High performance, low cost and low consumption Radio-over-Fiber systems for diversified communications applications

This dissertation aims to analyze the possibility of improving in terms of cost and consumption the future Radio-over-Fiber (RoF) systems in different telecommunications scenarios, such as current and next generation of cellular networks and in other applications such as Radio Astronomy. The RoF system studied is hence composed of a Vertical Cavity Surface Emitting Laser (VCSEL) operating at 850 nm, standard single mode fiber (SSMF) and SiGe Heterojunction PhotoTransistor (HPT), adopting the technique called Intensity Modulation-Direct Detection which is nowadays the cheapest and simplest architecture for RoF. This dissertation describes in detail the multimode propagation within the SSMF which is present at 850 nm. Through a developed mathematical model, the two-modes propagation is described and the main phenomena involved are analyzed. The model developed is able to identify the main parameters which contribute to enhance the detrimental effects produced by intermodal dispersion and modal noise both in frequency and time domain. Starting from the model, possible techniques to improve the performances are then proposed. In particular, a pre-filtering technique is realized in order to avoid the excitation of the second order mode, allowing a quasi-single-mode propagation within the SSMF. The technique is theoretically and experimentally validated both for single radio frequency sinusoidal transmission and for bandpass signal. Furthermore, the technique is validated in a LTE transmission system, making the RoF technology proposed able to transmit 256-QAM LTE signal of 20 MHz bandwidth, confirming the possibility to decrease the overall cost and consumption of the network. Further work has been done on the mathematical model. In particular the two modes propagation is exploited in order to characterize the chirp parameter of the VCSEL employed. Finally, the problem of coupling between fiber and opto-electronic devices is also discussed and investigated, in order to improve the efficiency while keeping low the costs

Controlling Rayleigh-Backscattering-Induced Distortion in Radio over Fiber Systems for Radioastronomic Applications

Radio over Fiber (RoF) Systems exploiting a direct modulation of the laser source are presently utilized within important Radioastronomic scenarios. Due to the particular operating conditions of some of these realizations, the phenomena which typically generate nonlinearities in RoF links for telecommunications applications can be here regarded as substantially harmless. However, these same operating conditions can make the RoF systems vulnerable to different kinds of nonlinear effects, related to the influence of the Rayleigh Backscattered signal on the transmitted one. A rigorous description of the phenomenon is performed, and an effective countermeasure to the problem is proposed and demonstrated, both theoretically and experimentally.Comment: Accepted for publication in IEEE/OSA Journal of Lightwave Technolog

Insidious diagnosis of breast cancer in patient with previous macrolaneTM breast infiltration: A case-report

Breast augmentation is one of the most performed aesthetic surgery. In addition to the silicone breast implants, hyaluronic acid base fillers represent a non-surgical alternative. There are different types of hyaluronic acid for this purpose, including MacrolaneTM. In addition to the classic complications associated with the mammary injection of these fillers, Macrolane may cause a well-known radiological ambiguity potentially leading to a delay in the diagnosis of an underlying breast cancer. The patient underwent breast augmentation with hyaluronic acid and after several years from the procedure she noted the appearance of subcutaneous nodules and discontinuous mastodynia, attributed to previous Macrolane infiltrations: unfortunately the radiological images did not immediately show the underlying contextual cancer of the right breast. Patient underwent therapeutic right mastectomy and prophylactic left mastectomy, because of the presence of BRCA1 mutation. Simultaneously we performed an immediate reconstruction with mammary implants and biological meshes. No complications arose in the follow up. Several authors have already carried out studies on Macrolane focusing on its interference and delay in the diagnosis of malignant breast diseases. At present there is only one other case in literature reporting on a patient diagnosed with physical and instrumental examinations and delaying the diagnosis. We believe that the use of hyaluronic acid (Macrolane) fillers for breast augmentation should be avoided. In view of the complexity of these cases, a multidisciplinary approach is always advisable: we believe that a continuous dialogue between the Plastic surgeon, the Breast-dedicated Radiologist and the Oncologist is pivotal

Optimal Dithering Configuration Mitigating Rayleigh-Backscattering-Induced Distortion in Radioastronomic Optical Fiber Systems

In the context of Radioastronomic applications where the Analog Radio-over-Fiber technology is used for the antenna downlink, detrimental nonlinearity effects arise because of the interference between the forward signal generated by the laser and the Rayleigh backscattered one which is re-forwarded by the laser itself toward the photodetector. The adoption of the so called dithering technique, which involves the direct modulation of the laser with a sinusoidal tone and takes advantage of the laser chirping phenomenon, has been proved to reduce such Rayleigh Back Scattering - induced nonlinearities. The frequency and the amplitude of the dithering tone should both be as low as possible, in order to avoid undesired collateral effects on the received spectrum as well as keep at low levels the global energy consumption. Through a comprehensive analysis of dithered Radio over Fiber systems, it is demonstrated that a progressive reduction of the dithering tone frequency affects in a peculiar fashion both the chirping characteristics of the field emitted by the laser and the spectrum pattern of the received signal at the fiber end. Accounting for the concurrent effects caused by such phenomena, optimal operating conditions are identified for the implementation of the dithering tone technique in radioastronomic systems.Comment: 11 pages. Accepted for Journal of Lightwave Technolog

Linearity improvement of VCSELs based radio over fiber systems utilizing digital predistortion

The article proposes a Digital Predistortion (DPD) methodology that substantially meliorates the linearity of limited range Mobile Front Haul links for the extant Long-Term Evolution (LTE) and future (5G) networks. Specifically, the DPD is employed to Radio over Fiber links that contrive of Vertical Cavity Surface Emitting Lasers (VCSELs) working at 850 nm. Both, Memory and Generalized Memory Polynomial models are implied to Single Mode (SM) and Multi-Mode (MM) VCSELs respectively. The effectiveness of the proposed DPD methodology is analyzed in terms of Normalized Mean Square Error, Normalized Magnitude, Normalized phase and Adjacent Channel Power Ratio. The demonstration has been carried out with a complete (Long Term Evolution) LTE frame of 10 ms having 5 MHz bandwidth with 64-QAM modulation configuration. Additionally, the effectuality of the proposed DPD technique is evaluated for varying levels of input power and link lengths. The experimental outcomes signify the novel capability of the implied DPD methodology for different link lengths to achieve higher system linearization

Radio frequency over fiber technology for SKA-low receiver

The signal reception chain is an essential element for achieving the square kilometer array-low (SKA-low) system requirements in terms of high sensitivity and dynamic range. The balance between gain, linearity, and low power consumption, as well as the cost, are fundamental parameters that influence the selection of the most suitable technology for SKA-low. Further factors, such as low self-generated radio frequency (RF) interference, high reliability, robustness under extreme environment, and last but not least, the distance between the antennas and the acquisition systems, have impacts on the selection for both architecture and receiver system design. The selected technology for the SKA-low RF signal transportation is RF-over-fiber systems, where the preamplified RF signal picked up by the antennas is carried via analogue modulation over optical fiber. The rationales behind the selection are reported, along with descriptions on the development of the receiver prototypes. The prototypes were deployed and installed on the demonstrator arrays at the selected SKA-low site in Western Australian. Particular attention has been put on the thermal characterization of the receiver system under the actual operating temperature on site, especially when both transmitting part and the optical medium are subjected to external ambient temperature variations. Performance issues encountered in the demonstrator arrays are also discussed along with some proposals for future activities

Improved Nonlinear Model Implementation for VCSEL Behavioral Modeling in Radio-Over-Fiber links

Open Access provided by `Alma Mater Studiorum - Università di Bologna' within the CRUI CARE AgreementInternational audienc

Long-Term Outcome After Adoptive Immunotherapy With Natural Killer Cells: Alloreactive NK Cell Dose Still Matters

Recently, many reports were published supporting the clinical use of adoptivelytransferred natural killer (NK) cells as a therapeutic tool against cancer, including acutemyeloid leukemia (AML). Our group demonstrated promising clinical response usingadoptive immunotherapy with donor-derived alloreactive KIR-ligand-mismatched NK cellsin AML patients. Moreover, the antileukemic effect was correlated with the dose of infusedalloreactive NK cells (“functional NK cell dose”). Herein, we update the results of ourprevious study on a cohort of adult AML patients (median age at enrollment 64) infirstmorphological complete remission (CR), not eligible for allogeneic stem celltransplantation. After an extended median follow-up of 55.5 months, 8/16 evaluablepatients (50%) are still off-therapy and alive disease-free. Overall survival (OS) and disease-free survival (DFS) are related with the dose of infused alloreactive NK cells (≥2×105/kg

The baseline comorbidity burden affects survival in elderly patients with acute myeloid leukemia receiving hypomethylating agents: Results from a multicentric clinical study

Background: In older patients with acute myeloid leukemia (AML), the definition of fitness, prognosis, and risk of death represents an open question. Methods: In the present study, we tested the impact on survival of disease- and patient-related parameters in a large cohort of elderly AML patients homogeneously assigned to treatment with hypomethylating agents (HMAs). Results: In 131 patients with a median age of 76 years, we confirmed that early response (<0.001) and biology-based risk classification (p = 0.003) can select patients with better-predicted survival. However, a full disease-oriented model had limitations in stratifying our patients, prompting us to investigate the impact of baseline comorbidities on overall survival basing on a comorbidity score. The albumin level (p = 0.001) and the presence of lung disease (p = 0.013) had a single-variable impact on prognosis. The baseline comorbidity burden was a powerful predictor of patients' frailty, correlating with increased incidence of adverse events, especially infections, and predicted overall survival (p < 0.001). Conclusion: The comorbidity burden may contribute to impact prognosis in addition to disease biology. While the therapeutic armamentarium of elderly AML is improving, a comprehensive approach that combines AML biology with tailored interventions to patients' frailty is likely to fully exploit the anti-leukemia potential of novel drugs

Systèmes radio-sur-fibre bas coût, basse consommation et hautes performances pour des applications de communications diversifiées

This dissertation aims to analyze the possibility of improving in terms of cost and consumption the future Radio-over-Fiber (RoF) systems in different telecommunication scenarios, such as current and next generation of cellular networks and in other applications such as Radio Astronomy. The RoF system studied is hence composed of a Vertical Cavity Surface Emitting Laser (VCSEL) operating at 850 nm, standard single mode fiber (SSMF) and SiGe Heterojunction Phototransistor (HPT), adopting the technique called Intensity Modulation{Direct Detection which is nowadays the cheapest and simplest architecture for RoF. This dissertation describes in detail the multimode propagation within the SSMF (designed to operate only at 1310 nm and 1550 nm) which is present at 850 nm. Through a developed mathematical model, the two-modes propagation is described and the main phenomena involved are analyzed. In particular, the model focus on intermodal dispersion and modal noise which are considered the two main contributions of performance detrimental. The model developed is able to identify the main parameters which contribute to enhance the detrimental effects produced by intermodal dispersion and modal noise both in frequency and time domain. Starting from the model, possible techniques to improve the performances are then proposed. In particular, a pre-filtering technique is realized in order to avoid the excitation of the second order mode, allowing a quasi-single-modepropagation within the SSMF. The technique is theoretically and experimentally validated either for single radio frequency sinusoidal transmission either for bandpass signal transmission centered in radio frequency band. In particular it is demonstrated experimentally the possibility of increasing the modulationbandwidth of the RoF system, reducing at the same time the fluctuations of power and gain. Furthermore, the technique is validated in a real LTE transmission system, making the RoF technology proposed able to transmit 256-QAM LTE signal of 20 MHz bandwidth, confirming the possibility of using this technology to decrease the overall cost and consumption of the network. Further work hasbeen done on the mathematical model. In particular the two modes propagation is exploited reversely in order to characterize the chirp parameter of the VCSEL employed. Finally, the problem of coupling between fiber and opto-electronic devices is also discussed and investigated, in order to enhance theperformances while keeping low the cost. The possibility of utilizing a collective and passive ploymerbased structure for coupling the optical fiber with small area photodetectors and VCSEL is presented, showing important improvements on coupling efficiency and tolerance to misalignmentCette thèse vise à analyser en détails la possibilité d'améliorer les futurs systèmes Radio-sur-Fibre (RoF) dans différents scénarios de télécommunication, tels que les réseaux cellulaires actuels et de la prochaine génération, ainsi que dans d'autres applications telles que la radioastronomie. Le système RoF étudié est donc composé d’un laser à cavité verticale (VCSEL) fonctionnant à 850 nm, d'une fibre standard monomode (SSMF) et d'un phototransistor à hétérojonction SiGe (HPT), adoptant la technique appelée détection directe par modulation d'intensité qui est aujourd'hui l'architecture à moindre coût et la plus simple pour RoF. Cette thèse décrit en détail la propagation non naturelle dans le SSMF (conçue pour fonctionner uniquement à 1310 nm et 1550 nm) à 850 nm. A travers un modèle mathématique développé, la propagation à deux modes est décrite et les principaux phénomènes impliqués sont analysés. En particulier, le modèle se concentre sur la dispersion intermodale et le bruit modal, considérés comme les deux principales contributions de performance nuisible. Le modèle mis au point permet d'identifier les principaux paramètres qui contribuent à renforcer les effets néfastes de la dispersion intermodale et du bruit modal, à la fois en fréquence et dans le temps. A partir du modèle, des techniques possibles pour améliorer les performances sont alors proposées. En fait, une technique de pré-filtrage est réalisée afin d'éviter l'excitation du mode du second ordre, permettant une propagation quasi-monomode au sein du SSMF. La technique est validée théoriquement et expérimentalement soit pour une transmission sinusoïdale à radiofréquence unique, soit pour une transmission de signal passe-bande centrée sur une bande de radiofréquence. Il est démontré expérimentalement que possibilité d'augmenter la bande passante de modulation du système RoF, tout en réduisant les fluctuations de puissance et de gain. De plus, la technique est validée dans un véritable système de transmission LTE, ce qui permet à la technologie RoF de transmettre un signal LTE 256-QAM de 20 MHz, confirmant la possibilité d'utiliser cette technologie pour réduire le coût global et la consommation du réseau. Des travaux supplémentaires ont été réalisés sur le modèle mathématique. En fait, la propagation des deux modes est exploitée en sens inverse pour caractériser le chirp du VCSEL utilisé. Enfin, le problème du couplage entre les fibres et les dispositifs optoélectroniques est discuté et étudié afin d’améliorer les performances tout en gardant un faible coût. La possibilité d'utiliser une structure collective et passive pour coupler la fibre optique avec des photodétecteurs à petite surface et VCSEL est présentée, montrant des améliorations importantes sur l'efficacité du couplage et la tolérance au désalignemen