Network planning for the future railway communications

Los Sistemas Inteligentes de Transporte están cambiando la forma en que concebimos el futuro de la movilidad. En particular, los ferrocarriles están experimentando un proceso de transformación para modernizar el transporte público y las operaciones ferroviarias. Tecnologías como el 5G, la fibra óptica y la nube han surgido como catalizadores para digitalizar el ferrocarril proporcionando comunicaciones de alta velocidad y baja latencia. Este TFG se centra en la exploración de redes que permitan el control del tren y la transmisión de datos a bordo. El objetivo es planificar la infraestructura de red (dimensionamiento y asignación de recursos) necesaria para las futuras comunicaciones del sistema ferroviario de larga distancia de la Deutsche Bahn en Alemania. En este trabajo, proponemos una arquitectura de red que puede satisfacer los requisitos de rendimiento de las aplicaciones para trenes y pasajeros. Presentamos un método para la colocación de estaciones base 5G a lo largo de las vías del tren para garantizar el rendimiento necesario en el borde de la celda. Por último, presentamos el problema de colocación y asignación de centros de datos. El objetivo es encontrar el número necesario de centros de datos y su ubicación en la red, y asignarlos a cada estación de tren. Realizamos simulaciones en cuatro escenarios diferentes, en los que modificamos parámetros de entrada como la latencia máxima tolerada y el número máximo de centros de datos. Los resultados obtenidos muestran el compromiso entre la latencia alcanzada y el coste de la infraestructura.Els Sistemes Intel·ligents de Transport estan canviant la manera en què concebem el futur de la mobilitat. En particular, els ferrocarrils estan experimentant un procés de transformació per modernitzar el transport públic i les operacions ferroviàries. Tecnologies com el 5G, la fibra òptica i el núvol han sorgit com a catalitzadors per digitalitzar el ferrocarril proporcionant comunicacions d'alta velocitat i baixa latència. Aquest TFG se centra en l'exploració de xarxes que permetin el control dels trens i la transmissió de dades a bord. L'objectiu és planificar la infraestructura de xarxa (dimensionament i assignació de recursos) necessària per a les futures comunicacions del sistema ferroviari de llarga distància de la Deutsche Bahn a Alemanya. En aquest treball, proposem una arquitectura de xarxa que pot satisfer els requisits de rendiment de les aplicacions per a trens i passatgers. Presentem un mètode per a la col·locació d'estacions base 5G al llarg de les vies del tren per garantir el rendiment necessari a la vora de la cel·la. Per últim, presentem el problema de col·locació i assignació de centres de dades. L'objectiu és trobar el nombre necessari de centres de dades i la seva ubicació a la xarxa, i assignar-los a cada estació de tren. Realitzem simulacions en quatre escenaris diferents, on modifiquem paràmetres d'entrada com la latència màxima tolerada i el nombre màxim de centres de dades. Els resultats obtinguts mostren el compromís entre la latència assolida i el cost de la infraestructura.Smart Transportation Systems are changing the way we conceive the future of mobility. In particular, railways are undergoing a transformation process to modernize public transportation and rail operation. Technologies like 5G, optical fiber and the cloud have emerged as catalysts to digitalize the railway by providing high-speed and low-latency communications. This bachelor's thesis focuses on the exploration of networks enabling train control and on-board data communications. The goal is to plan the network infrastructure (dimensioning and resource allocation) needed for the future communications in the train mobility scenario for Deutsche Bahn's long-distance railway system in Germany. In this work, we propose a network architecture that can meet the performance requirements of train and passenger applications. We present an approach for 5G base station placement along the rail tracks to guarantee the necessary throughput at the cell edge. Finally, we introduce the data center placement and assignment problem. The objective is to find the required number of data centers and their location in the network, and to assign them to each train station. We perform simulations in four different scenarios, in which we modify input parameters such as the maximum tolerated latency and the maximum number of data centers. The obtained results show the trade-off between the achieved latency and the infrastructure cost

Otimização do fronthaul ótico para redes de acesso de rádio (baseadas) em computação em nuvem (CC-RANs)

Doutoramento conjunto (MAP-Tele) em Engenharia Eletrotécnica/TelecomunicaçõesA proliferação de diversos tipos de dispositivos moveis, aplicações e serviços com grande necessidade de largura de banda têm contribuído para o aumento de ligações de banda larga e ao aumento do volume de trafego das redes de telecomunicações moveis. Este aumento exponencial tem posto uma enorme pressão nos mobile operadores de redes móveis (MNOs). Um dos aspetos principais deste recente desenvolvimento, é a necessidade que as redes têm de oferecer baixa complexidade nas ligações, como também baixo consumo energético, muito baixa latência e ao mesmo tempo uma grande capacidade por baixo usto. De maneira a resolver estas questões, os MNOs têm focado a sua atenção na redes de acesso por rádio em nuvem (C-RAN) principalmente devido aos seus benefícios em termos de otimização de performance e relação qualidade preço. O standard para a distribuição de sinais sem fios por um fronthaul C-RAN é o common public radio interface (CPRI). No entanto, ligações óticas baseadas em interfaces CPRI necessitam de uma grande largura de banda. Estes requerimentos podem também ser atingidos com uma implementação em ligação free space optical (FSO) que é um sistema ótico que usa comunicação sem fios. O FSO tem sido uma alternativa muito apelativa aos sistemas de comunicação rádio (RF) pois combinam a flexibilidade e mobilidade das redes RF ao mesmo tempo que permitem a elevada largura de banda permitida pelo sistema ótico. No entanto, as ligações FSO são suscetíveis a alterações atmosféricas que podem prejudicar o desempenho do sistema de comunicação. Estas limitações têm evitado o FSO de ser tornar uma excelente solução para o fronthaul. Uma caracterização precisa do canal e tecnologias mais avançadas são então necessárias para uma implementação pratica de ligações FSO. Nesta tese, vamos estudar uma implementação eficiente para fronthaul baseada em tecnologia á rádio-sobre-FSO (RoFSO). Propomos expressões em forma fechada para mitigação das perdas de propagação e para a estimação da capacidade do canal de maneira a aliviar a complexidade do sistema de comunicação. Simulações numéricas são também apresentadas para formatos de modulação adaptativas. São também considerados esquemas como um sistema hibrido RF/FSO e tecnologias de transmissão apoiadas por retransmissores que ajudam a alivar os requerimentos impostos por um backhaul/fronthaul de C-RAN. Os modelos propostos não só reduzem o esforço computacional, como também têm outros méritos, tais como, uma elevada precisão na estimação do canal e desempenho, baixo requisitos na capacidade de memória e uma rápida e estável operação comparativamente com o estado da arte em sistemas analíticos (PON)-FSO. Este sistema é implementado num recetor em tempo real que é emulado através de uma field-programmable gate array (FPGA) comercial. Permitindo assim um sistema aberto, interoperabilidade, portabilidade e também obedecer a standards de software aberto. Os esquemas híbridos têm a habilidade de suportar diferentes aplicações, serviços e múltiplos operadores a partilharem a mesma infraestrutura de fibra ótica.The proliferation of different mobile devices, bandwidth-intensive applications and services contribute to the increase in the broadband connections and the volume of traffic on the mobile networks. This exponential growth has put considerable pressure on the mobile network operators (MNOs). In principal, there is a need for networks that not only offer low-complexity, low-energy consumption, and extremely low-latency but also high-capacity at relatively low cost. In order to address the demand, MNOs have given significant attention to the cloud radio access network (C-RAN) due to its beneficial features in terms of performance optimization and cost-effectiveness. The de facto standard for distributing wireless signal over the C-RAN fronthaul is the common public radio interface (CPRI). However, optical links based on CPRI interfaces requires large bandwidth. Also, the aforementioned requirements can be realized with the implementation of free space optical (FSO) link, which is an optical wireless system. The FSO is an appealing alternative to the radio frequency (RF) communication system that combines the flexibility and mobility offered by the RF networks with the high-data rates provided by the optical systems. However, the FSO links are susceptible to atmospheric impairments which eventually hinder the system performance. Consequently, these limitations prevent FSO from being an efficient standalone fronthaul solution. So, precise channel characterizations and advanced technologies are required for practical FSO link deployment and operation. In this thesis, we study an efficient fronthaul implementation that is based on radio-on-FSO (RoFSO) technologies. We propose closedform expressions for fading-mitigation and for the estimation of channel capacity so as to alleviate the system complexity. Numerical simulations are presented for adaptive modulation scheme using advanced modulation formats. We also consider schemes like hybrid RF/FSO and relay-assisted transmission technologies that can help in alleviating the stringent requirements by the C-RAN backhaul/fronthaul. The propose models not only reduce the computational requirements/efforts, but also have a number of diverse merits such as high-accuracy, low-memory requirements, fast and stable operation compared to the current state-of-the-art analytical based approaches. In addition to the FSO channel characterization, we present a proof-of-concept experiment in which we study the transmission capabilities of a hybrid passive optical network (PON)-FSO system. This is implemented with the real-time receiver that is emulated by a commercial field-programmable gate array (FPGA). This helps in facilitating an open system and hence enables interoperability, portability, and open software standards. The hybrid schemes have the ability to support different applications, services, and multiple operators over a shared optical fiber infrastructure

Cooperative Radio Communications for Green Smart Environments

The demand for mobile connectivity is continuously increasing, and by 2020 Mobile and Wireless Communications will serve not only very dense populations of mobile phones and nomadic computers, but also the expected multiplicity of devices and sensors located in machines, vehicles, health systems and city infrastructures. Future Mobile Networks are then faced with many new scenarios and use cases, which will load the networks with different data traffic patterns, in new or shared spectrum bands, creating new specific requirements. This book addresses both the techniques to model, analyse and optimise the radio links and transmission systems in such scenarios, together with the most advanced radio access, resource management and mobile networking technologies. This text summarises the work performed by more than 500 researchers from more than 120 institutions in Europe, America and Asia, from both academia and industries, within the framework of the COST IC1004 Action on "Cooperative Radio Communications for Green and Smart Environments". The book will have appeal to graduates and researchers in the Radio Communications area, and also to engineers working in the Wireless industry. Topics discussed in this book include: • Radio waves propagation phenomena in diverse urban, indoor, vehicular and body environments• Measurements, characterization, and modelling of radio channels beyond 4G networks• Key issues in Vehicle (V2X) communication• Wireless Body Area Networks, including specific Radio Channel Models for WBANs• Energy efficiency and resource management enhancements in Radio Access Networks• Definitions and models for the virtualised and cloud RAN architectures• Advances on feasible indoor localization and tracking techniques• Recent findings and innovations in antenna systems for communications• Physical Layer Network Coding for next generation wireless systems• Methods and techniques for MIMO Over the Air (OTA) testin

Cooperative Radio Communications for Green Smart Environments

The demand for mobile connectivity is continuously increasing, and by 2020 Mobile and Wireless Communications will serve not only very dense populations of mobile phones and nomadic computers, but also the expected multiplicity of devices and sensors located in machines, vehicles, health systems and city infrastructures. Future Mobile Networks are then faced with many new scenarios and use cases, which will load the networks with different data traffic patterns, in new or shared spectrum bands, creating new specific requirements. This book addresses both the techniques to model, analyse and optimise the radio links and transmission systems in such scenarios, together with the most advanced radio access, resource management and mobile networking technologies. This text summarises the work performed by more than 500 researchers from more than 120 institutions in Europe, America and Asia, from both academia and industries, within the framework of the COST IC1004 Action on "Cooperative Radio Communications for Green and Smart Environments". The book will have appeal to graduates and researchers in the Radio Communications area, and also to engineers working in the Wireless industry. Topics discussed in this book include: • Radio waves propagation phenomena in diverse urban, indoor, vehicular and body environments• Measurements, characterization, and modelling of radio channels beyond 4G networks• Key issues in Vehicle (V2X) communication• Wireless Body Area Networks, including specific Radio Channel Models for WBANs• Energy efficiency and resource management enhancements in Radio Access Networks• Definitions and models for the virtualised and cloud RAN architectures• Advances on feasible indoor localization and tracking techniques• Recent findings and innovations in antenna systems for communications• Physical Layer Network Coding for next generation wireless systems• Methods and techniques for MIMO Over the Air (OTA) testin