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11th International conference on Informatics in Control, Automation and Robotics, ICINCO 2014

作者： Gómez, Arthur T. Nesi, Luan C. Martins, Marcio G. Chiwiacowsky, Leonardo D. Master Program on Applied Computing University of the Sinos Valley Av. Unisinos 950 São Leopoldo/RS Brazil

ISBN: (纸本)9789897580390

The advent of the digital television in Brazil has allowed users to access interactive channels. Once interactive channels are available, the users are able to find multimedia content such as movies and breaking news programs, to send and/or receive emails, to access interactive applications and also other contents. In this context, a high demand of requests from users is expected. Therefore, from the content provider's point of view, the determination of transmission parameters is needed in order to ensure the best quality of transmission to every user. The aforementioned identification problem is modelled as an optimization problem and a solution procedure based on metaheuristic techniques is proposed. Genetic Algorithm and Tabu Search metaheuristics are employed separately and coupled in a hybrid scheme to define the best transmission policy, optimizing the transmission parameters, such as audio and video transmission rates. Based on the experimental results, the hybrid algorithm has produced better solutions which meet the quality requirements.

关键词： Genetic algorithms

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Coding for Caching in 5G Networks

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IEEE COMMUNICATIONS MAGAZINE 2017年第2期55卷 106-113页

作者： Fadlallah, Yasser Tulino, Antonia M. Barone, Dario Vettigli, Giuseppe Llorca, Jaime Gorce, Jean-Marie INSA Lyon Lyon France Univ Sci & Arts Lebanon Beirut Lebanon Univ Naples Federico II Naples Italy Univ Naples Federico II Telecommun Engn Naples Italy Univ Naples Federico II Comp Sci Naples Italy Nokia Bell Labs Holmdel NJ USA Nokia Bell Labs Network Algorithms Grp Holmdel NJ USA

One of the major goals of the 5G technology roadrnap is to create disruptive innovation for the efficient use of the radio spectrum to enable rapid access to bandwidth-intensive multimedia services over wireless networks. The biggest challenge toward this goal lies in the difficulty in exploiting the multicast nature of the wireless channel in the presence of wireless users that rarely access the same content at the same time. Recently, the combined use of wireless edge caching and coded multicasting has been shown to be a promising approach to simultaneously serve multiple unicast demands via coded multicast transmissions, leading to order-of-magnitude bandwidth efficiency gains. I lowever, a crucial open question is how these theoretically proven throughput gains translate in the context of a practical implementation that accounts for all the required coding and protocol overheads. In this article, we first provide an overview of the emerging caching-aided coded multicast technique, including state-of-the-art schemes and their theoretical performance. We then focus on the most competitive scheme proposed to date and describe a fully working prototype implementation in CorteXlab, one of the few experimental facilities where wireless multiuser communication scenarios can be evaluated in a reproducible environment. We use our prototype implementation to evaluate the experimental performance of state-of-the-art caching-aided coded multicast schemes corn pared to state-of-the-art uncoded schemes, with special focus on the impact of coding computation and communication overhead on the overall bandwidth efficiency performance. Our experimental results show that coding overhead does not significantly affect the promising performance gains of coded multicasting in small-scale real world scenarios, practically validating its potential to become a key next generation CG technology.

关键词： 5G mobile communication Bandwidth Encoding Mobile computing Multicast communication Wireless communication

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Asymptotic performance of ML channel estimators in WCDMA systems: Randomized codes approach

Asymptotic performance of ML channel estimators in WCDMA sys...

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IEEE International conference on Acoustics, Speech, and Signal Processing

作者： Mestre, X Fonollosa, JR Univ Politecn Catalunya Dept Signal Theory & Commun ES-08034 Barcelona Spain

ISBN: (纸本)0780370414

This paper analyzes the asymptotic performance of Maximum Likelihood (ML) channel estimation algorithms in wideband code division multiple access (WCDMA) scenarios. We concentrate on systems with periodic spreading sequences (period larger than or equal to the symbol span) with high spreading factors, where the transmitted signal contains a code division multiplexed pilot for channel estimation purposes. Assuming randomized training and code sequences, we derive and compare the asymptotic covariances of the training-only (TO), semi-blind conditional ML (CML) and semi-blind Gaussian ML (GML) channel estimators.

关键词： Code division multiple access

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Understanding Performance of Edge Prefetching 23rd

Understanding Performance of Edge Prefetching

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23rd International conference on multimedia Modeling (MMM)

作者： Pang, Zhengyuan Sun, Lifeng Wang, Zhi Xie, Yuan Yang, Shiqiang Tsinghua Univ Dept Comp Sci & Technol Beijing Peoples R China Tsinghua Univ Grad Sch Shenzhen Beijing Peoples R China Indiana Univ Dept Comp Sci Bloomington IN 47405 USA

ISBN: (纸本)9783319518114;9783319518107

When using online services, the time that users wait for the requested content to be downloaded from online servers to local devices can significantly influence user experience. To reduce user waiting time, the content which are likely to be requested in the future can be predownloaded to the local cache on edge proxies (i.e. edge prefetching). This paper addresses the performance issues of prefetching at edge proxies (e.g. Wi-Fi access Points (APs), cellular base stations). We introduce an AP-based prefetching framework and study the impact of several factors on the benefit and the cost of this framework based on trace-driven simulation experiments. Useful insights which can be used to guide the design of prediction algorithms and edge prefetching systems are gained from our experimental results. First, increasing prediction window size of the prediction algorithms used by mobile applications can significantly reduce user waiting time. Second, the cache size is important to reducing user waiting time before a certain threshold. Third, the ratio of correct predictions to all actual requests (i.e. recall) can reduce user waiting time linearly while the ratio of correct predictions to all predictions (i.e. precision) will influence the traffic cost, so a trade-off should be made when designing a prediction algorithm.

关键词： Edge prefetching Wi-Fi access Point Performance Verification

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Logo identification algorithm for TV Internet

Logo identification algorithm for TV Internet

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Federated conference on Computer Science and Information systems (FedCSIS)

作者： Chodyka, Marta Mosorov, Volodymyr Pope John Paul II Univ Inst Comp Sci Biala Podlaska Poland Lodz Univ Technol Inst Appl Comp Sci Lodz Poland

ISBN: (纸本)9781467344715

content inappropriate for children on Internet television is a serious problem in today's multimedia world. There are numerous methods which are used to control the content of the transmitted television programmes. However, these well-known methods do not solve the above mentioned problem completely. The paper presents a more effective method for automatic identification of the provider's logo based on an original image sequence analysis. The automatic identification of the provider's logo can be used to block access to video programmes of the selected providers. The method has been tested on some chosen video transmissions on-line, achieving over 98% of correct identification.

关键词： Automatic identification Video transmission Web TV Television Television programs Videotapes Image sequence analysis Internets access original image Authentication

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Ethersim: A simulator for wireless and mobile networks

Ethersim: A simulator for wireless and mobile networks

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IEEE GLOBECOM 1996 - Communications: The Key to Global Prosperity

作者： Mishra, P Srivastava, M Agrawal, P Nguyen, G Univ of California at Berkeley Berkeley United States

ISBN: (纸本)0780333373

The paper describes Ethersim, a simulation tool to model and study the performance of integrated service networks that provide multimedia (audio, video, data) information access to mobile users carrying portable wireless terminals and hosts. The design process of such networks requires a proper understanding of how network and multimedia application performance is affected by (i) the choice of algorithms and protocols at various network layers, (ii) the wireless link characteristics, (iii) the presence of mobile hosts, and (iv) the host mobility patterns. Analytic approaches to study these problems suffer from intractability in such complex systems, while the inflexibility of making measurements on testbed systems makes it difficult to draw generalized conclusions. Simulation is an alternative, but available simulators provide poor support, many, for mobility and wireless. Ethersim has been built using a discrete event based simulator core and incorporates models of user applications and transport, network and MAC layer protocols. It provides the capability to specify network topology and host mobility patterns. The software architecture of Ethersim employs five special entities: an air module, a map, a mover, mobile hosts, and basestations. The air module models the physical air-interface effects (e.g., RF power decay, frequency collisions etc.). The mover is a central entity that moves the mobile hosts on the map. Ethersim allows for both random and goal-directed movements of mobile hosts, and also allows synchronized goal-directed movements to model conference room type mobility patterns. We also present case-studies of using Ethersim to model and study the interaction of transport layer, connection rerouting protocol, and radio characteristics in a mobile and wireless ATM network at Bell Laboratories.

关键词： Mobile radio systems

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Developing a comprehensive system for content-based retrieval of image and text data from a national survey

Developing a comprehensive system for content-based retrieva...

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Medical Imaging 2005 conference

作者： Antani, S Natarajan, M Long, JL Long, LR Thoma, GR NIH Lister Hill Natl Ctr Biomed Commun Natl Lib Med DHHS Bethesda MD 20894 USA

ISBN: (纸本)0819457221

The article describes the status of our ongoing R&D at the U.S. National Library of Medicine (NLM) towards the development of an advanced multimedia database biomedical information system that supports content-based image retrieval (CBIR). NLM maintains a collection of 17,000 digitized spinal X-rays along with text survey data from the Second National Health and Nutritional Examination Survey (NHANES ii). These data serve as a rich data source for epidemiologists and researchers of osteoarthritis and musculoskeletal diseases. It is currently possible to access these through text keyword queries using our Web-based Medical Information Retrieval System (WebMIRS). CBIR methods developed specifically for biomedical images could offer direct visual searching of these images by means of example image or user sketch. We are building a system which supports hybrid queries that have text and image-content components. R&D goals include developing algorithms for robust image segmentation for localizing and identifying relevant anatomy, labeling the segmented anatomy based on its pathology, developing suitable indexing and similarity matching methods for images and image features, and associating the survey text information for query and retrieval along with the image data. Some highlights of the system developed in MATLAB and Java are: use of a networked or local centralized database for text and image data;flexibility to incorporate new research work;provides a means to control access to system components under development;and use of XML for structured reporting. The article details the design, features, and algorithms in this third revision of this prototype system, CBIR3.

关键词： content-based image retrieval (CBIR) NHANES ii anterior osteophytes medical image databases medical image informatics image segmentation shape similarity procrustes distance Fourier descriptors polygon approximation

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A class of asymptotically optimum iterated-decision multiuser detectors

A class of asymptotically optimum iterated-decision multiuse...

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IEEE International conference on Acoustics, Speech, and Signal Processing

作者： Chan, AM Wornell, GW MIT Res Lab Elect Cambridge MA 02139 USA

ISBN: (纸本)0780370414

A promising class of nonlinear multiuser detectors is introduced for CDMA systems. These "iterated-decision" multiuser detectors use optimized multipass algorithms to successively cancel multiple-access interference (MAI) from received data and generate symbol decisions whose reliability increases monotonically with each iteration. They significantly outperform decorrelating detectors and linear minimum mean-square error (MMSE) multiuser detectors, but have the same order of computational complexity., When the ratio of the number of users to the spreading factor is below a certain threshold, iterated-decision multiuser detectors asymptotically achieve the performance of the "optimum" multiuser detector, i.e., maximum-likelihood (ML) decoding.

关键词： Code division multiple access

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content-based video retrieval via motion trajectories

Content-based video retrieval via motion trajectories

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Proceedings of the 1998 conference on Electronic Imaging and multimedia systems ii

作者： Shan, Man-Kwan Lee, Suh-Yin Natl Chiao Tung Univ HsinChu Taiwan

Motion is one of the most prominent features of video. For content-based video retrieval, motion trajectory is the intuitive specification of motion features. In this paper, approaches for video retrieval via single motion trajectory and multiple motion trajectories are addressed. For the retrieval via single motion trajectory, the trajectory is modeled as a sequence of segments and each segment is represented as the slope. Two quantitative similarity measures and corresponding algorithms based on the sequence similarity are presented. For the retrieval via multiple motion trajectories, the trajectories of the video are modeled as a sequence of symbolic pictures. Four quantitative similarity measures and algorithms, which are also based on the sequence similarity, are proposed. All the proposed algorithms are developed based on the dynamic programming approach.

关键词： Pattern matching

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Scalable Coding of 360-degree Video for Streaming Adaptation at 5G Network Edges 15

Scalable Coding of 360-degree Video for Streaming Adaptation...

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15th IEEE International Symposium on Broadband multimedia systems and Broadcasting (BMSB)

作者： Carreira, J. de Faria, Sergio M. M. Tavora, Luis M. N. Navarro, Antonio Assuncao, Pedro A. A. Inst Telecomunicacoes Lisbon Portugal Polytech Leiria ESTG Leiria Portugal Univ Aveiro Aveiro Portugal

ISBN: (纸本)9781728157849

YY The huge amount of data that is necessary to capture the full field-of-view (FoV) in omnidirectional video, i.e., 360 degrees, imposes the use of highly efficient compressed formats as well as adaptive broadcast and streaming mechanisms, such as those foreseen for 5G networks. To cope with the demanding requirements of 360 degrees video streaming over 5G networks, this work proposes a scalable 360 degrees video coding architecture, by enabling adaptation through the Multi-access Edge Computing (MEC) server in two different domains of the spherical visual content, namely spatial resolution and FoV. In the proposed architecture two-layers are encoded from the input 360 degrees video content: (i) the base-layer (BL), encoding each 360 degrees image as a whole, at a lower spatial resolution;(ii) the enhancement-layer (EL) encoding each spherical image as a set of multiple FoVs with higher spatial resolution. Such arrangement enables flexible stream adaptation for the smart decision algorithms to be implemented at the MEC server, enabling significant reduction of the overall bit rate through the radio interface. The simulation results show that the proposed scalable coding scheme allows a great deal of bit rate savings across the 5G network, achieving 36% of bit rate saving, on average, for a 90 degrees FoV in comparison with conventional single-layer coding.

关键词： Scalable video coding & content adaptation Future broadcasting services

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