204 research outputs found

    Modeling and Analysis of MPTCP Proxy-based LTE-WLAN Path Aggregation

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    Long Term Evolution (LTE)-Wireless Local Area Network (WLAN) Path Aggregation (LWPA) based on Multi-path Transmission Control Protocol (MPTCP) has been under standardization procedure as a promising and cost-efficient solution to boost Downlink (DL) data rate and handle the rapidly increasing data traffic. This paper aims at providing tractable analysis for the DL performance evaluation of large-scale LWPA networks with the help of tools from stochastic geometry. We consider a simple yet practical model to determine under which conditions a native WLAN Access Point (AP) will work under LWPA mode to help increasing the received data rate. Using stochastic spatial models for the distribution of WLAN APs and LTE Base Stations (BSs), we analyze the density of active LWPA-mode WiFi APs in the considered network model, which further leads to closed-form expressions on the DL data rate and area spectral efficiency (ASE) improvement. Our numerical results illustrate the impact of different network parameters on the performance of LWPA networks, which can be useful for further performance optimization.Comment: IEEE GLOBECOM 201

    Multi-Stage Transfer Learning System with Light-weight Architectures in Medical Image Classification

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    Transfer Learning methods are extensively applied with standard CNN architectures for various medical diagnoses. However, these architectures are computationally expensive, tend to be over parameterized, and requires a relatively large labeled datasets which are often not available in the medical image domain. Accordingly, this paper proposes a Multi-Stage Transfer Learning System using lightweight architectures to address problems with limited data and to improve training time. Preliminary results suggest that our model performed well on CT Head images over traditional single-stage transfer learning

    Consistent Video Filtering for Camera Arrays

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    International audienceVisual formats have advanced beyond single-view images and videos: 3D movies are commonplace, researchers have developed multi-view navigation systems, and VR is helping to push light field cameras to mass market. However, editing tools for these media are still nascent, and even simple filtering operations like color correction or stylization are problematic: naively applying image filters per frame or per view rarely produces satisfying results due to time and space inconsistencies. Our method preserves and stabilizes filter effects while being agnostic to the inner working of the filter. It captures filter effects in the gradient domain, then uses \emph{input} frame gradients as a reference to impose temporal and spatial consistency. Our least-squares formulation adds minimal overhead compared to naive data processing. Further, when filter cost is high, we introduce a filter transfer strategy that reduces the number of per-frame filtering computations by an order of magnitude, with only a small reduction in visual quality. We demonstrate our algorithm on several camera array formats including stereo videos, light fields, and wide baselines

    FLEXNET: Flexible Networks for IoT based services

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    Internet of Things is becoming one of the main triggers in designing and deploying new services aiming at fulfilling the wide demand imposed by end-users. Usually, concrete solutions addressing the optimization of the wireless segment are found in the literature. However, it is much less frequent to find end-to-end solutions to be easily adopted by the corresponding stakeholders. It is in this context that FLEXNET brings an integrated solution, relying on cutting-edge technologies, dealing with a wide set of technical requirements imposed by the different applications and services.This work was supported by FLEXNET Project: "Flexible IoT Networks for Value Creators" (Celtic 2016/3), in the Eureka Celtic-Next Cluster

    Performance Optimization and FPGA Implementation of Real-Time Tone Mapping

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    This brief analyzes the performance of the hardware-based tone mapping operators for compression of high dynamic range images. The bottlenecks of a tone mapping system are determined and a high-performance field programmable gate array (FPGA) implementation of an operator is introduced. The operator utilizes polynomial mapping technique, adaptive to the pixel values; hence preserving high contrast areas. The technique is further optimized for the presented resource-efficient FPGA implementation. We show that the timing optimization does not reduce the image quality, by obtaining high peak signal-to-noise ratio of the resulting images. The timing comparison to the similar implementations shows 2.5 times increase in the achieved throughput, irrespective of the hardware platform

    Study of mm-wave Fixed Beam and Frequency Beam-Scanning Antenna Arrays

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    Millimeter-wave frequencies are anticipated to be widely adapted for future wireless communication systems to resolve the demand of high data-rate and capacity issues. The millimeter-wave frequency range offers wide spectrum and a shift for most newly developing technologies as the microwave and lower frequency bands are becoming overcrowded and congested. These high frequency bands offer short wavelengths which has enabled the researchers to design and implement compact and adaptable antenna solutions. This research focuses on the implementation, transformation and modification of antenna structures used in lower frequency bands to millimeter-wave applications with high gain and multi-band and wideband performances. The first part of the thesis presents a microstrip patch array antenna with high gain in the upper 26 GHz range for 5G applications. The tolerance of the antenna, on widely used Rogers RT/duroid 5880 substrate, is observed with the edge-fed structure when curved in both concave and convex directions. In the second part of the thesis, 20 rectangular loops are arranged in a quasi-rhombic shaped planar microstrip grid array antenna configuration with dual-band millimeter-wave performance. A comparison with equal sized microstrip patch array is also presented to analyse the performance. The antenna operates in the upper 26 GHz band and has two frequency bands in close proximity. The third part of the thesis discusses the transition from wire Bruce array antenna to planar technology. Having been around for nearly a century and despite the simplicity of structure, the research community has not extended the concept of Bruce array antenna for further research. The proposed planar Bruce array antenna operates in three frequency v bands with optimization focus on 28.0 GHz band that has a directive fan-beam radiation pattern at broadside whereas the other two frequency ranges, above 30 GHz, have dual-beam radiation patterns which provide radiation diversity in narrow passages. The final part of the thesis deals with the transformation and modification of wire Bruce array antenna geometry to edge-fed printed leaky-wave antennas for millimeter-wave frequency scanning applications. In the first approach, the lengths of the unit-cell are optimised, without any additional circuitry, to enable two scanning ranges and mitigate the Open-Stopband, at broadside, for seamless scanning in the first range. A Klopfen-stein tapered divider is then deployed to make a linear array of the proposed antenna to achieve high gain. In the second approach, the horizontal and vertical lengths of the meandered unit-cell are replaced with semi-circular and novel bowtie elements, respectively, to obtain wide scanning range. The numerical results and optimizations have been performed using CST Micro-wave Studio where the effects of metallization and dielectric losses are properly consid-ered. The prototypes of the proposed antennas have been fabricated and experimentally validated

    Radio-over-fiber-supported 60GHz multiuser transmission using leaky wave antenna

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    Simultaneous transmission to multiple users using a single-feed leaky-wave antenna (LWA) has been demonstrated. A composite signal transported through a Radio-over-Fibre (RoF) setup is upconverted to V-band frequencies and a LWA is used to direct different user data to their respective locations. An EVM analysis has been performed for two-user and three-user transmission for a range of angular locations. A performance analysis for user interference has been carried out by varying the signal spacing for 152 MHz and 305 MHz bandwidth OFDM signals, centered at 61.75 GHz after 4m of wireless transmission. The experimental results show degradation not only due to insufficient frequency spacing between the channels but also when the sidelobe interference of the neighboring data channels is higher

    Public Field Trial of a Multi-RAT (60 GHz 5G/LTE/WiFi) Mobile Network

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    A public field trial showcasing an operational multi-Radio Access Technology (RAT) mobile network that was implemented in one of the largest shopping mall in Warsaw, Poland. The network supports novel 60 GHz 5G mobile access as well as legacy LTE and WiFi services All mobile access services of the network are interconnected via optical fiber to the data centers of a mobile network operator and an internet service provider. Fronthauling for the 60 GHz 5G hotspot radio access unit (RAU) and for LTE is realized by analog Radio-over-Fiber (RoF) via a fiber-optic distributed antenna system (DAS). The 60 GHz 5G radio access units (RAUs) for the enhanced mobile broadband (eMBB) use case and the WiFi access point (AP) are both backhauled via optical Gigabit Ethernet. The 60 GHz RAUs for the eMBB and hotspot use case feature 2D beam-switching and 1D beam-steering, respectively. Inter-RAT switching between the different mobile services with seamless user experience is achieved using a Mobile IP system with Fast Initial Link Setup (FILS)

    Techno-economic analysis of a 5G network in Spain

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    Information society and mobile society are two concepts that are both linked and undeniable. The first one refers to the necessity of high amount of information to develop most aspects of our lives, while the second one is related to the importance of mobile devices to get, analyse and use that information. In other words, every mobile device (that embraces not only mobile phones but also many other gadgets) has become a tool that shall interact with information. In order to fulfil those needs, technology has evolved, resulting into faster, more secure and more reliable networks. Needless to say, mobile networks are playing an indispensable role, as long as the society is evolving to a more and more mobile one, as above mentioned. Furthermore, new applications that had not been even imagined years ago must be fulfilled as well (i.e. smart cities). There are many industries that carry the weight of this progress. Companies of various sectors of our economy must develop each piece of the puzzle to ensure that the jigsaw is solved. Another important player should not be forgotten. The regulatory institutions and frameworks must coordinate all this investigations and progress in order to assure the universality, integrity and reachability of itself. The purpose of this document is to consider what the mobile communications needs of today’s society are, what they will be on a short, mid and long run, and how can they be solved. To face this task, the two main actors above mentioned will be taken into account. From the regulatory perspective, the proposals and law measures (i.e. IMT-2020 and new frequency allocations) must be considered, as well as the technical requirements for 5G generation, whether to be considered the subsequent evolution of LTE network or a new network, or even both. From the mobile companies’ point of view, a dense analysis on technical solutions to reach the above mentioned requirements will be followed by an economic analysis to discuss the profitability of the deployment of a 5G network. It must be understood that this study contemplates several scenarios, due to the different possibilities in terms of the spectrum policies and demand evolution in the forthcoming years. To this end, the several scenarios combined with the different cases of use must be taken into account, as well as many other KPIs. The coherent combination and analysis of all this parameters will reveal the requirements’ feasibility amongst varying scenarios.Ingeniería en Tecnologías de Telecomunicació

    Analysing Interface Bonding in 5G WLANs

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