The integration of Multiple Input Multiple Output (MIMO) and Orthogonal Frequency Division Multiplexing (OFDM) techniques has become a preferred solution for the high rate wireless technologies due to its high spectral efficiency, robustness to frequency selective fading, increased diversity gain, and enhanced system capacity. The main drawback of OFDM-based systems is their susceptibility to impairments such as Carrier Frequency Offset (CFO), Sampling Frequency Offset (SFO), Symbol Timing Error (STE), Phase Noise (PHN), and fading channel. These impairments, if not properly estimated and compensated, degrade the performance of the OFDM-based systems In this thesis, a system model for MIMO-OFDM that takes into account the effects of all these impairments is formulated. Using this system model, we de-rive Cramer-Rao Lower Bounds (CRLBs) for the joint estimation of deterministic impairments in MIMO-OFDM system, which show the coupling effect among different impairments and the significance of the joint estimation. Also, Bayesian CRLBs for the joint estimation of random impairments in OFDM system are derived. Similarly, we derive Hybrid CRLBs for the joint estimation of random and deterministic impairments in OFDM system, which show the significance of using Bayesian approach in estimation. Further, we investigate different algorithms for the joint estimation of all impairments in OFDM-based system. Maximum Likelihood (ML) algorithms and its low complexity variants, for the joint estimation of CFO, SFO, STE, and channel in MIMO-OFDM system, are proposed. We propose a low complexity ML algorithm which uses Compressed Sensing (CS) based channel estimation method in a sparse fading sce-nario, where the received samples used for estimation are less than that required for a Least Squares (LS) or Maximum a posteriori (MAP) based estimation. Also, we propose MAP algorithms for the joint estimation of the random impairments, PHN and channel, utilizing their statistical knowledge which is known a priori. Joint estimation algorithms for SFO and channel in OFDM system, using Bayesian framework, are also proposed in this thesis. The performance of the estimation methods is studied through simulations and numerical results show that the performance of the proposed algorithms is better than existing algorithms and is closer to the derived CRLBs.

[ES] Los esquemas de antenas de múltiples entradas y múltiples salidas (MIMO) pueden maximizar la eficiencia espectral de los sistemas de Televisión Digital Terrestre (TDT) para la provisión de contenidos de gran capacidad, como los servicios emergentes de televisión de ultra alta definición (UHDTV), en el cada vez más escaso y limitado espectro radioeléctrico de la TDT debido a la creciente demanda de servicios inalámbricos de banda ancha (4G y 5G). Las tecnologías MIMO han sido desarrolladas inicialmente en la especificación técnica de TDT DVB-NGH (Digital Video Broadcasting Next Generation Handheld) y estandarizadas en el último estándar de TDT, ATSC 3.0 (Advanced Television Systems Committee 3rd Generation). Sin embargo, no hay despliegues comerciales MIMO de TDT. Por otro lado, la industria móvil ha desarrollado una tecnología de radiodifusión móvil, conocida como hoy en día como 5G Broadcast, basado en LTE (Long Term Evolution). Aunque LTE incorpora MIMO para transmisiones unicast punto a punto, 5G Broadcast sólo utiliza una única antenna en transmisión. Esta tesis doctoral tiene como objetivo evaluar el rendimiento de MIMO para radiodifusión (terrestrial broadcast) para sistemas inalámbricos de radiodifusión de nueva generación, tanto TDT como sistemas celulares. Durante la estandarización de los sistemas MIMO TDT, el diseño inicial tiene en cuenta condiciones de recepción perfectas, por ejemplo, demoduladores óptimos, información de estado del canal (CSI) perfecta, estimación perfecta de la potencia del ruido, etc. El objetivo principal de esta tesis doctoral es evaluar y optimizar el rendimiento de las transmisiones de radiodifusión MIMO en escenarios realistas. Esta tesis doctoral propone nuevos modelos de canales de propagación MIMO terrestres basados en medidas de campo que pueden utilizarse para la evaluación del rendimiento del sistema MIMO TDT. Además, también optimiza las diferentes configuraciones de transmisión y recepción MIMO, como la estimación de los canales MIMO en el receptor, y el procesado de señal. El escenario considerado en la tesis son torres de alta potencia con recepción fija, característico de las redes de TDT. Los resultados de esta tesis han contribuido al foro de estandarización ATSC, al sector de radiocomunicaciones de la Unión Internacional de Telecomunicaciones (UIT-R) y al proyecto nacional japonés de investigación sobre el sistema TDT de próxima generación. / [CA] Els esquemes d"antenes de múltiples entrades i múltiples sortides (MIMO) poden maximitzar l"eficiència espectral dels sistemes de Televisió Digital Terrestre (TDT) per a la provisió de continguts de gran capacitat, com els serveis emergents de televisió d"ultra alta definició (UHDTV) , en el cada vegada més escàs i limitat espectre radioelèctric de la TDT a causa de la creixent demanda de serveis sense fil de banda ampla (4G i 5G). Les tecnologies MIMO han estat desenvolupades inicialment en l'especificació tècnica de TDT DVB-NGH (Digital Video Broadcasting Next Generation Handheld) i estandarditzades a l'últim estàndard de TDT, ATSC 3.0 (Advanced Television Systems Committee 3rd Generation). No obstant això, no hi ha desplegaments comercials MIMO de TDT. D'altra banda, la indústria mòbil ha desenvolupat una tecnologia de radiodifusió mòbil, coneguda com avui dia com a 5G Broadcast, basat en LTE (Long Term Evolution). Tot i que LTE incorpora MIMO per a transmissions unicast punt a punt, 5G Broadcast només utilitza una única antena en transmissió. Aquesta tesi doctoral té com a objectiu avaluar el rendiment de MIMO per a radiodifusió (terrestrial broadcast) per a sistemes sense fil de radiodifusió de nova generació, tant TDT com sistemes cel·lulars. Durant l'estandardització dels sistemes MIMO TDT, el disseny inicial té en compte condicions de recepció perfectes, per exemple demoduladors òptims, informació d'estat del canal (CSI) perfecta, estimació perfecta de la potència del soroll, etc. L¿objectiu principal d¿aquesta tesi doctoral és avaluar i optimitzar el rendiment de les transmissions de radiodifusió MIMO en escenaris realistes. Aquesta tesi doctoral proposa nous models de canals de propagació MIMO terrestres basats en mesures de camp que es poden utilitzar per a l'avaluació del rendiment del sistema MIMO TDT. A més, també optimitza les diferents configuracions de transmissió i recepció MIMO, com l'estimació dels canals MIMO al receptor, i el processament de senyal. L'escenari considerat a la tesi són torres d'alta potència amb recepció fixa, característic de les xarxes de TDT. Els resultats d"aquesta tesi han contribuït al fòrum d"estandardització ATSC, al sector de radiocomunicacions de la Unió Internacional de Telecomunicacions (UIT-R) i al projecte nacional japonès de recerca sobre el sistema TDT de propera generació. / [EN] Multiple-Input Multiple-Output (MIMO) antenna schemes in Digital Terrestrial Television (DTT) systems aim to maximize the spectral efficiency for the provision of large capacity contents in the scarce and limited DTT Radio-Frequency (RF) channel. The delivery of the emerging Ultra-High Definition TV (UHDTV) services as well as the continuous broadcast spectrum shortage due to the rapidly growing demand for wireless broadband services (4G and 5G) are the motivations for this proposal. MIMO technologies have been firstly developed in the DTT technical specification DVB-NGH (Digital Video Broadcasting Next Generation Handheld) and standardized in the latest DTT standard, ATSC3.0 (Advanced Television Systems Committee 3rd Generation). However, MIMO broadcasting has not been commercialized due to the additional investment for both service providers and receivers. On the other hand, mobile industry has developed mobile broadcast technologies known today as 5G Broadcast based on LTE (Long Term Evolution). Although LTE incorporates MIMO for point to point unicast, 5G Broadcast only uses a single antenna in transmission at the moment. The Ph.D. aims at assessing the performance of MIMO for broadcasting (terrestrial broadcast) for next-generation wireless broadcasting systems, including next-generation wireless broadcasting systems, both DTT and cellular system. During the standardization of MIMO DTT systems, the initial design accounts for perfect reception conditions, e.g., optimal demodulators, perfect Channel State Information (CSI), perfect noise power estimation. The main goal of this PhD is to assess and optimize the performance of MIMO wireless broadcast transmissions in realistic scenarios. This PhD proposes new models of terrestrial MIMO propagation channels based on field measurements which can be utilized for the evaluation of MIMO DTT system. Furthermore, it also optimizes the different MIMO transmission and reception configurations, such as broadcast MIMO channel estimation and signal processing. The scenarios considered in the thesis are high-power high-tower transmitter with fixed reception and characteristics of DTT networks. The results of the PhD have contributed to the ATSC standardization forum, International Telecommunication Union Radiocommunication Sector (ITU-R), and the Japanese national research project on next generation DTT system. / Shitomi, T. (2023). Evaluation and Optimization of Multiple-Input Multiple-Output Antenna Schemes for Next-Generation Wireless Broadcasting [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/202598

[pt] Na primeira parte desta tese, são desenvolvidos dois esquemas de detecção por listas para sistemas MIMO multiusuário. As técnicas propostas usam uma única transformação de redução de reticulado (LR) para modificar a matriz de canal entre os usuários e a estação base (BS). Após a transformação LR, um candidato confiável do sinal transmitido é obtido usando um detector de cancelamento sucessivo de interferências (SIC). No detector em múltiplos ramos com redução de reticulado e cancelamento sucessivo de interferências (MB-LR-SIC) proposto, um número fixo de diferentes ordenamentos para o detector SIC gera uma lista de possíveis candidatos para a informação transmitida. O melhor candidato é escolhido usando o critério maximum likelihood (ML). No detector por listas de tamanho variável (VLD) proposto, um algoritmo que decide se o candidato atual tem uma boa qualidade ou se é necessário continuar procurando por um candidato melhor nos ordenamentos restantes é utilizado. Os resultados numéricos mostram que os esquemas propostos têm um desempenho quase ótimo com uma complexidade computacional bem abaixo do detector ML. Um esquema de detecção e decodificação iterativa (IDD) baseado no algoritmo VLD é também desenvolvido, produzindo um desempenho próximo a um sistema mono usuário (SU) livre de interferências. Na segunda parte desta tese, uma técnica de detecção desacoplada de sinais (DSD) para sistemas MIMO massivo é proposta. Esta técnica permite que o sinal composto recebido na BS seja separado em sinais independentes, correspondentes a diferentes classes de usuários, viabilizando assim o uso dos procedimentos de detecção propostos na primeira parte desta tese em sistemas MIMO massivos. Um modelo de sinais para sistemas MIMO massivo com antenas centralizadas e/ou antenas distribuídas operando em redes heterogêneas de quinta geração é proposto. Uma análise baseada na soma das taxas e um estudo de custo computacional para DSD são apresentados. Os resultados numéricos ilustram o excelente compromisso desempenho versus complexidade obtido com a técnica DSD quando comparada com o esquema de detecção conjunta tradicional. / [en] In the first part of this thesis, we introduce two list detection schemes for the uplink scenario of multiuser multiple-input multiple-output (MUMIMO) systems. The proposed techniques employ a single lattice reduction (LR) transformation to modify the channel matrix between the users and the base station (BS). After the LR transformation, a reliable candidate for the transmitted signal vector, provided by successive interference cancellation (SIC) detection is obtained. In the proposed multi-branch lattice reduction SIC (MB-LR-SIC) detector, a fixed number of different orderings, generates a list of SIC detection candidates. The best candidate is chosen according to the maximum likelihood (ML) selection criterion. For the proposed variable list detection (VLD) scheme, an algorithm to decide if the current candidate has good quality or if it is necessary to further explore different orderings to improve the detection performance is employed. Simulation results indicate that the proposed schemes have a near-optimal performance while keeping its computational complexity well below that of the ML detector. An iterative detection and decoding (IDD) scheme based on the VLD algorithm is also developed, producing an excellent performance that approaches the single user (SU) scenario. In the second part of this thesis, a decoupled signal detection (DSD) technique which allows the separation of uplink signals, for each user class, at the base station (BS) for massive MIMO systems is proposed. The proposed DSD allows to implement the detection procedures proposed in the first part of this thesis in massive MIMO scenarios. A mathematical signal model for massive MIMO systems with centralized and distributed antennas in the future fifth generation (5G) heterogeneous cellular networks is also developed. A sum-rate analysis and a study of computational cost for DSD are also presented. Simulation results show excellent performance of the proposed DSD algorithm when combined with linear and SIC-based detectors.