Telfor Journal Vol.4 No.1 (2012)

Content

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

Volunteer-Based System for Research on the Internet Traffic

T. Bujlow, K. Balachandran, S. Ligaard Nørgaard Hald, T. Riaz, and J. Myrup Pedersen
Topic:
Telecommunications Networks
Abstract
To overcome the drawbacks of existing methods for traffic classification (by ports, Deep Packet Inspection, statistical classification) a new system has been developed, in which data are collected and classified directly by clients installed on machines belonging to volunteers. Our approach combines the information obtained from the system sockets, the HTTP content types, and the data transmitted through network interfaces. It allows grouping packets into flows and associating them with particular applications or types of service. This paper presents the design of our system, implementation, the testing phase and the obtained results. The performed threat assessment highlights potential security issues and proposes solutions in order to mitigate the risks. Furthermore, it proves that the system is feasible in terms of uptime and resource usage, assesses its performance and proposes future enhancements. We released the system under The GNU General Public License v3.0 and published as a SourceForge project called Volunteer-Based System for Research on the Internet.
Keywords
computer networks, data collecting, performance monitoring, volunteer-based system.
Full Text
HyperLink Volunteer-Based System for Research on the Internet Traffic
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2-7

Packet Delay Variation Analysis of the CQ Switch

M. Radonjić, I. Radusinović, and Ivo Maljević
Topic:
Telecommunications Networks
Abstract
Packet delay variation analysis for a 32x32 crosspoint queued switch under uniform and IBP arrival traffic is presented in this paper. Different buffer sizes and several scheduling algorithms are observed: longest queue first, round robin, exhaustive round robin and frame based round robin matching. Results show that the least packet delay variation, among observed algorithms, causes round robin algorithm.
Keywords
Buffer length, crossbar switch, delay variation, scheduling algorithm
Full Text
HyperLink Packet Delay Variation Analysis of the CQ Switch
Page(s)
8-13

OFDM AF Variable Gain Relay System for the Next Generation Mobile Cellular

E. Kocan and M. Pejanovic-Djurisic
Topic:
Radio Communications
Abstract
In this paper we present analytical performance evaluation of a dual-hop OFDM amplify-andforward (AF) variable gain (VG) relay system implementing ordered subcarrier mapping (SCM) at the relay station (R), considered to be a very interesting solution for the next generation mobile cellular networks. A scenario with no direct communication between the source of information (S) and destination terminal (D), with the Rayleigh fading statistics on both hops is assumed. A closed form analytical expression for the bit error rate (BER) performance of the considered system with DPSK modulation is derived, while for its ergodic capacity performance, a tight upper bound expression is obtained. The accuracy of the undertaken analytical approach is confirmed through comparison with simulation results. It is shown that significant capacity enhancement can be achieved through SCM implementation at R, for all the signal-to-noise ratio (SNR) values on both hops, but especially in the region of small SNRs on hops. BER analysis reveals that in the region of small and medium average SNRs on both hops BER performance may also be improved with SCM at R station.
Keywords
BER, ergodic capacity, OFDM AF relay system, subcarrier mapping, variable gain.
Full Text
HyperLink OFDM AF Variable Gain Relay System for the Next Generation Mobile Cellular
Page(s)
14-19

Novel Scheduling Algorithms for LTE Downlink Transmission

D. Talevski and L. Gavrilovska
Topic:
Radio Communications
Abstract
Long Term Evolution (LTE) is the new standard specified by 3GPP on the way towards the fourth generation mobile network. The LTE introduces enhanced data link mechanisms to support successful implementation of new data services across the network. The incorporated scheduling mechanisms can significantly contribute to this goal. In this paper novel scheduling algorithms are presented and compared to the Max C/I Downlink scheduler for LTE, which is characterized by high data rates at cell level, but poor fairness. The newly developed algorithms allow fair distribution of available resources. Simulation results presented in the paper show that the implementation of these newly developed algorithms enables improvement of the overall system capacity and user level performances.
Keywords
LTE, MAC layer, scheduling.
Full Text
HyperLink Novel Scheduling Algorithms for LTE Downlink Transmission
Page(s)
20-25

LTE Network Radio Planning

I. R. Maravić and A. M. Nešković
Topic:
Radio Communications
Abstract
In this paper different ways of planning the radio resources within an LTE network are analyzed. All simulations were carried out using 3GPP recommendations. Soft frequency reuse (SFR), soft fractional frequency reuse (SFFR) and hard fractional frequency reuse (HFFR) radio resource allocation schemes are compared to fixed frequency reuse 1 (R1) and reuse 3 (R3) radio resource allocation schemes. An optimum way of planning radio resources in a LTE network is proposed at the end of paper.
Keywords
LTE, radio planning, simulation.
Full Text
HyperLink LTE Network Radio Planning
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26-30

Using Radio Irregularity for Increasing Residential Energy Awareness

B. Mrazovac, M. Z. Bjelica, B. M. Todorović, A. Miljković, and D. Samardžija
Topic:
Radio Communications
Abstract
Radio irregularity phenomenon is often considered as a shortcoming of wireless networks. In this paper, the method of using radio irregularity as an efficient human presence detection sensor in smart homes is presented. The method is mainly based on monitoring variations of the received signal strength indicator (RSSI) within the messages used for the communication between wireless smart power outlets. The radio signals used for the inter-outlets communication can be absorbed, diffracted or reflected by objects in their propagation paths. When a human enters the existing radio communication field, the variation of the signal strength at the receiver is even more expressed. Based on the detected changes and compared to the initial thresholds set during the initialization phase, the system detects human presence. The proposed solution increases user awareness and automates the power control in households, with the primary goal to contribute in residential energy savings. Compared to conventional sensor networks, this approach preserves the sensorial intelligence, simplicity and low installation costs, without the need for additional sensors integration.
Keywords
Energy awareness, presence detection, radio irregularity, RSSI, smart outlets, Smart Home, Zigbee.
Full Text
HyperLink Using Radio Irregularity for Increasing Residential Energy Awareness
Page(s)
31-36

Investigation of Wide-FSR SOI Optical Filters Operating in C and L Bands

B. Troia, V. M. N. Passaro, and F. De Leonardis
Topic:
Optical Communications
Abstract
In this paper we present the investigation of optical filters based on triple ring resonator architectures in silicon-on-insulator technology. The generalized approach based on Mason’s rule and delay line signal processing has been implemented for modeling optical filters in Z-domain. A numerical investigation based on the coefficient map has been adopted for designing optical add-drop multiplexers with wide free spectral ranges, as large as 12 THz (~ 96 nm). Low crosstalk, of the order of -20 dB, has been numerically demonstrated in overall transmittances of optimized filters.
Keywords
Free spectral range, optical add-drop multiplexers, ring resonators, silicon-on-insulator.
Full Text
HyperLink Investigation of Wide-FSR SOI Optical Filters Operating in C and L Bands
Page(s)
37-42

Data Sorting Using Graphics Processing Units

M. J. Mišić and M. V. Tomašević
Topic:
Software Tools and Applications
Abstract
Graphics processing units (GPUs) have been increasingly used for general-purpose computation in recent years. The GPU accelerated applications are found in both scientific and commercial domains. Sorting is considered as one of the very important operations in many applications, so its efficient implementation is essential for the overall application performance. This paper represents an effort to analyze and evaluate the implementations of the representative sorting algorithms on the graphics processing units. Three sorting algorithms (Quicksort, Merge sort, and Radix sort) were evaluated on the Compute Unified Device Architecture (CUDA) platform that is used to execute applications on NVIDIA graphics processing units. Algorithms were tested and evaluated using an automated test environment with input datasets of different characteristics. Finally, the results of this analysis are briefly discussed.
Keywords
CUDA, data sorting, graphics processing units, parallel processing, parallel programming.
Full Text
HyperLink Data Sorting Using Graphics Processing Units
Page(s)
43-48

Measuring the Quality Characteristics of an Assembly Code on Embedded Platforms

I. Považan, M. Popović, M. Đukić, and M. Krnjetin
Topic:
Software Tools and Applications
Abstract
The paper describes the implementation of a programming tool for measuring the quality characteristics of an assembly code. The aim of this paper is to prove the usability of these metrics for evaluation of an assembly code's quality, which is generated by C Compiler for 32bit DSP architecture. The analysis of test results has shown that the compiler generates a good quality assembly code.
Keywords
Assembly code quality, CCC compiler, disassembler, DSP.
Full Text
HyperLink Measuring the Quality Characteristics of an Assembly Code on Embedded Platforms
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49-53

Automated Proving Properties of Expectation-Maximization Algorithm using Symbolic Tools

V. Mladenovic, M. Lutovac, and M. Lutovac
Topic:
Software Tools and Applications
Abstract
In many analyses based on estimating the parameters of probability distribution functions, the algorithms are developed for unknown probabilities. Some algorithms are derived starting from previous solutions and algorithms. One very popular algorithm is the EM (Expectation-Maximization) algorithm. The EM algorithm is a starting point for developing other advanced algorithms. Features of EM and other algorithms are observed with the traditional numerical approach. In this paper, we present a new approach of analysing the EM algorithm using computer algebra tools (Mathematica). We automatically derive properties of the algorithm. The knowledge embedded in symbolic expressions was used to simulate an example system and EM algorithm to generate the implementation code and to understand the nature of the error produced by selecting the total number of observed elements.
Keywords
Convergence, EM algorithm, iteration, ML estimation, symbolic processing.
Full Text
HyperLink Automated Proving Properties of Expectation-Maximization Algorithm using Symbolic Tools
Page(s)
54-59

Test-Driven Development of IEEE 1451 Transducer Services and Application

D. Marković, U. Pešović, Ž. Jovanović, and S. Ranđić
Topic:
Software Tools and Applications
Abstract
IEEE 1451 standard defines the methods of integrating smart transducers into communicating networks. Interface between a user application and a field of transducers, known as Transducer Services API is defined by standrad IEEE 1451.0. This paper presents the use of Test- Driven Design (TDD) in developing methods for accessing transducer services using Transducer Services API and developing web applications which access this services over the network. The characteristics of TDD and its benefits are presented and the way of realization for one method is shown using Java and JUnit framework to run tests.
Keywords
IEEE 1451.0 standard, smart transducers, test-driven developement, Web application.
Full Text
HyperLink Test-Driven Development of IEEE 1451 Transducer Services and Application
Page(s)
60-65

A User-Centric WS-Mediator Framework for on-the-fly Web Service Composition

T. Zhang and K. Chen
Topic:
Software Tools and Applications
Abstract
Nowadays, the effective and adaptive dynamic Web service composition is a major challenge for a real success of Web services among ordinary users. For the latter, and from the viewpoint of a user centric paradigm, existing work has limitation on their agility to create a composed service on the fly according to the desire/need of an end-user at a given time/place. This article presents our approach which consists in providing a comprehensive framework for a user centric WS-mediator which is capable of dynamic service composition. It is based on a composition engine which follows user’s specific needs and which yields a composed service through a WS knowledge base. Users can mash up the services at run time with their own logic and have a fully dynamic composition with context adaptation through a WS-mediator that is also capable of supporting the semantic web.
Keywords
Context adaptation, mash up, mediator, semantic Web, user centric, Web service composition.
Full Text
HyperLink A User-Centric WS-Mediator Framework for on-the-fly Web Service Composition
Page(s)
66-71

Exact Time Speaking System

I. Vidaković, P. Daković, D. Jonić, Z. Nedelicki, D. Mitić, T. Šuh, and A. Lebl
Topic:
Telecommunications Services
Abstract
The paper describes a system for speaking the exact time, a VoIP solution produced by IRITEL, based on a family of domestic media gateways. System contains two media gateways for reliability reasons. Media gateway is a result of R&D effort in IRITEL. Exploitation experience and some traffic characteristics are described.
Keywords
RTP, service 95, SIP, VoIP.
Full Text
HyperLink Exact Time Speaking System
Page(s)
72-76