9 research outputs found

    Photonic and Electronic Co-integration for Millimetre-Wave Hybrid Photonic-Wireless Links

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    Photonic and Electronic Co-integration for Millimetre-Wave Hybrid Photonic-Wireless Links

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    Towards optical beamforming systems on-chip for millimeter wave wireless communications

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    Towards optical beamforming systems on-chip for millimeter wave wireless communications

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    High-capacity 5G fronthaul networks based on optical space division multiplexing

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    \u3cp\u3eThe introduction of 5G mobile networks, bringing multi-Gbit/s user data rates and reduced latency, opens new opportunities for media generation, transport and distribution, as well as for new immersive media applications. The expected use of millimeter-wave carriers and the strong network densification resulting from a much reduced cell size--which enable the expected performance of 5G--pose major challenges to the fronthaul network. Space division multiplexing (SDM) in the optical domain has been suggested for ultra-high capacity fronthaul networks that naturally support different classes of fronthaul traffic and further enable the use of analog radio-over-fiber and advanced technologies, such as optical beamforming. This paper discusses the introduction of SDM with multi-core fibers in the fronthaul network as suggested by the blueSPACE project, regarding both digitized and analog radio-over-fiber fronthaul transport as well as the introduction of optical beamforming for high-capacity millimeter-wave radio access. Analog and digitized radio-over-fiber are discussed in a scenario featuring parallel fronthaul for different radio access technologies, showcasing their differences and potential when combined with SDM.\u3c/p\u3

    Design and implementation of low complexity adaptive optical OFDM systems for software-defined transmission in elastic optical networks

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    Due to the increasing global IP traffic and the exponential growing demand for broadband services, optical networks are experimenting significant changes. Advanced modulation formats are being implemented at the Digital Signal Processing (DSP) level as key enablers for high data rate transmission. Whereas in the network layer, flexi Dense Wavelength-Division Multiplexing (DWDM) grids are being investigated in order to efficiently use the optical spectrum according to the traffic demand. Enabling these capabilities makes high data rate transmission more feasible. Hence, introducing flexibility in the system is one of the main goals of this thesis. Furthermore, minimizing the cost and enhancing the Spectral Efficiency (SE) of the system are two crucial issues to consider in the transceiver design. This dissertation investigates the use of Optical Orthogonal Frequency Division Multiplexing (O-OFDM) based either on the Fast Fourier Transform (FFT) or the Fast Hartley Transform (FHT) and flexi-grid technology to allow high data rate transmission over the fiber. Different cost-effective solutions for Elastic Optical Networks (EON) are provided. On the one hand, Direct Detection (DD) systems are investigated and proposed to cope with present and future traffic demand. After an introduction to the principles of OFDM and its application in optical systems, the main problems of such modulation is introduced. In particular, Peak-to-Average Power Ratio (PAPR) is presented as a limitation in OFDM systems, as well as clipping and quantization noise. Hence, PAPR reduction techniques are proposed to mitigate these impairments. Additionally, Low Complexity (LC) PAPR reduction techniques based on the FHT have also been presented with a simplified DSP. On the other hand, loading schemes have also been introduced in the analyzed system to combat Chromatic Dispersion (CD) when transmitting over the optical link. Moreover, thanks to Bit Loading (BL) and Power Loading (PL), flexible and software-defined transceivers can be implemented maximizing the spectral efficiency by adapting the data rate to the current demand and the actual network conditions. Specifically, OFDM symbols are created by mapping the different subcarriers with different modulation formats according to the channel profile. Experimental validation of the proposed flexible transceivers is also provided in this dissertation. The benefits of including loading capabilities in the design, such as enabling high data rate and software-defined transmission, are highlighted.Degut al creixement del tr脿fic IP i de la demanda de serveis de banda ampla, les xarxes 貌ptiques estan experimentant canvis significatius. Els formats avan莽ats de modulaci贸, implementats a nivell de processat del senyal digital, habiliten la transmissi贸 a alta velocitat. Mentre que a la capa de xarxa, l'espectre 貌ptic es dividit en ranures flexibles ocupant l'ample de banda necessari segons la demanda de tr脿fic. La transmissi贸 a alta velocitat 茅s fa m茅s tangible un cop habilitades totes aquestes funcionalitats. D'aquesta manera un dels principals objectius d'aquesta tesis es introduir flexibilitat al sistema. A dem茅s, minimitzar el cost i maximitzar l'efici猫ncia espectral del sistema s贸n tamb茅 dos aspectes crucials a considerar en el disseny del transmissor i receptor. Aquesta tesis investiga l'煤s de la tecnologia Optical Orthogonal Frequency Division Multiplexing (OFDM) basada en la transformada de Fourier (FFT) i la de Hartley (FHT) per tal de dissenyar un sistema flexible i capa莽 de transmetre a alta velocitat a trav茅s de la fibra 貌ptica. Per tant, es proposen diferent solucions de baix cost v脿lides per a utilitzar en xarxes 貌ptiques el脿stiques. En primer lloc, s'investiguen i es proposen sistemes basats en detecci贸 directa per tal de suportar la present i futura demanda. Despr茅s d'una introducci贸 dels principis d' OFDM i la seva aplicaci贸 als sistemes 貌ptics, s'introdueixen alguns dels problemes d'aquesta modulaci贸. En particular, es presenten el Peak-to-Average Power Ratio (PAPR) i els sorolls de clipping i de quantizaci贸 com a limitaci贸 dels sistemes OFDM. S'analitzen t猫cniques de reducci贸 de PAPR per tal de reduir l'impacte d'aquests impediments. Tamb茅 es proposen t猫cniques de baixa complexitat per a reduir el PAPR basades en la FHT. Finalment, s'utilitzen algoritmes d'assignaci贸 de bits i de pot猫ncia, Bit Loading (BL) i Power Loading (PL), per tal de combatre la dispersi贸 crom脿tica quan es transmet pel canal 貌ptic. Amb la implementaci贸 dels algoritmes de BL i PL, es poden dissenyar transmissors i receptors flexibles adaptant la velocitat a la demanda del moment i a les actuals condicions de la xarxa. En particular, els s铆mbols OFDM es creen mapejant cada portadora amb un format de modulaci贸 diferent segons el perfil del canal. El sistema 茅s validat experimentalment mostrant les prestacions i els beneficis d'incloure flexibilitat per tal de facilitar la transmissi贸 a alta velocitat i cobrir les necessitats de l'Internet del futurDebido al crecimiento del tr谩fico IP y de la demanda de servicios de banda ancha, las redes 贸pticas est谩n experimentando cambios significativos. Los formatos avanzados de modulaci贸n, implementados a nivel de procesado de la se帽al digital, habilitan la transmisi贸n a alta velocidad. Mientras que en la capa de red, el espectro 贸ptico se divide en ranuras flexibles ocupando el ancho de banda necesario seg煤n la demanda de tr谩fico. La transmisi贸n a alta velocidad es m谩s tangible una vez habilitadas todas estas funcionalidades. De este modo uno de los principales objetivos de esta tesis es introducir flexibilidad en el sistema. Adem谩s, minimizar el coste y maximizar la eficiencia espectral del sistema son tambi茅n dos aspectos cruciales a considerar en el dise帽o del transmisor y receptor. Esta tesis investiga el uso de la tecnologia Optical Orthogonal Frequency Division Multiplexing (OFDM) basada en la transformada de Fourier (FFT) y en la de Hartley (FHT) con tal de dise帽ar un sistema flexible y capaz de transmitir a alta velocidad a trav茅s de la fibra 贸ptica. Por lo tanto, se proponen distintas soluciones de bajo coste v谩lidas para utilizar en redes 贸pticas el谩sticas. En primer lugar, se investigan y se proponen sistemas basados en detecci贸n directa con tal de soportar la presente y futura demanda. Despu茅s de una introducci贸n de los principios de OFDM y su aplicaci贸n en los sistemas 贸pticos, se introduce el principal problema de esta modulaci贸n. En particular se presentan el Peak-to-Average Power Ratio (PAPR) y los ruidos de clipping y cuantizaci贸n como limitaciones de los sistemas OFDM. Se analizan t茅cnicas de reducci贸n de PAPR con tal de reducir el impacto de estos impedimentos. Tambi茅n se proponen t茅cnicas de baja complejidad para reducir el PAPR basadas en la FHT. Finalmente, se utilizan algoritmos de asignaci贸n de bits y potencia, Bit Loading (BL) y Power Loading (PL), con tal de combatir la dispersi贸n crom谩tica cuando se transmite por el canal 贸ptico. Con la implementaci贸n de los algoritmos de BL y PL, se pueden dise帽ar transmisores y receptores flexibles adaptando la velocidad a la demanda del momento y a las actuales condiciones de la red. En particular, los s铆mbolos OFDM se crean mapeando cada portadora con un formato de modulaci_on distinto seg煤n el perfil del canal. El sistema se valida experimentalmente mostrando las prestaciones y los beneficios de incluir flexibilidad con tal de facilitar la transmisi贸n a alta velocidad y cubrir las necesidades de Internet del futuro

    Energy-efficient design of optical transport networks

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    Energy efficiency is becoming a key factor in the design and operation of telecommunications networks as a way to reduce operational expenditures and the carbon footprint associated to telecom operators. This Ph.D. thesis evaluates and proposes novel energy-efficient approaches in three design areas of optical transport networks: (1) Network architectures and operation modes; (2) Resilience schemes; and (3) Optical amplifier placements. The solutions proposed in these areas are shown to significantly reduce the power consumption in realistic deployment scenarios and could be applied by telecom operators in the near and medium-term future to enhance the energy efficiency of optical transport networks

    Physical Layer Aware Optical Networks

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    This thesis describes novel contributions in the field of physical layer aware optical networks. IP traffic increase and revenue compression in the Telecom industry is putting a lot of pressure on the optical community to develop novel solutions that must both increase total capacity while being cost effective. This requirement is pushing operators towards network disaggregation, where optical network infrastructure is built by mix and match different physical layer technologies from different vendors. In such a novel context, every equipment and transmission technique at the physical layer impacts the overall network behavior. Hence, methods giving quantitative evaluations of individual merit of physical layer equipment at network level are a firm request during network design phases as well as during network lifetime. Therefore, physical layer awareness in network design and operation is fundamental to fairly assess the potentialities, and exploit the capabilities of different technologies. From this perspective, propagation impairments modeling is essential. In this work propagation impairments in transparent optical networks are summarized, with a special focus on nonlinear effects. The Gaussian Noise model is reviewed, then extended for wideband scenarios. To do so, the impact of polarization mode dispersion on nonlinear interference (NLI) generation is assessed for the first time through simulation, showing its negligible impact on NLI generation. Thanks to this result, the Gaussian Noise model is generalized to assess the impact of space and frequency amplitude variations along the fiber, mainly due to stimulated Raman scattering, on NLI generation. The proposed Generalized GN (GGN) model is experimentally validated on a setup with commercial linecards, compared with other modeling options, and an example of application is shown. Then, network-level power optimization strategies are discussed, and the Locally Optimization Global Optimization (LOGO) approach reviewed. After that, a novel framework of analysis for optical networks that leverages detailed propagation impairment modeling called the Statistical Network Assessment Process (SNAP) is presented. SNAP is motivated by the need of having a general framework to assess the impact of different physical layer technologies on network performance, without relying on rigid optimization approaches, that are not well-suited for technology comparison. Several examples of applications of SNAP are given, including comparisons of transceivers, amplifiers and node technologies. SNAP is also used to highlight topological bottlenecks in progressively loaded network scenarios and to derive possible solutions for them. The final work presented in this thesis is related to the implementation of a vendor agnostic quality of transmission estimator for multi-vendor optical networks developed in the context of the Physical Simulation Environment group of the Telecom Infra Project. The implementation of a module based on the GN model is briefly described, then results of a multi-vendor experimental validation performed in collaboration with Microsoft are shown
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