Zugl.: Ulm, Univ., Diss., 2007

Zugl.: Erlangen, Nürnberg, Univ., Diss., 2007

Zugl.: Hamburg, Harburg, Techn. Univ., Diss., 2009

Zugl.: Zürich, Techn. Hochsch., Diss., 2009

Asim M. Mazin, for the Master of Science degree in Electrical and Computer Engineering, presented on Mar 27, 2013, at Southern Illinois University Carbondale. TITLE: REDUCING THE PEAK TO AVERAGE POWER RATIO OF MIMO-OFDM USING PSO BASED PTS. MAJOR PROFESSOR: Dr. Garth V. Crosby, In this thesis we proposed PSO based PTS to accomplish the lowest Peak-to-Average Power Ratio of MIMO-OFDM system. We applied the PSO based PTS on each antenna of the system in order to find the optimal phase factors which is a straightforward method to get the minimum PAPR in such a system. The performance of PSO based PTS algorithm in MIMO-OFDM with a wide range of phase factor tends to give a high performance according to the simulation results. In addition, there is no need to increase the number of particles of the PSO algorithm to enhance the performance of the system, which keeps the complexity of finding the minimum PAPR reasonable.

La 5ème génération de réseaux mobiles (5G), actuellement en cours de standardisation, prévoit de nouveaux scénarios de communication dans l’évolution vers un monde entièrement connecté et communicant. Dans ce contexte, un nombre très important de techniques avancées sont en cours d’exploration pour répondre aux nombreux défis imposés en termes de débit, de latence, de consommation énergétique, et de capacité à faire communiquer entre eux, efficacement, des milliards d'objets très différents. Parmi les techniques les plus prometteuses de la couche physique, de nouvelles formes d'ondes multiporteuses filtrées sont proposées. Bien qu’elles offrent un meilleur confinement spectral et une meilleure localisation en temps et en fréquence par rapport à l’OFDM de la 4G, elles présentent des limitations soit en termes de complexité soit en termes de performance et d’intégration. De plus, ces formes d’ondes sont évaluées d’un point de vue théorique et les résultats ne sont pas toujours validés sur des plateformes matérielles de preuve de concept reproduisant les conditions réelles des scénarios de la 5G.Dans ce contexte, les travaux de cette thèse proposent plusieurs contributions originales aussi bien au niveau algorithmes de traitement qu’au niveau architectures matérielles. Dans le domaine algorithmique,les travaux réalisés ont mené aux contributions suivantes : (1) Un nouveau filtre prototype court est proposé pour la forme d’onde FBMC/OQAM. Des analyses analytiques, complétées par simulation,montrent que le filtre proposé permet d’améliorer la résistance aux erreurs de synchronisation temporel et de réduire la complexité du récepteur FBMC de type « frequency-spread » comparé aux autres filtres de la littérature, (2) Un nouveau type de récepteur FBMC adapté pour les filtres courts est proposé. Ce récepteur a la particularité d’améliorer sensiblement la résistance aux canaux doublement dispersifs pour des filtres courts, et de supporter les communications asynchrones, (3) Un émetteur UF-OFDM original de complexité significativement réduite par rapport à la littérature est proposé. Contrairement aux techniques existantes, l’émetteur proposé n’introduit aucune approximation dans le signal généré, et préserve ainsi le confinement spectral de la forme d’onde. Dans le domaine de la conception matérielle, les travaux réalisés durant cette thèse ont mené aux contributions suivantes : (4) Une architecture matérielle optimisée des émetteurs FBMC et UF-OFDM de complexité comparable à OFDM, (5) Une architecture matérielle optimisée de l’étage de filtrage du récepteur FBMC « frequency-spread », avec une complexité comparable à celle d’un récepteur « polyphase-network », et (6) Une des premières plateformes matérielles de preuve de concept de la 5G, pouvant évaluer les performances des formes d’ondes pour les différents services de la 5G. / The 5th generation of mobile communications is fore seen to cope with a high degree of heterogeneity in terms of services: enhanced mobile broadband, massive machine, vehicular and mission critical communications, broadcast services. Consequently, diverse and often contradicting key performance indicators need to be supported, such as high capacity/user-rates, low latency, high mobility, massive number of devices, low cost and low power consumption. 4G is not designed to efficiently meet such a high degree of heterogeneity: the OFDM waveform exhibits several limitations in terms of spectrum usage and robustness to frequency and timing synchronization errors. In order to overcome these limitations and to cope with the new 5G requirements,several research initiatives have been conducted to design new waveforms. Proposed candidates, such as FBMC/OQAM or UF-OFDM,are mainly based on multicarrier modulation with specific filtering scheme used on the top of the OFDM basis. However, most of the proposed new waveforms are often studied and analyzed at the algorithmic level considering mainly the quality of the communication link. Therefore, the investigation of low-complexity implementations and the availability of real hardware prototypes are of high interest for performance validation and proof-of-concept of the diverse proposed communication techniques. In the above context, this thesis work proposes several original contributions in the algorithm and the hardware design domains. In the algorithm domain, this work leads to the following contributions: (1) Anovel short prototype filter for FBMC allowing for near perfectreconstruction and having the same size as one OFDM symbol is proposed. Using the Frequency Spread implementation for the FBMC receiver, analytical studies and simulation results show that the proposed filter exhibits better robustness to several types of channel impairments when compared to state-of-the-art short prototype filters and OFDM modulation. (2) A novel FBMC receiver technique suitable for short filters is proposed. This receiver enables to greatly improve the robustness against double dispersive channels for short filters, and enables the support of asynchronous communications, (3) A novel low complexityUF-OFDM transmitter without any signal quality loss isproposed. For small subband sizes, the complexity becomescomparable to OFDM regardless of the number of allocated subbands.In the hardware design domain, this thesis work leads to the following contributions: (4) An efficient pipelined hardware architecture of the FBMC/OQAM transmitter capable of supporting several filter lengths and targeting low complexity is proposed and compared to typical FBMC/OQAM and OFDM implementations, (5) An optimized frequency spread based hardware architecture of the filtering stage is proposed for the designed short prototype filter, showing lower complexity than the classical Poly Phase-Network-based implementation, (6) One of the first flexible and efficient hardware platforms for 5G waveform design, allowing the support of several communication scenarios as foreseen in 5G.

The number of wireless systems, services, and users are constantly increasing and therefore the bandwidth requirements have become higher. One of the most robust modulations is Orthogonal Frequency-Division Multiplexing (OFDM). It has been considered as an attractive solution for future broadband wireless communications. This dissertation investigates bit and power allocation, joint resource allocation, user scheduling, and limited feedback problem in multi-user OFDM systems. The following dissertation contributes to improved OFDM systems in the following manner. (1) A low complexity sub-carrier, power, and bit allocation algorithm is proposed. This algorithm has lower computational complexity and results in performance that is comparable to that of the existing algorithms. (2) Variations of the proportional fair scheduling scheme are proposed and analyzed. The proposed scheme improves system throughput and delay time, and achieves higher throughput without sacrificing fairness which makes it a better scheme in terms of efficiency and fairness. (3) A DCT feedback compression algorithm based on sorting is proposed. This algorithm uses sorting to increase the correlation between feedback channel quality information of frequency selective channels. The feedback overhead of system is successfully reduced.

This study is based on applying a non-linear mapping method, here the unscented Kalman filter; to estimate and optimize data rate resulting from the arrival rate having a Poisson distribution in an orthogonal frequency division multiplexing (OFDM) transmission system. OFDM is an emerging multi-carrier modulation scheme. With the growing need for quality of service in wireless communications, it is highly necessary to optimize resources in such a way that the overall performance of the system models should rise while keeping in mind the objective to achieve high data rate and efficient spectral methods in the near future. In this study, the results from the OFDM-TDMA transmission system have been used to apply cross-layer optimization between layers so as to treat different resources between layers simultaneously. The main controller manages the transmission of data between layers using the multicarrier modulation techniques. The unscented Kalman filter is used here to perform nonlinear mapping by estimating and optimizing the data rate, which result from the arrival rate having a Poisson distribution.

The thesis is focused on designing OFDM modem, which should be implemented into the FPGA device. The advantages of using OFDM signals in order to provide high baud rates together with high multipath immunity has provoked a mass expansion into media systems such as DSL, DVB, Wi-Fi, WLAN, etc. . Thanks to this technology we can quarantee high modulation rates with minimal negative disturbance eects. The rst part is dedicated to characterise OFDM signals, their generation and the algorithm producing the OFDM which is implemented in DSP devices. For the purpose of using the fastest algorithm, the Fast Fourier Transform using Cooley-Tukey algorithm was shown. Before we can implement OFDM modem into the FPGA device, we have to simulate its correct function. Because there is no OFDM analyser available at our departement, its necessary to prove its correct function by simulations. Therefore a large part of this thesis is focused on simulations using Matlab and ModelSim, in order to show comparison between the theoretical, and simulated results. Between the theoretical and practical simulations there is a part which shows the brief characteristics of available FPGA devices. Detailed view is presented just for the Virtex II device, which the implementation is made for. As a suitable FPGA device, we have chosen Virtex II XC2V1000 which is available for students. In the last part the measured results were shown to prove the corect function of the modem. Programming the FPGA using VHDL language is realized in the software ISE Xilinx (distributed in Xilinx software support). All programmed scrits and data used in this thesis are included on distributed media.

This master thesis is focused on description of the standards for mobile and portable receive of a digital television broadcast DVBT2Lite and DVBNGH. In MATLAB has been developed an application simulator with adjustable parameters of the transmitter and transmission channel. Application shows the constellation diagram of the received signal, resultant bit error and frequency characteristic of transmission channel. In this thesis are discussed simulation results with measured results from different simulation scenarios.