Highly coherent light, although beneficial in specific applications, suffers from the formation of speckles, resulting in poor imaging, lighting, and projection/display quality. Moreover, the long coherence length limits the resolution in interference based sensing. This has led to the emergence of edge-emitting semiconductor low coherence light sources (e.g., broadband lasers, superluminescent diodes, etc.), which have been used in display applications, optical coherence tomography, and random bit generation. However, edge emission prevents the ease of fabricating two-dimensional arrays. Conversely, vertical-cavity surface-emitting lasers (VCSELs) have recently been widely used in consumer electronics due to the unique advantages of surface emission. Nevertheless, they still suffer from issues caused by high coherence. The aim of this dissertation is to design low-coherence surface-emitting lasers to push simultaneous illumination and optical wireless communication (OWC) toward reliable implementation with higher speeds. To that end, we demonstrate, for the first time, the use of chaotic cavities to lower the coherence of VCSELs without increasing their emission area, which would lower their speed. Not only did the chaotic cavity result in doubling the number of modes (lowering the coherence) compared to conventional VCSELs, but it also resulted in an increase in the optical power of up to 60%. We also show that chaotic-cavity broad-area VCSELs can achieve significantly broader modulation bandwidths (up to 5 GHz) and higher data rates (up to 12.6 Gb/s) compared to other low-coherence light sources, while achieving a lower speckle contrast. We further report a novel technique of lowering the speckle contrast 2 by carefully designing the AC signal used for communication. We show that the apparent spatial coherence is dramatically decreased by inserting a short chirp signal between symbols. Using this method with a chaotic-cavity VCSEL, the number of apparent modes can be up to 450 modes, compared to 88 modes measured from a conventional broad-area VCSEL. The simplicity of implementing the reported design, which requires no additional fabrication steps, makes it a promising solution for applications that would benefit from the lower speckle density of the emitted light as well as those that rely on lower temporal coherence.

Indoor positioning is an enabling technology primed to impact the indoor application space as Global Navigation Satellite Systems (GNSS) did for the outdoor space. Amongst the competing positioning technologies are methods of different mediums: light, radio frequency and ultra-wideband, ultrasonic, and imaging; methods of different modalities: received signal strength, angle-of-arrival, time-of-flight; and methods of different mathematics: trilateration, triangulation, machine learning, and signal processing. Light-based positioning compared to other positioning schemes exploits fixed-location directional luminaires placed regularly throughout a space as anchor points -- there is an efficiency argument for multi-purpose lighting and a cost-share argument for infrastructure-based positioning. Similar to the satellite infrastructure with GNSS, with anchor points and models for light propagation and construction, position is estimated based on received signals at active photodiode-equipped target devices. Received signal strength, a common first order attribute, alone is not noise resilient enough for centimeter-level 3D positioning. Methods using angle diversity produce better results particularly in 3D but with more complex hardware. For this dissertation, we exploit angle diversity and modulated optical sources in light-based positioning systems to estimate position to centimeter-level accuracy in 3D. We propose, analyze, and contribute two novel positioning schemes that use these concepts. One of the proposed schemes is a new hybrid 3D indoor positioning technique, Ray-Surface Positioning (RSP), which incorporates a narrow field-of-view (FOV) optical source (Ray) with wide diffuse optical sources (Surfaces) to position active devices in 3D. The second scheme, a Zone-based Positioning Service (ZPS), is a positioning scheme and architecture that incorporates an angle diverse narrow FOV optical source at the positioned device. This unique design decision allows the active device to position itself directly with respect to photovoltaic anchor points but also to position other devices in its FOV called transitive positioning. Along with these contributions, we also investigate several other related topics. Concisely, as part of the dissertation, we contribute (a) review of the state-of-the-art, (b) analysis for steering Lambertian sources, (c) method of creating angle diversity from a narrow FOV optical source, (d) novel positioning approaches in (1) RSP and (2) ZPS, (e) proof of concept prototypes for (1) RSP and (2) ZPS, and (f) architectures for indoor positioning applications.

This dissertation thesis deals with a long range free space optical links for communication over the distance of few tens of kilometers in the atmosphere. The problematic of the beam propagation and atmospheric effects influencing the beam and the quality of the communication protocol are discussed. The measuring link is also designed to study the parameters of the communication link work conditions. The measuring link consists of two heads. The transmitter head is designed to use two optical beams with laser diodes at the wavelength of the atmospheric windows 850 or 1550 nm and the overall power of hundredths of mW. The receiver head includes the Fressnel lens. For the detection of very weak signal, the avalanche photodiode is used. In the end of this work, due to the high power of the transmitting optical beam, the laser safety conditions are also discussed, including the deduced optical transmitters construction recommendations.

[ES] La red de sexta generación (6G) es la solución potencial para satisfacer los requisitos exponencialmente crecientes de los servicios y aplicaciones emergentes. La plataforma 6G espera ofrecer altas velocidades de datos, conectividad ultra alta y baja latencia en función de los indicadores clave de rendimiento (KPI) requeridos. La tecnología de comunicación por luz visible (VLC) representa una tecnología clave para la red 6G, pero requiere una técnica de modulación avanzada eficiente para cumplir con dichos requisitos. En las últimas décadas, las señales ópticas basadas en el esquema de multiplexación por división de frecuencia ortogonal (OFDM) han atraído mucha atención y se han convertido en la modulación más popular entre varios esquemas de acceso multiportadora, gracias a su robustez y simplicidad frente a la cancelación por trayectos múltiples utilizando el prefijo cíclico (CP). Una de las formas de onda más prometedoras para redes de próxima generación es la técnica de modulación Filter Bank MultiCarrier (FBMC). El principal beneficio del esquema FBMC es que no depende de CP y de un gran número de muestras de banda de guarda, por lo tanto, emplea varias funciones de pulso localizadas en el tiempo con una alta relación de supresión de lóbulos laterales, lo que permite mejorar la eficiencia espectral y el rendimiento del sistema como factores clave en las redes ópticas de próxima generación, y proporciona una buena alternativa a la técnica CP-OFDM. Esta Tesis pretende dar un paso adelante en la propuesta de formatos de modulación para ser utilizados en sistemas VLC como tecnología habilitadora en redes 6G. Por lo tanto, se propone el sistema Flip-FBMC con un algoritmo de truncamiento para ofrecer una transmisión de alta velocidad con baja latencia Flip-FBMC mediante el uso del algoritmo de transformación ortogonal isotrópica (IOTA) y la capa PHYsical para DYnamic AccesS y filtros de radio cognitiva (PHYDYAS). En esta Tesis se propone la ecualización multitap con el fin de mitigar la Interferencia imaginaria intrínseca (IMI) en un canal con perfiles de retardos elevado en sistemas VLC de interiores. Además, se ha mejorado rendimiento de error de las señales FBMC no coherentes mediante el análisis de la propiedad de la localización de tiempo-frecuencia con la función gaussiana extendida (EGF), donde el factor de dispersión desempeña un papel crucial en la determinación del equilibrio entre las características espectrales y la reconstrucción óptima de la calidad de la señal. Además, la Tesis proporciona el primer análisis teórico que informa de la degradación en la estimación para varios factores de clipping basada en el impacto del nivel de interferencia imaginario fuera de la zona de primer orden que no puede ser estimada mediante el preámbulo de IAM. Sin embargo, se debe enfatizar en el valor de la técnica Flip-FBMC/IAM para proporcionar el modelo unipolar en comparación con el uso del formato FBMC óptico polarizado con corriente continua (DCO-FBMC) que sufre una reducción en la estimación de la precisión. Por lo tanto, se ha demostrado el descenso del rendimiento con el sistema DCO-FBMC debido al IMI inducido fuera de los símbolos de orden cero, y que es más evidente cuando se requieren niveles bajos de corriente DC. Desde esta perspectiva, la técnica de repetición de tramas con señales Flip-FBMC ha demostrado ser una solución importante para minimizar la interferencia inducida. Por lo tanto, en esta Tesis, la modulación Flip-FBMC con repetición de tramas y perfil de filtro PHYDYAS se propone como un candidato viable para hacer frente al rango dinámico restringido del LED, en comparación con el rendimiento de los sistemas Flip-CP-OFDM y Flip-FBMC/IAM en futuras redes 6G basadas en acceso VLC. / [CA] La xarxa de sexta generació (6G) és la solució potencial per a satisfer els requisits exponencialment creixents dels servicis i aplicacions emergents. La plataforma 6G espera oferir altes velocitats de dades, connectivitat ultra alta i baixa latència en funció dels indicadors clau de rendiment (KPI) requerits. La tecnologia de comunicació per llum visible (VLC) representa una tecnologia clau per a la xarxa 6G, però requerix una tècnica de modulació avançada eficient per a complir amb estos requisits. En les últimes dècades, els senyals òptics basats en l'esquema de multiplexació per divisió de freqüència ortogonal (OFDM) han atret molta atenció i s'han convertit en la modulació més popular entre diversos esquemes d'accés multiportadora, gràcies a la seua robustesa i simplicitat enfront de la cancel·lació per trajectes múltiples utilitzant el prefix cíclic (CP). Una de les formes d'ona més prometedores per a xarxes de pròxima generació és la tècnica de modulació Filter Bank MultiCarrier (FBMC). El principal benefici de l'esquema FBMC és que no depén de CP i d'un gran nombre de mostres de banda de guarda, per tant, empra diverses funcions de pols localitzades en el temps amb una alta relació de supressió de lòbuls laterals, la qual cosa permet millorar l'eficiència espectral i el rendiment del sistema com a factors clau en les xarxes òptiques de pròxima generació, i proporciona una bona alternativa a la tècnica CP-OFDM. Esta Tesi pretén fer un pas avant en la proposta de formats de modulació per a ser utilitzats en sistemes VLC com a tecnologia habilitadora en xarxes 6G. Per tant, es proposa el sistema Flip-FBMC amb un algoritme de truncament per a oferir una transmissió d'alta velocitat amb baixa latència Flip-FBMC mitjançant l'ús de l'algoritme de transformació ortogonal isotròpica (IOTA) i la capa PHYsical per a DYnamic AccesS i filtres de ràdio cognitiva (PHYDYAS). En aquesta Tesi, es proposa l'equalització multitap per als sistemes VLC en interiors per a mitigar la interferència imaginària intrínseca (IMI) en un canal amb perfils de retards elevat. A més, el rendiment d'error dels senyals FBMC no coherents es millora mitjançant l'anàlisi de la propietat de la localització de temps-freqüència amb la funció gaussiana estesa (EGF), on el factor de dispersió exercix un paper crucial en la determinació de l'equilibri entre les característiques espectrals i la reconstrucció òptima de la qualitat del senyal. En tal escenari, a causa del rang dinàmic limitat del díode emissor de llum (LED), la millora de la precisió de l'estimació depén dels nivells de potència dels pseudopilots amb l'ús de l'arquitectura del Mètode d'Aproximació d'Interferència (IAM) i per tant, no és adequada en sistemes VLC d'il·luminació i comunicació. A més, la Tesi proporciona la primera anàlisi teòrica que informa de la degradació en l'estimació per a diversos factors de clipping basada en l'impacte del nivell d'interferència imaginari fora de la zona de primer orde que no pot ser estimada mitjançant el preàmbul de IAM. No obstant això, s'ha d'emfatitzar en el valor de la tècnica Flip-FBMC/IAM per a proporcionar el model unipolar en comparació amb l'ús del format FBMC òptic polaritzat amb corrent continu (DCO-FBMC) que patix una reducció en l'estimació de la precisió. Per tant, s'ha demostrat el descens del rendiment amb el sistema DCO-FBMC a causa del IMI induït fora dels símbols d'orde zero, i que és més evident quan es requerixen nivells baixos de corrent DC. Des d'esta perspectiva, la tècnica de repetició de trames amb senyals Flip-FBMC ha demostrat ser una solució important per a minimitzar la interferència induïda. Per tant, en esta Tesi, la modulació Flip-FBMC amb repetició de trames i perfil de filtre PHYDYAS es proposa com un candidat viable per a fer front al rang dinàmic restringit del LED, en comparació amb el rendiment dels sistemes Flip-CP-OFDM i Flip-FBMC/IAM en futures xarxes 6G basades en accés VLC. / [EN] The sixth generation (6G) network is the potential solution to meet the exponentially increasing requirements of the emerging services and applications. The 6G platform expects to offer high data rates, ultra-high connectivity, and low latency based on the required key performance indicators (KPIs). The visible light communication (VLC) technology represents a key technology for 6G network but requires an efficient advanced modulation technique to support such requirements. In the last decades, optical signals based on Orthogonal Frequency Division Multiplexing (OFDM) scheme has attracted a lot of attention and become the most popular modulation among several multicarrier access schemes, thanks to its robustness and simplicity against multipath fading using the cyclic prefix (CP). One of the most candidate waveforms that is considered as the promising modulation technique for the next generation requirements and applications is Filter Bank MultiCarrier (FBMC) multiplexing. The major benefit of FBMC scheme is non-reliance on CP and high numbers of guard band samples, thereby, it employs several well time-frequency localized pulse functions with high side-lobe suppression ratio instead, which allows enhancing the spectral efficiency and system performance as key factors in next generation optical networks, and provides a good alternative to CP-OFDM technique. This Thesis aims to make a step forward in proposing modulation formats to be used in VLC systems as enabling technology in 6G networks. Hence, Flip-FBMC system with a truncation algorithm is proposed to offer a high-speed transmission with low latency by tackling the doubled-overhead tails at the subframes of Flip-FBMC burst by the use of the isotropic orthogonal transformation algorithm (IOTA) and PHYsical layer for DYnamic AccesS and cognitive radio (PHYDYAS) filters. Multitap equalization is proposed in this Thesis for the sake of mitigating the intrinsic imaginary interference (IMI) over a channel with high delays profile for indoor VLC system. Moreover, the error performance of non-coherent FBMC signals is enhanced by analysing the property of time-frequency localization with Extended Gaussian Function (EGF), where the spreading factor plays a crucial role in determining the trade-off between the spectral features and optimal reconstruction of signal quality. In such scenario, due to the limited dynamic range of light emitting diode (LED), improving in the accuracy of estimation depends on the power-levels of pseudo pilots with the use of Interference Approximation Method (IAM) architecture. Thereby, the analysis reveals that IAM sequence is not suitable for a real transmission scenario due to high power of IAM over the payload data which conflicts with VLC purposes of illumination and communication simultaneously. Additionally, the Thesis provides the first theoretical analysis reporting the degradation of estimation accuracy for several clipping ratios based on the impact of imaginary interference level outside the first order neighbourhood zone that cannot be estimated by IAM preamble. However, the value of Flip-FBMC/IAM technique in providing the unipolar model must be emphasized compared to the use of Direct Current biased Optical FBMC (DCO-FBMC) format that suffers from a reduction in estimating accuracy. Thereby, the downfall performance with DCO-FBMC system has been reported because of the induced IMI that spreads out the first neighbourhood symbols, which is more evident when low levels of the added DC-bias are required. From such perspective, the frame repetition technique with Flip-FBMC signals has been demonstrated as a major solution for minimizing the induced interference. Therefore, in this Thesis, Flip-FBMC/frame repetition with PHYDYAS profile is proposed as a viable candidate to cope with the restricted dynamic range of the LED, compared to the performance for each Flip-CP-OFDM and Flip-FBMC/IAM system in future 6G networks based on VLC access. / Bahaaelden, MS. (2024). Novel 5G-Modulation Formats and Their Application in Optical Wireless Communications [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/204634

Cette thèse est axée sur le domaine de la communication optique sans fil en intérieur pour la surveillance de la santé basée sur des capteurs corporels. L’état de l'art des communications optique sans fil dans les domaines infrarouge, visible et UV ainsi que l'analyse des systèmes liés à la santé utilisant cette technologie ont été fournis. Cela a permis de définir les objectifs et l'orientation de cette thèse. Nous avons étudié l'utilisation de la technologie infrarouge pour la transmission de données entre un capteur porté par un patient et des récepteurs situés aux coins d'un panneau d'éclairage central au plafond de l'environnement. Un lien en visible a été utilisé pour la transmission de données du luminaire vers le patient portant un smartphone équipé d'un décodeur. Les principaux défis étaient la robustesse des liens infrarouge et visible en ce qui concerne la mobilité du patient et l'impact du corps de l'utilisateur en raison de l'emplacement du capteur. Les simulations de canaux réalisées grâce à la technique de Ray-Tracing associée à la méthode de Monte-Carlo ont permis de déterminer le gain de canal qui est le paramètre principal représentant la performance. En raison de la mobilité du patient, l'analyse a été réalisée de manière statistique et en tenant compte de différents emplacements du capteur sur le corps, de la cheville à l'épaule. Les paramètres physiques et géométriques optimaux relatifs aux émetteurs et aux récepteurs afin de garantir les meilleures performances ont été déduites. Il a été démontré qu’il est essentiel de modéliser la présence du corps pour les deux liaisons montante et descendante. Les performances globales du système ont mis en évidence le potentiel des transmissions sans fil entièrement optiques pour la surveillance médicale basée sur des capteurs corporels. Cela a été en partie confirmé par des expérimentations menées à partir de prototypes de capteur communicant en infrarouge et de produits commerciaux pour la liaison en visible. / This thesis is focused on the field of indoor optical wireless communication for health monitoring based on body sensors. The state of the art of optical wireless in the infrared, visible and UV domains as well as the analysis of health related systems using this technology have been provided. This helped to define the objectives and orientations of this thesis. We have studied the use of infrared technology for data transmission between a sensor worn by a patient and receivers located at the corners of a central lighting panel at the ceiling of the environment. A link in visible was used for the transmission of data from the luminaire to the patient carrying a smartphone equipped with a decoder. The main challenges were the robustness of the infrared and visible links with regard to patient mobility and the impact of the user's body due to the location of the sensor. The channel simulations performed using the Ray-Tracing technique associated with the Monte-Carlo method allowed determining the channel gain, which is the main parameter representing the performance. Due to the patient mobility, the analysis was performed statistically and taking into account different locations of the sensor on the body, from the ankle to the shoulder. The optimal physical and geometrical parameters for transmitters and receivers to ensure the best performance have been deduced. It has been shown that it is essential to model the presence of the body for both uplink and downlink. The overall performance of the system has highlighted the potential of fully optical wireless transmissions for medical surveillance based on body sensors. This has been partly confirmed by experiments carried out from infrared communicating sensor prototypes and commercial products for the visible link.

Technology for wireless information access has enabled innovation of 'smart' portable consumer devices. These have been widely adopted and have become an integral part of our daily lives. They need ubiquitous connectivity to the internet to provide value added services, maximize their functionality and create a smarter world to live in. Cisco's visual networking index currently predicts wireless data consumption to increase by 61% per year. This will put additional stress on the already stressed wireless access network infrastructure creating a phenomenon called 'spectrum crunch'. At the same time, the solid state devices industry has made remarkable advances in energy efficient light-emitting-diodes (LED). The lighting industry is rapidly adopting LEDs to provide illumination in indoor spaces. Lighting fixtures are positioned to support human activities and thus are well located to act as wireless access points. The visible spectrum (380 nm - 780 nm) is yet unregulated and untapped for wireless access. This provides unique opportunity to upgrade existing lighting infrastructure and create a dense grid of small cells by using this additional 'optical' wireless bandwidth. Under the above model, lighting fixtures will service dual missions of illumination and access points for optical wireless communication (OWC). This dissertation investigates multiple-input multiple-output (MIMO) optical wireless broadcast system under unique constraints imposed by the optical channel and illumination requirements. Sample indexed spatial orthogonal frequency division multiplexing (SIS-OFDM) and metameric modulation (MM) are proposed to achieve higher spectral efficiency by exploiting dimensions of space and color respectively in addition to time and frequency. SIS-OFDM can provide significant additional spectral efficiency of up to (Nsc/2 - 1) x k bits/sym where Nsc is total number of subcarriers and k is number of bits per underlying spatial modulation symbol. MM always generates the true requested illumination color and has the potential to provide better color rendering by incorporating multiple LEDs. A normalization framework is then developed to analyze performance of optical MIMO imaging systems. Performance improvements of up to 45 dB for optical systems have been achieved by decorrelating spatially separate links by incorporating an imaging receiver. The dissertation also studies the impact of visual perception on performance of color shift keying as specified in IEEE 802.15.7 standard. It shows that non-linearity for a practical system can have a performance penalty of up to 15 dB when compared to the simplified linear system abstraction as proposed in the standard. Luminous-signal-to-noise ratio, a novel metric is introduced to compare performance of optical modulation techniques operating at same illumination intensity. The dissertation then introduces singular value decomposition based OWC system architecture to incorporate illumination constraints independent of communication constraints in a MIMO system. It then studies design paradigm for a multi-colored wavelength division multiplexed indoor OWC system.

Traffic from wireless and mobile devices is predicted to increase 10-fold between 2014 and 2019, surpassing wired data traffic by 2016. Given the expected radio frequency (RF) capacity crunch, this growing wireless demand will have to be met using a variety of new technologies exploiting other parts of the electromagnetic spectrum. Promising research areas include the Millimetre Band as well as Optical Wireless Communications (OWC). Millimetre Band demonstrations have accomplished ultrafast multi-Gigabit links, making use of state-of-the-art fibre transmission systems. However, complex opto-electronic (OE) interfaces are required to convert the optical carrier into Millimetre wireless signals. To avoid these interfaces, an all-optical transparent network is proposed here, spanning over both the fibre and OWC domains, in order to deliver ultrahigh data rates to mobile end-users in indoor environments. This is supported by the recent deployment of fibre-to-the-home (FTTH) networks creating the potential for Terabit aggregate connections at the user's doorstep. Therefore, infrared fibre-wireless-fibre (FWF) links are studied to support data rates over 100 Gb/s in nomadic applications. The link coverage is achieved via narrow beam beamsteering over a wide field-of-view (FOV) using suitable localization and tracking techniques. The proposed model is inherently bidirectional and transparent, i.e. independent of the data rate and modulation format. In this thesis, the potential for ultrafast wide coverage OWCs using SMF-based transceivers and coherent transmission is demonstrated. A record data rate of 418 Gb/s and 209 Gb/s with a wide FOV of θ_FOV=±30° and θ_FOV=±20°, respectively, is shown at a free space range of 3 m. To the best of our knowledge, this is the fastest demonstration of an indoor wireless link that offers practical room-scale coverage. The automated alignment of this FWF link is also demonstrated with the design and implementation a mm-accurate localization and tracking system. Finally, architectures for point-to-multipoint communications are explored in order to adapt the system to multiple users.

Abstract In visible light communication (VLC), light emitting diodes (LEDs) are used as transmitters; the air is the transmission medium and the photodiodes are used for receivers. This is often referred to as light fidelity (Li-Fi). In this thesis, we provide the methodology to evaluate the performance of VLC hotspot networks in the context of data downloading on the move scenarios by using throughput-distance relationship models. In this context, first we study the different properties of optical transceiver elements, noise sources, characterization and modelling of artificial light interference, different link topologies and then we introduce the throughput-distance relationship model. Secondly, the analytically based throughput-distance relationship has been developed for evaluating the performance of VLC hotspot networks in indoor environment in both day and night conditions. Simulation results reveal that background noise has a significant impact on the performance of VLC hotspots. As expected, in both indoor and outdoor environments the VLC hotspot performs better at night than during day. The performance of VLC hotspot networks is also quantified in terms of received file size at different bit error rate requirements and velocities of the mobile user. Thirdly, we study the performance of hybrid (Radio-Optical) WLAN-VLC hotspot and compare its performance with stand-alone VLC-only or WLAN-only hotspot cases. In this case, we also consider the data download on the move scenarios in an indoor environment for a single-user as well as for multi-user cases. In this hybrid WLAN-VLC hotspot, both the WLAN and the VLC are characterized by their throughput and communication range. Simulations have been performed to evaluate the performance of such network for data downloading on the move scenario by taking into account performance metrics such as filesize, average connectivity and system throughput. Simulation results reveal that the considered hybrid WLAN-VLC performs always better than stand-alone VLC-only or WLAN-only hotspot both for a single and multi-user cases. Finally, this thesis analyses the feasibility and potential benefits of using hybrid radio-optical wireless systems. In this respect, cooperative communication using optical relays are also introduced in order to increase the coverage and energy efficiency of the battery operated device. Potential benefits are identified as service connectivity and energy efficiency of battery operated device in an indoor environment. Simulation results reveal that user connectivity and energy efficiency depend on user density, coverage range ratio between single-hop and multi-hop, relay probabilities and mobility of the user. / Tiivistelmä Näkyvään valoon pohjautuvassa tiedonsiirrossa (VLC) valodiodeja (LED) käytetään lähettiminä, ilma on siirtokanava ja valoilmaisimia käytetään vastaanottimina. Tätä kutsutaan usein nimellä light fidelity (Li-Fi). Tässä työssä tarjoamme menetelmiä VLC ”hotspot” verkkojen suorituskyvyn arviointiin tiedonsiirtonopeus-etäisyysmalleilla skenaarioissa, jossa tietoa ladataan liikkeessä. Tässä kontekstissa tutkimme ensin optisen lähettimen komponenttien eri ominaisuuksia, kohinan lähteitä, keinovalon häiriömalleja ja tiedonsiirtolinkkien topologioita, jonka jälkeen esittelemme tiedonsiirtonopeuden ja etäisyyden välisen mallin. Toiseksi kehitetyn analyyttisen tiedonsiirto-etäisyys mallia käytetään arvioitaessa VLC hotspot verkkojen suorituskykyä sisäympäristössä sekä päivä että yö olosuhteissa. Simulointien tulokset osoittavat, että taustakohinalla on suuri vaikutus VLC verkkojen suorituskykyyn. Kuten odotettua, sisä- ja ulkotiloissa VLC hotspot toimii paremmin yöllä kuin päivällä. VLC hotspot verkkojen suorituskyky arvioidaan myös vastaanotetun tiedoston koon, eri bittivirhesuhteen vaatimuksilla ja liikkuvan käyttäjän nopeuden suhteen. Kolmanneksi tutkimme hybridi WLAN-VLC hotspot verkon suorituskykyä ja vertaamme sen suorituskykyä pelkän VLC- tai WLAN hotspot tapauksessa. Käsittelemme myös skenaarioita jossa tiedoston lataus tapahtuu liikkeessä sisätilassa yhden käyttäjän sekä monen käyttäjän tapauksissa. Tässä hybridi WLAN-VLC hotspot, sekä erilliset WLAN- ja VLC verkot ovat määritelty niiden tiedonsiirtonopeuden ja kantaman perusteella. Näiden verkkojen suorituskykyä arvioitaessa on tehty joukko tietokonesimulointeja verkossa tapahtuvasta tietojen lataamisesta liikkeessä ottamalla huomioon suorituskyvyn mittarit kuten tiedoston koko, keskimääräinen yhteyden kesto ja saavutettu läpäisy. Simuloinnin tulokset paljastavat, että hybridi WLAN-VLC toimii aina paremmin kuin pelkkä VLC tai WLAN hotspot sekä yhden että monen käyttäjän tapauksessa. Lopuksi työssä analysoidaan ehdotetun järjestelmän toteutettavuus ja mahdolliset edut käytettäessä hybridejä radio-optisia langattomia järjestelmiä. Tältä osin esitellään myös kooperatiiviseen viestintään perustuvat optiset releet parantamaan verkon kattavuutta ja energiatehokkuutta akkukäyttöisissä laitteissa. Mahdolliset hyödyt tunnistetaan palvelun konnektiivisuudessa ja energiatehokkuudessa akkukäyttöisissä laitteissa sisätiloissa. Simulointien tulokset osoittavat, että käyttäjien konnektiivisuus ja energiatehokkuus riippuvat käyttäjätiheydestä, kantaman ja etäisyyden välisestä suhteesta yhden hypyn ja monen hypyn välillä, releointi todennäköisyydestä ja käyttäjien mobiliteetista.

L'explosion de demande de bande passante est une conséquence de l'augmentation du volume de trafic. Il est important de proposer des mécanismes pour transférer le trafic entre les réseaux interconnectés de manière efficace. D'autre part, il est prévu que les réseaux d'accès (optiques et mobiles) constituent les plus grands consommateurs d'énergie dans les réseaux optiques pour les dix prochaines années. Cette situation et l'impact croissant des réseaux sur l'environnement ont fait devenir l'efficacité énergétique dans les réseaux de télécommunications un thème important de recherche. Cette thèse se concentre donc sur la proposition de nouvelles solutions aux problèmes liées à l'augmentation du volume de trafic dans différentes segments des réseaux. Tout d'abord, nous avons étudié différents schèmes de transfert du trafic entre les réseaux interconnectes en utilisant la synchronisation. Puis, nous avons exploré la possibilité d'offrir différents services dans les réseaux intégrés optiques-mobiles. Nous avons présenté une nouvelle architecture pour la conception de l'unité de réseau optique (ONU). Ensuite, nous nous sommes focalisés sur l'économie de l'énergie et des solutions efficaces pour l'allocation de bande passante ont été proposées. Nous avons également proposé un algorithme qui fournit l'efficacité énergétique pour les récepteurs sans fil dans les ONUs hybride. Une analyse des performances en utilisant modèles de files d'attente a été présentée. Finalement, nous avons analysé le trafic hétérogène dans l'ONU hybride, et nous avons proposé un cadre pour un algorithme d'ordonnancement qui puisse mettre à jour les règles de service de façon dynamique / A big growth in the number of subscribers is increasing the traffic volume passing through each sector in a telecommunication network. Mechanisms are required to solve the traffic shift problem between two sectors of the network in an efficient way. Additionally, it is expected that the access networks (optical and wireless) will constitute the largest energy consumers among the networks for the next ten years. This situation and the increasing impact of networks on the environment have made become the energy efficiency in telecommunication networks an important theme for researches. This dissertation hence focuses on the proposition of novel solutions for deal with the problems due to the growing of traffic in different segments of the network. Firstly, we have studied the traffic shift between interconnected networks by using the synchronization as technique to solve this problem. Secondly, we have explored the possibility of provisioning different services over the integration of optical-wireless technologies, which has been considered as a promising candidate for the deployment of high-speed access networks. Architecture of design for the Optical Network Unit (ONU) is presented. Then, energy efficiency has been focused and effective bandwidth management solutions have been proposed. We have also proposed an energy efficiency algorithm for wireless receiver at hybrid ONUS. A performance analysis by queuing models was presented for the implementation of proposed solutions. Finally, we have analyzed the heterogeneous traffic at hybrid ONU, and we have proposed a framework for a scheduling algorithm considering the characteristics of different traffic sources

Integration of optical wireless communications (OWC) within switched-mode power supplies (SMPS) / Although visible light communication(VLC) systems can provide high density links for use with IoT devices, an energy efficient, high rate method of designing a VLC transmitter is still unclear. Present designs for transmitters such as the bias-T, designs with switch manipulation, and interleaved converters are not commercially viable due to costly and complex designs that sacrifice energy efficiency for data rate. A design allowing for efficient, high rate communications, while maintaining a low cost would allow for widespread adoption of this technology. In this thesis, a novel approach of integrating power converters and VLC systems is explored by replacing commutating diodes with LEDs. By leveraging switched-mode power supply(SMPS) structures, the power dissipated within the converter may be harnessed and used for communications. The result is a simple and energy efficient solution capable of high rate links. Simulation and experimental results demonstrate buck and boost SMPS topologies that simultaneously increase energy efficiency and provide communications at SMPS switching rate without increasing component count. / Thesis / Master of Applied Science (MASc)