Técnicas de gestão de feixe de onda para sistemas Massive MIMO nas redes 5G NR

The use of Millimeter wave (mmWave) spectrum frequencies is seen as a key enabler technology for the future wireless communication systems to overcome the bandwidth shortage of the sub 6GHz microwave spectrum band, enabling high speed data transmissions in the 5G/6G systems. Nevertheless, mmWave propagation characteristics are associated to significant free-path losses and many more attenuations that become even more harsher as the frequency increases, rendering the communication challenging at this frequencies. To overcome these distinct disadvantages, multiple antenna arrays are employed to allow beamforming techniques for the transmission of narrower concentrated beams in more precise directions and less interference levels between them, consequently improving the link budget. Thus, to constantly assure that the communication with each device is done using the beam pair that allows the best possible connectivity, a set of Beam Management control procedures is necessary to assure an efficient beamformed connection establishment and its continuous maintenance between the device and the network. This dissertation will address the description of the Initial Beam Establishment (IBE) BM procedure, focusing the selection of the most suitable transmit-receive beam pair available after completed beam sweeping techniques to measure the different power levels of the received signal. The main goal is to design a new 3GPP-standard compliant beam pair selection algorithm based on SSS angle estimation (BSAE), that makes use of multiple Synchronization Signal Blocks (SSBs) to maximize the Reference Signal Received Power (RSRP) value at the receiver, through the selected beam pair. This optimization is done using the Secondary Synchronization Signals (SSSs) present in each SSB to perform channel estimation in the digital domain (comprising the effects of the analog processing). Afterwards, the combination of those estimations were used to perform the equivalent channel propagation matrix estimation without the analog processing effects. Finally, through the channel propagation matrix, the angle that maximizes the RSRP was determined to compute the most suitable beam through the aggregated response vector. The obtained results show that the proposed algorithm achieves better performance levels compared to a conventional beam pair selection algorithm. Furthermore, a comparison with an optimal case is also done, i.e., the situation where the channel is known, and the optimal beam pair angle can be determined. Therefore, the similar performance results compared to the optimal case indicates that the proposed algorithm is interesting for practical 5G mmWave mMIMO implementations, according to 3GPP-compliant standards.O uso de frequências na banda das ondas milimétricas é visto como uma tecnologia chave para os futuros sistemas de comunicação móveis, tendo em vista a ultrapassar o problema da escassez de banda a sub-6 GHz, e por permitir as elevadas taxas de dados requeridas para sistemas 5G/6G. Contudo, a propagação deste tipo de ondas está associado a perdas acentuadas em espaço livre e várias atenuações que se tornam cada vez mais significativas com o aumento do valor da frequência, impondo obstáculos à comunicação. Para ultrapassar estas adversidades, agregados constituídos por múltiplos elementos de antena são implementados por forma a permitir técnicas de formação de feixe e possibilitar a transmissão de feixes mais estreitos e altamente direcionais, diminuindo os níveis de interferência e melhorando consequentemente o link budget. Deste modo, para assegurar constantemente que a comunicação efetuada em cada dispositivo ocorre utilizando o conjunto de feixes que proporciona o melhor nível de conectividade, é então necessário um conjunto de procedimentos de controlo de gestão de feixe, assegurando um estabelecimento eficiente da comunicação e a sua contínua manutenção entre um dispositivo e a rede. Esta dissertação descreve o procedimento de gestão de feixe conhecido como estabelecimento inicial de feixe, focando o processo de seleção do melhor par de feixe de transmissão-receção disponível após o uso de técnicas de varrimento de feixe por fim a efetuar medições dos diferentes níveis de potência do sinal recebido. O principal objetivo passa pela conceção de um novo algoritmo de estabelecimento de par de feixes baseado em estimações de ângulo (BSAE), que explora o uso de múltiplos SSBs definidos pelo 3GPP, por forma a maximizar o RSRP no recetor, através do feixe selecionado. Esta otimização é feita usando os sinais de sincronização secundários (SSSs) presentes em cada SSB para efetuar uma estimação de canal no domínio digital (que contém o efeito do processamento analógico). Depois, combinando essas estimações, foi feita uma estimação da matriz do canal de propagação, sem o efeito desse processamento analógico. Finalmente, através da matriz do canal de propagação, foi determinado o ângulo que maximiza o RSRP, e calculado o feixe através do vetor de resposta do agregado. Os resultados obtidos demonstram que o algoritmo proposto atinge melhor desempenho quando comparado com o algoritmo convencional de seleção de par de feixes. Foi feita ainda uma comparação com o caso ótimo, isto é, com o caso em que se conhece completamente o canal e se obtém um ângulo ótimo. Os resultados obtidos pelo algoritmo proposto foram muito próximos do caso ótimo, pelo que é bastante interessante para sistemas práticos 5G mmWave mMIMO, que estejam de acordo com o padrão 3GPP.Mestrado em Engenharia Eletrónica e Telecomunicaçõe

LEVERAGING OPENAIRINTERFACE AND SOFTWARE DEFINED RADIO TO ESTABLISH A LOW-COST 5G NON-STANDALONE ARCHITECTURE

Includes Supplementary MaterialCommercial cellular service providers are at the forefront of the paradigm shift from 4G Long Term Evolution (LTE) to 5G New Radio (NR). The increase in throughput, provisioning of ultra-low latency, and greater reliability of 5G enable potential uses that no other wireless communication could support. The Department of Defense (DOD) is interested in 5G NR technologies, but the implementation of the architecture can be lengthy and costly. This capstone configured a 4G LTE network and a 5G non-standalone network using OpenAirInterface and software defined radios (SDRs). Universal Subscriber Identity Module (USIM) cards were configured and introduced to user equipment and attached to the 4G LTE network. A gNodeB (gNB) was added to the 4G LTE network to establish the 5G non-standalone (NSA) network architecture (3GPP Option 3). The testbed developed in this research was able to connect the core to a commercial internet service provider and browse the internet using third-party applications. Our analysis educates future researchers on the challenges and lessons learned when implementing the OpenAirInterface 4G LTE and 5G NSA networks. This work also provides a better understanding of 4G LTE and 5G NSA OpenAirInterface software usability, flexibility, and scalability for potential use cases for the DOD.Chief Petty Officer, United States NavyApproved for public release. Distribution is unlimited

A Tutorial on Beam Management for 3GPP NR at mmWave Frequencies

The millimeter wave (mmWave) frequencies offer the availability of huge bandwidths to provide unprecedented data rates to next-generation cellular mobile terminals. However, mmWave links are highly susceptible to rapid channel variations and suffer from severe free-space pathloss and atmospheric absorption. To address these challenges, the base stations and the mobile terminals will use highly directional antennas to achieve sufficient link budget in wide area networks. The consequence is the need for precise alignment of the transmitter and the receiver beams, an operation which may increase the latency of establishing a link, and has important implications for control layer procedures, such as initial access, handover and beam tracking. This tutorial provides an overview of recently proposed measurement techniques for beam and mobility management in mmWave cellular networks, and gives insights into the design of accurate, reactive and robust control schemes suitable for a 3GPP NR cellular network. We will illustrate that the best strategy depends on the specific environment in which the nodes are deployed, and give guidelines to inform the optimal choice as a function of the system parameters.Comment: 22 pages, 19 figures, 10 tables, published in IEEE Communications Surveys and Tutorials. Please cite it as M. Giordani, M. Polese, A. Roy, D. Castor and M. Zorzi, "A Tutorial on Beam Management for 3GPP NR at mmWave Frequencies," in IEEE Communications Surveys & Tutorials, vol. 21, no. 1, pp. 173-196, First quarter 201

Channel estimation techniques for next generation mobile communication systems

Mención Internacional en el título de doctorWe are witnessing a revolution in wireless technology, where the society is demanding new services, such as smart cities, autonomous vehicles, augmented reality, etc. These challenging services not only are demanding an enormous increase of data rates in the range of 1000 times higher, but also they are real-time applications with an important delay constraint. Furthermore, an unprecedented number of different machine-type devices will be also connected to the network, known as Internet of Things (IoT), where they will be transmitting real-time measurements from different sensors. In this context, the Third Generation Partnership Project (3GPP) has already developed the new Fifth Generation (5G) of mobile communication systems, which should be capable of satisfying all the requirements. Hence, 5G will provide three key aspects, such as: enhanced mobile broad-band (eMBB) services, massive machine type communications (mMTC) and ultra reliable low latency communications (URLLC). In order to accomplish all the mentioned requirements, it is important to develop new key radio technologies capable of exploiting the wireless environment with a higher efficiency. Orthogonal frequency division multiplexing (OFDM) is the most widely used waveform by the industry, however, it also exhibits high side lobes reducing considerably the spectral efficiency. Therefore, filter-bank multi-carrier combined with offset quadrature amplitude modulation (FBMC-OQAM) is a waveform candidate to replace OFDM due to the fact that it provides extremely low out-ofband emissions (OBE). The traditional spectrum frequencies range is close to saturation, thus, there is a need to exploit higher bands, such as millimeter waves (mm-Wave), making possible the deployment of ultra broad-band services. However, the high path loss in these bands increases the blockage probability of the radio-link, forcing us to use massive multiple-input multiple-output (MIMO) systems in order to increase either the diversity or capacity of the overall link. All these emergent radio technologies can make 5G a reality. However, all their benefits can be only exploited under the knowledge and availability of the channel state information (CSI) in order to compensate the effects produced by the channel. The channel estimation process is a well known procedure in the area of signal processing for communications, where it is a challenging task due to the fact that we have to obtain a good estimator, maintaining at the same time the efficiency and reduced complexity of the system and obtaining the results as fast as possible. In FBMC-OQAM, there are several proposed channel estimation techniques, however, all of them required a high number of operations in order to deal with the self-interference produced by the prototype filter, hence, increasing the complexity. The existing channel estimation and equalization techniques for massive MIMO are in general too complex due to the large number of antennas, where we must estimate the channel response of each antenna of the array and perform some prohibitive matrix inversions to obtain the equalizers. Besides, for the particular case of mm-Wave, the existing techniques either do not adapt well to the dynamic ranges of signal-to-noise ratio (SNR) scenarios or they assume some approximations which reduce the quality of the estimator. In this thesis, we focus on the channel estimation for different emerging techniques that are capable of obtaining a better performance with a lower number of operations, suitable for low complexity devices and for URLLC. Firstly, we proposed new pilot sequences for FBMC-OQAM enabling the use of a simple averaging process in order to obtain the CSI. We show that our technique outperforms the existing ones in terms of complexity and performance. Secondly, we propose an alternative low-complexity way of computing the precoding/postcoding equalizer under the scenario of massive MIMO, keeping the quality of the estimator. Finally, we propose a new channel estimation technique for massive MIMO for mm-Wave, capable of adapting to very variable scenarios in terms of SNR and outperforming the existing techniques. We provide some analysis of the mean squared error (MSE) and complexity of each proposed technique. Furthermore, some numerical results are given in order to provide a better understanding of the problem and solutions.Programa de Doctorado en Multimedia y Comunicaciones por la Universidad Carlos III de Madrid y la Universidad Rey Juan CarlosPresidente: Antonia María Tulino.- Secretario: Máximo Morales Céspedes.- Vocal: Octavia A. Dobr

Cellular Planning and Optimization for 4G and 5G Mobile Networks

Cellular planning and optimization of mobile heterogeneous networks has been a topic of study for several decades with a diversity of resources, such as analytical formulations and simulation software being employed to characterize different scenarios with the aim of improving system capacity. Furthermore, the world has now witnessed the birth of the first commercial 5G New Radio networks with a technology that was developed to ensure the delivery of much higher data rates with comparably lower levels of latency. In the challenging scenarios of 4G and beyond, Carrier Aggregation has been proposed as a resource to allow enhancements in coverage and capacity. Another key element to ensure the success of 4G and 5G networks is the deployment of Small Cells to offload Macrocells. In this context, this MSc dissertation explores Small Cells deployment via an analytical formulation, where metrics such as Carrier plus Noise Interference Ratio, and physical and supported throughput are computed to evaluate the system´s capacity under different configurations regarding interferers positioning in a scenario where Spectrum Sharing is explored as a solution to deal with the scarcity of spectrum. One also uses the results of this analyses to propose a cost/revenue optimization where deployment costs are estimated and evaluated as well as the revenue considering the supported throughput obtained for the three frequency bands studied, i.e., 2.6 GHz, 3.5 GHz and 5.62 GHz. Results show that, for a project life time of 5 years, and prices for the traffic of order of 5€ per 1 GB, the system is profitable for all three frequency bands, for distances up to 1335 m. Carrier Aggregation is also investigated, in a scenario where the LTE-Sim packet level simulator is used to evaluate the use of this approach while considering the use of two frequency bands i.e., 2.6 GHz and 800 MHz to perform the aggregation with the scheduling of packets being performed via an integrated common radio resource management used to compute Packet Loss Ratio, delay and goodput under different scenarios of number of users and cell radius. Results of this analysis have been compared to a scenario without Carrier Aggregation and it has been demonstrated that CA is able to enhance capacity by reducing the levels of Packet Loss Ratio and delay, which in turn increases the achievable goodput.O planeamento e otimização de redes de redes celulares heterogéneas tem sido um tópico de investigação por várias décadas com diversas abordagens que incluem formulações analíticas e softwares de simulação, sendo aplicados na caracterização de diferentes cenários, com o objetivo de melhorar a capacidade de sistema. Além disso, o mundo testemunhou o nascimento das primeiras redes 5G New Radio, com uma tecnologia que foi desenvolvida com o objetivo de garantir taxas de transferência de dados muito superiores, com níveis de latência comparativamente inferiores. Neste cenário de desafios pós-4G, a agregação de Espectro tem sido proposta como uma solução para permitir melhorias na cobertura e capacidade do sistema. Outro ponto para garantir o sucesso das redes 5G é a utilização de Pequenas Células para descongestionar as Macro células. Neste contexto, esta dissertação de mestrado explora a utilização de Pequenas Células através de uma formulação analítica, onde se avaliam métricas como a relação portadora-interferência-mais-ruído, débito binário e débito binário suportado, sob diferentes configurações de posicionamento de interferentes em cenários onde a partilha de espectro é explorada como uma solução para enfrentar a escassez de espectro. Os resultados dessa análise são também considerados para propor uma otimização de custos/proveitos, onde os custos de implantação são estimados e avaliados, assim como os proveitos ao se considerar o débito binário suportado obtido para as três bandas de frequência em estudo, a saber, 2.6 GHz, 3.5 GHz e 5.62 GHz. Os resultados demonstram que, para um tempo de vida do projeto de 5 anos, e para preços de tráfego de cerca de 5 € por GB, o sistema é lucrativo para as três bandas de frequência, para distâncias até 1335 m. Também se investiga a agregação de espectro recorrendo ao simulador de pacotes LTE-Sim para avaliar o uso de duas bandas de frequência, a saber, 2.6 GHz e 800 MHz, considerando agregação com a calendarização de pacotes por meio de um gestor comum de recursos de rádio integrado, utilizado para computar a taxa de perda de pacotes, o atraso e o débito binário na camada de aplicação, em cenários com diferentes valores de número de utilizadores e raios das células. Os resultados dessa análise foram comparados com o desempenho de um cenário sem agregação. Foi demonstrado que a agregação é capaz de aumentar a capacidade de sistema, ao reduzir os níveis de perda de pacotes e do atraso, o que por sua vez possibilita a elevação dos níveis de débito binário atingidos