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Conference on Next Generation Internet Networks, NGI

作者： Christos Bouras Apostolos Gkamas Georgios Kioumourtzis Computer Engineering and Informatics Department University of Patras Patras Greece Research Academic Computer Technology Institute Patras Greece

In this paper we introduce an equation-based smooth multicast congestion control for adaptive multimedia transmission over best-effort wired networks. Target of the proposed schema is (a) smooth transmission rate, in order to minimize the audio-video (AV) encoding and decoding distortion and (b) TCP friendly transmission. The "smoothness" lays in the way the TCP-friendly transmission rate is filtered. We integrate the congestion control functions in the RTP protocol and use the RTCP sender and receiver reports to provide the necessary feedback information for the sender's adaptive transmission rate. The performance evaluation of the smooth adaptation and TCP-friendliness is conducted through a number of simulations with the network simulator software (ns2). Our intention is to use this congestion control in the context of a proposed framework for multimedia transmission over wired and wireless networks.

关键词： Programmable control Adaptive control Bandwidth Feedback Multicast protocols Delay Decoding Equations Data communication Wireless application protocol

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A novel power counting mechanism for enhanced MBMS performance in UMTS networks

IFIP Advances in Information and Communication Technology

引用

IFIP Advances in Information and Communication technology 2008年 284卷 57-68页

作者： Alexiou, Antonios Bouras, Christos Rekkas, Evangelos Computer Engineering and Informatics Department University of Patras Greece Research Academic Computer Technology Institute 26500 Rio Patras Greece

ISBN: (纸本)9780387848389

One of the key objectives of Universal Mobile Telecommunications System (UMTS) is the realization of enhanced end-user experience through the provision of rich multimedia services, ensuring in parallel an economical delivery cost for service providers. Multimedia Broadcast/Multicast Services (MBMS) framework of UMTS epitomizes the increasing popularity of such applications by efficiently delivering multimedia traffic to a large number of users and optimizing the radio interface of UMTS networks. For exploiting resource efficiency, MBMS specifications consider the Counting Mechanism which decides whether it is more economic to deliver MBMS multicast traffic over point-to-point (PTP) or point-to multipoint (PTM) bearers. However, the necessity to further improve MBMS resource efficiency and integrate new technologies such as High Speed Downlink Packet Access (HSDPA) stresses the need for an advanced Counting Mechanism. To this direction, in this paper we propose a novel Power Counting Mechanism which performs optimal power resource utilization and incorporates the HSDPA broadband extension of UMTS for enhanced performance. © 2008, IFIP International Federation for Information Processing. All rights reserved.

关键词： Universal Mobile Telecommunications System

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Routing and scheduling connections in networks that support advance reservations

Routing and scheduling connections in networks that support ...

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International Conference on Broadband Networks (BroadNets)

作者： Emmanouel Varvarigos Vasileios Sourlas Konstantinos Christodoulopoulos Department of Computer Engineering and Informatics University of Patras Greece Research Academic Computer Technology Institute Patras Greece Department of Computer and Communication Engineering University of Thessally Greece

A key problem in networks that support advance reservations is the routing and time scheduling of connections with flexible starting time. In this paper we present a multicost routing and scheduling algorithm for selecting the path to be followed by such a connection and the time the data should start so as to minimize the reception time at the destination, or some other QoS requirement. The utilization profiles of the network links, the link propagation delays, and the parameters of the connection to be scheduled form the inputs to the algorithm. We initially present a scheme of non-polynomial complexity to compute a set of so-called non-dominated candidate paths, from which the optimal path can be found. By appropriately pruning the set of candidate paths using path pseudo-domination relationships, we also find multicost routing and scheduling algorithms of polynomial complexity. We examine the performance of the algorithms in the special case of an Optical Burst Switched network. Our results indicate that the proposed polynomial time algorithms have performance that it is very close to that of the optimal algorithm.

关键词： Routing Polynomials Scheduling algorithm Quality of service Processor scheduling computer networks Propagation delay Optical fiber networks informatics Protocols

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Adaptive smooth multicast protocol for multimedia data transmission

Adaptive smooth multicast protocol for multimedia data trans...

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International Symposium on Performance Evaluation of computer & Telecommunication Systems SPECTS

作者： Christos Bouras Apostolos Gkamas Georgios Kioumourtzis Research Academic Computer Technology Institute University of Patras Rion Greece Research Unit 6 Research Academic Computer Technology Institute Patras Greece Department of Telecommunications Science and Technology of Peloponnesus University of Greece Rion Greece Computer Engineering and Informatics Department University of Patras Rion Greece

ISBN: (纸本)9781424434497

We introduce Adaptive Smooth Multicast Protocol (ASMP), for multimedia transmission over best-effort networks. The smoothness lays in the calculation and adaptation of the transmission rate, which is based on dynamic estimation of protocol parameters and dynamic adjustment of the ldquosmoothness factorrdquo. ASMP key attributes are: (a) adaptive scalability to large sets of receivers, (b) TCP-friendly behavior, (c) high bandwidth utilization, and finally (d) smooth transmission rates, which are suitable for multimedia applications. We evaluate the performance of ASMP and investigate its behavior under various network conditions through extensive simulations, conducted with the network simulator software (ns2).

关键词： Multicast protocols Data communication Bandwidth Scalability Transport protocols Telecommunication computing Application software informatics Paper technology Streaming media

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New architectures for optical packet switching using QD-SOAs for multi-wavelength buffering

New architectures for optical packet switching using QD-SOAs...

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IEEE Workshop on High Performance Switching and Routing

作者： Kyriakos Vlachos Wojciech Kabacinski Slawomir Weclewski LComputer Engineering & Informatics Department and Research Academic Computer Technology Institute University of Patras Rio Greece Poznan University of Technology Poland

We present two architectures for implementing optical buffers. Both use multi-wavelength selective elements like quantum dot semiconductor optical amplifiers (QD-SOAs) as multi-wavelength converters and fixed-length delay lines that are combined to form both an output queuing and a parallel buffer switch design. The output queuing buffer design requires less active devices (QD-SOA) when implementing large buffers, but the parallel buffer design becomes more profitable, when the number of wavelength channels that can be simultaneously processed by the wavelength selective switches (QD-SOAs) increases. This is because the number of active devices depends only on the buffer size. We also proposed scheduling algorithm to resolve packet contention in parallel buffer architecture and carried out a simulation considering mean packet delay, maximum buffer occupancy and packet loss probability.

关键词： Optical packet switching Optical buffering Optical switches Delay lines Optical wavelength conversion Feedforward systems Dairy products Optical fiber networks Quantum dots Scheduling algorithm

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Balancing between power optimization and Iub efficiency in MBMS enabled UMTS networks

IFIP Advances in Information and Communication Technology

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IFIP Advances in Information and Communication technology 2008年 284卷 355-368页

作者： Alexiou, Antonios Bouras, Christos Kokkinos, Vasileios Computer Engineering and Informatics Dept Univ. of Patras Greece Research Academic Computer Technology Institute Greece University of Patras Rio Campus Rio Patras26500 Greece

ISBN: (纸本)9780387848389

Multicast transmission is one of the major goals for Universal Mobile Telecommunication System (UMTS) that motivated the 3rd Generation Partnership Project (3GPP) to launch the Multimedia Broadcast/Multicast Service (MBMS) framework. MBMS is a key framework that constitutes a significant step towards the so-called Mobile Broadband by efficiently utilizing network and radio resources, both in the core network and more importantly, in the UMTS Terrestrial Radio Access Network (UTRAN). One of most important problems that MBMS is currently facing is the assignment of the appropriate transport channel for the transmission of MBMS data. This paper proposes an alternative solution to the problem of efficient transport channel selection. In particular, we introduce a cost-based scheme for the efficient radio bearer selection that minimizes the delivery cost of the multicast data. In our approach, the telecommunication cost over the most crucial interfaces of UMTS is calculated and based on this cost, the appropriate radio bearer is selected. © 2008, IFIP International Federation for Information Processing. All rights reserved.

关键词： Costs

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Performance study of the Mobile IPv6 protocol and its variations

Performance study of the Mobile IPv6 protocol and its variat...

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International Symposium on Communication Systems, Networks and Digital Signal Processing, CNSDSP

作者： George Aristomenopoulos Christos Bouras Kostas Stamos Computer Engineering and Informatics Department University슠of슠Patras Greece Computer Engineering and Informatics Department University of Patras Patras Greece Research Academic Computer Technology Institute N.Kazantzaki Str. Patras Univ. GR-26500 Rion Greece

In this paper, we use the OMNET++ simulator in order to evaluate the performance of the basic mobile IPv6 protocol and some of its proposed variations. The most important metric we are interested in is the handover latency, which is measured for various combinations of the proposed mobile IPv6 variations and then this metric is used, combined with factors such as the complexity of the implementation, in order to evaluate and identify the best possible configuration for the operation of the protocol.

关键词： Mobile communication Manganese Protocols Mobile computing Internet Force Object oriented modeling

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Extending QoS support from Layer 3 to Layer 2

Extending QoS support from Layer 3 to Layer 2

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International Conference on Telecommunications (ICT)

作者： C. Bouras V. Kapoulas V. Papapanagiotou L. Poulopoulos D. Primpas K. Stamos Computer Engineering and Informatics Department University of Patras Greece Research Academic Computer Technology Institute Greece Res. Acad. Comput. Technol. Inst. Rion

This paper presents some of the results obtained by the application of Ethernet layer 2 quality of service in IP networks. IP networks traditionally provide quality of service in Layer 3. However, since there is an enormous existing Layer 2 infrastructure, todaypsilas networks could benefit from the deployment of Layer 2 quality of service and the cooperation between layer 2 quality of service and layer 3 quality of service. In this paper, experiments are suggested and conducted and a scheme is suggested for efficient cooperation between Layer 2 and Layer 3 QoS provisioning.

关键词： Quality of service Jitter Ethernet networks IP networks Bandwidth Throughput Loss measurement

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A General Analytical Method for the Performance Evaluation of Multistage Interconnection Networks Supporting Multi-Class Priority Traffic

A General Analytical Method for the Performance Evaluation o...

引用

4th Advanced International Conference on Telecommunications (AICT 2008)

作者： John Garofalakis Eleftherios Stergiou Department of Computer Engineering and Informatics University of Patras and Research Academic Computer Technology Institute Patras Greece Department Teleinformatics and Communication ATEI of Epirus Arta Greece

In this paper, our investigation focuses on the performance evaluation of Omega multistage interconnection networks which can natively support multi-class priority traffic. For this reason, a multi-buffered, single server switching element is presented and used in the construction of those networks, providing thus better quality of services. The performance evaluation model is based on steady state queuing analysis that leads to a novel utilization's formula. Based on the proposed analysis, other major performance indicators can also be accurately calculated The analytical method was meticulously validated by classic simulation and a part of obtained results was also compared by existing related work. Moreover, the proposed analytical method was found to be very accurate on performance estimations for various network sizes under different offered loads supporting multi-priority traffic. The rationale behind investigating a multi-priority traffic system is to provide efficient networks supporting optimum quality of services (i.e. streaming media vs. file transfer).

关键词： Performance analysis Multiprocessor interconnection networks Telecommunication traffic Traffic control Quality of service Network servers Steady-state Queueing analysis Analytical models Streaming media

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Evaluation of the multicast mode of MBMS

Evaluation of the multicast mode of MBMS

引用

18th IEEE International Symposium on Personal, Indoor and Mobile Radio Communication

作者： Alexiou, Antonios Bouras, Christos Kokkinos, Vasileios Rekkas, Evangelos Research Academic Computer Technology Institute Computer Engineering and Informatics Dept. Univ. of Patras Greece

ISBN: (纸本)9781424411436

Multicasting is an efficient way for delivering rich multimedia applications to large user groups as it allows the transmission of packets to multiple destinations using fewer network resources. Content and service providers are increasingly interested in supporting multicast communications over wireless networks and in particular over Universal Mobile Telecommunications System (UMTS). To this direction, the third Generation Partnership Project (3GPP) is currently standardizing the Multimedia Broadcast/Multicast Service (MBMS) framework of UMTS. In this paper, we present an overview of the MBMS multicast mode of UMTS. We analytically present the multicast mode of the MBMS and analyze its performance in terms of packet delivery cost under various network topologies, cell environments and multicast users' distributions. Furthermore, for the evaluation of the scheme, we consider different transport channels for the transmission of the data over the UTRAN interfaces and propose a cost based scheme for the efficient radio bearer selection that minimizes the packet delivery cost.

关键词： Multicasting

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