The main aim of this thesis is to familiarize with options of services using real-time data transfer in wireless networks. Theoretical part presents wireless network based on IEEE 802.11 standard and its practical use. Large part is focuses on 802.11e standart, that provides support for quality of service in wireless networks. Furthemore this thesis deals with transport and applicaton protocols supporting multimedia streaming over computer network. Second chapter is focused on analyzing real computer network with purpose in measuring parametrs influencing quality of service such as bandwith, delay, jitter and loss. Last part deals with the design of wireless network in OPNET Modeler enviroment with focus on simulating parameters that influence quality of service.

The thesis examines the impact of VoIP transmission channel characteristics on speech parameters. It seeks ways of emulating properties of a selected VoIP transmission channel and creating a network emulation environment. Several scripts have been created in the Matlab development environment and used to modify and divide a continuous recording into parts identical to the original speeches, before passing through the transmission channel. Subsequently a database of speech recordings is created, as affected by selected characteristics - jitter, bandwidth, loss. Within these databases, symptoms are sought as the most evident characteristics of the transmission channel. Using correlation, symptoms are selected that are best suited for automated determination of the properties of transmission channel characteristics such as jitter, loss and bandwidth.

The aim of this thesis was to study problems of prediction of data in computer networks. Furthermore, this work deals with network traffic and analyzing its properties. In this study were analyzed the possibilities of network traffic prediction using Farima model, the theory of chaos with Lyapunov exponents and neural networks. Possibilities of prediction with the focus on neural network were discussed in detail here, mainly on recurrent neural networks. Prediction was performed in Matlab development environment in Neural Network Toolbox, where they were created, trained and evaluated neural network to predict specific types of network traffic. For testing were selected Elman network NARX network and general LRN recurrent network. The results were clearly organized into tables and plotted in graphical relationships before and after the use of predictive techniques designed to final evaluation.

This master’s thesis deals with problems of analog differential converters, which are used in measuring circuits working in the current mode. The aim of this thesis is to propose a new voltage to current and current to voltage converter, that should influence measured frequency properties as little as possible. Commercial active elements are use to design converters. Active components are compared on the basis of properties as bandwidth and slew rate. Designed converters are simulated in Orcad PSpice program. Converters, of the best behavior are practically implemented and measured. Measured and simulated values are compared.

This dissertation is particularly focused on a novel approach of a wirelessly powered neuromodulation system for chronic patients. The inductively coupled transmitter (TX) and receiver (RX) coils are designed through optimization to achieve maximum efficiency. A power management unit (PMU) consisting of a voltage rectifier, voltage regulator along with a stimulation circuitry is also designed to provide pulse stimulation to genetically modified neurons. For continuous health monitoring purposes, the response from the brain due to stimulation needs to be recorded and transmitted wirelessly outside the brain for analysis. A low-power high-data duty-cycled impulse-radio ultra-wideband (IR-UWB) transmitter is designed and implemented using the standard CMOS process. Another focus of this dissertation is the design of a reverse electrowetting-on-dielectric (REWOD) based energy harvesting circuit for wearable sensor applications which is capable of generating a very low-frequency signal from motion activity such a walking, running, jogging, etc. A commercial off-the-shelf (COTS) based and on-chip based energy harvesting circuit is designed for very low-frequency signals. The experimental results show promising progress towards the advancement in the wirelessly powered neuromodulation system and building the self-powered wearable sensor.

Streaming 360° video has become more commonplace with content delivery services such as YouTube having support for it. By its nature, 360° video requires more bandwidth as only a fraction of the image is actually in view, while the user is expecting the same "in view" quality as with a regular video. Several studies and lots of work have been done to mitigate this higher demand for bandwidth. One solution is advanced algorithms that take in to account the direction that the user is looking when fetching the video from the server; e.g., by fetching content that is not in the user’s view at a lower quality or by not fetching this data at all. Developing these algorithms is a timely process, especially in the later stages where tweaking one parameter might require the video to be re-encoded, and therefore taking up time that could otherwise be spent on getting results and continued iteration on the algorithm. The viewer should also be considered as the best experience might not correlate with the mathematically best solution calculated by the algorithm. This thesis presents a modular emulator that allows for easy implementation of fetching algorithms that make use of state-of-the-art techniques. It intends to reduce the time it takes to iterate over an algorithm through removing the need to set up a server and encode the video in all of the wanted quality levels when a parameter change would require it. It also makes it easy to include the viewer in the process so that the subjective performance is taken into consideration. The emulator is evaluated through the implementation and evaluation of two algorithms, one serving as a baseline to the second one, which is based on an algorithm developed by another group of researchers. These algorithms are tested on two different types of 360° videos, under four different network conditions and with two values for the maximum buffer size. The results from the evaluation of the two algorithms suggest that the emulator functions as intended from a technical point of view, and as such fulfills its purpose. There is, however, future work that would further prove the emulators performance in regards to replicating real scenarios and a few examples are suggested.

La récupération d'énergie ambiante permet d’alimenter de manière autonome des systèmes de petite taille tels que des neouds de capteurs ou des objets connectés à internet (IoT) en remplacement des batteries. Les sources d’énergie ambiante sont par exemple, l’énergie solaire, le gradient thermique, les forces mécaniques, le rayonnement électromagnétique et la pile microbienne. Les matériaux piézoélectriques permettent de valoriser électriquement l’énergie mécanique de vibration en la convertissant directement en énergie électrique. Les niveaux de puissance assez faible (de quelques μW au mW) ont amené à développer des interfaces électriques de récupération afin d’extraire le maximum d'énergie en améliorant le couplage électromécanique. Dans ce travail, nous nous intéressons à l’amélioration de dispositif de récupération d’énergie. Deux aspects sont abordés : dans un premier temps l’étude d’un commutateur hybride synchrone électrique-mécanique est faite pour remplacer le transistor MOSFET couramment utilisé, afin de réduire sa consommation d’énergie ; dans un deuxième temps, un travail est mené sur une nouvelle structure mécanique à base de poutres reliées entre elle par des forces de répulsion magnétique. La structure obtenue par cet ensemble de poutres et de type non-linéaire à plusieurs degrés de liberté (MDOF) ce qui permet augmenter la bande passante. / The future trend of Internet of Things (IoT) is bringing energy harvesting in to the core technique due to its requirement of self-power supplying. For best customer interface and eco-friendly issues, additional sensing systems are to be designed small, wireless and self-powering. Energy harvesting provides a way to realize the wireless self-powered system, it enables the device itself to obtain its own energy from their environment. Solar energy, thermal gradient, mechanical forces, are some commonly seen methods to obtain energy from the environment. The piezoelectric energy harvester is chosen to harvest vibrational energy in this study. In this work, a simple model of the original electrical smart switch driven under ultra-low power is proposed. By using the miniature device to drive the smart switch, the efficiency when low power is provided was examined. To construct an energy harvesting system in a more complete aspect, two newly proposed methods are as below: First, the hybrid-electrical-mechanical switches were utilized to replace the commonly seen electrical smart switches, to reduce its energy consumption such as threshold loss. Secondly, we designed a new mechanical structure for the cantilever array by connecting the beams using magnetic repelling force. In this way, the beams within the array were connected physically, forming a nonlinear multi-degree of freedom (MDOF) -like result.

Indiana University-Purdue University Indianapolis (IUPUI) / Retrieving data from a patient in real-time is a challenging operation, especially when requiring information from the network to support the patient’s health. A real-time healthcare system process is conducted with a continual input, processing, and output of data. It needs to have the ability to provide different priorities to different applications, users, or data flows, or to guarantee a certain level of performance to a data flow. The current Internet does not allow applications to request any special treatment. Every packet, including delay-sensitive audio and video packets, is treated equally at the routers. This simplest type service of network is often referred to as best effort, a network service in which the network does not provide any guarantees that data is delivered or that a user is given a guaranteed QoS level or a certain priority. Providing guaranteed services requires routers to manage per-flow states and perform per-flow operations. Such network architecture requires each router to maintain and manage perflow state on the control path, and to perform per-flow classification, scheduling, and buffer management on the data path. This complicated and expensive network architecture is less scalable and robust than today’s modern stateless network architectures such as Random Early Dropping (RED) for congestion control, DiffServ for QoS, and the original IP network. This thesis introduces a new DiffServ-based scheme of IP bandwidth allocation during congestion, called Proportional Allocation of Bandwidth (PAB) which can be used in all networks. In PAB scheme, the bandwidth is allocated in proportion to Subscripted Information Rate (SIR) of the competing flows. PAB implementation uses multiple token buckets to label the packets at the edge of the network and multilevel threshold queue at the IP routers to discard packets during congestion.

My thesis will demonstrate that Rate Adaptive Runlength Limited encoding (RA-RLL) achieves high data rates with acceptable error rate over a wide range of signal distortion/attenuation, and background noise. RA-RLL has performance superior to other infrared modulation schemes in terms of bandwidth efficiency, duty cycle control, and synchronization frequency. Rate adaptive techniques allow for quick convergence of RA-RLL parameters to acceptable values. RA-RLL may be feasibly implemented on systems with non-ideal timing and digital synchronization.

With the ongoing surge in electrification within the automotive industry, the demand for high-power inverters is steadily on the rise. Furthermore, these inverters are now expected to handle increased power loads while maintaining enhanced efficiency. Fulfilling these demanding prerequisites, places significant importance on the current sensors that meticulously monitor each phase of the inverter. This thesis tackles the deep study of a current sensor that has been chosen by Scania to be introduced in the new generation of inverters. The chosen sensor is based on the Integrated Magnetic Concentrator (IMC)- Hall technology. Given its innovative nature within the company’s scope, there exists a keen interest in investigating its performance. The principal parameters that will be assessed during this thesis are accuracy, temperature dependencies, bandwidth and noise immunity. The evaluation of these properties will be done though the creation of a test rig capable of producing current pulses, spanning the range necessary for the sensor evaluation. A high-end current sensor based on the fluxgate technology will be used as a reference during the assessment. Across the course of the research, diverse experiments and modifications to the testing setup will be undertaken to accommodate the assessment of each individual parameter. The acquired data will be summarized and presented with simplified figures. The results of this study show that the accuracy of the sensor highly depends on a proper end of line calibration and a mechanical assembly, in other words, the sensor must be perfectly centered within the IMC. Moreover, the study identifies linear relationships between temperature and accuracy, while exponential correlations are found between the impact of an external magnetic field and its distance. / Med den pågående ökningen av elektrifiering inom fordonsindustrin ökar efterfrågan på högeffektsväxelriktare stadigt. Dessutom förväntas dessa växelriktare nu hantera ökad effektbelastning samtidigt som de bibehåller förbättrad effektivitet. Att uppfylla dessa krävande förutsättningar lägger stor vikt vid strömsensorerna som noggrant övervakar varje fas i omriktaren. Denna avhandling tar upp den djupgående studien av en strömsensor som har valts ut av Scania för att introduceras i den nya generationen växelriktare. Den valda sensorn är baserad på Integrated Magnetic Concentrator (IMC)- Hall-teknologi. Med tanke på dess innovativa karaktär inom företagets ram finns det ett stort intresse för att undersöka dess prestationer. De huvudsakliga parametrarna som kommer att bedömas under detta examensarbete är noggrannhet, temperaturberoende, bandbredd och brusimmunitet. Utvärderingen av dessa egenskaper kommer att göras genom skapandet av en testrigg som kan producera strömpulser som spänner över det intervall som krävs för sensorutvärderingen. En avancerad strömsensor baserad på fluxgate-tekniken kommer att användas som referens under bedömningen. Under forskningens gång kommer olika experiment och modifieringar av testuppsättningen att genomföras för att tillgodose bedömningen av varje enskild parameter. De insamlade uppgifterna kommer att sammanfattas och presenteras med förenklade siffror. Resultaten av denna studie visar att sensorns noggrannhet i hög grad beror på korrekt ”end of line” kalibrering samt mekanisk montering. Med andra ord måste sensorn vara perfekt centrerad inom IMC. Dessutom identifierar studien linjära samband mellan temperatur och noggrannhet, medan exponentiella korrelationer finns mellan påverkan av ett externt magnetfält och dess avstånd.