Medium-transparent MAC protocols for converged optical wireless networks

In order to address the explosive demand for high-capacity and omnipresent wireless access, modern cell-based wireless networks are slowly adopting two major solution roadmaps. The first is the employment of small-cell formations in order to increase the overall spectral efficiency, whereas the second is the employment of higher frequency bands, such as the mm-wave 60GHz band, that offers vast amounts of bandwidth. Depending on the specific application, the above solutions inevitably require the installation and operational management of large amounts of Base Stations (BSs) or Access Points (APs), which ultimately diminishes the overall cost-effectiveness of the architecture. In order to reduce the system cost, Radio over Fiber (RoF) technology has been put forward as an ideal candidate solution, due to the fact that it provides functionally simple antenna units, often termed as Remote Antenna Units (RAUs) that are interconnected to a central managing entity, termed as the Central Office (CO), via an optical fiber. Although extensive research efforts have been dedicated to the development of the physical layer aspects regarding RoF technologies, such as CO/RAU physical layer design and radio signal transport techniques over fiber, very limited efforts have con-centrated on upper layer and resource management issues. In this dissertation, we are concerned with access control and resource management of RoF-based mm-wave network architectures targeting the exploitation of the dual medium and its centralized control properties in order to perform optimal optical/wireless/time resource allocation. In this dissertation, we propose a Medium-Transparent MAC (MT-MAC) protocol that concurrently administers the optical and wireless resources of a 60GHz RoF based network, seamlessly connecting the CO to the wireless terminals through minimal RAU intervention. In this way, the MT-MAC protocol forms extended reach 60GHz WLAN networks offering connectivity amongst wireless devices that are attached to the same or different RAUs under both Line of Sight (LOS) and non LOS conditions. The notion of medium-transparency relies on two parallel contention periods, the first in the optical domain and the second in the wireless frequency and time domains, with nested dataframe structures. The MT-MAC operation is based on a proposed RAU design that allows for wavelength selectivity functions, thus being compatible with completely passive optical distribution network implementations that are predominately used by telecom operators today. Two variants of the MT-MAC protocol are considered. The first offers dynamic wavelength allocation with fixed time windows, whereas the second targets fairness-sensitive applications by offering dynamic wavelength allocation with dynamic transmission opportunity window sizes, based on the number of active clients connected at each RAU. Both variants of the protocol are evaluated by both simulation and analytical means. For the latter part, this thesis introduces two analytical models for calculating saturation throughput and non-saturation packet delay for the converged MT-MAC protocol. Finally, this thesis presents an extensive study regarding the network planning and formation of 60GHz Gigabit WLAN networks when the latter are deployed over existing Passive Optical Network (PON) infrastructures. Three possible architectures where studied: i) the RoF approach, ii) the Radio & Fiber approach and iii) the hybrid RoF-plus-R&F approach that combines the properties of both the aforementioned architectures. During the elaboration of this thesis, one major key conclusion has been extracted. The work proposed in this thesis considers that there is a fundamental requirement for implementing new converged optical/wireless MAC protocols, that have the complete overview of both available resources in order to effectively administer the hybrid Radio-over-Fiber networks.A fin de atender la demanda explosiva de alta capacidad y acceso inalámbrico omnipresente, las redes inalámbricas basadas en celdas están poco a poco adoptando dos principales guías de solución. La primera es el empleo de formaciones de celdas pequeñas con el fin de aumentar la eficiencia espectral global, mientras que la segunda es el empleo de bandas de frecuencia superior, como la banda de 60GHz, la cual ofrece una gran cantidad de ancho de banda. Dependiendo de la aplicación en específico, las soluciones anteriores inevitable-mente requieren de una instalación y una gestión operativa de grandes cantidades de Estaciones Base o Puntos de Acceso, que en última instancia disminuye la rentabilidad de la arquitectura. Para reducir el coste, la tecnología radioeléctrica por fibra (RoF) se presenta como una solución ideal debido al hecho de que proporciona unidades de antenas de sim-ple funcionamiento, a menudo denominadas Unidades de Antenas Remotas (RAUs), las cuales están interconectadas a una entidad central de gestión, denominada Oficina Central (CO), a través de la fibra óptica. A pesar de que se han dedicado muchos esfuerzos de investigación al desarrollo de varios aspectos de las capas física con respecto a las tecnologías RoF, muy pocos esfuerzos se han concentrado en la capa superior y cuestiones de gestión de recursos. En esta tesis, nos enfocando en el control de acceso y gestión de recursos de arquitecturas RoF y comunicaciones milimétricas, con el fin de aprovechar y explotar el medio dual y las propiedades para realizar una óptima asignación de los recursos ópticos, inalámbricos y temporales. Nosotros proponemos un protocolo Transparente al Medio MAC (MT-MAC) que simultáneamente administre los recursos ópticos e inalámbricos de una red RoF a 60GHz, conectando a la perfección el CO a los terminales inalámbricos a través de una mínima intervención RAU. El protocolo MT-MAC forma unas redes WLAN 60GHz de alcance extendido, ofreciendo así conectividad entre los dispositivos inalámbricos que están conectados al mismo o diferentes RAUs bajo con o sin Línea de Vista (condiciones LOS o NLOS) respectivamente. La noción de transparencia al medio se basa en dos períodos de contención para-lelos, el primero en el dominio óptico y el segundo en la frecuencia inalámbrica y dominio del tiempo, con estructuras de datos anidados. La operación MT-MAC se basa en proponer un diseño RAU que permita la selectividad de funciones de longitud de onda. Dos variantes del protocolo MT- MAC son considerados; el primer ofrece asignación de longitud de onda dinámica con ventanas de tiempo fijo, mientras que la segunda tiene como objetivo entornos de aplicaciones sensibles ofreciendo asignación de longitud de onda con tamaño de ventana de oportunidad de transmisión dinámico, basado en el número de clientes conectados en cada RAU. Ambas variantes del protocolo están evaluadas tanto por medios analíticos como de simulación. En la segunda parte, esta tesis introduce dos modelos analíticos para calcular el rendimiento de saturación y no saturación del retardo de paquetes para el protocolo MT-MAC convergente. Finalmente, esta tesis presenta un extenso estudio de la planificación de red y la formación de redes 60GHz Gigabit WLAN cuando esta se encuentra desplegada sobre las ya existente infraestructuras de Redes Ópticas Pasivas (PONs). Tres posibles arquitecturas han sido estudiadas: i) el enfoque RoF, ii) el enfoque Radio y Fibra , y iii) el enfoque híbrido, RoF más R&F el cual combina las propiedades de ambas arquitecturas anteriormente mencionadas. Durante la elaboración de esta tesis, se ha extraído una importante conclusión: hay un requerimiento fundamental para implementar nuevos protocolos ópticos/inalámbricos convergentes, que tengan una completa visión de ambos recursos disponibles para poder administrar efectivamente las redes de tecnología RoF.Postprint (published version

Estado del arte de las redes ópticas de acceso con baja latencia

La incursión en el internet de las cosas IoT, inteligencia artificial, entre otros, han llevado a buscar nuevas soluciones en cuanto a tecnologías de acceso en telecomunicaciones, puesto que su infraestructura debe también de evolucionar acorde a las necesidades que requieran los usuarios, basándose en parámetros como latencia, eficiencia, ancho de banda, etc. Lo antes mencionado es la base sobre la cual se ha trabajado en la presente investigación, mediante la elaboración de un estado del arte de las redes ópticas de acceso con baja latencia. Primero, se empezó por la extracción de la información necesaria de diferentes repositorios electrónicos para cumplir con el método PICOC. Una posible solución es el empleo de una red Fronthauling óptica junto a red de acceso de radio 5G. Se encontró, además, que la arquitectura Radio sobre Fibra (RoF) ofrece la ventaja de que el mantenimiento de las estaciones base representa un coste significativamente bajo. Adicional también se presentan la tecnología Fi-Wi, la misma que se conforma de una red WDM-PON conjuntamente con la tecnología inalámbrica OFDM, con el fin de obtener una red con mayores beneficios propios de emplear fibra óptica más una red de radio.The incursion into the Internet of Things IoT, artificial intelligence, among others, have led to the search for new solutions in terms of telecommunications access technologies, since its infrastructure must also evolve according to the needs required by users, based on parameters such as latency, efficiency, bandwidth, etc. The aforementioned is the basis on which work has been done in this research, through the development of a state of the art of low latency optical access networks. First, it began by extracting the necessary information from different electronic repositories to comply with the PICOC method. One possible solution is the use of an optical Fronthauling network together with a 5G radio access network. It was also found that the Radio over Fiber (RoF) architecture offers the advantage that the maintenance of the base stations represents a significantly low cost. Additionally, Fi-Wi technology is also presented, which is made up of a WDM-PON network together with OFDM wireless technology, in order to obtain a network with greater benefits of using fiber optics plus a radio network

Green radio communication networks applying radio-over-fibre technology for wireless access

Wireless communication increasingly is becoming the first choice link to enter into the global information society. It is an essential part of broadband communication networks, due to its capacity to cover the end-user domain, outdoors or indoors. The use of mobile phones and broadband has already exceeded the one of the fixed telephones and has caused tremendous changes in peoples life, as not only to be recognised in the current political overthrows. The all-around presence of wireless communication links combined with functions that support mobility will make a roaming person-bound communication network possible in the near future. This idea of a personal network, in which a user has his own communication environment available everywhere, necessitates immense numbers of radio access points to maintain the wireless links and support mobility. The progress towards “all-around wireless” needs budget and easily maintainable radio access points, with simplified signal processing and consolidation of the radio network functions in a central station. The RF energy consumption in mobile base stations is one of the main problems in the wireless communication system, which has led to the worldwide research in so called green communication, which offers an environmentally friendly and cost-effective solution. In order to extend networks and mobility support, the simplification of antenna stations and broadband communication capacity becomes an increasingly urgent demand, also the extension of the wireless signal transmission distance to consolidate the signal processing in a centralised site. Radio-over-Fibre technology (RoF) was considered and found to be the most promising solution to achieve effective delivery of wireless and baseband signals, also to reduce RF energy consumption. The overall aim of this research project was to simulate the transmission of wireless and baseband RF signals via fibre for a long distance in high quality, consuming a low-power budget. Therefore, this thesis demonstrated a green radio communication network and the advantage of transmitting signals via fibre rather than via air. The contributions of this research work were described in the follows: Firstly, a comparison of the power consumption in WiMAX via air and fibre is presented. As shown in the simulation results, the power budget for the transmission of 64 QAM WiMAX IEEE 802.16-2005 via air for a distance of 5km lies at -189.67 dB, whereas for the transmission via RoF for a distance of 140km, the power consumption ranges at 65dB. Through the deployment of a triple symmetrical compensator technique, consisting of SMF, DCF and FBG, the transmission distance of the 54 Mbps WiMAX signal can be increased to 410km without increasing the power budget of 65dB. An amendment of the triple compensator technique to SMF, DCF and CFBG allows a 120Mbps WiMAX signal transmission with a clear RF spectrum of 3.5 GHz and constellation diagram over a fibre length of 792km using a power budget of 192dB. Secondly, the thesis demonstrates a simulation setup for the deployment of more than one wireless system, namely 64 QAM WiMAX IEEE 802.16-2005 and LTE, for a data bit rate of 1Gbps via Wavelength Division Multiplexing (WDM) RoF over a transmission distance of 1800km. The RoF system includes two triple symmetrical compensator techniques - DCF, SMF, and CFBG - to obtain a large bandwidth, power budget of 393.6dB and a high signal quality for the long transmission distance. Finally, the thesis proposed a high data bit rate and energy efficient simulation architecture, applying a passive optical component for a transmission span up to 600km. A Gigabit Optical Passive Network (GPON) based on RoF downlink 2.5 Gbps and uplink 1.25Gbps is employed to carry LTE and WiMAX, also 18 digital channels by utilising Coarse Wavelength Division Multiplexing (CWDM). The setup achieved high data speed, a low-power budget of 151.2dB, and an increased service length of up to 600km

60 GHz photonic millimeter-wave communication systems

Currently available copper-based Internet access technologies like xDSL and DOCSIS cover data transmission speeds in the range of some 10 Mb/s. With new applications, an increase in bandwidth demand up to the Gb/s-range is expected for the next years. Therefore, an evolution of access networks by gradual replacement of copper-based by fiber-optic infrastructure is presently ongoing. A similar development can be predicted for wireless access technology operating within the classical microwave range. Due to regulatory requirements and a lack of bandwidth alternatives need to be developed in the millimeter-wave band. In this regard, the frequency range around 60 GHz has a special importance due to a worldwide available unlicensed spectrum of several GHz of bandwidth. In this context, the integration of wireless networks in fiber-optic networks by the fiber-optic transport of the radio signal (radio-over-fiber, RoF) is of particular importance. Besides the low-loss optical transport of a 60 GHz radio signal RoF technology furthermore allows to shift complexity from base stations to a central office by a centralized provision of the millimeter-wave carrier. This work deals with the modeling, realization and characterization of 60 GHz RoF systems providing data rates within the multi-Gb/s range. On the theoretical side, a system model has been developed comprising relevant electrical and optical noise sources and the transmission properties of fiber-optic and wireless links as well. This allows for instance to make reliable predictions of the expected system performance in the run-up to RoF system planning and thus to identify optimization potential. Using innovative approaches and technologies, 12.5 Gb/s data transmission has been realized via fiber and wirelessly for the first time over technical relevant distances. Also, if compared to conventional RoF systems the dispersion-limited fiber-optic range has been multiplied. Another RoF system in the frame of this work aimed for an uncompressed HDTV transmission, for instance for video conferencing with high resolution (1080p) and extremely low latency (telemedicine). The wireless transmission of an uncompressed HDTV signal has been successfully demonstrated. Including the previously achieved results and experiences, the system complexity has been significantly reduced

Comunicações avançadas com fibra óptica plástica

Nowadays, fiber to the Home/Curb/Building/Cabinet (FTTx) services that interconnect homes with a standard glass optical fiber cables to the core/access optical networks have brought the optical fiber at the doorsteps of our homes. However, the last few miles in home access network is still based on the limited bandwidth electronic component which supports by the cooper wires e.g. Cat-5, 6. The rapid growth of personal smart/mobile electronic devices with new developments such as video on demand, High Definition (HD) and three-Dimension (3D) television (TV), cloud computing, video conferences, etc. has been proposed new challenges for the next generation high bandwidth demand required for subscribers in home access network. In order to meet the more demanding expectations of the end user with new developments, it is necessary to improve the physical infrastructure of the existing in home networks in order to obtain the best ratio between quality of service and price of implementation. Plastic optical fibers (POFs) are point out as a promising transmission medium for short-range communication in compare to the “classic” single/multimode glass optical fibers and current cooper wire technology developments. The main advantages of POF are its easy to install, easy splicing and the possibility of using low cost optical transceivers, capability of being robust, and immunity to electromagnetic noise interference. However, the benefits of large-core POFs come at the expense of a less bandwidth and a higher attenuation than silica-based solution. The main objective of this doctoral dissertation is to explore the possibilities and develop low cost, short reach, high data rate POF-links for in home networks applications. This thesis investigates the use of multilevel modulation in particular, pulse amplitude modulation (PAM in combination of the receiver equalizer in order to overcome the bandwidth limitations of the graded index POFs. The possibility of the using multiple channels over a single fiber to increase the capacity of POF systems using commercially available multimode components is also analyzed in this dissertation. Moreover, a low cost Digitised radio signal over plastic fiber system is proposed and evaluated to deliver digital baseband data for wireline and wireless users in home access network. The deployment will be specified in terms of performance, maximum rates and any degradation that might appear in the network. Furthermore, the possibilities of the microstructured fibers in telecommunication application will be studied with main emphasis on their structural design. The photonic crystal fibers made of different highly nonlinear materials with different structures are optimized to achieve ultra-flat dispersion, high nonlinearity and low confinement loss over a broad range of wavelengths in the perspective of their usage in telecommunication applications.Hoje em dia, a possibilidade de a fibra óptica até casa (FTTH) para a transmissão simultânea de diferentes serviços como internet, telefone, televisão digital é uma realidade. No entanto, para satisfazer as expectativas mais exigentes do usuário final com novos desenvolvimentos, tais como vídeo sob demanda, de alta definição (HD) e tridimensional (3D) de televisão (TV), computação em nuvem, vídeo conferências, etc., é necessário melhorar a infra-estrutura física da existente em redes domésticas, a fim de obter a melhor relação entre a qualidade do serviço e preço de implementação. Fibra óptica de plástico (POF) é considerada um meio de transmissão promissor para comunicações de curto alcance, queando comparadas com a clássica fibra óptica de silica (tanto monomodo como multimodo) e com as tecnologias atuais baseadas em fio de cobre. As principais vantagens da POF encontramse na sua facilidade de instalação e conecção, possibilidade de uso de fontes e detectores de baixo custo, robustez e imunidade electromagnética. No entanto, o uso da POF de elevado diâmetro têm também desvantagens uma vez que esta oferece uma menor largura de banda e uma atenuação superior à fibra de sílica convêncional. Esta dissertação de doutoramento tem como principal objetivo explorar as possibilidades de desemvolvimento de componentes de baixo custo baseados em POF para redes de curto alcance, com alta taxa de transmisssão de dados. Esta tese investiga a utilização de vários formatos de modulação combinados com equalizador e receptor, de maneira a superar as limitações de largura de banda em sistemas de comunicação óptica de curto alcance. Em particular, a modulação em amplitude de impulso (PAM) é proposta e investigada a fim de aumentar a capacidade de tais sistemas. Além disso, a possibilidade de usar múltiplos canais, utilizando uma única fibra óptica, também conhecido por multiplexagem por divisão de comprimento de onda (WDM), será analisada neste trabalho. A viabilidade das tecnologias de redes de acesso tanto a nível individual como em sistemas WDM serão analisadas usando componentes multimodo disponíveis comercialmente. A implementação será especificada em termos de desempenho tanto a nível da taxas máximas de transmissão, bem como na degradação do sinal que possa ocorrer na rede. No capitulo 5 desta dissertação é apresentado sistema de radio através de fibra. Este tipo de sistemas permite a simplificação das estações base providenciando também uma elevada manutenção de custos. O principal objectivo deste estudo prende-se com a investigação do impacto da amostragem na preformance de digitalização de rádio através de fibra e também como a introdução de fibra óptica de plástico pode afetar o sistema. Além disso, a possibilidade da aplicação de fibras óticas microestruturadas em redes de telecomunicações serão estudadas com ênfase principal na sua concepção estrutural. As fibras de cristal fotônico feitas de diferentes materiais altamente não-lineares com diferentes estruturas serão otimizadas a fim de alcançar uma dispersão ultra-plana, elevada não linearidade e baixa perda de confinamento em uma vasta gama espectral, na perspectiva de seu uso em aplicações de telecomunicações.Programa Doutoral em Engenharia Eletrotécnic