Vehicular networks are an emerging technology that offer potential for providing a variety of new services. However, extending vehicular networks to include IP connections is still problematic, due in part to the incompatibility of mobile IP handovers with the increased mobility of vehicles. The handover process, consisting of discovery, registration, and packet forwarding, has a large overhead and disrupts connectivity. With increased handover frequency and smaller access point dwell times in vehicular networks, the handover causes a large degradation in performance. This thesis proposes a predictive handover solution, using a combination of a Kalman filter and an online hidden Markov model, to minimize the effects of prediction errors and to capitalize on advanced handover registration. Extensive simulated experiments were carried out in NS-2 to study the performance of the proposed solution within a variety of traffic and network topology scenarios. Results show a significant improvement to both prediction accuracy and network performance when compared to recent proposed approaches.

This thesis uses a modern control approach to address the Internet traffic control issues in the Transport Layer. Through literature review, we are interested in using the H2/H∞ formulation to obtain the good transient performance of an H2 controller and the good robust property from an H∞ controller while avoiding their deficiencies. The H2/H∞ controller is designed by formulating an optimization problem using the H2-norm and the H∞-norm of the system, which can be solved by an LMI approach using MATLAB. Our design starts with the modeling of a router and the control system by augmenting the network plant function with the Sensitivity function S, the Complementary Sensitivity function T and the Input Sensitivity function U. These sensitivity functions along with their weight functions are used to monitor the closed-loop dynamics of the traffic control. By choosing different combinations of the sensitivity functions, we can obtain the SU, the ST and the STU controllers. Both the window-based and rate-based version of these different types of H2/H∞ controllers have been designed and investigated. We have also proved that these controllers are stable using Lyapunov’s First Method. Next, we verify the performance of the controllers by OPNET simulation using different performance measures of queue length, throughput, queueing delay, packet loss rate and goodput. Our performance evaluation via simulation has demonstrated the robustness and the better transient response such as the rise/fall time and the peak queue value. We have also investigated the controller performances subject to network dynamics as well as through comparison with other controllers. Finally, we have improved these controllers for real-time application. They are capable to update/renew the controller in a short time whenever new network parameter values are detected so that the optimum performance can be maintained.

Les communications téléphoniques en voix sur IP souffrent de la perte de paquets causée par les problèmes d'acheminement dus aux nœuds du réseau. La perte d'un paquet de voix induit la perte d'un segment de signal de parole (généralement 10ms par paquet perdu). Face à la grande diversité des codeurs de parole, nous nous sommes intéressés dans le cadre de cette thèse à proposer une méthode de masquage de pertes de paquets générique, indépendante du codeur de parole utilisé. Ainsi, le masquage de pertes de paquets est appliqué au niveau du signal de parole reconstruit, après décodage, s'affranchissant ainsi du codeur de parole. Le système proposé repose sur une modélisation classique de type « modèles de Markov cachés » afin de suivre l'évolution acoustique de la parole. À notre connaissance, une seule étude a proposé l'utilisation des modèles de Markov cachés dans ce cadre [4]. Toutefois, Rødbro a utilisé l'utilisation de deux modèles, l'un pour la parole voisée, l'autre pour les parties non voisées, posant ainsi le problème de la distinction voisée/non voisée. Dans notre approche, un seul modèle de Markov caché est mis en œuvre. Aux paramètres classiques (10 coefficients de prédiction linéaire dans le domaine cepstral (LPCC) et dérivées premières) nous avons adjoint un nouvel indicateur continu de voisement [1, 2]. La recherche du meilleur chemin avec observations manquantes conduit à une version modifiée de l'algorithme de Viterbi pour l'estimation de ces observations. Les différentes contributions (indice de voisement, décodage acoutico-phonétique et restitution du signal) de cette thèse sont évaluées [3] en terme de taux de sur et sous segmentation, taux de reconnaissance et distances entre l'observation attendue et l'observation estimée. Nous donnons une indication de la qualité de la parole au travers d'une mesure perceptuelle : le PESQ. / Packet loss due to misrouted or delayed packets in voice over IP leads to huge voice quality degradation. Packet loss concealment algorithms try to enhance the perceptive quality of the speech. The huge variety of vocoders leads us to propose a generic framework working directly on the speech signal available after decoding. The proposed system relies on one single "hidden Markov model" to model time evolution of acoustic features. An original indicator of continuous voicing is added to conventional parameters (Linear Predictive Cepstral Coefficients) in order to handle voiced/unvoiced sound. Finding the best path with missing observations leads to one major contribution: a modified version of the Viterbi algorithm tailored for estimating missing observations. All contributions are assessed using both perceptual criteria and objective metrics.

The Target Positioning Sensor (TPS) is used by cranes to locate containers in ports and on cargo ships. The reliability of the communication network between the TPS and the Programmable Logic Controller (PLC) is important to optimise the productivity of the container terminal. Lost data messages between the network devices will lead to delays and production loss for the terminal. The main goal of this thesis project is to make the Ethernet-based network between the TPS and the PLC more reliable. The current sensor network protocol uses the User Datagram Protocol (UDP), and the project aims to replace that with the Transport Control Protocol (TCP). This includes designing a new message handling application and performing case studies on how to best handle compatibility issues between the TPS and the PLC, to improve the longevity of the application. The case studies led to considering an adaptable behaviour toward future software updates in different parts of the network. An application which used TCP to communicate between a PC and a PLC was developed, intended to be used as a reference during future integration into the actual sensor network. The TCP application works but needs to be improved before being implemented in a real system. In addition, the project also looked into Time-Sensitive Networking, which is a method of increasing link capacity and reliability in time-sensitive network implementations. This was done through a literature study on the IEEE Time-Sensitive Networking Standard, which showed that the application of the standard could be beneficial if more sensors are added to the network of if the sampling frequency of the TPS is increased.

No description available.

The aim of the graduation thesis is to evaluate the current development in the field of SDN and the possibility of programmability of SDN elements using the application programming interface. The first theoretical chapter describes the following: the basic architecture of SDN, the traffic within SDN between its individual layers, the communication protocols Southbound interface and Northbound interface. The second chapter of the thesis deals with the programmability of SDN elements with the help of API. The third theoretical chapter describes the current development in the field of SDN. The practical part of the thesis is devoted to creation of two laboratory tasks dealing with the programming of the SDN API. Laboratory tasks include BIG-IP programming from F5 Network and routers from Arista Network. Programming is done using Python via REST API for BIG-IP, or eAPI for Arista EOS. The Ansible setup tool is also used for the same purpose.

The diploma thesis deals with open source implementations of IMS technology. The theoretical part describes the functioning of IMS and its architecture, including the protocols used, the process of registration and connection establishment, as well as potential security threats to IMS systems. Two open source IMS projects were selected, Open IMS Core and Project Clearwater, on which the work is focused. In its next part, the diploma thesis deals with the description of selected open source IMS projects, this part also includes a description of the implemented security of both projects and a detailed procedure of system installation with any necessary configuration. In its practical part, the diploma thesis focused on performance testing of selected projects using the Abacus 5000 hardware tester. First, initialization tests were performed, which verified the possibility of communication between the tester and the tested projects. Subsequently, it was possible to perform performance testing of selected projects. In performance testing, emphasis is placed on system stability, performance in the area of call set-up speed and response time of SIP messages and speed of user registration in the network, at different load levels. The systems have been tested for both call set-up and user registration. Part of the testing is also the implementation of the flood DoS inviteflood attack and the system's response to the increasing intensity of the attack. The last chapter is devoted to the comparison of selected IMS projects, where the test results are clearly presented. This chapter is partly based on publicly available information, such as the technical documentation of individual projects and possibly publicly available mailing lists. Part of the diploma thesis is also a laboratory task in which the student tries to work with Open IMS Core. The laboratory task focuses on the process of creating a user and his registration in the IMS network, establishing a call between individual users and internal routing in IMS networks. The task focuses mainly on signaling processes within the implemented tasks.

The thesis is about industrial automatic CIP protocol, which belongs to SCADA systems. The first part is focused on basic principles of CIP protocol and on analysis of two protocols (EtherNET/IP and DeviceNet), which are based on CIP protocol. The second part deals with designing scenarios for a simulation. The simulation of one-way communication, two-way communication with help of reads from the console and two-way real time communication between Raspberries PI 3B+. The third part deals with a realization of the simulation, a start-up and a function of predefined scenarios and graphic interface. The fourth part deals with analysis network communication in situations, which occur during a protocol EtherNet/IP simulation.

This work deal with simulation of basic structure of OFDM modulator and demodulator of the upcoming standard 5G NR. In MATLAB are simulated basic parts including modulation, reference signal inserting, Fourier transform, cyclic prefix inserting, AWGN and multi-path propagation. In this work is proposed implementation of the modulator and demodulator into RFSoC board and his configuration. Designed generator is implemented with the use of STEMLab RedPitaya platform. In Matlab software is generated 5G OFDM signal used to transmitt. Received signal is evaluated in Matlab software.

The diploma thesis deals with the issue of virtual commissioning of the workplace and the commissioning of communication channels needed for this purpose. The theoretical part describes the benefits of virtual commissioning, robot and PLC programming and effectors for robots. The practical part deals with the design of the final robot effector, virtual commissioning using the programs Process Simulate and TwinCAT 3, communication between programs and creation of programs for the workplace.