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Telecommunications (CONATEL), 2011 2nd National Conference on

Date 17-20 May 2011

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Displaying Results 1 - 25 of 29
  • [Title page]

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  • [Copyright notice]

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  • Foreword

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  • Program committee

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    Provides a listing of current committee members. View full abstract»

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  • Subject index

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  • Reviewers and referee listings

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  • Executive Committee

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  • Sponsors

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  • 2-STCg optical multicast traffic grooming node for the fishbone-like Peruvian WDM core network

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (441 KB) |  | HTML iconHTML  

    In some developing countries, like Peru, optical transport networks are not widely deployed, mainly because of economical factors and geographical difficulties. Its topology has a fishbone-like structure, and it may not need powerful all-optical multicast nodes in order to attend multicast demands. Also, traffic demands may not occupy all the wavelength capacities, which make traffic grooming a necessary capability for saving bandwidth. In the present work we propose an optical node capable of performing multicast routing tasks at traffic grooming level. The node's architecture has been based on two previous works: the 2-Split-Tap-and-Continue (2-STC) node (a multicast capable node with a simple structure, constrained to binary-splitting, but efficient regarding the use of power levels and the number of elements used), and the Stop-and-Go (S/G) Light Tree node (a multicast grooming capable node that uses a labeling technique based on FSK modulation, allowing multicast requests to be routed at the optical level). In this sense, the proposed node improves the use of the optical power, waste of bandwidth and delay, taking advantage of the physical distribution presented in this particular fishbone-like network. Several simulations have been done and results show these assessments. View full abstract»

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  • A framework for simulation and evaluation of cross-layer techniques in wireless sensor networks

    Page(s): 1 - 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1015 KB) |  | HTML iconHTML  

    Cross-Layer design is a new technique which can be used to improve the performance in wireless sensor networks under the severe restrictions of the energy consumption. Cross-layer techniques intended to create an optimization of the limited resources, taking into account factors associated with different layers of traditional communication schemes, opening a new way for the development of complex communications mechanism. However, because these techniques are based on a non-standard architecture, its structure has a lot of dissimilar characteristics that obstruct a comprehensive comparison of its performance. In this paper, we propose a framework for simulation and evaluation of cross-layer techniques in wireless sensor networks. Our framework promotes a fairness comparison of different communication schemes, a realistic model simulation, an experiment design and a rigorous analysis of results with ANOVA (Analysis of Variance) technique. As a case study, we test our comparative simulation framework with to two popular cross-layer schemes showing the facility of use and the result of the analysis of the data. View full abstract»

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  • A novel fuzzy logic-based metric for audio quality assessment: Objective audio quality assessment

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (515 KB) |  | HTML iconHTML  

    ITU-R BS.1387 states a method for objective assessment of perceived audio quality. This Recommendation, known also as PEAQ (Perceptual Evaluation of Audio Quality) is based on a psychoacoustic model of the human ear and was standardized by the International Telecommunications Union as an alternative to subjective tests, which are expensive and time-consuming processes. PEAQ combines various physiological and psycho-acoustical properties of the human ear to give a measure of the quality difference between a reference audio and a test audio. The reference audio signal could be considered as a distortion-free source, whereas the test signal is a distorted version of the reference, which may have audible artifacts because of compression. The algorithm computes the Model Output Variables (MOVs) which are mapped to a single quality measure, Objective Difference Grade (ODG), using a three-layer perceptron artificial neural network. The ODG estimates the perceived distortion between both audio signals. In this paper we propose a new metric of low computational complexity called FQI (Fuzzy Quality Index) which is based on Fuzzy Logic reasoning and has been incorporated into the existing PEAQ model to improve its overall performance. Results show that the modified version slightly outperforms PEAQ. View full abstract»

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  • An evaluation of power line communication channel modelling for indoor environment application

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (340 KB) |  | HTML iconHTML  

    Nowadays, Power Line Communication is becoming an attractive solution to deliver broadband services to indoor and outdoor environment because this technology allows the use of the existing infrastructure. The knowledge of the channel characteristics is very important. A perfect real multipath model is very difficult to be found out because depends on cable models and topology but an accuracy approach is fundamental to evaluate the power line communication by the transfer function. Multi conductor Transmission line theory is an accurate tool to model the transfer function of the channel using complex circuit level models that can be represented in terms of cascaded two-port network. Then it is possible to compute a priori and in a deterministic fashion a transfer function of the PLC channel. This paper is based on the chain matrix method and shows the indoor PLC evaluation with regard to network load impedances, branched line length and number of branches. View full abstract»

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  • Analysis of Phase-Shift DFB lasers using the dynamic transfer-matrix-method

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (393 KB) |  | HTML iconHTML  

    A time domain model based on matricial techniques is used to study the large-signal dynamics in an asymmetric three Phase-Shift DFB laser structure, which has been optimized in a previous work of the authors near threshold and been referred as being potentially stable for single longitudinal mode operation in the high power regime. These models, generally designated as dynamic transfer-matrix models, are very flexible and are indispensable for a proper evaluation of the device performance. View full abstract»

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  • BiSpectral contactless hand based biometric system

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (699 KB) |  | HTML iconHTML  

    This paper presents a contactless hand based biometric identification system using geometric and palm features. Hand images are acquired using two commercial webcams with 1200×1600 pixel resolution which are referred to as the “IR” and “visible” webcams. The IR webcam has been modified by exchanging the IR filter with a visible filter lens and reducing the gain and exposure time to improve the hand contour extraction. The hand was illuminated using 24 infra-red LEDs and 4 white light LEDs. Images acquired from the IR webcam were binarized and the normalized widths from the index to little finger were used as features. A Least Square Support Vector Machine was then used for verification. The palm features were obtained by the Orthogonal Line Ordinal Features approach applied to the image acquired by the visible webcam. The hand image from the visible webcam was segmented using an Active Shape Model guided by the hand contour from the IR webcam as an initial guest. A Hamming distance was used as verifier. More than 8000 hand images from three public databases were used in order to compare the features extraction approaches. A score level fusion of both biometrics is performed obtaining an Equal Error Rate of 0.17% with a proprietary database of 100 users acquired with the proposed device. View full abstract»

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  • Coverage and service testing of Terrestrial television systems: Practical aspects

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (211 KB) |  | HTML iconHTML  

    Evaluation of coverage and service of television systems requires the application of normalized procedures in order to compare data obtained in different measurement campaigns. There is a large quantity of documentation about general aspects of these processes, which is useful in the stage of planning. This is not the case when detailed aspects like the correct configuration of the measuring equipment or processing of collected data are required. This document pretends to provide some practical information about testing of coverage and service of analog and digital television transmitter systems. View full abstract»

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  • Design considerations for implant — On-body UWB communication for medical applications

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (156 KB) |  | HTML iconHTML  

    In this paper, we analyze the current issues for designing a communications system among implant and on-body nodes employing ultra wideband (UWB) technology. As a result, we propose a modulation scheme ad-hoc for this environment that besides being suitable for this propagation channel, it allows to employ antenna diversity on the on-body nodes. Antenna diversity permits to improve signal to noise ratio and avoid using transmission diversity, which limits the exposition of human tissue to electromagnetic radiation. View full abstract»

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  • Design of a compact diplexer for multisystem DAS solutions

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (353 KB) |  | HTML iconHTML  

    This paper presents a microstrip diplexer for multisystem Distributed Antenna System (DAS) solutions, namely for DCS and UMTS systems. A low-pass quasi-elliptic filter with a stub-like structure is used for the 1800 MHz band while a band-pass Chebychev filter with a hairpin line structure is employed for the 2150 MHz band. Both filters are connected to the common port through a T junction. The diplexer layout has been optimized in order to ensure compactness. Good agreement between simulated and measured results has been obtained. The diplexer shows excellent performance in terms of high isolation and low insertion loss. A semi-lumped element model of the diplexer is also presented. View full abstract»

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  • FR-4 microstrip transmission lines behavior in high frequency range

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (750 KB) |  | HTML iconHTML  

    The consequences of the current electronic equipment market demands is causing designers to develop ever faster circuits in ever smaller devices. The miniaturization of circuits together with increased operating speeds shows several functional difficulties, which require skills and knowledge of the designer so that the final product fits into operation standards and can be produced. The objectives of this research are to address the adverse effects on the operation of electronic equipment, demystifying the network of influences present when a circuit is in operation and find methodologies to identify and reduce critical problems on these devices. The study was done on hypothetical printed circuit boards, created specifically to simulate and demonstrate the desired effects. Although hypothetical, part of its settings can be found in commercially produced plates. The results were obtained through numerical models, computational simulations and measurements in physical prototypes. Through these, it was possible to identify critical topologies, asymmetries to be avoided and develop methodologies to avoid adverse problems. Another important point was the validation of theories and the comparison of the results measured in physical prototypes with the results originated by simulation and numerical modeling in order to trace its fidelity with real models. View full abstract»

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  • Internet-based collaborative E-exercisebook system for primary math teaching

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (514 KB) |  | HTML iconHTML  

    The academic performance and social competence of a child in school is positively associated with the involvement of their parents. However, the researches about educational learning models often ignore the parents' part. Internet opens a new paradigm: education and communication approach is more complex than ever. Here, we would like to present an Internet based system to support students' homework. We believe that one of the major advantages of our system is time saving, particularly from the teacher's point of view. Also, this system gathers statistical data concerning different groups of students selected by the teacher. From these data on, the teacher can easily see where the students are having problems and decide what to do next. From the student (or parent) point of view, the prompt feedback about the exercises correctness, added to the training with different exercises sets about the same subject, besides the utilization of video, color, sound, etc., that positively reinforce child's senses, are elected as the main advantages. View full abstract»

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  • Low-complexity motion-based saliency map estimation for perceptual video coding

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (993 KB) |  | HTML iconHTML  

    In this paper, a low-complexity motion-based saliency map estimation method for perceptual video coding is proposed. The method employs a camera motion compensated vector map computed by means of a hierarchical motion estimation (HME) procedure and a Restricted Affine Transformation (RAT)-based modeling of the camera motion. To allow for a computationally efficient solution, the number of layers of the HME has been restricted and the potential unreliable motion vectors due to homogeneous regions have been detected and specially managed by means of a smooth block detector. Special care has been taken of the smoothness of the resulting compensated camera motion vector map to avoid unpleasant artifacts in the perceptually-coded sequence, by including a final post-processing based on morphological filtering. The proposed saliency map has been both visually and subjectively assessed showing quality improvements when used as a part of the H.264/AVC standard codec at medium-to-low bitrates. View full abstract»

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  • Off-line signature verification using local patterns

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (387 KB) |  | HTML iconHTML  

    Recently, several papers have proposed pseudo dynamic methods for automatic handwritten signature verification. Each of these papers uses texture measures of the gray level signature strokes. This paper explores the usefulness of local binary pattern (LBP) and local directional pattern (LDP) texture measures to discriminate off-line signatures. A comparison between several texture normalizations is made so as to look for reducing pen dependence. The experiments conducted with MCYT off-line and GPDS960Graysignature corpuses show that LDPs are more useful than LBPs for automatic verification of static signatures. Additionally, the results show that the LDP codes of the contour are more discriminating than the LDPs of the stroke interior, although their combination at score level improves the overall scheme performance. The results are obtained by modeling the signatures with a Support Vector Machine (SVM) trained with genuine samples and random forgeries, while random and simulated forgeries have been used for testing it. View full abstract»

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  • On the optimal Lagrangian parameter for motion estimation: A low-cost and effective method for improving video coding performance

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (330 KB) |  | HTML iconHTML  

    The most recent video coding standards are usually based on a rate-distortion optimization (RDO) process that has been formulated in terms of an unconstrained Lagrangian optimization. The RDO provides outstanding results in exchange for a high computational cost, especially for the Inter frames, which require a computationally heavy motion estimation (ME) process. In particular, for H.264/AVC, this RDO process allows selecting both the MB partition size and the motion vector. However, as the optimum procedure is not feasible for computational reasons, the ME process uses a simplified rate-distortion (RD) cost function. Therefore, two RDO processes are involved, one for selecting the MB partition size and one for ME. Both RDO processes rely on an Lagrangian formulation and, for practical purposes, the corresponding Lagrangian parameters are related by a simple, experimentally obtained relationship. In this paper, some evidences of the weaknesses of such a relationship between the two Lagrangian parameters are given and a simple effective procedure to improve the R-D encoding performance is proposed according to such weaknesses. The proposed method has been comparatively evaluated with respect to one recently published method, showing significant average performance improvements, above 0.4 dB in terms of PSNR. View full abstract»

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  • Patch antennas for BAN/PAN applications at 2.45 GHz: A preliminary approach

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (861 KB) |  | HTML iconHTML  

    A preliminary approach for the analysis and design of patch antennas located over biological tissues is presented. The study is performed in the 2.4 GHz ISM band envisaging body area and personal area network applications. A moment method numerical analysis is used to check the effects of the biological tissues on the patch antenna performance. Both single patches and two element arrays are analyzed. The conclusions obtained can be used as guidelines to conduct a more accurate approach where the complete model of the human body (shape and size) is taken into account. View full abstract»

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  • Performance analysis of modulation formats for 40 Gb/s optical transmission

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1073 KB) |  | HTML iconHTML  

    In this paper different optical modulation formats at 40 Gb/s are theoretically evaluated under three transmission constraints: spectral narrowing due to filter cascading, chromatic dispersion and self-phase modulation. After a cost estimation for each format, multi-line rates and/or multiple format schemes for optical network capacity upgrade are proposed. View full abstract»

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  • Probabilistic description of the NGOSS Change Management process

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (342 KB) |  | HTML iconHTML  

    It is necessary for any telecommunication provider to introduce new products or changes of existing products as quickly and as often as possible. It helps them to stay ahead of competition. To achieve that they have to have an effective and efficient inner business processes. Almost every conscious company measure, assess and adjust its processes. This paper describes the Change Management process within New Generation Operation Support System (NGOSS) of one Czech telecommunication service provider. View full abstract»

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