Telfor Journal Vol.6 No.1 (2014)

Content

Editorial HyperLink
Editor-in-Chief: Prof. Dr Đorđe Paunović

Symbolic Analysis of Faulty Logic Circuits under Correlated Data-Dependent Gate Failures

S. S. Brkic, P. N. Ivanis, G. Djordjevic, and B. Vasic
Topic:
Communication Theory
Abstract
In this paper we present a method for symbolic analysis of unreliable logic circuits in the presence of correlated and data-dependent gate failures, described by Markov chains. Furthermore, using this method we investigate the influence of data-dependent failures on the performance of majority logic and multiple input XOR gates.
Keywords
Combinatorial circuits, fault-tolerance, Markov chains, symbolic analysis.
Full Text
HyperLink Symbolic Analysis of Faulty Logic Circuits under Correlated Data-Dependent Gate Failures
Page(s)
2-6

Performance Analysis of Faulty Gallager-B Decoding of QC-LDPC Codes with Applications

O. Al Rasheed, S. S. Brkic, P. N. Ivanis, and B. Vasic
Topic:
Communication Theory
Abstract
In this paper we evaluate the performance of Gallager-B algorithm, used for decoding low-density parity-check (LDPC) codes, under unreliable message computation. Our analysis is restricted to LDPC codes constructed from circular matrices (QC-LDPC codes). Using Monte Carlo simulation we investigate the effects of different code parameters on coding system performance, under a binary symmetric communication channel and independent transient faults model. One possible application of the presented analysis in designing memory architecture with unreliable components is considered.
Keywords
faulty hardware, Gallager-B decoder, Monte Carlo simulation, QC-LDPC codes.
Full Text
HyperLink Performance Analysis of Faulty Gallager-B Decoding of QC-LDPC Codes with Applications
Page(s)
7-11

A Comparative Analysis of Techniques for PAPR Reduction of OFDM Signals

M. Janjić and N. Nešković
Topic:
Communication Theory
Abstract
In this paper the problem of high Peak-to-Average Power Ratio (PAPR) in Orthogonal Frequency-Division Multiplexing (OFDM) signals is studied. Besides describing three techniques for PAPR reduction, SeLective Mapping (SLM), Partial Transmit Sequence (PTS) and Interleaving, a detailed analysis of the performances of these techniques for various values of relevant parameters (number of phase sequences, number of interleavers, number of phase factors, number of subblocks) depending on applied technique, is carried out. Simulation of these techniques is run in Matlab software. Results are presented in the form of Complementary Cumulative Distribution Function (CCDF) curves for PAPR of 30000 randomly generated OFDM symbols. Simulations are performed for OFDM signals with 32 and 256 subcarriers, oversampled by a factor of 4. A detailed comparison of these techniques is made based on Matlab simulation results.
Keywords
Interleaving, OFDM, PAPR, PTS, SLM.
Full Text
HyperLink A Comparative Analysis of Techniques for PAPR Reduction of OFDM Signals
Page(s)
12-17

End-to-end QoS Signaling Protocol and its Performance Analysis for LTE Networks

G. Horváth and P. Fazekas
Topic:
Telecommunications Networks
Abstract
In order to effectively deliver traffic from different applications, providing end-to-end Quality of Service (QoS) is critical in Long Term Evolution (LTE) networks. Mobility requires special handling of QoS enforcement rules and methods. The LTE QoS Signaling (LQSIG) protocol presented in this paper will allow ensuring resource reservation before using a data path. Operation of the proposed protocol in different mobility scenarios is also explained. The key features of the protocol include LTE QoS model mapping to QSPEC (QoS Specification) objects used in reservation and interworking with mobility protocols in the LTE protocol stack, especially with Radio Resource Control (RRC). The basics of an analytical model are proposed in order to determine the blocking probability at the bottlenecks of LTE network. A performance analysis of LQSIG describes its properties compared to legacy LTE networks.
Keywords
LTE, End-to-end QoS, Resource Reservation.
Full Text
HyperLink End-to-end QoS Signaling Protocol and its Performance Analysis for LTE Networks
Page(s)
18-23

Cross-layer TCP Performance Analysis in IEEE 802.11 Vehicular Environments

T. Janevski and I. Petrov
Topic:
Radio Communications
Abstract
In this paper we provide a performance analysis of TCP in IEEE 802.11 vehicular environments for different well-known TCP versions, such as Tahoe, Reno, New Reno, Vegas, and Sack. The parameters of interest from the TCP side are the number of Duplicate Acknowledgements - DupAck, and the number of Delayed Acknowledgements - DelAck, while on the wireless network side the analyzed parameter is the interface queue - IFQ. We have made the analysis for the worst-case distance scenario for single-hop and worst-case multihop vehicular environments. The results show that the number of wireless hops in vehicular environments significantly reduces the TCP throughput. The best average performances considering all scenarios were obtained for TCP Vegas. However, the results show that the interface queue at wireless nodes should be at least five packets or more. On the other side, due to shorter distances in the vehicular wireless network, results show possible flexibility of using different values for the DupAck without degradation of the TCP throughput. On the other side, the introduction of the DelAck parameter provides enhancement in the average TCP throughput for all TCP versions.
Keywords
DelACK, DupACK, IEEE 802.11, Multihop, TCP, Throughput, Vehicular, Wireless.
Full Text
HyperLink Cross-layer TCP Performance Analysis in IEEE 802.11 Vehicular Environments
Page(s)
24-29

Development of OFDM based Secondary Link: Some Experimental Results on USRP N210 Platform

M. Janjić, M. Brković, and M. Erić
Topic:
Radio Communications
Abstract
Some experimental results of the concept development and practical implementation of an Orthogonal Frequency Division Multiplexing (OFDM) based secondary cognitive link are presented in this paper. The secondary link is realized using Universal Software Radio Peripheral (USRP) N210 platforms. For communication with USRP, we use MATLAB toolbox. Several algorithms are used to overcome transmission problems. Time-synchronization is achieved using a method based on auto-correlation of two sliding windows. Frequency offset estimation is performed using a phase offset between samples in a signal header, comprised of a sinusoid. A channel is estimated using predefined symbols inserted at the beginning of every frame, which enables channel equalization. Also, the cognitive feature of spectrum sensing and changing transmission parameters is implemented. A least-mean-square adaptive filter is introduced to offer time-synchronization error estimation as well as an alternative option for channel equalization.
Keywords
Cognitive radio, OFDM, secondary link, spectrum sensing, USRP platform.
Full Text
HyperLink Development of OFDM based Secondary Link: Some Experimental Results on USRP N210 Platform
Page(s)
30-35

Single-Iteration Algorithm for Compressive Sensing Reconstruction

S. Stanković, I. Orović, L. Stanković, and A. Draganić
Topic:
Signal Processing
Abstract
A single-iteration algorithm is proposed for the reconstruction of sparse signal from its incomplete set of observations. Recently, the reconstruction algorithms have been intensively developed within the Compressive Sensing framework. Most of the existing solutions are based either on l1-norm optimization methods or greedy iterative procedures with a priori known number of components or predefined number of iterations. We propose a simple non-iterative algorithm based on the analysis of noise-effect that appears in the frequency domain as a consequence of missing samples. The noise variance can be related and controlled by the number of missing samples. Accordingly, it is possible to keep the level of spectral noise below the signal components, such as to be able to accurately detect signal support and to reconstruct the entire signal. The theory is proven on various examples with multicomponent signals.
Keywords
Compressive Sensing, missing samples, DFT, reconstruction algorithms.
Full Text
HyperLink Single-Iteration Algorithm for Compressive Sensing Reconstruction
Page(s)
36-41

Model of Three-Limb Three-Phase Transformer Based on Nonlinear Open Circuit Characteristic with Experimental Verification

M. Simić, T. B. Šekara, and S. Jokić
Topic:
Applied Electromagnetics
Abstract
This paper describes the realization of a three-phase transformer model based on a non-linear open-circuit characteristic. The proposed model is based on the fact that in case of a star connection with a neutral wire on the primary windings for all three phases, the applied voltage presents phase voltage and line (phase) currents are magnetization currents. These variables are available for measuring and it is easy to obtain three non-linear open circuit characteristics. The results of simulations and a comparison with references and experimental results verified this approach.
Keywords
harmonic analysis, nonlinear open-circuit characteristic, transformers.
Full Text
HyperLink Model of Three-Limb Three-Phase Transformer Based on Nonlinear Open Circuit Characteristic with Experimental Verification
Page(s)
42-47

Next Generation Mobility Applications: A Wireless Cooperative Access Architecture

C. Perra
Topic:
Software Tools and Applications
Abstract
Accessing cellular networks for downloading large-size contents is a common task performed from modern smart phones. Nevertheless, several problems need to be addressed in order to provide an acceptable quality of experience to the final users. This paper presents a smart phone application aiming at reducing both cellular network load and file downloading time by leveraging network resource sharing. Groups of neighboring devices are formed depending on geographical position and battery consumption. WWAN and WLAN are then shared under an altruistic cooperative scenario for an increased user experience when accessing multimedia content.
Keywords
Cooperative access, Network cooperation.
Full Text
HyperLink Next Generation Mobility Applications: A Wireless Cooperative Access Architecture
Page(s)
48-52

An Analysis of OpenACC Programming Model: Image Processing Algorithms as a Case Study

M. J. Mišić, D. D. Dašić, and M. V. Tomašević
Topic:
Software Tools and Applications
Abstract
Graphics processing units and similar accelerators have been intensively used in general purpose computations for several years. In the last decade, GPU architecture and organization changed dramatically to support an ever-increasing demand for computing power. Along with changes in hardware, novel programming models have been proposed, such as NVIDIA’s Compute Unified Device Architecture (CUDA) and Open Computing Language (OpenCL) by Khronos group. Although numerous commercial and scientific applications have been developed using these two models, they still impose a significant challenge for less experienced users. There are users from various scientific and engineering communities who would like to speed up their applications without the need to deeply understand a low-level programming model and underlying hardware. In 2011, OpenACC programming model was launched. Much like OpenMP for multicore processors, OpenACC is a high-level, directive-based programming model for manycore processors like GPUs. This paper presents an analysis of OpenACC programming model and its applicability in typical domains like image processing. Three, simple image processing algorithms have been implemented for execution on the GPU with OpenACC. The results were compared with their sequential counterparts, and results are briefly discussed.
Keywords
CUDA, graphics processing units, image processing, OpenACC, parallel programming.
Full Text
HyperLink An Analysis of OpenACC Programming Model: Image Processing Algorithms as a Case Study
Page(s)
53-58

A Software Tool for the Assessment of Salivary Gland Function

M. M. Jankovic, A. Koljević Marković, S. Odalović, D. B. Popović, N. Petrović, and V. Artiko
Topic:
Software Tools and Applications
Abstract
Salivary gland scintigraphy (SGS) is a noninvasive, simple and reproducible technique for the functional evaluation of salivary gland involvement in patients with Sjögren’s syndrome. Using Labview environment (National Instruments, Austin, Texas) we have developed a software tool for the automatic calculation of most commonly investigated salivary and oral indices derived from salivary time-activity curves. We have shown examples that illustrate the application of the software. Our software enables the comparison of findings among several research centers with the aim of standardizing a processing protocol, defining the reference values of quantitative indices and introducing new salivary indices.
Keywords
quantitative salivary gland scintigraphy, Sjögren’s syndrome, time-activity-curve.
Full Text
HyperLink A Software Tool for the Assessment of Salivary Gland Function
Page(s)
59-63

Evaluation and Classification of Syntax Usage in Determining Short-Text Semantic Similarity

V. Batanović and D. Bojić
Topic:
Software Tools and Applications
Abstract
This paper outlines and categorizes ways of using syntactic information in a number of algorithms for determining the semantic similarity of short texts. We consider the use of word order information, part-of-speech tagging, parsing and semantic role labeling. We analyze and evaluate the effects of syntax usage on algorithm performance by utilizing the results of a paraphrase detection test on the Microsoft Research Paraphrase Corpus. We also propose a new classification of algorithms based on their applicability to languages with scarce natural language processing tools.
Keywords
natural language processing, MSRPC, parsing, part-of-speech tagging, semantic role labeling, short-text semantic similarity, syntax, word order.
Full Text
HyperLink Evaluation and Classification of Syntax Usage in Determining Short-Text Semantic Similarity
Page(s)
64-68

Techniques for Automated Testing of Lola Industrial Robot Language Parser

M. M. Lutovac and D. Bojić
Topic:
Software Tools and Applications
Abstract
The accuracy of parsing execution directly affects the accuracy of semantic analysis, optimization and object code generation. Therefore, parser testing represents the basis of compiler testing. It should include tests for correct and expected, but also for unexpected and invalid cases. Techniques for testing the parser, as well as algorithms and tools for test sentences generation, are discussed in this paper. The methodology for initial testing of a newly developed compiler is proposed. Generation of negative test sentences by modifying the original language grammar is described. Positive and negative test cases generated by Grow, Purdom’s algorithm with and without length control, CDRC-P algorithm and CDRC-P algorithm with length control are applied to the testing of L-IRL robot programming language. For this purpose two different tools for generation of test sentences are used. Based on the presented analysis of possible solutions, the appropriate method can be chosen for testing the parser for smaller grammars with many recursive rules.
Keywords
automated testing, grammar-based test generator, parser testing, robot programming.
Full Text
HyperLink Techniques for Automated Testing of Lola Industrial Robot Language Parser
Page(s)
69-74

A Cost Effective Solution for Development Environment for Data Acquisition, Monitoring and Simulation of PLC Controlled Applications

O. Bjelica and S. Lale
Topic:
Software Tools and Applications
Abstract
It is very important to test and monitor the operation of Programmable Logic Controller (PLC) in real time (online). Nowadays, conventional, but expensive monitoring systems for PLCs, such as Supervisory Control and Data Acquisition (SCADA) systems, software and hardware simulators (or debuggers), are widely used. This paper proposes a user friendly and cost-effective development environment for monitoring, data acquisition and online simulation of applications with PLC. The purpose of this solution is to simulate the process which is controlled by the PLC. The performances of the proposed development environment are presented on the examples of washing machine and dishwasher simulators.
Keywords
Data acquisition, monitoring, PLC, simulation.
Full Text
HyperLink A Cost Effective Solution for Development Environment for Data Acquisition, Monitoring and Simulation of PLC Controlled Applications
Page(s)
75-79

Do ICTs Affect Workforce Productivity in Egyptian Industrial Organizations?

M. Elsaadani
Topic:
Telecommunications Policy, Regulatory Aspects and Services
Abstract
The present study aims to investigate the influence of Information Communication Technologies-ICTs’ dimensions (Information Technology (IT), Management Information System (MIS), Office automation (OA), Intranet and Internet) on workforce productivity for a group of industrial organizations in Alexandria - Egypt. The population of the study included managers and staff members working in different areas related to ICTs in selected industrial organizations at various managerial levels. A descriptive-statistical combined research study was conducted. Simple random sampling was used for the selection of the participating industrial organization. A questionnaire was used as the data collection method. Expert comments were used to check the validity of study instrument, and the reliability of questions was calculated as 79% using Cronbach’s Alpha coefficient. Single variable t-test, Friedman and variance analysis tests were used for the analysis. Study findings revealed that the specified dimensions of ICTs positively affect workforce productivity of industrial organizations in Alexandria - Egypt.
Keywords
ICTs, Productivity Management, IT, MIS, OA, Intranet, Internet, Egypt, Industrial Organizations.
Full Text
HyperLink Do ICTs Affect Workforce Productivity in Egyptian Industrial Organizations?
Page(s)
80-84