Outage Probability Analysis of RF/FSO-VLC Communication Relaying System

This paper presents an analysis of the asymmetric relaying system which provides communication between hybrid outdoor sub-system and indoor visible light communications (VLC) access points. The outdoor sub-system represents a hybrid radio-frequency (RF)/free-space optical (FSO) system, introduced to reduce the impact of weather conditions on transmission quality. Closed-form outage probability analytical expression is derived. Numerical results are presented and confirmed by Monte Carlo simulations. The effects of system and channel parameters on the outage probability performance are investigated and discussed. Greater optical transmitted power of the VLC subsystem reflects in better system performance, as well as lower indoor environment height. When the indoor room is higher, the propagation of the optical signal is longer, and there will be greater power dissipation and performance deterioration. In addition, the outage probability floor is noticed, which is important limiting factor for relaying system design.Comment: Published in: 2018 11th International Symposium on Communication Systems, Networks & Digital Signal Processing (CSNDSP

Mixed RF-VLC Relaying System with Radio-Access Diversity

We present a statistical analysis of a mixed radio-frequency (RF)-visible light communications (VLC) relaying system, where outdoor millimeter wave based RF links are utilized to provide backhaul connectivity for indoor VLC broadcasting. The multiple RF links are assumed to communicate with the VLC access point through decode-and-forward relay. Novel closed-form outage probability and average bit error rate expressions are derived and utilized to obtain numerical results. Monte Carlo simulations validate presented numerical results, which are further used to examine the effects of system and channel parameters on system performance.Comment: Presented at 2019 28th Wireless and Optical Communications Conference (WOCC

Гидролитические ферменты слюны в оценке состояния онкологических больных

Определение активности калликреина слюны является одним из перспективных методов контроля за развитием опухолей в области головы и шеи и эффективности лучевой терапии. Цель исследования заключалась в изучении активности амилазы и калликреина слюны в условиях проведения курса сочетанной лучевой терапии больных со злокачественными новообразованиями области головы и шеи. Определяли активность ?-амилазы (по наборам Лахема, Чехия) и калликреина (по БАЭЭ-эстеразной активности). Активность калликреина и калликреиногена слюны у больных со злокачественными опухолями головы и шеи была в 2,6 и 3,8 раза выше, чем в группе практически здоровых лиц, в то время как активность амилазы не изменялась. При сочетанной нейтронно-фотонной лучевой терапии активность калликреина слюны снижалась до 20 % от исходного уровня. Обнаружена дозовая зависимость угнетения активности калликреина слюны, более выраженная при действии нейтронов, чем фотонов. Снижение активности калликреина до критической величины, составляющей 100 Е/л, является показателем необратимых реакций, связанных с дистрофическими изменениями слюнных желез и слизистой полости рта

Mixed RF-VLC Relaying Systems for Interference-Sensitive Mobile Applications

Due to their Radio-Frequency (RF) immunity, Visible Light Communications (VLC) pose as a promising technology for interference sensitive applications such as medical data networks. In this paper, we investigate mixed RF-VLC relaying systems especially suited for this type of applications that support mobility. In this system setup, the end-user, who is assumed to be on a vehicle that is in dynamic movement, is served by an indoor VLC system, while the outdoor data traffic is conveyed through multiple backhaul RF links. Furthermore, it is assumed that a single backhaul RF link is activated by the mobile relay and due to feedback delay, the RF link activation is based on outdated channel state information (CSI). The performance of this system is analyzed in terms of outage probability and bit error rate (BER), and novel closed form analytical expressions are provided. Furthermore, the analysis is extended for the case where the average SNR over the RF links and/or LED optical power is high, and approximate analytical expressions are derived which determine performance floors. Numerical results are provided which demonstrate that the utilization of multiple RF backhaul links can significantly improve overall RF-VLC system performance when outage/BER floors are avoided. This calls upon joint design of both subsystems. Additionally, the outdated CSI exploited for active RF selection can significantly degrade the quality of system performance.Comment: Published in IEEE Transactions on Vehicular Technolog

Enhanced Multicarrier Techniques for Professional Ad-Hoc and Cell-Based Communications (EMPhAtiC) Document Number D3.3 Reduction of PAPR and non linearities effects

Livrable d'un projet Européen EMPHATICLike other multicarrier modulation techniques, FBMC suffers from high peak-to-average power ratio (PAPR), impacting its performance in the presence of a nonlinear high power amplifier (HPA) in two ways. The first impact is an in-band distortion affecting the error rate performance of the link. The second impact is an out-of-band effect appearing as power spectral density (PSD) regrowth, making the coexistence between FBMC based broad-band Professional Mobile Radio (PMR) systems with existing narrowband systems difficult to achieve. This report addresses first the theoretical analysis of in-band HPA distortions in terms of Bit Error Rate. Also, the out-of band impact of HPA nonlinearities is studied in terms of PSD regrowth prediction. Furthermore, the problem of PAPR reduction is addressed along with some HPA linearization techniques and nonlinearity compensation approaches

Breitband MIMO-Funkkanal-Modellierung

Diese Arbeit konzentriert sich auf die Klasse der stochastischen geometrie-basierten Kanalmodelle, die einen guten Kompromiss zwischen Komplexität und Realismus bieten. Die flexible Struktur des geometrie-basierten stochastischen Kanalmodells ermöglicht eine generische Darstellung der unterschiedlichen Ausbreitungsszenarien, so dass dieses Modell für die Simulation von heterogenen Netzwerken geeignet ist. Da die Parametrisierung des zweiseitig richtungsaufgelösten Modells keine Information über die Positionen der Streuobjekte relativ zu dem Sende-und Empfangsantennen erfordert, ist es möglich, ein Modell zu entwerfen, welches nicht explizit die Position der Streuer während der Synthese bestimmt. Die Entwicklung eines solchen Modells, welches für die Beschreibung der physikalischen Wellenausbreitung nur die parametrische Dimensionen verwendet, begann mit dem 3GPP Spatial Channel Modell und es während der verschiedenen WINNER Projekte weiterentwickelt. Die betrachteten Modelle nutzen diese Parameter wie "Delay Spread", "Winkelstreuung", "Shadowing", etc. um die Leistungsverteilung in den verschiedenen Kanaldimensionen zu quantifizieren. Deren statistischen Eigenschaften (statistische Verteilungen und Korrelationsfunktionen) werden auf der Ebene der Ausbreitungsszenarien charakterisiert und stellen damit den wichtigsten Teil des Modells dar.Die Repräsentation der Messdaten/Kanaleigenschaften in WINNER spezifischen parametrischen Dimensionen und deren weitere Abstraktion als multivariaten normalverteilten Prozess ermöglicht eine einfache Quantifizierung der Szenarioähnlichkeit basierend auf einer relativen Entropiemetrik. Dieses Ähnlichkeitsmaß kann dann genutzt werden, um die erforderliche Anzahl von unterschiedlichen Klassen an Referenzszenario zu minimieren, welches die Komplexität des Gesamtmodells reduziert. Die vereinfachte Parametrierung des 3GPP Spatial Channel Modell führt zu einer schwachen Konsistenz der räumlich-zeitlichen Kanalevolution. Die Ursache liegt in der abstrahierten Ausbreitungsumgebung, also dem Fehlen von vordefinierten Streuobjekten. Im WINNER -Modell werden die Intra-Zell-Korrelationen ausgenutzt um Ähnlichkeiten von benachbarten Positionen mobiler Endgerät zu erzwingen. Die Intra-Zell-Korrelationen sind aber immer noch nicht angemessen vertreten und reproduziert durch dieses Modell. Hier sind weitere zukünftige Arbeiten notwendig. Diese Doktorarbeit schlägt eine Modellerweiterung für kooperative (Down)Links vor, hierbei wird die Interaktion der Large Scale Parameter durch eine Begrenzung des Dynamikbereichs der Empfänger eingeführt.This thesis concentrates on the class of geometry-based stochastic channel models that offer a good trade-off between complexity and realism. The flexible structure of the geometry-based stochastic channel model enables generic representation of different propagation scenarios, making the model suitable for simulation of heterogeneous networks. Since the parameterization of the double-directional model does not require information on the positions of the scattering objects relative to the transmitting and receiving antennas, it is possible to design a model that does not explicitly position the scatterers during the synthesis. Development of such a model, which uses purely parametric domains to represent physical propagation started with the 3GPP Spatial Channel Model, and it advanced during the WINNERproject. These particular models use the control parameters such as “delay spread”, “angular spread”, “shadowing”, etc. to quantify the power distribution over different channel dimensions. Their statistical properties (statistical distributions and correlation functions) are characterized on the propagation scenario level, and represent the most important part of the model. The representation of measurement in WINNER parametric space and its further abstraction as a multi-variate normal process enables the straightforward quantification of the similarity by relative entropy measure. This similarity metric can be exploited to minimize the required number of distinct reference scenario classes, which reduces the overall model complexity. The simplified parameterization of the 3GPP Spatial Channel Model results in weak consistency of the spatio-temporal channel evolution. This comes as a direct consequence of the abstracted propagation environment, i.e., the lack of predefined scatterer setup. In the WINNER model, the intra-cell correlations are exploited to enforce similarity in the close positions of a mobile terminal. The intra-cell correlations are still not properly represented and reproduced by this model, which defines the necessary future work. The thesis proposes a model extension in which the interaction of large-scale parameters, describing the cooperative (down)links, is established through a limited dynamic range of the receiver