High mobility in OFDM based wireless communication systems

Orthogonal Frequency Division Multiplexing (OFDM) has been adopted as the transmission scheme in most of the wireless systems we use on a daily basis. It brings with it several inherent advantages that make it an ideal waveform candidate in the physical layer. However, OFDM based wireless systems are severely affected in High Mobility scenarios. In this thesis, we investigate the effects of mobility on OFDM based wireless systems and develop novel techniques to estimate the channel and compensate its effects at the receiver. Compressed Sensing (CS) based channel estimation techniques like the Rake Matching Pursuit (RMP) and the Gradient Rake Matching Pursuit (GRMP) are developed to estimate the channel in a precise, robust and computationally efficient manner. In addition to this, a Cognitive Framework that can detect the mobility in the channel and configure an optimal estimation scheme is also developed and tested. The Cognitive Framework ensures a computationally optimal channel estimation scheme in all channel conditions. We also demonstrate that the proposed schemes can be adapted to other wireless standards easily. Accordingly, evaluation is done for three current broadcast, broadband and cellular standards. The results show the clear benefit of the proposed schemes in enabling high mobility in OFDM based wireless communication systems.Orthogonal Frequency Division Multiplexing (OFDM) wurde als Übertragungsschema in die meisten drahtlosen Systemen, die wir täglich verwenden, übernommen. Es bringt mehrere inhärente Vorteile mit sich, die es zu einem idealen Waveform-Kandidaten in der Bitübertragungsschicht (Physical Layer) machen. Allerdings sind OFDM-basierte drahtlose Systeme in Szenarien mit hoher Mobilität stark beeinträchtigt. In dieser Arbeit untersuchen wir die Auswirkungen der Mobilität auf OFDM-basierte drahtlose Systeme und entwickeln neuartige Techniken, um das Verhalten des Kanals abzuschätzen und seine Auswirkungen am Empfänger zu kompensieren. Auf Compressed Sensing (CS) basierende Kanalschätzverfahren wie das Rake Matching Pursuit (RMP) und das Gradient Rake Matching Pursuit (GRMP) werden entwickelt, um den Kanal präzise, robust und rechnerisch effizient abzuschätzen. Darüber hinaus wird ein Cognitive Framework entwickelt und getestet, das die Mobilität im Kanal erkennt und ein optimales Schätzungsschema konfiguriert. Das Cognitive Framework gewährleistet ein rechnerisch optimales Kanalschätzungsschema für alle möglichen Kanalbedingungen. Wir zeigen außerdem, dass die vorgeschlagenen Schemata auch leicht an andere Funkstandards angepasst werden können. Dementsprechend wird eine Evaluierung für drei aktuelle Rundfunk-, Breitband- und Mobilfunkstandards durchgeführt. Die Ergebnisse zeigen den klaren Vorteil der vorgeschlagenen Schemata bei der Ermöglichung hoher Mobilität in OFDM-basierten drahtlosen Kommunikationssystemen

The Potential of light fields in media productions

Comunicació presentada a: The 12th ACM SIGGRAPH Conference and Exhibition on Computer Graphics and Interactive Techniques in Asia, celebrada del 17 al 20 de novembre de 2019 a Brisbane, Austràlia.One aspect of the EU funded project SAUCE is to explore the pos-sibilities and challenges of integrating light field capturing andprocessing into media productions. A special light field camera wasbuild by Saarland University [Herfet et al.2018] and is first testedunder production conditions in the test production “Unfolding” aspart of the SAUCE project. Filmakademie Baden-Württemberg de-veloped the contentual frame, executed the post-production and pre-pared a complete previsualization. Calibration and post-processingalgorithms are developed by the Trinity College Dublin and theBrno University of Technology. This document describes challengesduring building and shooting with the light field camera array, aswell as its potential and challenges for the post-production.The project has received funding from the European Union’s Hori-zon 2020 Research and Innovation Programme under Grant Agree-ment No. 780470

The Potential of light fields in media productions

Comunicació presentada a: The 12th ACM SIGGRAPH Conference and Exhibition on Computer Graphics and Interactive Techniques in Asia, celebrada del 17 al 20 de novembre de 2019 a Brisbane, Austràlia.One aspect of the EU funded project SAUCE is to explore the pos-sibilities and challenges of integrating light field capturing andprocessing into media productions. A special light field camera wasbuild by Saarland University [Herfet et al.2018] and is first testedunder production conditions in the test production “Unfolding” aspart of the SAUCE project. Filmakademie Baden-Württemberg de-veloped the contentual frame, executed the post-production and pre-pared a complete previsualization. Calibration and post-processingalgorithms are developed by the Trinity College Dublin and theBrno University of Technology. This document describes challengesduring building and shooting with the light field camera array, aswell as its potential and challenges for the post-production.The project has received funding from the European Union’s Hori-zon 2020 Research and Innovation Programme under Grant Agree-ment No. 780470