Applying prediction techniques to reduce uplink transmission and energy requirements in mobile free-viewpoint video applications

The increased efficiency of video compression algorithms, the improvements registered in reliability, data rates and quality of service of wireless transmission technologies, and the development of mobile multimedia terminals have made possible the implementation of Free-Viewpoint Video (FVV) technology on mobile platforms. The mobile environment however presents several restrictions. Two of these limiting factors being bandwidth constraints and energy availability in battery-operated mobile terminals. This paper looks at the possibility of employing prediction algorithms at the FVV server to anticipate the next viewpoint expected by the user. In doing so, the number of uplink requests is reduced to situations where the estimated view defers from the requested one and the associated transmissions required in retraining the algorithm once this occurs. Simulation results on two different prediction techniques demonstrate that the uplink transmission rate is reduced by up to 96.7% when emulating a conventional FVV usage scenario. Both prediction algorithms infer a substantial decrease in the mobile terminal’s power consumption and reduce the network’s uplink bandwidth utilization.peer-reviewe

A comparison of the performance of prediction techniques in curtailing uplink transmission and energy requirements in mobile free-viewpoint video applications

The rapid deployment of multimedia services on mobile networks together with the increase in consumer demand for immersive entertainment have paved the way for innovative video representations. Amongst these new applications is free-viewpoint video (FVV), whereby a scene is captured by an array of cameras distributed around a site to allow the user to alter the viewing perspective on demand, creating a three-dimensional (3D) effect. The implementation on mobile infrastructures is however still hindered by intrinsic wireless limitations, such as bandwidth constraints and limited battery power. To this effect, this paper presents a solution that reduces the number of uplink requests performed by the mobile terminal through view prediction techniques. The implementation and performance of four distinct prediction algorithms in anticipating the next viewpoint request by a mobile user in a typical FVV system are compared and contrasted. Additionally, each solution removes the jitter experienced by the user whilst moving from a view pattern to another by allowing some hysterisis in the convergence signal. Thus, this technique enhances the performance of all the algorithms by taking into consideration the fact that the user adapts to the presented views and will react accordingly. Simulation results illustrate that an uplink transmission reduction of up to 96.7% can be achieved in a conventional FVV simulation scenario. Therefore, the application of prediction schemes can drastically reduce the mobile terminal’s power consumption and bandwidth resource requirements on the uplink channel.peer-reviewe

Efficient material characterization by means of the Doppler effect in microwaves

Subject of this thesis is the efficient material characterization and defects detection by means of the Doppler effect with microwaves. The first main goal of the work is to develop a prototype of a microwave Doppler system for Non-Destructive Testing (NDT) purposes. Therefore it is necessary that the Doppler system satisfies the following requirements: non-expensive, easily integrated into industrial process, allows fast measurements. The Doppler system needs to include software for hardware control, measurements, and fast signal processing. The second main goal of the thesis is to establish and experimentally confirm possible practical applications of the Doppler system. The Doppler system consists of the following parts. The hardware part is designed in a way to ensure fast measurement and easy adjustment to the different radar types. The software part of the system contains tools for: hardware control, data acquisition, signal processing and representing data to the user. In this work firstly a new type of 2D Doppler amplitude imaging was developed and formalized. Such a technique is used to derive information about the measured object from several angles of view. In the thesis special attention was paid to the frequency analysis of the mea- sured signals as a means to improve spatial resolution of the radar. In the context of frequency analysis we present 2D Doppler frequency imaging and compare it with amplitude imaging. In the thesis the spatial resolution ability of CW radars is examined and im- proved. We show that the joint frequency and the amplitude signal processing allows to significantly increase the spatial resolution of the radar.Das Thema dieser Dissertation ist die effiziente Materialcharakterisierung und Fehlerdetektion durch Nutzung des Dopplereffektes mittels Mikrowellen. Das erste Hauptziel der Arbeit ist die Entwicklung eines Prototyps eines Mikrowellen-Doppler-Systems im Bereich der zerstörungsfreien Prüfung. Das Doppler-System muss folgenden Voraussetzungen erfüllen: es sollte preisgünstig sein, leicht in industrielle Prozesse integrierbar sein und schnelle Messungen erlauben. Das Doppler-System muss die Software für die Hardware-Kontrolle, den Messablauf und die schnelle Signalverarbeitung beinhalten. Das zweite Hauptziel der Dissertation ist es, mögliche praktische Anwendungsfelder des Doppler-Systems zu identifizieren und experimentell zu bearbeiten. Das Doppler-System besteht aus zwei Teilen. Der Hardware-Teil ist so konstruiert, dass er schnelle Messungen und leichte Anpassungen an verschiedene Sensor- und Radartypen zulässt. Der Software-Teil des Systems beinhaltet Werkzeuge für: Hardware-Kontrolle, Datenerfassung, Signalverarbeitung und Programme, um die Daten für den Benutzer zu präsentieren. In dieser Arbeit wurde zuerst ein neuer Typ der 2D-Doppler-Amplitudenbildgebung entwickelt und formalisiert. Dieser Technik wird dafür benutzt, Informationen über die gemessenen Objekte von verschiedenen Blickpunkten aus zu erhalten. In dieser Doktorarbeit wird der Frequenzanalyse der gemessenen Signale besondere Aufmerksamkeit geschenkt, um die Ortsauflösung des Radars zu verbessern. Im Kontext der Frequenzanalyse wird die 2D-Doppler-Frequenzbildgebung präsentiert und mit der Amplitudenbildgebung vergleichen. In dieser Dissertation werden die räumliche Auflösungsmöglichkeiten von CW-Radaren untersucht und verbessert. Es wird gezeigt, dass es die Frequenz- und Amplitudensignalverarbeitung erlaubt, die Ortsauflösung des Radars erheblich zu erhöhen