bluuebunny/crossref_metadata_2025_split huggingface dataset:
Defining Quantiles for Estimating IP Packet Delay Variation in NGN Core Networks
Authors: Lam Dao Ngoc , Thang Le Nhat , Lap Le Huu 
Published: May 2016

Traffic delay is one of the important metrics used for evaluating network performance. Delay and delay variation characteristics of IP packets transferred over multi-section networks can be derived, estimated or composed from component distributions of IP package delay in each network section. Approximate methods are needed in the cases of unknown or complicated delay distribution functions, which are unavailable or unusable in practice. The ITU-T has proposed a method for estimating IP packet delay variation. One of noticeable factors affecting the estimation accuracy is the packet delay population quantile which has not been adequately considered. The objective of this paper is to examine the optimal range of quantiles used for estimating the IP packet delay variation in the NGN (Next Generation Network) core networks. The paper is composed from the following ideas. Firstly, several concepts and mathematical formulas related to delay metrics based on probability and statistics theory are defined. The approximate method of ITU-T for estimating the IP packet delay variation in a multi-section network is revised. Then, another method based on convolution for composing the empirical IPTD distribution functions is proposed for the same target as the first one. Secondly, a number of test cases are implemented to measure the IP packet delay on several sections of an NGN core network. Sample data are used for computing and estimating the IP packet delay variation for multi-section networks by two methods with certain hypotheses. Finally, these methods are compared and evaluated both theoretically and empirically in regards to the estimation accuracy versus quantiles of the IP packet transfer delay. The best range of quantiles is determined to ensure the accuracy of the estimation method applied for the NGN core network.
Multihop Decode-and-Forward Relay Networks: Secrecy Analysis and Relay Position Optimization
Authors: Bao Vo Nguyen Quoc , Linh-Trung Nguyen 
Published: May 2016

Relay communication has advantages over direct transmission in terms of secrecy capacity. In this paper, the performance of secrecy, offered by multihop decode-and-forward relaying, is investigated and compared to its counterpart in direct transmission. Three key performance measures are derived over Rayleigh fading channels: probability of non-zero secrecy capacity, secure outage probability and secrecy capacity, which are valid for an arbitrary number of hops. Based on the tractable form of the probability of non-zero secrecy capacity, the optimization problem of trusty relay replacement is also studied. Numerical results indicate that a proper relay replacement can increase the network security without extra network resources. The correctness of analytical results is confirmed by using a MATLAB-based independent simulation model.
Joint Optimization of Precoder and Decoder in Multiuser MIMO Systems
Authors: Raja M. , Nguyen Ha H. , Muthuchidambaranathan P. 
Published: May 2016

This paper considers the joint optimization of precoder and decoder for both uplink and downlink transmissions in multiuser multiple-input, multiple-output (MU-MIMO) systems. Focusing on the scenario when an improper constellation such as binary phase shift-keying (BPSK) or M-ary amplitude shift-keying (M-ASK) is employed, novel joint linear precoders and decoders are proposed to minimize the total mean squared error (TMSE) of the symbol estimation. The superiority of the proposed transceivers over the previously-proposed designs is thoroughly verified by simulation results.
Forecasting the Bandwidth of Digital Links to the Internet
Authors: Bludov Dimitry , Golovko Vitaly , Simonov Mikhail , Vikhlyantsev Peter 
Published: May 2016

In this paper, we propose a new efficient technique for forecasting the bandwidth of digital access links to the Internet. This technique can be used for calculating the throughput of access links in implementing electronic document management systems and in organizing information portals. The main idea is to estimate the bandwidth of digital access links to the Internet using the statistics of the service load. The main result is the derivation of analytical expressions to estimate the required bandwidth.
Modified Tapered Slot-line Antennas for Special Applications
Authors: Zhang Wen-Xun 
Published: May 2016

Tapered slot-line antenna (TSA) is a well known printed end-fire antenna with traveling-wave feature. In order to further improve its performances and extend its functions, several techniques with patents were developed in SEU, and summarized in this article. Here include: grating-loaded TSA for gain enhancement, CPW back-fed TSA for broadening impedance bandwidth, asymmetric TSA structure for beam shaping and optimization, coupled TSA with hybrid network for monopulse beam forming. Both conceptual illumination and simulated/measured results are described.
A New Approach and Tool in Verifying Asynchronous Circuits
Authors: Nguyen Tin T. , Le-Huu Khoi-Nguyen , Bui Thang H. , Dinh-Duc Anh-Vu 
Published: May 2016

Research in asynchronous circuit approach has been carried out recently when asynchronous circuits are presented more widely in electronic systems. As they are more important in human life, their correctness should be considered carefully. Although there are some EDA tools for design and synthesis of asynchronous circuits, they are lack of methods for verifying the correctness of the produced circuits. In this work, we are about to propose a verification method and apply it in making a new version of the PAiD tool that can enable engineers to design, synthesize and verify asynchronous circuits. Experiments in verifying circuits have been also provided in this work.
Opportunistic Unsynchronized Cognitive Radio Networks
Authors: Bellanger Maurice 
Published: May 2016

The challenge of opportunistic networks is to maximize the usage of the spectrum by offering quick and easy access to independent systems and their users. A physical layer able to operate efficiently in an unsynchronized environment is needed and it is shown that the filter bank multicarrier (FBMC) technique can meet the objectives in terms of performance and flexibility. Then, a protocol must be developed to ensure global convergence and an overall transmission capacity close to the optimal possible value at a given place and a given time. An approach called “good neighbour” is presented, which consists of building the capacity requested by the users through a threshold regulated local search and with minimum changes in frequency band allocation to reduce interference non-stationarity to other systems. Finally, potential applications of opportunistic networks are reviewed and the conditions for proliferation of this kind of network are discussed.
Performance Analysis of AntNet-LA Protocol for Ad-hoc Networks based on Disaster Area Mobility Model
Authors: Godbole Vaibhav 
Published: May 2016

Availability of cheap positioning instruments like GPS receivers makes it possible for routing algorithms to use the position of nodes in an ad hoc mobile network. Regular position based routing algorithms fail to find a route from a source to a destination in some cases when the network contains nodes with irregular transmission ranges or they find a route that is much longer than the shortest path. On the other hand routing algorithms based on Ant Colony Optimization (ACO) find routing paths that are close to the shortest paths even if the nodes in the network have different transmission ranges. The drawback of these algorithms is the large number of messages that needs to be sent or the long delay before the routes are established. In this paper, we propose a novel protocol AntNet-LA which combines the idea of ACO with information about position of all nodes. In this technique the distance between the nodes is considered to transmit the packets, hence overcomes the drawbacks of AntNet algorithm which considers only cumulative probability for packet transmission. We compare performance of AntNet-LA with AntNet, Ad-hoc On Demand Distance Vector (AODV), Ad-hoc On Demand Multipath Distance Vector (AOMDV), Dynamic Source Routing (DSR) and Destination-Sequenced Distance-Vector Routing (DSDV) protocols. We also compare performance of AntNet-LA with distance-aware protocols such as Location Aided Routing (LAR), Geographical AODV GeoAODV and Position Based ANT colony optimization (PBANT).
A New High Performance Decoder for LDPC Codes
Authors: Hung Nguyen Tung , Duan Nguyen Van 
Published: May 2016

The article introduces a new decoder for LDPC codes based on the general check matrix and soft syndrome. Simulation result shows that the new decoder can improve the performance of LDPC codes. Compared with some other improvements, the new decoding algorithm is simpler, and it can detect errors and be applied to great length LDPC codes.
Geographic-based Routing in Smart Grid’s Neighbor Area Networks
Authors: Ho Quang-Dung , Rajalingham Gowdemy , Le-Ngoc Tho 
Published: May 2016

Neighbor area network (NAN), also known as smart meter communication network, is one of the most important segments of smart grid communications network (SGCN). This paper studies the performance of greedy perimeter stateless routing (GPSR), a representative implementation of geographic-based routing class, in the NAN scenario and investigates the feasibility of this routing protocol in supporting SG applications. Specifically, packet transmission delay and reliability of GPSR in an IEEE 802.15.4-based wireless mesh NAN with practical system parameters are measured by simulations. The results show that, at the data rate required for conventional SG applications including smart metering, real-time pricing and demand response, the delay can always be maintained below 70 ms (in 95th-percentile perspective) while packet delivery ratio is higher than 90%. However, due to that fact that more advanced applications that require information exchange at higher rates and more stringent delays are emerging in SG, the performance of GPSR in NAN scenarios using radio technologies that can support higher loads and/or larger network scales needs to be studied.
Multi-level Scalable Textual-Graphical Password Authentication Scheme for Web based Applications
Authors: Behl Umedha , Bhat Divya , Ubhaykar Neha , Godbole Vaibhav , Kulkarni Saurabh 
Published: May 2016

Nowadays, user authentication is one of the important topics in information security. Authentication is necessary in multi-user systems. User name and password are used to authenticate a user. Text-based strong password scheme can provide security to a certain degree. Users tend to pick short passwords or passwords that are easy to remember, which makes the passwords vulnerable for attackers to break. Furthermore, textual password is vulnerable to shoulder-surfing, hidden camera and spy-ware attacks. Graphical authentication has been proposed as a possible alternative solution to text-based authentication, motivated particularly by the fact that humans can remember images better than text. However, they are mostly vulnerable to shoulder surfing. In this paper, we propose a Multi-level Scalable Textual-Graphical Password Authentication Scheme for web based applications. This scheme integrates both graphical and textual password schemes, and provides multi-level authentication scheme as compared to previously proposed single level scheme. In this scheme multi-level authentication is obtained by making use of SMS service, hence provides more secure service. This scheme shows significant potential bridging the gap between conventional textual password and graphical password. Further enhancements of this scheme are proposed and briefly discussed.
Toward A Full Implementation of the Operation and Support Subsystem (OSS) in IMS Networks
Authors: Hung Nguyen Tai , Thanh Nguyen Huu , Mueller Julius 
Published: May 2016

Recently, mobile operators all over the world are facing big challenges on the decreasing of the revenues from its traditional killer-applications like SMS/MMS and even voice services. The challenges come from a new trend of services called OTT (Over The Top). These OTT services provide the mobile users with flexible, convenient and more importantly free means to do their daily multimedia communication needs and seamlessly without any border so that operators couldn’t be just simply block it, but in opposite, need to find solutions to compete against it. Because of that, nowadays, more and more operators choose to deploy the standard RCS (Rich Communication Suite). RCS is a set of rich features communication services developed on top of IMS framework. Although there have been tremendous efforts to develop the architecture and protocols for IMS, which is a key technology of the NGN, it is far from being widely deployed. There are many reasons for that unpopularity (of IMS commercial deployment), namely, the lacking of clear business model for IMS-based services, no big difference between IMS-based services and SOA (Service Oriented Architecture) services, lack of the true demands for features that IMS based services have, etc... However, one of the most important reason that till now not many researchers have pointed out and addressed it, is about the OSS (Operation and Support Subsystem) functions. The lacking of OSS clearly defined functions and interfaces make the difficulties for operators and even equipment manufacturers to collect the pay back for any big scale IMS deployment for their networks. This paper presents our proven that IMS can provide the killer applications with blending features like mash-up and readily equipped with the intelligent charging and policy control functions. That may partly help to speed up the deployment process of IMS in real networking environment.
Band Selection for Hyperspectral Images Using Non-Negativity Constraints
Authors: Gruninger John , Dothe Hoang 
Published: May 2016

This paper presents a new factorization technique for hyperspectral signal processing based on a constrained singular value decomposition (SVD) approach. Hyperpectral images typically have a large number of contiguous bands that are highly correlated. Likewise the field of view typically contains a limited number of materials and the spectra are also correlated. Only a selected number of bands, the extreme bands that include the dominant materials spectral signatures, are needed to express the data. Factorization can provide a means for interpretation and compression of the spectral data. Hyperspectral images are represented as non-negative matrices by graphic concatenation, with the pixels arranged into columns and each row corresponding to a spectral band. SVD and principal component analysis enjoy a broad range of applications, including, rank estimation, noise reduction, classification and compression, with the resulting singular vectors forming orthogonal basis sets for subspace projection techniques. A key property of non-negative matrices is that their columns/rows form non-negative cones, with any non-negative linear combination of the columns/rows belonging to the cone. Data sets of spectral images and time series reside in non-negative orthants and while subspaces spanned by SVD include all orthants, SVD projections can be constrained to the non-negative orthants. In this paper we utilize constraint sets that confine projections of SVD singular vectors to lie within the cones formed by the spectral data. The extreme vectors of the cone are found and these vectors form a basis for the factorization of the data. The approach is illustrated in an application to hyperspectral data of a mining area collected by an airborne sensor.
Efficient Image Watermarking Using Filtered DWT-Blocks for Quantization of Significant Differences
Authors: Huynh-The Thien , Le-Tien Thuong , Nguyen-Thanh Tuan 
Published: May 2016

In the paper, a robust blind watermarking method is introduced for gray-scale images based on wavelet tree quantization with an adaptive threshold in the extraction. Every block of 2×2 coefficients of High-Low subbands of the Wavelet tranform are grouped in a block through the parent-child relationship of the wavelet tree. Every scrambled binary watermark bit is embedded into each block based on the difference value of two largest coefficients. The watermark is recovered by comparing the difference values in each block to an adaptive threshold. The accuracy of an extracted watermark depends on the threshold which is determined by minimizing the sum of weighted within-class variance. The performance of the proposed watermarking method is represented through experimental results under various types of attack such as, Histogram Equalization, Cropping, Low-pass Filtering, Gaussian noise, Salt & Pepper noise and JPEG compression. In additions, the proposed method is also compared to recent methods in the extraction performance.
High-Level Modeling and Simulation of a Novel Reconfigurable Network-on-Chip Router
Authors: Le-Van Thanh-Vu , Tran Xuan-Tu 
Published: May 2016

In this paper, we present a novel router architecture for implementing a Reconfigurable Network-on-Chip (RNoC) at high-level design using SystemC. The RNoC is an adaptive NoC-based system-on-chip providing a dynamic reconfigurable communication mechanism. By adding a virtual port – named Routing Modification port – into the conventional router architecture, the network router is able to route communication data flexibly whenever the target routing path is blocked, by unwanted defects or intently by a software programme to meet the requirements of applications. The proposed architecture has been modeled in SystemC/C++, simulated and verified within a 2D mesh 5×5 network platform. In normal communication mode, the static XY routing algorithm is used while the West-First algorithm with a proposed prohibited router surrounding technique is applied in reconfiguration mode. Experimental results are also reported to compare the performance of the network architecture in different operation modes as well as with other works.
A Complete Method for Reconstructing an Elevation Surface of 3D Point Clouds
Authors: Nguyen Van Sinh , Tran Manh Ha , Nhan Ba Cong 
Published: May 2016

Reconstructing the surface of 3D point clouds is a reconstruction from a cloud of 3D points to a triangular mesh. This process approximates a discrete point cloud by a continuous/smooth surface depending on the input data and the applications of users. In this paper, we propose a complete method to reconstruct an elevation surface from 3D point clouds. The method consists of three steps. In the first step, we triangulate an elevation surface of 3D point cloud structured in a 3D grid. In the second step, we remove the outward triangles to deal with concave regions on the boundary of the triangular mesh. In the third step, we reconstruct this surface by filling the hole of triangular mesh. Our method could process very fast for triangulating the surface, preserve the topology and characteristic of the input surface after reconstruction.
Proposal of MIMO Ultra-Wide Band Antenna with Low Mutual Coupling
Authors: Trung Le Trong , Dinh Nguyen Quoc , Hieu Ta Chi 
Published: May 2016

In this paper, a new ultra-wide band (UWB) MIMO antenna is proposed. A MIMO antenna set consists of two single ultra-wide band antennas. This simple and compact MIMO antenna, which is designed to work from 3.1 GHz to 10.6 GHz, has a broad bandwidth with the VSWR ≤ 2. In addition, MIMO antenna characteristics such as radiation pattern, maximal gain are thoroughly investigated.
Efficient Load Balancing Algorithm over Heterogeneous Wireless Packet Networks
Authors: Nguyen-Vuong Quoc-Thinh , Agoulmine Nazim 
Published: May 2016

The paper aims at improving the load balancing algorithm in wireless packet cellular networks and particularly in coordinated heterogeneous wireless packet networks. Our main contributions are two-fold. First, we introduce a new approach to compute the network load metric based on the radio link quality and scheduling information, which can be applied to any wireless packet system. This load metric hides the radio resources heterogeneity of different access technologies from the load balancer. Secondly, we propose a new practical load balancing algorithm which provides a more efficient way to manage the scarce radio resources. The proposed approach has been compared with different existing schemes and the results show the superiority of the proposed solution.
A Survey on Approximations of One-Dimensional Gaussian Q-Function
Authors: Bao Vo Nguyen Quoc , Tuyen Luu Pham , Tue Huynh Huu 
Published: May 2016

Predicting the digital communication system performance plays a very important role in the process of system design. This performance is usually quantified by symbol error probability or bit error probability. Computing these probabilities in presence of Additive White Gaussian Noise requires to work with integrals involving the Gaussian Qfunction, which cannot be expressed in closed-form in terms of elementary functions. As a result, approximating the Gaussian Q-function in closed-form expressions with high accuracy becomes a necessity. In this paper, we give an overview about the Gaussian Q-function approximations and via some illustrating examples, we discuss their accuracy, tractability as well as their computational complexity
Simulation and Measurement Methods for RCS Estimations of a Scale Model Airplane
Authors: Michishita Naobumi , Dinh Nguyen Quoc , Yamada Yoshihide 
Published: May 2016

In a military context, the radar cross section (RCS) of an airplane is a very important subject. For an RCS estimation object, a scaled-down model is often employed for ease of measurements. Recently, electromagnetic simulations of the RCS has become very convenient because of developments in high-speed calculation methods such as MLFMM and HOBF in electromagnetic simulators employing the MoM algorithm. As for the measurements, high-resolution measurements via the time domain analysis are promising. In this paper, important estimation expressions for use with a scale model are briefly explained. In terms of calculations, comparisons are drawn between the actual calculation abilities of MoM, MLFMM, and HOBF at 18 GHz for a 1/48-scale model. In terms of measurement, a high-resolution measurement system employing a compact range and time domain analysis that is used in this study is explained. Next, the calculated and measured results are compared in order to show the accuracy of the obtained results. The results in vertical and horizontal planes of a scale model are shown at vertical and horizontal polarizations. Moreover, using the calculation method to determine estimates at higher frequencies is also investigated in order to obtain the practical RCS value of a real-sized airplane
Decentralized Online Social Network Using Peer-to-Peer Technology
Authors: Tran Manh Ha , Nguyen Van Sinh , Ha Synh Viet Uyen 
Published: May 2016

This paper presents a social network with a peer-to-peer architecture that facilitates social computing services in distributed environments. This social network aims to provide users the capability of managing the dissemination of user data, searching user data on the data silos of the network, and consolidating user data from various social networks. The social network employs a super peer peer-to-peer architecture that contains peers and super peers. Users use peers to participate the network and services. Peers with sufficient storage, bandwidth and processing power become super peers that support peers for complex operations such as user authentication or group communication. We have extended the Gnutella protocol to provide the authentication and posting services on the social network. The design of these services copes with the distributed setting of the social network. The evaluation of the prototyping social network has performed on a number of laboratory workstations to investigate its scalability, reliability and performance.