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51.
V. P. Demesticha E. C. Tzifa P. P. Demestichas M. E. Theologou 《International Journal of Communication Systems》1998,11(2):79-91
Future mobile communcation systems will have to provide sophisticated services at quality levels comparable with those provided by fixed systems. An additional requirement is that these systems should be deployed by minimally impacting the existing infrastructures. In this respect an important component of future mobile communication systems is their intelligent network segment, which contains the logic of the services provided and the relevant data required for providing these services. In the context of this paper we study the problem of designing this segment. Our reference system is UMTS, but the practices presented herein may be applied to other systems as well. We identify two major problems, the first at the Mobility and Services Control Point (MSCP) level and the second at the Mobility and Services Data Point (MSDP) level. Our aim in this paper is the following. First, the overall design process is decomposed into a sequence of well-defined problems. Second, the problems are formally stated and theoretically formulated. Third, owing to the computational complexity associated with the theoretical formulations, we take the first steps towards the design of approximate (heuristic) algorithms. Finally we provide results and draw subsequent conclusions. © 1998 John Wiley & Sons, Ltd. 相似文献
52.
I. Z. Koukoutsidis P. P. Demestichas M. E. Theologou 《Wireless Communications and Mobile Computing》2003,3(8):975-985
The essence of designing a good paging strategy is to incorporate the user mobility characteristics in a predictive mechanism that reduces the average paging cost with as little computational effort as possible. In this scope, we introduce a novel paging scheme based on the concept of reinforcement learning. Learning endows the paging mechanism with the predictive power necessary to determine a mobile terminal's position, without having to extract a location probability distribution for each specific user. The proposed algorithm is compared against a heuristic randomized learning strategy akin to reinforcement learning, that we invented for this purpose, and performs better than the case where no learning is used at all. It is shown that if the user normally moves only among a fraction of cells in the location area, significant savings can be achieved over the randomized strategy, without excessive time to train the network. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
53.
Cognitive radio is a highly promising answer to the complexity and heterogeneity characterizing the beyond 3G wireless scenario. In this context, this article advances from the field of interference sensing to the fields of (basic) reasoning and robust reasoning. Interference sensing is concerned with the acquisition of interference related measurements for frequency bands of interest. The article describes how a cognitive radio system can reason on these measurements to obtain estimations for the capabilities of alternate configurations, especially in terms of achievable transmission capacity and coverage. Subsequently, it focuses on robust reasoning, namely, on enhancing these estimations by employing machine learning, which constitutes an important aspect of cognitive radio. Several relevant solutions are sketched and explained, with a view to providing a complete picture. 相似文献
54.
P. P. Demestichas V. P. Demesticha Y. I. Manolessos G. D. Stamoulis M. E. Theologou 《Journal of Network and Systems Management》1999,7(2):177-197
The complexity and sophistication of integratedbroadband networks call for a broad repertoire ofmanagement methods. Foreseen intensive competition ofthe communications market, and the upgrade ofend-customer's satisfaction as the focal point of anymanagement policy, raise a very important problem: howto utilize efficiently the resources of the networkwhile maintaining the Quality of Service (QoS) provided to end-users within a pre-negotiated range. Inthis paper, a QoS management architecture for multimediaapplications based on an application control scheme isproposed. Adhering to the Total Quality Management (TQM) paradigm, we let management span over theentire communication stack, the entire network(end-to-end) and the entire call duration. Applicationcontrol scheme aims to meet pre-specified QoS goals by adjusting the traffic produced by theend-user applications. The adjustment technique is basedon the notion that each multimedia session is allowed tooperate on a set of discrete application quality levels. A method for monitoring and assessingthe end-user perceived quality is presented. Themathematical problem of optimal resources allocation andan associated heuristic are specified. Finally, a specific instantiation of the introduced QoSmanagement architecture on a real testbed is describedand experimentation results are presented andevaluated. 相似文献
55.
P. P. Demestichas E. C. Tzifa M. E. Anagnostou 《International Journal of Communication Systems》1998,11(5):337-349
A fundamental problem in third-generation mobile systems is the adaptation of the channel allocation to the traffic volume variation. Traffic adaptation may be partly achieved by the following (aggregate channel allocation) problem: given the set of channels, the cell structure and the load to be accommodated in each cell within a certain time zone, find the optimal allocation of channels to cells subject to the restrictions arising from the minimum permissible distance of cells where the same channel can be used at the same time. In this paper the problem is optimally formulated and efficiently solved by a heuristic. In the sequel the performance of a combined channel management scheme that uses the above problem for handling major traffic variations and a distributed DCA scheme for handling local traffic variations is assessed. Finally, results are presented and some concluding remarks are made. © 1998 John Wiley & Sons, Ltd. 相似文献
56.
57.
Louta M.D. Demestichas P.P. Loutas E.D. Kraounakis S.K. Theologou M.E. Anagnostou M.E. 《Wireless Personal Communications》2003,27(1):57-87
In future broadband fixed wireless access systems the overall design procedure is critical for their successful commercial deployment as well as their efficient operation and management. The problem addressed in this paper is twofold. Specifically, at a first phase the radio access network planning problem is addressed, which aims at finding the minimum-cost configuration of Access Point Transceivers (APTs) given thegeographical layout of the area to be covered. At the second phase, the interconnecting planning problem is addressed and aims at finding the minimum-cost configuration of the AccessPoint Controllers (APCs) and Inter-Working Units (IWUs) given the Access PointTransceivers layout. Both problems are formally defined, optimally formulated, and solved by computationally efficient heuristics. Finally, results are provided and subsequent conclusions are drawn. 相似文献
58.
A. Oikonomou P. Demestichas K. Tsagkaris G. Koundourakis M. Theologou 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2005,9(2):128-142
BRAN/WLAN systems, e.g., HIPERLAN/2, IEEE 802.11a, etc., are seen as a promising solution for covering residential, business, transport, tourism, etc., environments, and generally areas of high demand, characterized as “hot spots”. This paper presents management functionality for augmenting the potential exploitation of one of these systems, HIPERLAN/2, by making feasible their (loose or tight) integration in a composite radio (CR) context. The approach will be the following. The first point will be to revisit the main features of a HIPERLAN/2 system. Next, the architecture of a general Service and Network Management System (SNMS), which has been developed for assisting wireless systems in their operation in a CR context, will be briefly presented. The next main point will be the presentation of the functionality of the SNMS component that is tailored to the managed HIPERLAN/2 technology and specifically to the configuration of the Power Control (PC) functionality. An algorithm for configuring the PC operation, based on a greedy algorithm and a neural network, will be presented. A relevant resource management problem, which should be efficiently solved for exploiting HIPERLAN/2 networks, will be addressed. Numerical results will be presented.
Acknowledgment This work was partially funded by the Commission of the European Communities, under the Fifth Framework Program, within the IST project MONASIDRE (IST-2000-26144: Management of Networks and Services in Diversified Radio Environment). 相似文献
59.
Aimilia Bantouna Giorgos Poulios Kostas Tsagkaris Panagiotis Demestichas 《Journal of Network and Systems Management》2014,22(2):150-173
The pervasiveness of computers in everyday life has already increased and keeps increasing the available digital data both in volume and variety/disparity. This large and dynamic availability of digital data is referred to as Big Data and is very promising in bringing forward new insights and knowledge. For obtaining these insights, the proper combination and processing of the data is required. However, the dynamicity and the increasing size of data start making their handling impossible for analysts and raise many concerns on the manner in which data will be processed from now on. Towards this direction, this paper proposes a tool that processes and combines disparate data in order to create insights regarding a future network load. In particular, the tool (based on the unsupervised machine learning technique of Self-Organizing Maps) builds knowledge on the network load that is encountered with respect to the date of interest, the location, the weather, and the features of the day (e.g., weekend, bank holiday, etc.). The obtained results reveal that the tool is capable of learning the traffic pattern and thus predicting the network load that will be encountered in the near or distant future given information for the above presented parameters with small deviations (up to 0.000553 in terms of Mean Square Error). Moreover, the tool maintains only the most representative data instances and thus reduces the data storage requirements with no loss of information. 相似文献
60.
Panagiotis Demestichas Apostolos Katidiotis Kostas A. Tsagkaris Evgenia F. Adamopoulou Konstantinos P. Demestichas 《Wireless Personal Communications》2009,49(1):87-105
This paper proposes enhancements to the channel(-state) estimation phase of a cognitive radio system. Cognitive radio devices
have the ability to dynamically select their operating configurations, based on environment aspects, goals, profiles, preferences
etc. The proposed method aims at evaluating the various candidate configurations that a cognitive transmitter may operate
in, by associating a capability e.g., achievable bit-rate, with each of these configurations. It takes into account calculations
of channel capacity provided by channel-state estimation information (CSI) and the sensed environment, and at the same time
increases the certainty about the configuration evaluations by considering past experience and knowledge through the use of
Bayesian networks. Results from comprehensive scenarios show the impact of our method on the behaviour of cognitive radio
systems, whereas potential application and future work are identified.
Panagiotis Demestichas was born in Athens, Greece, in 1967. He received the Diploma and the Ph.D. degrees in Electrical and Computer Engineering from the National Technical University of Athens (NTUA). From December 2007 he is Associate Professor at the University of Piraeus, in the department of Technology Education and Digital Systems. From September 2002–December 2007 he was Assistant Professor at the University of Piraeus, in the department of Technology Education and Digital Systems. From 1993–2002 he has been with the Telecommunications Laboratory in NTUA. From February 2001 until August 2002 he was adjunct lecturer at NTUA, in the department of Applied Mathematics and Physics. From September 2000 until August 2002 he taught telecommunication courses, in the department of Electronics of the Technological Education Institute of Piraeus. He leads the laboratory of Telecommunication Networks and Services, of the University of Piraeus. At the international level he actively contributes to research funded from various EU frameworks for research and technological development. Most of his current activities focus on the FP7 “End-to-End Efficiency” (E3) project, which is targeted to the introduction of cognitive systems in the wireless B3G world. He has actively participated to projects of the IST/FP6, IST/FP5, ACTS, RACE II, BRITE/EURAM and EURET frameworks. In IST/FP6, in the time frame 2004–2007, he participated to the “End-to-End Reconfigurability” (E2R) project, where he was leader of the workpackage on “proof of concept and validation”. In IST/FP5 he was involved in the management of the MONASIDRE project, which was targeted to the collaboration of UMTS, WLAN and DVB technologies, in the context of a B3G infrastructure. He is the chairman of Working Group 6 (WG6), titled “Cognitive Wireless Networks and Systems”, of the Wireless World Research Forum (WWRF). He is involved in standardisation in the context of ETSI and IEEE SCC4 He has extensive collaborations with Greek companies of the IT and telecommunications sectors. His research interests include the design, management and performance evaluation of mobile and broadband networks, service and software engineering, algorithms and complexity theory, and queuing theory. He is a member of the IEEE, ACM and the Technical Chamber of Greece.
Apostolos Katidiotis was born in Maroussi, Athens in November, 1980. He received his diploma in 2003 from the Department of Technology Education and Digital Systems in University of Piraeus. Since September 2003 he is a research engineer and Ph.D. candidate at the University of Piraeus, Laboratory of Telecommunication Networks and Services. His research interests include the design, management and performance evaluation of mobile and broadband networks, reconfigurable and cognitive systems, service and software engineering.
Kostas A. Tsagkaris was born in Lamia, Greece. He received his diploma (in 2000) and his Ph.D. degree (in 2004) from the School of Electrical Engineering and Computer Science of the National Technical University of Athens (NTUA). His Ph.D. thesis was awarded in 2005 “Ericsson’s awards of excellence in Telecommunications”. He has been involved in many international and national research projects, especially working on the area of wireless networks resource management and optimization. He has been involved in many international and national research projects, especially working on the area of wireless networks resource management and optimization. Since January 2004 he is working as a senior research engineer at the Department of Technology Education and Digital Systems of the University of Piraeus. From September 2005 he is an adjunct Lecturer in the undergraduate and postgraduate programs of the Department of Technology Education and Digital Systems of the University of Piraeus. His current interests are in the design and management of wireless reconfigurable networks, optimization algorithms, learning techniques and software engineering. Dr. Tsagkaris is a member of IEEE, ACM and a member of the Technical Chamber of Greece.
Evgenia F. Adamopoulou (jenny@cn.ntua.gr) was born in Athens, Greece, on November 15, 1982. She received her Dipl.- Ing. degree from the School of Electrical and Computer Engineering of the National Technical University of Athens (NTUA) in 2005. She is currently working toward a Ph.D. degree at the same institution. Her research interests include wireless communication systems, information systems and telecommunication software design and implementation. She is a member of the Technical Chamber of Greece.
Konstantinos P. Demestichas (cdemest@cn.ntua.gr) was born in Athens, Greece, on May 19, 1982. He received his Dipl.-Ing. degree from the School of Electrical and Computer Engineering of the National Technical University of Athens (NTUA) in 200 He is currently working toward a Ph.D. degree at the same institution. His research interests include wireless communication systems, information systems and telecommunication software design and implementation. He is a member of the Technical Chamber of Greece. 相似文献
Konstantinos P. DemestichasEmail: |
Panagiotis Demestichas was born in Athens, Greece, in 1967. He received the Diploma and the Ph.D. degrees in Electrical and Computer Engineering from the National Technical University of Athens (NTUA). From December 2007 he is Associate Professor at the University of Piraeus, in the department of Technology Education and Digital Systems. From September 2002–December 2007 he was Assistant Professor at the University of Piraeus, in the department of Technology Education and Digital Systems. From 1993–2002 he has been with the Telecommunications Laboratory in NTUA. From February 2001 until August 2002 he was adjunct lecturer at NTUA, in the department of Applied Mathematics and Physics. From September 2000 until August 2002 he taught telecommunication courses, in the department of Electronics of the Technological Education Institute of Piraeus. He leads the laboratory of Telecommunication Networks and Services, of the University of Piraeus. At the international level he actively contributes to research funded from various EU frameworks for research and technological development. Most of his current activities focus on the FP7 “End-to-End Efficiency” (E3) project, which is targeted to the introduction of cognitive systems in the wireless B3G world. He has actively participated to projects of the IST/FP6, IST/FP5, ACTS, RACE II, BRITE/EURAM and EURET frameworks. In IST/FP6, in the time frame 2004–2007, he participated to the “End-to-End Reconfigurability” (E2R) project, where he was leader of the workpackage on “proof of concept and validation”. In IST/FP5 he was involved in the management of the MONASIDRE project, which was targeted to the collaboration of UMTS, WLAN and DVB technologies, in the context of a B3G infrastructure. He is the chairman of Working Group 6 (WG6), titled “Cognitive Wireless Networks and Systems”, of the Wireless World Research Forum (WWRF). He is involved in standardisation in the context of ETSI and IEEE SCC4 He has extensive collaborations with Greek companies of the IT and telecommunications sectors. His research interests include the design, management and performance evaluation of mobile and broadband networks, service and software engineering, algorithms and complexity theory, and queuing theory. He is a member of the IEEE, ACM and the Technical Chamber of Greece.
Apostolos Katidiotis was born in Maroussi, Athens in November, 1980. He received his diploma in 2003 from the Department of Technology Education and Digital Systems in University of Piraeus. Since September 2003 he is a research engineer and Ph.D. candidate at the University of Piraeus, Laboratory of Telecommunication Networks and Services. His research interests include the design, management and performance evaluation of mobile and broadband networks, reconfigurable and cognitive systems, service and software engineering.
Kostas A. Tsagkaris was born in Lamia, Greece. He received his diploma (in 2000) and his Ph.D. degree (in 2004) from the School of Electrical Engineering and Computer Science of the National Technical University of Athens (NTUA). His Ph.D. thesis was awarded in 2005 “Ericsson’s awards of excellence in Telecommunications”. He has been involved in many international and national research projects, especially working on the area of wireless networks resource management and optimization. He has been involved in many international and national research projects, especially working on the area of wireless networks resource management and optimization. Since January 2004 he is working as a senior research engineer at the Department of Technology Education and Digital Systems of the University of Piraeus. From September 2005 he is an adjunct Lecturer in the undergraduate and postgraduate programs of the Department of Technology Education and Digital Systems of the University of Piraeus. His current interests are in the design and management of wireless reconfigurable networks, optimization algorithms, learning techniques and software engineering. Dr. Tsagkaris is a member of IEEE, ACM and a member of the Technical Chamber of Greece.
Evgenia F. Adamopoulou (jenny@cn.ntua.gr) was born in Athens, Greece, on November 15, 1982. She received her Dipl.- Ing. degree from the School of Electrical and Computer Engineering of the National Technical University of Athens (NTUA) in 2005. She is currently working toward a Ph.D. degree at the same institution. Her research interests include wireless communication systems, information systems and telecommunication software design and implementation. She is a member of the Technical Chamber of Greece.
Konstantinos P. Demestichas (cdemest@cn.ntua.gr) was born in Athens, Greece, on May 19, 1982. He received his Dipl.-Ing. degree from the School of Electrical and Computer Engineering of the National Technical University of Athens (NTUA) in 200 He is currently working toward a Ph.D. degree at the same institution. His research interests include wireless communication systems, information systems and telecommunication software design and implementation. He is a member of the Technical Chamber of Greece. 相似文献