication networks and there are several different protocols like EtherCAT, PROFINET IO, SERCOS competing each other in the market. Many of the products in this industry are subjected to hard real-time communication requirements. The purpose of this thesis is in introducing tools to automatically test the various requirements that are helpful in deciding the performance of real time communication systems. Developing a well-defined test framework is one of the important tasks in this thesis project. The end users of the test framework can focus more on managing and analyzing the results from the framework instead of the design process. The thesis work presents the test requirements, design of test system and automating the measurement process by selecting appropriate hardware. The report also explains the design of commands, method used for communication between different systems and also discusses the different methods that could be applied for measuring the performance, the limitations of some of these methods when applied to the framework. The architecture and the working of the framework is covered in later chapters. The framework uses EtherCAT master communication stack developed in-house at ABB. EtherCAT is just used as a pilot test case, but in general the framework could be applied to other Ethernet based industrial communication protocols with suitable hardware or software modifications.