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Analysis of Content Quality Evaluation within 3DTV Service Distribution Systems, Journal of Telecommunications and Information Technology, 2014, nr 1
Get PDFIn the following paper, evaluation of quality of content distributed within 3DTV service is assessed. The performed analysis reveals a multiplicity of parameters as a compound factor defining the contemporary approach towards quality assessment. Taking into consideration a successful telecommunication service creation, an examination of content chain identifies crucial stages founding the path of modern services of stereoscopic content distribution quality evaluation
Optymalizacja sieci FTTH. Telekomunikacja i Techniki Informacyjne, 2014, nr 3-4
Get PDFFiber To The Home (FTTH) to najbardziej nowoczesna technologia wśród światłowodowych sieci dostępowych. Podstawowymi wyzwaniami w procesie budowy sieci FTTH są wysoka cena urządzeń i koszt instalacji kabli. Cena urządzeń optycznych wprawdzie stale się obniża, jednak położenie kabla optycznego nadal generuje bardzo duże koszty. W niniejszym artykule przedstawiono problem optymalizacji kosztów instalacji kabla optycznego. Jego rozwiązanie będzie miało praktyczne zastosowanie w projektowaniu sieci FTTH. Ponieważ prezentowany problem jest NP-trudny (Non-deterministic Polynomial-time hard), w celu jego rozwiązania posłużono się algorytmem aproksymacyjnym. Algorytm został zaimplementowany w celu analizy wydajności, która wykazała zadowalającą jakość wyników działania algorytmu z dopuszczalną czasochłonnością. W związku z tym autor proponuje zastosowanie algorytmu w narzędziach do projektowania sieci FTTH
QoS Equalization in a W-CDMA Cell Supporting Calls of Innite or Finite Sources with Interference Cancelation, Journal of Telecommunications and Information Technology, 2014, nr 3
Get PDFIn this paper, a multirate loss model for the calculation of time and call congestion probabilities in a Wideband Code Division Multiple Access (W-CDMA) cell is considered. It utilizes the Bandwidth Reservation (BR) policy and supports calls generated by an innite or nite number of users. The BR policy achieves QoS equalization by equalizing congestion probabilities among calls of dierent service-classes. In the proposed models a multiple access interference is considered, and the notion of local blocking, user's activity and interference cancelation. Although the analysis of the proposed models reveals that the steady state probabilities do not have a product form solution, the authors show that the calculation of time and call congestion probabilities can be based on approximate but recursive formulas, whose accuracy is veried through simulation and found to be quite satisfactory
Mobility-Aware, Correlation-Based Node Grouping and Selection for Cooperative Spectrum Sensing, Journal of Telecommunications and Information Technology, 2014, nr 2
Get PDFCooperative spectrum sensing has been proposed as a solution to increase the sensing function accuracy in cognitive radio networks, but the research has, so far, mainly focused on static scenarios, all but neglecting the impact of mobility on spectrum sensing. In this work a novel cooperative spectrum sensing scheme for mobile cognitive networks, based on a correlation-based, mobility-aware node selection algorithm is proposed. Correlation among sensing decisions is used to divide nodes into groups, and mobility is taken into account in the group leaders selection by means of a node selection metric that considers both sensing performance and mobility. Performance of the proposed algorithm is evaluated by computer simulations taking into account mobility and a detailed modeling of temporal and spatial correlation of fading and shadowing components in the channel path loss, going way beyond the performance evaluation carried out in previous works on correlation-based cooperative sensing schemes. Simulation results highlight that the proposed metric leads to a signi cant increase of the update period required to maintain acceptable sensing performance, and correspondingly to a strong reduction in the overhead caused by the grouping and node selection procedure
Videotoms in Objective and Subjective Quality Tests of Video , Journal of Telecommunications and Information Technology, 2014, nr 1
Get PDFThis paper proposes idea of videotoms usage in quality tests of video signals. This concept simplifies parametric model creation for television services such as IPTV (Internet Protocol Television), VoD (Video on Demand) and others. Videotom is simple, well-defined video sequence in the context of video quality tests. Presented idea was used in both objective and subjective tests of influence selected network parameters: jitter of delay, packet loss and packet corrupt on the video quality measured using Mean Square Error (MSE) and Mean Opinion Score (MOS) metrics. Results showed that proposed method is useful especially for subjective tests and it can reduce costs and time for them
Data and Task Scheduling in Distributed Computing Environments, Journal of Telecommunications and Information Technology, 2014, nr 4
Get PDFecome a major research and engineering issue. Data Grids (DGs), Data Clouds (DCs) and Data Centers are designed for supporting the processing and analysis of massive data, which can be generated by distributed users, devices and computing centers. Data scheduling must be considered jointly with the application scheduling process. It generates a wide family of global optimization problems with the new scheduling criteria including data transmission time, data access and processing times, reliability of the data servers, security in the data processing and data access processes. In this paper, a new version of the Expected Time to Compute Matrix (ETC Matrix) model is defined for independent batch scheduling in physical network in DG and DC environments. In this model, the completion times of the computing nodes are estimated based on the standard ETC Matrix and data transmission times. The proposed model has been empirically evaluated on the static grid scheduling benchmark by using the simple genetic-based schedulers. A simple comparison of the achieved results for two basic scheduling metrics, namely makespan and average flowtime, with the results generated in the case of ignoring the data scheduling phase show the significant impact of the data processing model on the schedule execution times
An Ontological Framework for Representing Clinical Knowledge in Decision Support Systems, Journal of Telecommunications and Information Technology, 2014, nr 1
Get PDFIn the last decades, clinical evidence and expert consensus have been encoded into advanced Decision Support Systems (DSSs) in order to promote a better integration into the clinical workflow and facilitate the automatic provision of patient specific advice at the time and place where decisions are made. However, clinical knowledge, typically expressed as unstructured and free text guidelines, requires to be encoded into a computer interpretable form suitable for being interpreted and processed by DSSs. For this reason, this paper proposes an ontological framework, which enables the encoding of clinical guidelines from text to a formal representation, in order to allow querying, advanced reasoning and management in a well defined and rigorous way. In particular, it jointly manages declarative and procedural aspects of a standards based verifiable guideline model, named GLM-CDS (GuideLine Model for Clinical Decision Support), and expresses reasoning tasks that exploit such a represented knowledge in order to formalize integrity constraints, business rules and complex inference rules
Digital Fingerprinting Based on Quaternion Encryption Scheme for Gray-Tone Images, Journal of Telecommunications and Information Technology, 2014, nr 2
Get PDFIn this paper a new idea of digital images fi ngerprinting is proposed. The method is based on quaternion encryption in the Cipher Block Chaining (CBC) mode. Quaternions are hyper-complex numbers of rank 4 and thus often applied to mechanics in three-dimensional space. The encryption algorithm described in the paper is designed for graytone images but can easily be adopted for color ones. For the encryption purpose, the algorithm uses the rotation of data vectors presented as quaternions in a three-dimensional space around another quaternion (key). On the receiver's side, a small amount of unnoticeable by human eye errors occurs in the decrypted images. These errors are used as a user's digital ngerprint for the purpose of traitor tracing in case of copyright violation. A computer-based simulation was performed to scrutinize the potential presented quaternion encryption scheme for the implementation of digital ngerprinting. The obtained results are shown at the end of this paper
Utilization of the SOA Deep Saturation and Power Averaging Effect to Counteract Intra-Channel Crosstalk in DWDM System , Journal of Telecommunications and Information Technology, 2014, nr 2
Get PDFThe Semiconductor Optical Amplifier (SOA) is a key component of cost-effective short/medium range transmission systems. However it can introduce signal distortions. In this paper the authors investigate the possibility to reduce the signal distortions in SOA operating with the multiple wavelength channels. Using numerical simulations the negative influence of the nonlinear effects, namely cross-gain modulation (XGM) and the patterning effect can be reduced in deep SOA saturation regime. The self-healing effect is pronounced for the 4 or more wavelength channels and the transmitted symbol length longer than double of the SOA recovery tim