Institute of Electron Technology
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2189 research outputs found
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Dynamic Contracting of IP Services – System Architecture and Prototype, Journal of Telecommunications and Information Technology, 2011, nr 2
Get PDFProposition of architecture and implementation of prototype system for dynamic contracting IP services is presented. The system serves requests issued by users demanding setting up network service of specified parameters. DiffServ technology together with traffic engineering and admission control are used. Implementation details and results of tests are described. Necessary extensions and possibility of commercialization of such a system are discussed
Higher Order Cumulants for Identification and Equalization of Multicarrier Spreading Spectrum Systems, Journal of Telecommunications and Information Technology, 2011, nr 2
Get PDFThis paper describes two blind algorithms for multicarrier code division multiple access (MC-CDMA) system equalization. In order to identify, blindly, the impulse response of two practical selective frequency fading channels called broadband radio access network (BRAN A and BRAN E) normalized for MC-CDMA systems, we have used higher order cumulants (HOC) to build our algorithms. For that, we have focussed on the experimental channels to develop our blind algorithms able to simulate the measured data with high accuracy. The simulation results in noisy environment and for different signal to noise ratio (SNR) demonstrate that the proposed algorithms are able to estimate the impulse response of these channels blindly (i.e., without any information about the input), except that the input excitation is i.i.d. (identically and independent distributed) and non-Gaussian. In the part of MC-CDMA, we use the zero forcing and the minimum mean square error equalizers to perform our algorithms. The simulation results demonstrate the effectiveness of the proposed algorithms
The IP QoS System, Journal of Telecommunications and Information Technology, 2011, nr 3
Get PDFThis paper shortly describes the IP QoS System which offers strict quality of service (QoS) guarantees in IP-based networks and supports a number of, so called, classes of services. Such solution requires to implement in the network a set of QoS mechanisms and algorithm working on packet, connection request and provisioning levels. Furthermore, we require signaling system for informing the network about new connection request and network resource allocation capabilities for providing required resources to given connection. The IP QoS System is based on the next generation networks (NGN) and differentiated services (DiffServ) architectures and, at least for now, it is designed for single domainonly
Improving Population-Based Algorithms with Fitness Deterioration, Journal of Telecommunications and Information Technology, 2011, nr 4
Get PDFThis work presents a new hybrid approach for supporting sequential niching strategies called Cluster Supported Fitness Deterioration (CSFD). Sequential niching is one of the most promising evolutionary strategies for analyzing multimodal global optimization problems in the continuous domains embedded in the vector metric spaces. In each iteration CSFD performs the clustering of the random sample by OPTICS algorithm and then deteriorates the fitness on the area occupied by clusters. The selection pressure pushes away the next-step sample (population) from the basins of attraction of minimizers already recognized, speeding up finding the new ones. The main advantages of CSFD are low memory an computational complexity even in case of large dimensional problems and high accuracy of deterioration obtained by the flexible cluster definition delivered by OPTICS. The paper contains the broad discussion of niching strategies, detailed definition of CSFD and the series of the simple comparative tests
Benchmarking Procedures for Continuous Optimization Algorithms, Journal of Telecommunications and Information Technology, 2011, nr 4
Get PDFReliable comparison of optimization algorithms requires the use of specialized benchmarking procedures. This paper highlights motivations which influence their structure, discusses evaluation criteria of algorithms, typical ways of presenting and interpreting results as well as related statistical procedures. Discussions are based on examples from CEC and BBOB benchmarks. Moreover, attention is drawn to these features of comparison procedures, which make them susceptible to manipulation. In particular, novel application of the weak axiom of revealed preferences to the field of benchmarking shows why it may be misleading to assess algorithms on basis of their ranks for each of test problems. Additionally, an idea is presented of developing massively parallel implementation of benchmarks. Not only would this provide faster computation but also open the door to improving reliability of benchmarking procedures and promoting research into parallel implementations of optimization algorithms
On Testing IPv6 in Small ISP’s Networks, Journal of Telecommunications and Information Technology, 2011, nr 2
Get PDFTesting process allows to detect potential faults of implementation of IPv6 in the phase preceding migration, thus minimizing the risk of problems in IPv6 deployment. In general the IPv6 tests should be performed by all network providers, however the test range should fit their needs. It causes that test range for small network operators (offering basic set of services) could be limited in comparison to larger ISPs. In this paper, we propose an approach to IPv6 tests with regard to IPv6 deployment by small operators. We present tools and specifications for IPv6 tests and propose a test platform optimized to small ISP’s needs. The test platform is a dedicated LiveCD distribution based on FreeBSD operating system with IPv6 test environment and set of pre-defined tests. An advantage of this solution is the ability to launch the test tool software on any computer equipped with an Ethernet card and CD-ROM/DVD-ROM drive. LiveCD test tool allows users to execute tests and analyze the results in graphical environment.We believe that this approach will help to simplify and shorten the IPv6 testing process in small ISP’s networks
Teraźniejszość i przyszłość telewizji cyfrowej w Polsce. Telekomunikacja i Techniki Informacyjne, 2011, nr 1-2
Get PDFOpisano stan cyfryzacji transmisji telewizyjnych w Polsce zarówno satelitarnych, jak i kablowych oraz proces cyfrowego przełączenia telewizji naziemnej, będący obecnie najważniejszym wydarzeniem związanym z rozwojem usług telewizyjnych w Polsce. Przedstawiono prognozę rozwoju tych usług w bieżącej dekadzie
Optimization of Call Admission Control for UTRAN, Journal of Telecommunications and Information Technology, 2011, nr 3
Get PDFThis paper addresses the traffic’s grade of service indicators: call blocking and dropping rates as well as the optimization of their mutual relation, corresponding to the call admission control procedure configuration. In the presented results of simulations authors showed opportunities for the CAC load threshold adaptation according to the traffic volume and user mobility changes observed in the mobile radio network
SVD Audio Watermarking: A Tool to Enhance the Security of Image Transmission over ZigBee Networks, Journal of Telecommunications and Information Technology, 2011, nr 4
Get PDFThe security is important issue in wireless networks. This paper discusses audio watermarking as a tool to improve the security of image communication over the IEEE 802.15.4 ZigBee network. The adopted watermarking method implements the Singular-Value Decomposition (SVD) mathematical technique. This method is based on embedding a chaotic encrypted image in the Singular Values (SVs) of the audio signal after transforming it into a 2-D format. The objective of chaotic encryption is to enhance the level of security and resist different attacks. Experimental results show that the SVD audio watermarking method maintains the high quality of the audio signals and that the watermark extraction and decryption are possible even in the presence of attacks over the ZigBee network