The Experts below are selected from a list of 482859 Experts worldwide ranked by ideXlab platform
Harald Haas - One of the best experts on this subject based on the ideXlab platform.
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CSCN - SDN-enabled Li-Fi/Wi-Fi wireless medium access technologies integration framework
2016 IEEE Conference on Standards for Communications and Networking (CSCN), 2016Co-Authors: Hamada Alshaer, Harald HaasAbstract:The integration of Li-Fi and IEEE 802.11x Wi-Fi wireless access networks represents an opportunity for users to receive secure ubiquitous indoor HD video and voice services, and internet service providers to diversify services portfolio. For the first time, this paper introduces an application-medium access control (MAC) cross-layer scheme for integrating Li-Fi and Wi-Fi access networks using software-defined networking. The scheme comprises a flow admission control mechanism, which inter-operates with a mechanism that dynamically allocates resources of Li-Fi and Wi-Fi MAC layers. It leverages the capacity diversity of Li-Fi and Wi-Fi access networks to support OoS per-flow service class. The proposed scheme runs in the SDN controller and interacts with SDN agents functionalities running in the APs, which consider traffic parameters of applications running on mobile devices to efficiently support real-time services. The parameters underlying Li-Fi and Wi-Fi AP MAC protocols can be configured by the proposed SDN scheme to support dynamic and granular services provisioning to end-users.
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Dynamic Load Balancing with Handover in Hybrid Li-Fi and Wi-Fi Networks
Journal of Lightwave Technology, 2015Co-Authors: Y C Wang, Yunlu Wang, Harald HaasAbstract:In this paper, a hybrid network combining light fidelity (Li-Fi) with a radio frequency (RF) wireless fidelity (Wi-Fi) network is considered. An additional tier of very small Li-Fi attocells which utilize the visible light spectrum, offers a significant increase in the wireless data throughput in an indoor environment, while at the same time providing room illumination. Importantly, there is no interference between Li-Fi and Wi-Fi. A Li-Fi attocell covers a significantly smaller area than a Wi-Fi access point (AP). This means that even with a moderate user movement a large number of handover between Li-Fi attocells can occur, and this compromises the system throughput. Dynamic load balancing (LB) can mitigate this issue so that the quasi-static users are served by Li-Fi attocells, while moving users are served by a Wi-Fi AP. However, due to the user movement, local overload situations may occur which prevent handover, leading to a lower throughput. This research studies LB in a hybrid Li-Fi/Wi-Fi network by taking into account user mobility and handover signalling overheads. Furthermore, a dynamic LB scheme is proposed, where the utility function considers system throughput and fairness. In order to better understand the handover effect on the LB, the service areas of different APs are studied, and the throughput of each AP by employing the proposed LB scheme is analyzed.
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dynamic load balancing with handover in hybrid li fi and wi fi networks
Personal Indoor and Mobile Radio Communications, 2014Co-Authors: Yunlu Wang, Stefan Videv, Harald HaasAbstract:In this paper, a hybrid network combining visible light communication (VLC) with a radio frequency (RF) wireless local area network (WLAN) is considered. In indoor scenarios, a light fidelity (Li-Fi) access point (AP) can provide very high throughput and satisfy any illumination demands while wireless fidelity (Wi-Fi) offers basic coverage. Such a hybrid network with both fixed and mobile users has the problem of variable user locations, and thus large fluctuations in spatially distributed traffic demand. Generally, a handover occurs in such a method when a user is allocated by the central controller unit to a different AP which is better placed to serve the user. In order to be representative of real deployments, this paper studies the problem of load balancing of a dynamic system where we consider the signalling overhead for handover. We propose a scheme for dynamic allocation of resources to users, where the utility function takes into account both throughput and fairness. The simulation results show that there is a trade off between the aggregate throughput and user fairness when handover overhead is considered. The proposed dynamic scheme always outperforms the considered benchmarks in terms of fairness and can achieve better aggregate throughput in the case of low user density.
Carlo Filice - One of the best experts on this subject based on the ideXlab platform.
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accuracy of real time shear wave elastography for assessing liver fibrosis in chronic hepatitis c a pilot study
Hepatology, 2012Co-Authors: Giovanna Ferraioli, Carmine Tinelli, Barbara Dal Bello, Mabel Zicchetti, G Filice, Carlo FiliceAbstract:Real-time shear wave elastography (SWE) is a novel, noninvasive method to assess liver fibrosis by measuring liver stiffness. This single-center study was conducted to assess the accuracy of SWE in patients with chronic hepatitis C (CHC), in comparison with transient elastography (TE), by using liver biopsy (LB) as the reference standard. Consecutive patients with CHC scheduled for LB by referring physicians were studied. One hundred and twenty-one patients met inclusion criteria. On the same day, real-time SWE using the ultrasound (US) system, Aixplorer (SuperSonic Imagine S.A., Aix-en-Provence, France), TE using FibroScan (Echosens, Paris, France), and US-assisted LB were consecutively performed. Fibrosis was staged according to the METAVIR scoring system. Analyses of receiver operating characteristic (ROC) curve were performed to calculate optimal area under the ROC curve (AUROC) for F0-F1 versus F2-F4, F0- F2 versus F3-F4, and F0-F3 versus F4 for both real-time SWE and TE. Liver stiffness values increased in parallel with degree of liver fibrosis, both with SWE and TE. AUROCs were 0.92 (95% confidence interval [CI]: 0.85-0.96) for SWE and 0.84 (95% CI: 0.76-0.90) for TE (P = 0.002), 0.98 (95% CI: 0.94-1.00) for SWE and 0.96 (95% CI: 0.90-0.99) for TE (P = 0.14), and 0.98 (95% CI: 0.93-1.00) for SWE and 0.96 (95% CI: 0.91-0.99) for TE (P = 0.48), when comparing F0-F1 versus F2- F4, F0- F2 versus F3-F4, and F0 -F3 versus F4, respectively. Conclusion: The results of this study show that real-time SWE is more accurate than TE in assessing significant fibrosis (≥F2). With respect to TE, SWE has the advantage of imaging liver stiffness in real time while guided by a B-mode image. Thus, the region of measurement can be guided with both anatomical and tissue stiffness information. (HEPATOLOGY 2012;56:2125–2133)
Giovanna Ferraioli - One of the best experts on this subject based on the ideXlab platform.
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accuracy of real time shear wave elastography for assessing liver fibrosis in chronic hepatitis c a pilot study
Hepatology, 2012Co-Authors: Giovanna Ferraioli, Carmine Tinelli, Barbara Dal Bello, Mabel Zicchetti, G Filice, Carlo FiliceAbstract:Real-time shear wave elastography (SWE) is a novel, noninvasive method to assess liver fibrosis by measuring liver stiffness. This single-center study was conducted to assess the accuracy of SWE in patients with chronic hepatitis C (CHC), in comparison with transient elastography (TE), by using liver biopsy (LB) as the reference standard. Consecutive patients with CHC scheduled for LB by referring physicians were studied. One hundred and twenty-one patients met inclusion criteria. On the same day, real-time SWE using the ultrasound (US) system, Aixplorer (SuperSonic Imagine S.A., Aix-en-Provence, France), TE using FibroScan (Echosens, Paris, France), and US-assisted LB were consecutively performed. Fibrosis was staged according to the METAVIR scoring system. Analyses of receiver operating characteristic (ROC) curve were performed to calculate optimal area under the ROC curve (AUROC) for F0-F1 versus F2-F4, F0- F2 versus F3-F4, and F0-F3 versus F4 for both real-time SWE and TE. Liver stiffness values increased in parallel with degree of liver fibrosis, both with SWE and TE. AUROCs were 0.92 (95% confidence interval [CI]: 0.85-0.96) for SWE and 0.84 (95% CI: 0.76-0.90) for TE (P = 0.002), 0.98 (95% CI: 0.94-1.00) for SWE and 0.96 (95% CI: 0.90-0.99) for TE (P = 0.14), and 0.98 (95% CI: 0.93-1.00) for SWE and 0.96 (95% CI: 0.91-0.99) for TE (P = 0.48), when comparing F0-F1 versus F2- F4, F0- F2 versus F3-F4, and F0 -F3 versus F4, respectively. Conclusion: The results of this study show that real-time SWE is more accurate than TE in assessing significant fibrosis (≥F2). With respect to TE, SWE has the advantage of imaging liver stiffness in real time while guided by a B-mode image. Thus, the region of measurement can be guided with both anatomical and tissue stiffness information. (HEPATOLOGY 2012;56:2125–2133)
Y C Wang - One of the best experts on this subject based on the ideXlab platform.
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Dynamic Load Balancing with Handover in Hybrid Li-Fi and Wi-Fi Networks
Journal of Lightwave Technology, 2015Co-Authors: Y C Wang, Yunlu Wang, Harald HaasAbstract:In this paper, a hybrid network combining light fidelity (Li-Fi) with a radio frequency (RF) wireless fidelity (Wi-Fi) network is considered. An additional tier of very small Li-Fi attocells which utilize the visible light spectrum, offers a significant increase in the wireless data throughput in an indoor environment, while at the same time providing room illumination. Importantly, there is no interference between Li-Fi and Wi-Fi. A Li-Fi attocell covers a significantly smaller area than a Wi-Fi access point (AP). This means that even with a moderate user movement a large number of handover between Li-Fi attocells can occur, and this compromises the system throughput. Dynamic load balancing (LB) can mitigate this issue so that the quasi-static users are served by Li-Fi attocells, while moving users are served by a Wi-Fi AP. However, due to the user movement, local overload situations may occur which prevent handover, leading to a lower throughput. This research studies LB in a hybrid Li-Fi/Wi-Fi network by taking into account user mobility and handover signalling overheads. Furthermore, a dynamic LB scheme is proposed, where the utility function considers system throughput and fairness. In order to better understand the handover effect on the LB, the service areas of different APs are studied, and the throughput of each AP by employing the proposed LB scheme is analyzed.
Barbara Dal Bello - One of the best experts on this subject based on the ideXlab platform.
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accuracy of real time shear wave elastography for assessing liver fibrosis in chronic hepatitis c a pilot study
Hepatology, 2012Co-Authors: Giovanna Ferraioli, Carmine Tinelli, Barbara Dal Bello, Mabel Zicchetti, G Filice, Carlo FiliceAbstract:Real-time shear wave elastography (SWE) is a novel, noninvasive method to assess liver fibrosis by measuring liver stiffness. This single-center study was conducted to assess the accuracy of SWE in patients with chronic hepatitis C (CHC), in comparison with transient elastography (TE), by using liver biopsy (LB) as the reference standard. Consecutive patients with CHC scheduled for LB by referring physicians were studied. One hundred and twenty-one patients met inclusion criteria. On the same day, real-time SWE using the ultrasound (US) system, Aixplorer (SuperSonic Imagine S.A., Aix-en-Provence, France), TE using FibroScan (Echosens, Paris, France), and US-assisted LB were consecutively performed. Fibrosis was staged according to the METAVIR scoring system. Analyses of receiver operating characteristic (ROC) curve were performed to calculate optimal area under the ROC curve (AUROC) for F0-F1 versus F2-F4, F0- F2 versus F3-F4, and F0-F3 versus F4 for both real-time SWE and TE. Liver stiffness values increased in parallel with degree of liver fibrosis, both with SWE and TE. AUROCs were 0.92 (95% confidence interval [CI]: 0.85-0.96) for SWE and 0.84 (95% CI: 0.76-0.90) for TE (P = 0.002), 0.98 (95% CI: 0.94-1.00) for SWE and 0.96 (95% CI: 0.90-0.99) for TE (P = 0.14), and 0.98 (95% CI: 0.93-1.00) for SWE and 0.96 (95% CI: 0.91-0.99) for TE (P = 0.48), when comparing F0-F1 versus F2- F4, F0- F2 versus F3-F4, and F0 -F3 versus F4, respectively. Conclusion: The results of this study show that real-time SWE is more accurate than TE in assessing significant fibrosis (≥F2). With respect to TE, SWE has the advantage of imaging liver stiffness in real time while guided by a B-mode image. Thus, the region of measurement can be guided with both anatomical and tissue stiffness information. (HEPATOLOGY 2012;56:2125–2133)
