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  • 51.
    Popescu, Adrian
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Dealing with QoE and Power Consumption in Video Distribution Networks2016Inngår i: 2016 INTERNATIONAL CONFERENCE ON COMMUNICATIONS (COMM 2016), 2016, s. 3-8Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The paper is about the problem of reducing the power consumption in Video Distribution Networks (VDNs) under the condition of best performance provision in terms of Quality of Experience (QuE) measured at the end user. Related to this, it has been observed that, given an end-to-end video distribution network, it is the last networking segment ending to terminal that has the dominant role in the provision of end-user performance. On the other hand, the rest of the video distribution chain can be optimized such to reduce the power consumption under the requirements of provision of specific Quality of Service (QoS) parameters. The paper first provides an overview of VDNs, which is followed by a short presentation of the CONVINcE project. The second part is focused on the problems of performance provision in VDN in terms of best possible Quality of Experience and minimum end-to-end power consumption.

  • 52.
    Popescu, Adrian
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Greening of IP-Based Video Distribution Networks: Developments and Challenges2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The creation and the distribution of video content is a multistage process that refers to the aquisition of video source, content production and packaging, and distribution to customers. The major components are the access networks, metro/edge networks, core networks, data centers and storage networks. Today, the access networks, of type wireless and wired, dominate the power consumption of the chain. However, it is expected that, with increasing access speeds, the core network routing will dominate the power consumption of the chain as well. Furthermore, it is also expected that the power consumption of Data Centers (DCs) and Content Distribution Networks (CDNs) will be dominated by the power consumption of data storage for content that is infrequently downloaded as well as by the transport of data for content that is frequently downloaded. The paper provides an overview of the problems related to the greening of IP-based video distribution, with particular focus on recent developments and the associated challenges. These are research topics planned to be solved by the last call Celtic-Plus project proposal CONVINcE (Consumption OptimizatioN in Video Networks). This research project has received the EUREKA Celtic-Plus label for funding approval in five European countries: France, Sweden, Finland, Romania and Turkey. It is considered to be a very high quality research and the topic is considered to be very relevant to our future from ecological and economical view.

  • 53.
    Popescu, Adrian
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Greening Video Distribution: Networks Energy-Efficient Internet Video Delivery2018Collection/Antologi (Fagfellevurdert)
    Abstract [en]

    This insightful text presents a guide to video distribution networks (VDNs), providing illuminating perspectives on reducing power consumption in IP-based video networks from an authoritative selection of experts in the field. A particular focus is provided on aspects of architectures, models, Internet protocol television (IPTV), over-the-top (OTT) video content, video on demand (VoD) encoding and decoding, mobile terminals, wireless multimedia sensor networks (WMSNs), software defined networking (SDN), and techno-economic issues.

    Topics and features: reviews the fundamentals of video over IP distribution systems, and the trade-offs between network/service performance and energy efficiency in VDNs; describes the characterization of the main elements in a video distribution chain, and techniques to decrease energy consumption in software-based VoD encoding; introduces an approach to reduce power consumption in mobile terminals during video playback, and in data center networks using the SDN paradigm; discusses the strengths and limitations of different methods for measuring the energy consumption of mobile devices; proposes optimization methods to improve the energy efficiency of WMSNs, and a routing algorithm that reduces energy consumption while maintaining the bandwidth; presents an economic analysis of the savings yielded by approaches to minimize energy consumption of IPTV and OTT video content services.

    The broad coverage and practical insights offered in this timely volume will be of great value to all researchers, practitioners and students involved with computer and telecommunication systems.​

  • 54. Popescu, Adrian
    IP QoS: The Challenge of Building Efficient Networks2002Annet (Annet vitenskapelig)
    Abstract [en]

    The tutorial is about the main challenges in developing the new Internet. Different aspects related to IP QoS are analyzed. Furthermore, a theoretical case-study on resource engineering for supporting Service Level Agreements (SLAs) on IP networks is used to support the analysis.

  • 55. Popescu, Adrian
    Modeling and Analysis of Network Applications and Services1998Annet (Annet vitenskapelig)
    Abstract [en]

    Recent traffic measurement studies from a wide range of working packet networks have convincingly shown the presence of self-similar (long-range dependence LRD) properties in both local and wide area traffic traces. LRD processes are characterized (in the case of finite variance) by self-similarity of aggregated summands, slowly decaying covariances, heavy-tailed distributions and a spectral density that tends to infinity for frequencies approaching zero. This discovery calls to question some of the basic assumptions made by most of the research in control, engineering and operations of broadband integrated systems. At the time being, there is mounting evidence that self-similarity is of fundamental importance for a number of teletraffic engineering problems, such as traffic measurements and modeling, queueing behavior and buffer sizing, admission control, congestion control, etc. These impacts have highlighted the need for precise and computationally feasible methods to estimate diverse LRD parameters. Especially real-time estimation of measured data traces and off-line analysis of enormous collected data sets call for accurate and effective estimation techniques. A wavelet-based tool for the analysis of LRD is presented in this paper together with a semi-parametric estimator of the Hurst parameter. The estimator has been proved to be unbiased under fractional Brownian motion fBm and Gaussian assumptions. Analysis of the Bellcore Ethernet traces using the wavelet-based estimator is also reported.

  • 56.
    Popescu, Adrian
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    Routing on Overlay Networks: Developments and Challenges2005Inngår i: IEEE Communications Magazine, ISSN 0163-6804, Vol. 43, nr 8Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Overlay networks are networks operating on the inter-domain level, where the edge hosts learn of each other and, based on knowledge of underlying network performance, they form loosely coupled neighboring relationships. These relationships can be used to induce a specific graph, where nodes are representing hosts and edges are representing neighboring relationships. Graph abstraction and the associated graph theory can be further used to formulate routing algorithms on overlay networks. The main advantage of overlay networks is that they offer the possibility to augment the IP routing as well as the QoS functionality offered by the Internet.

  • 57. Popescu, Adrian
    Traffic Self-Similarity2001Annet (Annet vitenskapelig)
    Abstract [en]

    The tutorial is about traffic self-similarity. It is a review of basic concepts in traffic self-similarity. It is about definitions of self-similarity, key properties, measurements, models, generation of synthetic traces, revealing of specific properties in self-similar traffic, origins as well as performance impacts

  • 58. Popescu, Adrian
    et al.
    Akyildizapo, Ian
    NEMESIS: A Multigigabit Optical Local Area Network1994Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A new architecture is developed for an integrated 20 Gbps fiber optic Local Area Network (LAN) that supports data rates up to 9.6 Gbps. The architecture does not follow the standard, vertically-oriented Open System Interconnection (OSI) layering approach of other LANs. Instead, a horizontally-oriented model is introduced for the communication process to open up the three fundamental bottlenecks, i.e., opto-electronic, service and processing bottlenecks, that occur in a multi-Gbps integrated communication over multiwavelength optical networks. Furthermore, the design follows also a new concept called Wavelength-Dedicated-to-Application (WDA) concept in opening up the opto-electronic and service bottlenecks. Separate, simplified, and application-oriented protocols supporting both circuit- and packet-switching are used to open up the processing bottleneck.

  • 59. Popescu, Adrian
    et al.
    Ayani, Rassul
    Modeling and Analysis of Multi-Access Mechanisms in SUPERLAN1999Inngår i: Network Systems Design / [ed] Gelenbe, Erol; Bagchi, Kallol K.; Zobrist, George W., Gordon and Breach Science Publishers , 1999, s. 47-68Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    Today, new multi-Gbps LANs are designed to support a wide range of applications generating isochronous and nonisochronous traffic at arbitrary bit rates. The growing demand for high bandwidth networking, under increasing performance constraints, has posed fundamental challenges to LAN design and implementation. Three fundamental bottlenecks exist in a multi-Gbps LAN environment that must be handled in order to achieve optimal performance. These are: opto-electronic bottleneck, service bottleneck, and processing bottleneck. A novel architectural solution is proposed to open up these bottlenecks. Total network throughput of about 20 Gbps is achievable. Performance modeling, analysis and evaluation is reported for a class of Medium Access Protocols (MAC) for isochronous traffic. The performance results show good and very good performance for this solution.

  • 60.
    Popescu, Adrian
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Chaudhry, Mohammad Asad Rehman
    Soptimizer, CAN.
    Managing the OTT Traffic in NFV Environment2018Inngår i: 2018 12th International Conference on Communications, COMM 2018 - Proceedings, Institute of Electrical and Electronics Engineers Inc. , 2018, s. 3-10, artikkel-id 8430182Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The emerging concepts Software Defined Networking (SDN) and Network Functions Virtualisation (NFV) lay the ground for system softwarization of future networks and services, under the umbrella of 5G. In this regard, a special focus is given to Video Distribution Networks (VDN), particularly in relation to existing difficulties in handling demands laid on the network as well as in relation to challenges in providing the expected Quality of Experience (QoE) and other performance demands like minimum energy consumption. The paper is focused on some of the most important elements associated with the virtualisation of Over-The-Top (OTT) video distribution networks and also advancing the system for managing the OTT traffic in Network Function Virtualisation (NFV) environment. The paper provides motivation, problem description, virtualisation target, standardisation efforts, NFV framework as well as short presentation of the main technical issues associated with managing the OTT traffic inNFV scenarios. © 2018 IEEE.

  • 61.
    Popescu, Adrian
    et al.
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    Constantinescu, Doru
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    Measurement of One-Way Transit Time in IP Routers2005Annet (Annet vitenskapelig)
    Abstract [en]

    The main goals of the tutorial are towards an understanding of the delay process in best-effort Internet for both non-congested and congested networks. A novel measurement system is reported for delay measurements in IP routers, which follows specifications of the IETF RFC 2679. The system is using both passive measurements and active probing and offers the possibility to measure and analyze different delay components of a router, e.g., packet processing delay, packet transmission time and queueing delay at the output link. Dedicated application-layer software is used to generate UDP traffic with TCP-like characteristics. Pareto traffic models are used to generate self-similar traffic in the link. The reported results are in form of several important statistics regarding processing and queueing delays of a router, router delay for a single data flow, router delay for more data flows as well as end-to-end delay for a chain of routers. We confirm results reported earlier about the fact that the delay in IP routers is generally influenced by traffic characteristics, link conditions and, at some extent, details in hardware implementation and different IOS releases. The delay in IP routers may also occasionally show extreme values, which are due to improper functioning of the routers. Furthermore, new results have been obtained that indicate that the delay in IP routers shows heavy-tailed characteristics, which can be well modeled with the help of three distributions, either in the form of single distribution or as a mixture of two distributions. There are several components contributing to the One-Way Transit Time (OWTT) in routers, i.e., processing delay, queueing delay and service time. Our results have shown that, e.g., the processing delay in a router can be modeled with the Normal or skewed Normal distribution, and the queueing delay is well modeled with a mixture of Normal distribution for the body probability mass and of Weibull distribution for the tail probability mass. It has been also observed that One-Way Transit Time (OWTT) is well modeled with the generalized Pareto distribution. Furthermore, OWTT has several component delays and it has been observed that the component delay distribution that is most dominant and heavy-tailed has a decisive influence on OWTT. To the best of our knowledge, this is the first time we understand the distributional properties of the delay process in an IP router.

  • 62. Popescu, Adrian
    et al.
    Constantinescu, Doru
    On Kleinrock's Independence Assumption2011Inngår i: Lecture Notes in Computer Science: Next Generation Internet / [ed] Kouvatsos, Demetres D., Heidelberg, Germany: Springer-Verlag , 2011, s. 1-13Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    The paper is about analyzing the delay performance in a chain of IP routers, with focus on queueing delay and the correlations existing in a tandem queueing system. Leonard Kleinrock independence assumption is particularly considered, based on which the correlations can be ignored, and the effect on delay performance is negligible, under specific assumptions like for instance Poisson arrival processes, Exponential distribution for packet lengths, sufficient traffic mixing and moderate-to-heavy traffic loads. Furthermore, the paper is reporting on results obtained in experiments done at the Blekinge Institute of Technology in Karlskrona, Sweden, on measurements, modeling and analysis of delay in a chain of IP routers. Particular focus is given to validating the Kleinrock independence assumption regarding the effect of correlations in a tandem queueing system. Our results show that this assumption is not valid in our experiments, and this is particularly observed in the end-to-end delay distribution.

  • 63.
    Popescu, Adrian
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Erman, David
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Ilie, Dragos
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Popescu, Alexandru
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Vogeleer, Karel De
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Seamless Roaming: Developments and Challenges2011Inngår i: Lecture Notes in Computer Science, ISSN 0302-9743, E-ISSN 1611-3349, Vol. 5233, s. 795-807Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The chapter reports on recent developments and challenges focused on seamless handover. These are subject for the research projects MOBICOME and PERIMETER, recently granted by the EU EUREKA and EU STREP FP7, respectively. The research projects are considering the recently advanced IP Multimedia Subsystem (IMS), which is a Set of technology standards put forth by the Internet Engineering Task Force (IETF) and two Third Generation Partnership Project groups, namely 3GPP and 3GPP2. The foundation of seamless handover is provided by several components, the most important ones being the handover, mobility management, connectivity management and Internet mobility. The paper provides an intensive analysis of these components.

  • 64. Popescu, Adrian
    et al.
    Erman, David
    Ilie, Dragos
    Popescu, Alexandru
    Fiedler, Markus
    Vogeleer, Karel De
    Seamless Roaming: Developments and Challenges2008Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    The paper reports on recent developments and challenges focused on seamless handover. These are subject for the research projects MOBICOME and PERIMETER, recently granted by the EU EUREKA and EU STREP FP7, respectively. The research projects are considering the recently advanced IP Multimedia Subsystem (IMS), which is a set of technology standards put forth by the Internet Engineering Task Force (IETF) and two Third Generation Partnership Project groups, namely 3GPP and 3GPP2. The foundation of seamless handover is provided by several components, the most important ones being the handover, mobility management, connectivity management and Internet mobility. The paper provides an intensive analysis of these components.

  • 65. Popescu, Adrian
    et al.
    Erman, David
    Vogeleer, Karel De
    Popescu, Alexandru
    Fiedler, Markus
    ROMA: A Middleware Framework for Seamless Handover2009Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The paper reports on a new middleware architecture suggested for seamless handover. The middleware is part of an architectural solution suggested by Blekinge Institute of Technology (BTH) for seamless handover, which is implemented at the application layer. This architecture is sub ject for the PERIMETER STREP and MOBICOME pro jects, granted by the EU FP7 and EUREKA, respectively. Compared to the existent handover solutions, implemented at the link layer and network layer, this solution offers the advantage of less dependence on physical parameters and more flexibility in the design of architectural solutions. Furthermore, it allows for dynamic combinations of services and underlying transport substrates (overlays and networks). The suggested middleware, called ROMA, represents a software system with two sets of APIs, one for application writers and another one for interfacing various overlay and un- derlay systems. ROMA thus provides a transport-agnostic platform for future Internet applications. The paper provides a short description of the ROMA middleware, with par- ticular focus on API design and address translation.

  • 66. Popescu, Adrian
    et al.
    Erman, David
    Vogeleer, Karel De
    Popescu, Alexandru
    Fiedler, Markus
    ROMA: A Middleware Framework for Seamless Handover2011Inngår i: Lecture Notes in Computer Science, ISSN 0302-9743, E-ISSN 1611-3349, Vol. 5233, s. 784-794Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The chapter reports on a new middleware architecture suggested for seamless handover. The middleware is part of an architectural solution suggested by Blekinge Institute of Technology (BTH) for seamless handover, which is implemented at the application layer. This architectures is subject for the PERIMETER STREP and MOBICOME projects, granted by the EU FP7 and EUREKA, respectively. The suggested middleware called ROMA represents a software system with two sets of Application Programmer Interface (API), one for application writers and another one for interfacing various overlay and underlay systems. ROMA thus provides a transport-agnostic platform for future Internet applications. The paper provides a short description of the ROMA middleware, with particular focus on API design and address translation.

  • 67. Popescu, Adrian
    et al.
    Fiedler, Markus
    Kouvatsos, Demetres
    Content Distribution over IP: Developments and Challenges2006Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This is an invited tutorial on "Content Distribution over IP: Developments and Challenges", with special focus on overlay routing

  • 68. Popescu, Adrian
    et al.
    Ilie, Dragos
    Erman, David
    Fiedler, Markus
    Popescu, Alexandru
    Vogeleer, Karel de
    An Application Layer architecture for Seamless Roaming2009Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The paper advances a new architecture for seamless roaming, which is implemented at the application layer. This architecture is subject for the research projects PERIMETER and MOBICOME, recently granted by the EU STREP FP7 and EUREKA, respectively. The research challenges are on mobility management, security, QoE management, overlay routing, node positioning, mobility modeling and prediction, middleware and handover. The foundation of seamless handover is provided by several components, the most important ones being the handover, mobility management, connectivity management and Internet mobility. The paper provides an analysis of these components

  • 69. Popescu, Adrian
    et al.
    Jena, Ajit K.
    Nilsson, Arne A.
    Modeling and Evaluation of Internet Applications2003Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The paper presents a modeling and evaluation study of the characteristics of SMTP and HTTP applications in terms of user behavior, nature of contents transferred and application layer protocol exchanges. Results are reported on measuring, modeling and analysis of application level traces collected, at client and server ends, from different environments such as university networks and commercial Frame Relay networks. The methodologies used for capturing traffic flows and for modeling are reported. Statistical models have been developed for diverse parameters of applications, which can be useful for building synthetic workloads for simulation and benchmarking purposes. Both applications possess a session oriented structure. Within each session, a number of transactions may occur, and this number has been modeled as well.

  • 70. Popescu, Adrian
    et al.
    Jena, Ajit K.
    Nilsson, Arne A.
    Resource Engineering for Internet Applications2003Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The focus of the paper is on resource engineering for supporting Service Level Agreements (SLAs) in IP networks. We review some of the recent developments in Internet service architecture and protocol developments as well as some of the most important challenges still to be considered. An important performance metrics that must be considered in developing the new Internet is regarding the delay and the delay variation/jitter. Connected with this, a case-study is reported on end-to-end delay performane in a simple model for best-effort Internet where the bandwidth is not a commodity. The case-study is based on a client-server simulation model. The client and the server nodes are running applications like HTTP and SMTP, and they are placed in two sites separated by an Internet cloud. Performance issues of Short Range Dependence (SRD) and Long Range Dependence (LRD) traffic under different resource control regimes are compared. The results highlight the importance of the queueing delay at the WAN ingress point, which is due to the significant bandwidth differences that may exist, in this case, between the LAN and WAN link layers. The results also highlight the role TCP window size and Frame Relay Permanent Virtual Channel (FR PVC) control mechanisms play in the provision of delay performance for Internet services.

  • 71.
    Popescu, Adrian
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Kim, Haesik
    Davoli, Franco
    Lopez, Raul Dopico
    Thao, Somsai
    Del Ser, Javier
    Wunder, Garhard
    ENVIRAN: Energy Efficient Virtual Radio Access Networks2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    ENVIRAN is a new research project aiming at the research, design and deployment of new architectural solutions for network virtualization and cognitive radio networks. The project is about developing and testing a new network architecture, to enable innovation through programmability and control of network functions and protocols. For doing this, we solve different technical challenges. These are about network virtualization, open architecture, reconfigurable software suite, virtual base station and decision support system. Another important part of the project is regarding the development of a cognitive virtualization platform, to test the new developed solutions. It is well known that cognitive radio technology is a key concept suggested to use the radio frequency spectrum in a more efficient manner than previous mobile networks. The difference in our case is that the cognition is used not only to provide better resource use for bandwidth but also for other categories of resources like energy/power consumption (by using, e.g., green routing, cooperative/relay networking), hardware utilization (in form of, e.g., virtual Base Stations, cognitive/reconfigurable wireless devices), reduce the cost of supporting the required QoS/QoE, new business models. Cognition and virtualization concepts are used to increase the efficiency of network management and resource utilization as well as to reduce the power consumption and the cost of supporting the expected QoS/QoE for communication. The expected research results will be tested, among others, in the world-wide virtual network PlanetLab.

  • 72. Popescu, Adrian
    et al.
    Kouvatsos, Demetres
    Remondo, David
    Giordano, Stefano
    Content Distribution over IP: Developments and Challenges2011Inngår i: Lecture Notes in Computer Science, ISSN 0302-9743, E-ISSN 1611-3349, Vol. 5233, s. 979-987Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This chapter focuses on the multimedia distribution over Internet IP under the auspices of the NoE Euro-NGI research project "Routing in Overlay Networks (ROVER)". The multimedia distribution is supported by several components such as services, content distribution chain, protocols and standards whilst Internet is used for content, acquisition, management and delivery as well as an Internet; Protocol Television (IPTV) infrastructure with QoS facilities. As the convergence between fixed and mobile services of wide and local area networks is also expected to take place in the home networking, this puts an extra burden on multimedia distribution, which requires the different, types of wireless access solutions (e.g., WiMAX). In this context, the ROVER, research project adopts the IP Multimedia Subsystem (IMS), which offers a wide range of multimedia services over a single IP infrastructure such as authentication and, for wireless services, roaming capabilities. The research project also considers overlay routing as an alternative solution for content distribution.

  • 73. Popescu, Adrian
    et al.
    Pruthi, Parag
    Dynamic Time Sharing: A New Approach For Congestion Management1996Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A new approach for bandwidth allocation and congestion control is reported in this paper, which is of the Rate Controlled admission with Priority Scheduling service type. It is called Dynamic Time Sharing (DTS), because of the dynamic nature of the procedure for resource partitioning to allocate and guarantee a required bandwidth for every traffic class. This approach is based on guaranteeing specific traffic parameters (bandwidth requirements) through a policing unit, and then optimizing the bandwidth assignment within the network for specific parameters of interest (like delay or jitter, and loss). The optimization process is based on the parameters guaranteed by the policing unit. A batch admission policy is used at the edges of the network according to a specific framing strategy to follow the traffic characteristics (e.g., the traffic constraint function) of different traffic classes. On the other hand, another framing (congestion control) strategy is used within the network, which is based on different (delay/loss) requirements of the traffic classes. Proper management of bandwidth and buffer resources is provided in every (switch) node of the network, such as to guarantee the diverse performance of interest.

  • 74. Popescu, Adrian
    et al.
    Pruthi, Parag
    Dynamic Time Sharing: A New Approach For Congestion Management1997Inngår i: ATM Networks: Performance Modelling and Analysis / [ed] Kouvatsos, Demetres, London: Chapman & Hall , 1997Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    A new approach for bandwidth allocation and congestion control is reported in this paper, which is of the Rate Controlled admission with Priority Scheduling service type. It is called Dynamic Time Sharing (DTS), because of the dynamic nature of the procedure for resource partitioning to allocate and guarantee a requested bandwidth for every traffic class. This approach is based on guaranteeing specific traffic parameters (bandwidth requirements) through a policing unit, and then optimizing the bandwidth assignment within the network for specific parameters of interest (like delay or jitter, and loss). The optimization process is based on the parameters guaranteed by the policing unit. The policing unit also functions to enforce the "fair" sharing of resources. A batch admission policy is used at the edges of the network according to a specific framing strategy to follow the traffic characteristics (e.g., the traffic constraint function) of different traffic classes. On the other hand, the DTS mechanism allows for another framing (congestion control) strategy to be used within the network, which is based on different (delay/loss) requirements of the traffic classes. Proper management of bandwidth and buffer resources is provided in every (switch) node of the network, such as to guarantee the diverse performance of interest.

  • 75.
    Popescu, Adrian
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Yao, Yong
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för teknik och estetik.
    Ducloux, Xavier
    Harmonic, FRA.
    Video Distribution Networks: Models and Performance2018Inngår i: Greening Video Distribution Networks: Energy-Efficient Internet Video Delivery / [ed] Adrian Popescu, Springer, 2018, s. 227-Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    The creation, distribution and delivery of video content is a sophisticated process with elements like video acquisition, preprocessing and encoding, content production and packaging as well as distribution to customers. IP networks are usually used for the transfer of video signals. The treatment of video content is also very complex, and we have a multidimensional process with elements like content acquisition, content exchange and content distribution. The focus of the chapter is on the presentation of models that can be used to characterize the main elements in a video distribution chain. These models are about video coding and compression, video streaming, video traffic models, energy consumption models, system performance, concepts of performance optimization and QoE- and energy-optimal streaming.

  • 76.
    Popescu, Adrian
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Yao, Yong
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Ilie, Dragos
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Video Distribution Networks: Architectures and System Requirements2018Inngår i: Greening Video Distribution Networks: Energy-Efficient Internet Video Delivery / [ed] Adrian Popescu, Springer, 2018Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    The creation of video content and its distribution over the Internet Protocol (IP) are sophisticated processes that follow a chain model from the acquisition of the video source, production and packaging, transport, and finally distribution to viewers. Video distribution networks refer to several parts, namely content contribution, primary distribution, secondary distribution, and video consumers. The focus of the chapter is on the presentation of video distribution systems over IP, categories of architectural solutions as well as a short presentation of several important applications associated with video distribution networks.

  • 77. Popescu, Alexandru
    et al.
    Erman, David
    Fiedler, Markus
    Popescu, Adrian
    Kouvatsos, Demetres
    A Middleware Framework for Communication in Cognitive Radio Networks2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Cognitive radio networks are expected to address and resolve important operational challenges such as opportunistic spectrum access, spectrum and network heterogeneities and requests for the provision of diverse Quality-of-Service (QoS) for different applications. Accordingly, a number of network functionalities are required to take into account these challenges towards the efficient management of cognitive radio networks. This paper advances a new architecture for the management of cognitive radio networks. The architecture is designed and developed at the application layer and incorporates sensing and prediction, addressing and routing, middleware and decision making. Accordingly, a number of management functions are required to address the challenges associated with the management of cognitive radio networks. The paper provides an analysis of these components as well.

  • 78.
    Popescu, Alexandru
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Yao, Yong
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Popescu, Adrian
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    A Management Architecture for Multimedia Communication in Cognitive Radio Networks2015Inngår i: Multimedia over Cognitive Radio Networks: Algorithms, Protocols, and Experiments / [ed] Hu, F; Kumar, S, CRC Press, 2015, s. 3-31Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 79.
    Popescu, Alexandru
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Yao, Yong
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Popescu, Adrian
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Communication Mechanisms for Cognitive Radio Networks2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Comprehensive communication in cognitive radio networks is an important research topic within the scope of empowering cognitive radio functionality in beyond-4G mobile networks. Providing communication for secondary users without interference with primary users is an ambitious task, which requires innovative management architecture designs and routing solutions. Operational challenges such as opportunistic spectrum access, solving problems related to spectrum and network heterogeneities and requests for the provisioning of Quality-of-Service to different applications must be resolved. As part of a novel management architecture, the paper advances a new approach to end-to-end communication in cognitive radio networks based on combining ad-hoc algorithms with spectrum mobility algorithms.

  • 80.
    Popescu, Alexandru
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Yao, Yong
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Popescu, Adrian
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Network Architecture to Support Multimedia over CRN2014Inngår i: Multimedia over Cognitive Radio Networks: Algorithms, Protocols, and Experiments / [ed] Hu, Fei; Kumar, Sunil, CRC Press , 2014Kapittel i bok, del av antologi (Fagfellevurdert)
  • 81. Pruthi, Parag
    et al.
    Ilie, Dragos
    Popescu, Adrian
    Application Level Performamce of Multimedia Services1999Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Quality of Service (QoS) is a difficult term to define for multimedia applications. The main reason is that both audio and video quality are subjective and difficult to quantify. Much work has been done in the past to map the subjective quality of video and audio into measurable quantities. Unfortunately, when it comes to IP environments, not much experience and mathematical work exists that can be used to define robust metrics for measurement of QoS. In this paper, we report on measurements of multimedia QoS and try to map subjective criteria to discrete measurables in terms of packet loss rates, packet delays, and other quantities. We report the results of measurements done at the application level and show how network characteristics affect the perceived quality of multimedia applications. In particular, we analyze the application traffic generated by MBone clients in a distributed network education scenario. In order to measure the traffic, we have implemented software on a non-intrusive probe developed by NIKSUN INC.\footnote{http://www.niksun.com} that can accurately monitor all traffic from a variety of networks. We have developed MBone aware software modules which can not only play back the recorded streams but also provide the essential statistics in real-time. We report in detail the results of our study of a particular end-to-end MBone session.

  • 82. Pruthi, Parag
    et al.
    Ilie, Dragos
    Popescu, Adrian
    Application level performance of multimedia services1999Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Quality of Service (QoS) is a difficult term to define for multimedia applications. The main reason is that bath audio and video quality are subjective and difficult to quantify. Much work has been done in the past to map the subjective quality of video and audio into measurable quantities. Unfortunately, when it comes to IP environments, not much experience and mathematical work exists that can be used to define robust metrics for measurement of QoS. In this paper, we report on measurements of multimedia QoS and try to map subjective criteria to discrete measurables in terms of packet loss rates, packet delays, and other quantities. We report the results of measurements done at the application level and show how network characteristics affect the perceived quality of multimedia applications. In particular, we analyze the application traffic generated by MBone clients in a distributed network education scenario. In order to measure the traffic, we have implemented software on a non-intrusive probe developed by NIKSUN INC.* that can accurately monitor all traffic from a variety of networks. We have developed MBone aware software modules which can not only play back the recorded streams but also provide the essential statistics in real-time. We report in detail the results of our study of a particular end-to-end MBone session.

  • 83. Pruthi, Parag
    et al.
    Jena, Ajit K.
    Popescu, Adrian
    HTTP Interactions with TCP1998Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper we describe our simulation models for evaluating end-to-end performance of HTTP transactions. We first analyze several gigabytes of collected traffic traces from a production Frame Relay network. Using these traces we extract web traffic and analyze the server web pages accessed by actual users. We analyze over 25000 web pages and develop a web client/server interaction model based upon our analysis of many server contents. We make specific contributions by analyzing the popularity of web servers and the number of bytes transferred from them during a busy hour. We also compute the distribution of the number of embedded items within a web document. We then use these models to drive a network simulation and show the interactions between the TCP/IP flow control and retransmission mechanism on source parameters. One of our important contributions has been to show that the Hurst parameter is robust with regard to TCP/IP flow and error control. Using the simulation studies we show that the distribution of end-to-end application message delay has a heavy-tail distribution and we discuss how these distributions arise in the network context.

  • 84. Pruthi, Parag
    et al.
    Popescu, Adrian
    Effect of Controls on Self-Similar Traffic1997Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Tremendous advances in technology have made possible Giga- and Terabit networks today. Simi- lar advances need to be made in the management and control of these networks if these technologies are to be successfully accepted in the market place. Although years of research have been expended at designing control mechanisms necessary for fair resource allocation as well as guaranteeing Quality of Service, the discovery of the self-similar nature of traffic ows in all packet networks and services, irrespective of topology, technology or protocols leads one to wonder whether these control mech- anisms are applicable in the real world. In an attempt to answer this question we have designed network simulators consisting of realistic client/server interactions over various protocol stacks and network topologies. Using this testbed we present some preliminary results which show that simple ow control mechanisms and bounded resources cannot alter the heavy-tail nature of the offered traffic. We also discuss methods by which application level models can be designed and their impacts on network performance can be studied.

  • 85.
    Rutabayiro Ngoga, Said
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Yao, Yong
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Popescu, Adrian
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    On Multi-channel Opportunistic Access in Heterogeneous Cognitive Radio Networks2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In the paper, we study optimal transmission strategies in multi-channel opportunistic spectrum access (OSA) networks where one secondary user (SU) opportunistically accesses multiple orthogonal channels of primary users (PUs) under a continuous time Markov chain modeling of the channel occupancy by the PUs. Referred to as tunable threshold strategy, at a given time the SU chooses one channel of a given PU, decides if it should transmits or not and if so it protects the PU of this channel. To be operational, such a structure depends on the capability of the SU radio front-end to perform channel sensing. We consider one scenario where the SU node can simultaneously sense multiple channels and another scenario where the SU node can sense only one channel at a time. For each scenario, we develop the structure of the optimal transmission strategy and analyse the performance. We show that the optimal transmission strategy can be implemented using a simple tunable threshold algorithm.

  • 86. Rönngren, Robert
    et al.
    Rajaei, Hassan
    Popescu, Adrian
    Ismailov, Yuri
    Ayani, Rassul
    Parallel Simulation of a High Speed LAN1994Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper we discuss modeling and simulation of a multigigabit/s LAN. We use parallel simulation techniques to reduce the simulation time. Optimistic and conservative parallel simulators have been used. Our results on a shared memory multiprocessor indicate that the conservative method is superior to the optimistic one for the specific application. Further, the parallel simulator based on the conservative scheme shows a linear speedup for large networks.

  • 87. Vogeleer, Karel De
    et al.
    Erman, David
    Fiedler, Markus
    Popescu, Adrian
    A Lightweight Macro-Mobility Framework2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents the design of a lightweight framework to provide vertical handover for macro-mobility on handheld devices. The framework is designed for mobile-controlled handover and does not require modification of the Internet infrastructure. The framework enables users to control the entire vertical handover process so handover decisions are driven by user preferences rather than ISP considerations. UDP tunneling is used as the basis for seamless roaming. Support nodes participate in mobility management by keeping track of the mobile users. We elaborate on a proof-of-concept implementation targeted to be deployed on the Android platform.

  • 88. Vogeleer, Karel De
    et al.
    Ickin, Selim
    Fiedler, Markus
    Erman, David
    Popescu, Adrian
    Estimation of Quality of Experience in 3G Networks with the Mahalanobis Distance2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Quality of Experience is a parameter used to express the relationship between Quality of Service and the satisfaction of network service subscribers. The modeling of Quality of Experience demands for solving a multidimensional problem. In this paper, we present a Quality of Experience analysis of streaming videos. Related to this, we show that we can reduce the dimensions of the Quality of Experience modeling with the help of Principle Component Analysis techniques. We demonstrate that for our data set the Zero Throughput Time and the Packet Delay Variation are enough to get a picture of the state of the network. We further calculate the Mahalanobis distance to analyze the outliers in the data set. We illustrate that for our data set the 97.5% quantile for the Mahalanobis distance is a good threshold that indicates low user perception. We also advocate the use of robust statistics in the analysis of Quality of Experience as we are dealing with contaminated data sets.

  • 89. Vogeleer, Karel De
    et al.
    Ilie, Dragos
    Popescu, Adrian
    Constrained-Path Discovery by Selective Diffusion2008Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The demand for live and interactive multimedia services over the Internet raises questions on how well the Internet Protocol (IP)’s best-effort effort service can be adapted to provide adequate end-to-end quality of service (QoS) for the users. Although the Internet community has developed two different IP-based QoS architectures, neither has been widely deployed. Overlay networks are seen as a step to address the demand for end-to-end QoS until a better solution can be obtained. As part of the telecommunication research at Blekinge Institute of Technology (BTH) in Karlskrona, Sweden we are investigating new theories and algorithms concerning QoS routing. We are in the process of developing Overlay Routing Protocol (ORP), a framework for overlay QoS routing consisting of two protocols: Route Discovery Protocol (RDP) and Route Management Protocol (RMP). In this paper we describe RDP and provide preliminary simulation results for it.

  • 90.
    Vogeleer, Karel De
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Popescu, Adrian
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Erman, David
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Content dependency of the traffic control in the darwin streaming server2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The Darwin Streaming Server employs stream thinning and transmission rate adaptation for traffic and congestion control. We investigate the relation of video content with the stream thinning and transmission rate adaptation process under 3GPP-adaptation. We observe that stream thinning is not only initiated upon fluctuation of network properties, but sometimes also upon the content of the streamed video. Moreover, we show that in extreme situations the video transmission is halted based merely on content dependent properties reflected in the RTSP feedback. This may have adverse consequences for the user experience. We put forward alterations to the 3GPP-adaptation traffic control of the Darwin Streaming Server that controls the stream thinning process. The alterations aim to avoid video freezes as a result of video content dependent properties. The results show that the probability of an interrupt-free playback is lower for the alterations than for the default streaming server algorithms.

  • 91. Yao, Yong
    et al.
    Erman, David
    Popescu, Adrian
    Spectrum Decision for Cognitive Radio Networks2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Cognitive Radio Networks (CRNs) are a key technology suggested to be part of 4G and beyond. The fundamental concept is to let Secondary Users (SUs) have temporal free access to spectrum bands not occupied by Primary Users (PUs). Since SUs are not allowed to cause harmful interference to PUs, SUs need to select the most available spectrum bands for access, also known as spectrum decision. In the paper, we suggest a middleware called Spectrum Decision Support System (SDSS) abstractly illustrated. The goal of SDSS is to combine the different decision methods together and to make intelligent band selection based upon partial characterizations of CRNs

  • 92.
    Yao, Yong
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Ngoga, Said Rutabayiro
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Erman, David
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Popescu, Adrian
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Competition-Based Channel Selection for Cognitive Radio Networks2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In cognitive radio networks, unlicensed users need to learn from environmental changes. This is a process that can be done in a cooperative or non-cooperative manner. Due to the competition for channel utilization among unlicensed users, the non-cooperative approach may lead to overcrowding in the available channels. This paper is about a fuzzy-logic based decision making algorithm for competition-based channel selection. The underlying decision criterion integrates both the statistics of licensed users' channel occupancy and the competition level of unlicensed users. By using such an algorithm, the unlicensed user competitors can achieve an efficient sharing of the available channels. Simulation results are reported to demonstrate the performance and effectiveness of our suggested algorithm.

  • 93.
    Yao, Yong
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Ngoga, Said Rutabayiro
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Erman, David
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Popescu, Adrian
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Performance of Cognitive Radio Spectrum Access with Intra- and Inter-Handoff2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Opportunistic spectrum access (OSA) is a technology that allows unlicensed users to access spectrum holes and to provide so efficient use of radio resources. Most of the studies done on OSA focus on the situation when the unlicensed user performs the spectrum handoff only within a single cognitive radio network (so-called intra-handoff). In this paper, we consider the users (licensed or unlicensed) to be able to do inter-handoff among different cognitive radio cells as well. The cells provide priority to inter-handoff users. By considering multiple cells being in steady-state, the arrival rates of inter-handoff users are determined. We study the OSA performance of unlicensed users under both intra- and inter-handoff schemes, with respect to the blocking and forced-termination probabilities of unlicensed users as well as the unlicensed user service-completion and inter-handoff throughputs. Our Markov chain based numerical analysis is validated by simulation experiments.

  • 94.
    Yao, Yong
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Ngoga, Said Rutabayiro
    Popescu, Adrian
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    A System for Spectrum Decision in Cognitive Radio Networks2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In Cognitive Radio (CR) networks, licensed radio channels are allowed to be used by Secondary Users (SUs) as long as SUs do not harmfully impair the transmission of Primary Users (PUs). Therefore, a crucial task for SUs is to decide which available channel should be selected, the so-called spectrum decision. To provide intelligent spectrum decision strategy to SUs, we suggest a system called Spectrum Decision Support System (SDSS). SDSS takes into account both heterogeneity aspects and interoperability requirements of CR networks. By this, SDSS is capable of jointly considering various channel characterizations and different decision making algorithms for doing spectrum decision. The paper is reporting the SDSS architecture as well as the related work-in-progress.

  • 95.
    Yao, Yong
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Ngoga, Said Rutabayiro
    Popescu, Adrian
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Cognitive Radio Spectrum Decision Based on Channel Usage Prediction2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The paper is about a new strategy suggested for spectrum decision in Cognitive Radio (CR) networks. By jointly considering sensing error, Secondary Users (SUs) competition and SUs transmission collision, a new parameter called Channel Usage State (CUS) is introduced. For a particular channel, we predict the respective probabilities of occurrence of CUS states by using the LeZi-update scheme. We also adopt a fuzzy comparison algorithm to combine the prediction results as a joint value. The largest joint value is associated with the most available channel for access by SUs in the near future. By comparing with random channel access, the suggested strategy can improve SUs transmission throughput. This is demonstrated by the simulation evaluations.

  • 96.
    Yao, Yong
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Popescu, Adrian
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    On Energy Consumption in Mobile Multimedia Networks with OpenFlow Switch2016Inngår i: 2016 INTERNATIONAL CONFERENCE ON COMMUNICATIONS (COMM 2016), IEEE, 2016, s. 309-312Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In mobile multimedia networks, the video flow usually operates in an end-to-end manner from Head-End to mobile terminals. However, measuring the energy consumption associated with a video flow is a sophisticated process due to the complexity related to this. In the paper, a theoretical measurement approach is suggested to estimate the energy consumption of a video flow through mobile multimedia networks enhanced with the support of OpenFlow switch. Two different power models are built up to compute the traffic related energy consumption at the network element side. The numerical derivation of these two theoretical models is presented.

  • 97.
    Yao, Yong
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Popescu, Adrian
    Blekinge Tekniska Högskola.
    On Energy Consumption in Mobile Multimedia Networks with OpwnFlow Switch2016Inngår i: International Conference on Communications (COMM), 2016, IEEE, 2016Konferansepaper (Fagfellevurdert)
    Abstract [en]

    With the advance of new wireless technologies and ubiquitous radio access, mobile multimedia is becoming a very important application for both service providers and end users. This also leads to different business models such as mobile television, mobile conferencing, and remote gaming. A Mobile Multimedia Network (MMN) generally refers to several parts, which are known as the video contribution, the network distribution and the mobile terminals. The video contribution is connected to the functions of generating and processing the video content, which is eventually transferred onto the network for further distribution to mobile terminals.

  • 98.
    Yao, Yong
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Popescu, Adrian
    Blekinge Tekniska Högskola.
    Fiedler, Markus
    Blekinge Tekniska Högskola.
    Ljung, Rickard
    Sony Mobile Communications, SWE.
    On the Performance of Video Streaming in Energy-Aware Wireless Mesh Networks2017Inngår i: European Conference on Networks and Communications (EuCNC) 2017, IEEE, 2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Mobile multimedia has today become a promising application for end users and service providers. With reference to the existing systems for mobile communications, this application further demands for solving several technical problems, especially regarding video streaming over wireless networks. An interesting approach is in form ofWireless Mesh Network (WMN) based networks, where the individual video flows operate in an end-to-end (e2e) manner along a particular networking scenario including several mesh routers. That means, a particular mesh router may be traversed by multiple video flows. This situation may become even more complicated in the case of a large amount of packet retransmissions, which may deteriorate the performance of video flows. To investigate this problem, a two-level Modulated Markov Poisson Process (MMPP) based queueing model is built up and the transport performance of e2e video streaming in WMN based mobile multimedia system is analysed. Four metrics are used to study the system performance, namely e2e throughput, e2e delay, e2e error-rate and traffic-related energy consumption. Numerical analysis and evaluation studies are done. Based on the reported results, two different solutions are suggested and discussed with regard to the trade-off among these metrics.

  • 99.
    Yao, Yong
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Popescu, Alexandru
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Ngoga, Said Rubatayiro
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Popescu, Adrian
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    On Prioritized Spectrum Access in Cognitive Radio Networks with Imperfect Sensing2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Cognitive Radio networks allow the unlicensed users to share the available spectrum opportunities. However, this demands for solving the problem of contention among multiple unlicensed user packets for transmission. In our paper, we consider the Opportunistic Spectrum Access model for packet transmission between two unlicensed users. We suggest a priority scheme for a unlicensed user to concurrently transmit different types of packets. Our scheme reserves a fixed number of queueing places in the buffer for the prioritized packets. We study the transmission performance under both the priority scheme and imperfect spectrum sensing, with respect to the blocking probabilities, average transmission delay and transmission throughput of unlicensed users packets. The Markov chain based numerical analysis is validated by simulation experiments. Our results show that the suggested priority scheme is able to enhance transmission throughput of unlicensed users packets, together with significant decreased average transmission delay and minor decreased total transmission throughput.

  • 100.
    Yao, Yong
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Popescu, Alexandru
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Popescu, Adrian
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    On Fuzzy Logic-Based Channel Selection in Cognitive Radio Networks2014Inngår i: Software-Defined and Cognitive Radio Technologies for Dynamic Spectrum Management / [ed] Kaabouch, Naima; Hu, Wen-Chen, Hershey, PA 17033, USA: IGI-Global , 2014Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    Cognitive radio networks are a new technology based on which unlicensed users are allowed access to licensed spectrum under the condition that the interference perceived by licensed users is minimal. That means unlicensed users need to learn from environmental changes and to take appropriate decisions regarding the access to the radio channel. This is a process that can be done by unlicensed users in a cooperative or non-cooperative way. Whereas the non-cooperative algorithms are risky with regard to performance, the cooperative algorithms have the capability to provide better performance. Our paper reports therefore a new fuzzy logic based decision making algorithm for channel selection. The underlying decision criterion considers statistics of licensed users channel occupancy as well as information about the competition level of unlicensed users. Our theoretical studies indicate that the unlicensed users can obtain an efficient sharing of the available channels. Simulation results are reported to demonstrate the performance and effectiveness of the suggested algorithm.

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