2014. 2nd issue
Full issue (27MB)
PAPERS FROM OPEN CALL
P. A. Kara, L. Bokor, and S. Imre
Analysis of Assessment Alteration Phenomena of Subjective Quality of Experience Measurements in 2D and 3D Mobile Video Services
The growing importance of Quality of Experience over Quality of Service demands precise results in the monitoring of experienced quality; empirical assessment of subjective QoE measurement on perceived quality is expected to deliver accurate reflection of reality. The goal of this paper is to highlight a specific potential error in existing subjective QoE measurement methodologies. Our approach focuses on a special topic of distortions caused by preconceptions based on prior technical knowledge of evaluation measurement test subjects. The paper presents two series of measurements where the test subjects were aware of the service parameters during the evaluation of the given services. The paper specifies the identified distortion phenomenon and shows how cognitive dissonance played a role in the formation of evaluation patterns and the distortion of the Mean Opinion Score.
T. J. Lampoltshammer and T. Heistracher
Ontology Evaluation with Protégé using OWLET
Amalgamation of formalised knowledge and realworld datasets is a pivotal challenge in the realm of information and communication technologies. Semi-automated classification of datasets can be performed by utilisation of ontologies. The detection process of image objects in Very High Resolution Satellite Imagery (VHRSI) gives a prominent example. The process of refinement of formalised expert knowledge within the related ontology still remains a challenging and time-consuming task. In this paper, the JSON2OWL Converter (OWLET) extension for Protégé is presented which supports experts during this refinement phase. The extension offers an integrated approach to transfer real-world dataset objects into the ontology modelling software for semi-automated classification. This transfer is achieved by combining open standard formats from both domains, the (Geo) Web domain (GeoJSON) and the Web ontology domain (OWL2). Thereby OWLET supports the process of accuracy analysis and accuracy fostering. By utilising the OWLET extension, experts can not only speed up their classification procedure considerably, but they can also refine their formalised knowledge by using the results of the classification process in conjunction with the outcomes of the accuracy analysis.
L. O. Widaa and S. M. Sharif
Design Optimization of Tracking Area List for Reducing Total Signaling Overhead in LTE Systems
In Long Term Evolution systems (LTE) the concept of Tracking Area List (TAL) is introduced. TAL consists of a group of Tracking Areas (TAs), and it is assigned to a User Equipment (UE), the UE does not need to register its location when it moves within TAs of the assigned TAL. If an optimum TAL design is implemented this may result in the reduction of total signaling overhead cost introduced by location update and paging procedures. One of the challenges of mobility management in cellular networks is the reduction of overall signaling overhead while maintaining acceptable performance. In this paper we propose a TAL design optimization for reducing overall signaling overhead algorithm. To achieve optimum TAL design a cell may change its current TAL, and this may cause a service interruption for active UEs in that cell. A budget constrain parameter is introduced to define the maximum number of cells change TALs while maintaining improved performance. For UE mobility modeling the data required can be obtain from the network management system which are cell load and handover statistical data. Markov model is used for UE mobility modeling. We present numerical results, from which we can say that the optimum TAL design returned from the proposed algorithm gave considerable reduction of overall signaling overhead cost compared to the traditional TA design.
L. Chiariglione and Cs. A. Szabó
Multimedia Communications: Technologies, Services, Perspectives / Part I. Technologies and Delivery Systems
This survey/position paper gives an overview of the state-of-the art multimedia communications technologies and services, analyses their evolution over the last decade, points out to their present significance and expected future role, and attempts to identify development trends. The paper consists of two parts. Part I deals with the technologies and systems for multimedia delivery. It covers the dedicated networks such as digital broadcasting systems and IPTV as well as the technologies of Internet based multimedia delivery. Networking issues in-cluding delivery over future Internet architectures and enabling technologies such as streaming and content delivery networks are dealt with in this part. Part II, to be published in the next issue of this journal, will address applications, services, and future directions..
PAPERS FROM RELATED AREAS
P. Fehér and P. Kristóf
Measuring and Controlling IT Services – The Case of Telecom Enterprises
Telecom enterprises are organizations with complex processes and structure the operation of which is highly dependent on information technology (IT) and the services provided by it. The landscape of the IT architecture reflects the complexity of the business processes. As this entanglement makes IT-based solutions and applications mission critical, securing the availability and operation of the services belongs to the top cost drivers at telecom enterprises, causing serious risks as well. Handling these costs and risks and aligning business strategy with IT-based solutions the use of Enterprise Architecture and IT controlling is suggested. The joint deployment of the two disciplines secure the measurement and controlling of IT services: the elaboration of the current state, the fact-based planning of the desired future state and the transition between them. Aligning business strategy and IT strategy helps optimizing infrastructure costs and mitigating risks. The paper gives a brief overview of the newest methodologies and emphasizes a holistic approach while bringing examples from the telecom industry.
High Speed Compression Algorithm for Columnar Data Storage
Lossless compression algorithms with very high compression and decompression speed are widely used in data warehouses today. Even small improvement of these algorithms can have high impact on storage space but more importantly on data access speed which effects response time of data analysis systems. We present a generic column storage compression algorithm (DictComp) with very fast compression and decompression speed. At worst the performance of the algorithm falls back to the LZ4  compression algorithm but on data dominated by few values (which is very frequent in unnormalized database tables) over 5 GB/sec/CPU core decompression speed can be achieved.
Gy. Hegedűs and K. Peeva-Müller
New Challenges and Comprehensive Risk Management Approaches in Modern Supply Chains
The highly specialized processes of modern supply chains, the diverse geographic distribution of suppliers and the complex electronic control systems are posing numerous new threats to companies in a global market environment more competitive than ever before. This article is about the risk-related challenges corporations face today as well as about the methods and practices they should consider applying in order to ensure the continuity of their daily operation and their supply chain in particular. In the introduction we present the current trends and fundamental challenges regarding modern supply chains. In the next chapter we introduce the method of ITBCP as a relatively new, but highly useful tool of managing IT-related operational risk factors and provide a high-level comparison with classic BCP methodologies. The third chapter is about the new challenges companies face in regard to various operational risks, while the fourth chapter briefly describes the most commonly used techniques of identifying and managing these threats. The last chapter serves as a conclusion, a summary why corporations need to take sophisticated preventive measures in order to minimize their risks threatening operational continuity.