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  • 101.
    Kassler, Andreas
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    QoE aware Multihop Networks2009Conference paper (Other (popular science, discussion, etc.))
  • 102.
    Kassler, Andreas
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    Bohnert, Thomas Michael
    Highlights from the WIRELESS4D '08 Workshop: Bridging the Digital Divide by Advancing Technology for Broadband Wireless Internet Access in Rural and Developing Regions2009In: Global Communications Newsletter, no April, p. 2,4-Article in journal (Other academic)
  • 103.
    Kassler, Andreas
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    Cavalcanti de Castro, Marcel
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT. Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Packet Aggregation for VoIP in Wireless Meshed Networks2009In: Traffic and QoS Management in Wireless Multimedia Networks, Springer , 2009Chapter in book (Other academic)
  • 104.
    Kassler, Andreas
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    Cavalcanti de Castro, Marcel
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT. Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Dely, Peter
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT. Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    VoIP Packet Aggregation based on Link Quality Metric for Multihop Wireless Mesh Networks2007Conference paper (Refereed)
    Abstract [en]

    Providing Voice over IP in WLAN based wireless meshed networks is an important service for the future wireless internet. However, the transmission of small (voice) packets imposes high overhead which leads to low capacity for VoIP over 802.11 based multihop meshed networks. By combining several small packets into larger aggregated ones, it is expected that overhead can be significantly reduced thus incapacity for VoIP services. When mesh relay nodes aggregate small packets, there is an inherent trade-off regarding packet size. Aggregating more packets leads to larger packets, reduces the overall number of packets in the mesh and thus reduces multi-hop contention and packet loss due to collisions. However, such larger aggregated packets can lead to higher packet loss for a link that operates at low signal quality. For such links, aggregating fewer packets can be beneficial. Classical aggregation strategies typically operate end-to-end without considering those aspects and are therefore suboptimal. In this paper, we propose a new adaptive hop-by-hop aggregation scheme that calculates target aggregation sizes per each hop based on wireless link characteristics. Simulation results show that our approach is very effective, outperforms static aggregation schemes in various performance parameters and increases capacity for VoIP in meshed networks significantly

  • 105.
    Kassler, Andreas
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Dely, Peter
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Beyer, Nico
    OpenFlow for Wireless Mesh Networks2011In: Proceedings of 20th International Conference on Computer Communications and Networks (ICCCN), Maui, HI: IEEE conference proceedings, 2011, p. 1-6Conference paper (Refereed)
    Abstract [en]

    Several protocols for routing and forwarding in Wireless Mesh Networks (WMN) have been proposed, such as AODV, OLSR or B.A.T.M.A.N. However, providing support for e.g. flow-based routing where flows of one source take different paths through the network is hard to implement in a unified way using traditional routing protocols. OpenFlow is an emerging technology which makes network elements such as routers or switches programmable via a standardized interface. By using virtualization and flow-based routing, OpenFlow enables a rapid deployment of novel packet forwarding and routing algorithms, focusing on fixed networks. We propose an architecture that integrates OpenFlow with WMNs and provides such flow-based routing and forwarding capabilities. To demonstrate the feasibility of our OpenFlow based approach, we have implemented a simple solution to solve the problem of client mobility in a WMN which handles the fast migration of client addresses (e.g. IP addresses) between Mesh Access Points and the interaction with re-routing without the need for tunneling. Measurements from a real mesh testbed (KAUMesh) demonstrate the feasibility of our approach based on the evaluation of forwarding performance, control traffic and rule activation time.

  • 106.
    Kassler, Andreas
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    Dely, Peter
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Skorin-Kapov, Lea
    Dobrijevic, Ognjen
    Matijasevic, Maja
    Towards QoE-driven Multimedia Service Negotiation and Path Optimization with Software Defined Networking2012In: Software, Telecommunications and Computer Networks (SoftCOM), 2012 20th International Conference on, IEEE Press, 2012Conference paper (Refereed)
    Abstract [en]

    This paper presents motivation and ongoing work towards a system for Quality of Experience (QoE)-driven path assignment for multimedia services. The system goal is to enable negotiation of service and network communication parameters between end-users and to assign the network paths that are used for delivering multimedia flows according to the agreed service configuration. The key concept behind the system is a centralized multi-user optimization of the path assignments, which maximizes QoE by taking into account service utility functions, network topology, link capacities, and delay. Based on the output of the optimization process, the system implementation uses the OpenFlow to set up forwarding paths for the network elements

  • 107.
    Kassler, Andreas
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Dini, Cosmin
    Advances in Mesh Networks: The Second International Conference on Advances in Mesh Networks2009Conference proceedings (editor) (Refereed)
  • 108.
    Kassler, Andreas
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    Guenkova-Luy, Teodora
    Schorr, Andreas
    Schmidt, Holger
    Hauck, Franz
    Wolf, Ingo
    Network-Based Content Adaptation of Streaming Media Using MPEG-21 DIA and SDPng2006Conference paper (Refereed)
    Abstract [en]

    The dynamic adaptation of multimedia content in distributed heterogeneous environments is a key enabler for next generation ubiquitous and pervasive services. Systems implementing the Universal Multimedia Access (UMA) approaches are predominantly combinations of MPEG-centric and/or proprie-tary solutions. However, it is important to reach interoperability between the IETF approach for multimedia-session establish-ment and control and the MPEG-21 efforts for metadata-driven adaptation, in order to enable personalized multimedia delivery for ubiquitous users, where media is delivered and adapted on the fly taking into account context and environment. In this pa-per, we present a format-independent model that enables con-verging IETF and MPEG-21 descriptions for streaming media. We introduce the architecture of a multimedia stream-adaptation service to enable communication between terminals having het-erogeneous capabilities and communicating over heterogeneous networks. We demonstrate how the service utilizes the converged session description model and how it can be deployed inside special adaptation nodes within any part of the network to enable dynamic content adaptation both at the terminal and within the network

  • 109.
    Kassler, Andreas
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    Karlsson, Jonas
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT. Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Performance Comparison of Different TCP Flavours2009In: Traffic and QoS Management in Wireless Multimedia Networks, Springer , 2009Chapter in book (Other academic)
  • 110.
    Kassler, Andreas
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    Kim, Wooseong
    Di Felice, Marco
    Gerla, Mario
    Cognitive Multi-Radio Mesh Networks for the Future Wireless Internet2010Conference paper (Refereed)
  • 111.
    Kassler, Andreas
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    Kim, Wooseong
    Di Felice, Marco
    Gerla, Mario
    TP-UrbanX - A New Transport Protocol for Cognitive Multi-Radio Mesh Networks2011Conference paper (Refereed)
  • 112.
    Kassler, Andreas
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    Kim, Wooseong
    UCLA.
    Gerla, Mario
    UCLA.
    TCP Performance in Cognitive Multi-Radio Mesh Networks2011In: CogART '11 Proceedings of the 4th International Conference on Cognitive Radio and Advanced Spectrum Management, New York: Association for Computing Machinery (ACM), 2011, p. art.No 44-Conference paper (Refereed)
  • 113.
    Kassler, Andreas
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    Matos, Ricardo
    Marques, Carlos
    Sargento, Susanna
    Chakareski, Jacob
    Quality of Experience-based Routing in Multi-Service Wireless Mesh Networks2012In: Communications (ICC), 2012 IEEE International Conference on ICC'12 WS — ViOpt: Realizing advanced video optimized wireless networks, IEEE Press, 2012, p. 7060-7065Conference paper (Refereed)
  • 114.
    Kassler, Andreas
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    Mnaouer, Ben
    Lei, C.
    Multicast Protocol Performance of Ad-Hoc Networks in a hotspot context2005Conference paper (Refereed)
    Abstract [en]

    This paper discusses the usage of Ad-hoc technologies as hotspot extension mechanisms. In this scenario, multicast gateways have fixed locations and speed and connect ad hoc islands to the internet. In such an environment, traffic is concentrated around such hotspot areas and protocol performance suffers from congestion. For improving multicast protocol performance in this scenario, we propose extensions for ODMRP and MAODV routing algorithms by augmenting them with a zone routing behavior, thus producing two new hybrid multicast routing algorithms, ZODMRP and ZMAODV. Our extensive simulation results show that ZODMRP provides the highest packet delivery ratio and lowest delay without introducing too much overhead, which makes it the protocol of choice for providing high quality packet delivery in multicast sessions

  • 115.
    Kassler, Andreas
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    Neves, A.P.
    Sargento, S
    Aguiar, R. L.
    Crisóstomo, S.
    Integration of Ad Hoc Networks with Infrastructure Networks ' a QoS Perspective2005Conference paper (Refereed)
  • 116.
    Kassler, Andreas
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    Sargento, S.
    Ben Mnaouer, A.
    Lei, C.
    Neves, P.
    Aguiar, R. L.
    Ruiz, P.
    Supporting Multicast in Ad-Hoc networks in a Hotspot Context2005Conference paper (Refereed)
    Abstract [en]

    This paper discusses the usage of Ad-Hoc technologies as hotspot extension mechanisms. We propose a hybrid network where 802.16 links are used for providing high-bandwidth access, and local distribution is performed by Ad-Hoc network nodes (based on 802.11 technologies), thus covering arbitrary areas around the 802.16 stations, which might be connected to the Internet. We evaluate the performance of the system and its efficiency in providing QoS in multicast connections. For providing multicasting services, we propose two extensions of the ODMRP and MAODV routing algorithms by augmenting them with a zone routing behavior, thus producing two new hybrid multicast routing algorithms, named ZODMRP and ZMAODV. The simulation results show that ZODMRP provides the highest packet delivery ratio and lowest delay without introducing large overhead, being then able to provide predictable QoS for packet delivery in multicast sessions

  • 117.
    Kassler, Andreas
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    Scopigno, Riccardo M
    Rocha, Rui
    Pedrosa, Luis
    Brunstrom, Anna
    Fileppo, Francesco
    Spirito, Maurizio
    Franceschinis, Mirko
    Test-beds for Opportunistic Communication Experiments2009Conference paper (Other (popular science, discussion, etc.))
  • 118.
    Kassler, Andreas
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    ShanShan, C.
    Quality of Service for MANETs connected to the Internet2005Conference paper (Refereed)
    Abstract [en]

    Ad-Hoc networks are flexible, adapt to topology changes due to mobility of nodes, and can de deployed where network infrastructure is not available. Research has been done mainly in the area of routing and for isolated Ad-Hoc networks. Some efforts are on the way to connect Ad-Hoc networks to the internet. It is however important to support QoS aware multimedia applications in this environment. A QoS architecture for Ad-Hoc networks is necessary that interworks with infrastructure based QoS approaches. Our approach extends SWAN and provides QoS support for communication between Ad-Hoc nodes and nodes located in the public internet. The gateway, which provides internet connectivity to Ad-Hoc nodes, is also responsible for QoS signaling interworking and participates in admission control decisions and traffic regulation

  • 119.
    Kassler, Andreas
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    Zdarsky, Frank
    Azcorra, Arturo
    Banchs, Albert
    Workshop on Carrier Grade Mesh Networks2009In: Global Communications Newsletter, no October, p. 2-2Article in journal (Other academic)
  • 120. Khoshkholghi, Mohammad Ali
    et al.
    Taheri, Javid
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Bhamare, Deval
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Kassler, Andreas
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT. Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Optimized Service Chain Placement Using Genetic Algorithm2019In: Proceedings of the 2019 IEEE Conference on Network Softwarization NetSoft 2019, Unleasing the Power of Network Softwarization / [ed] Christian Jacquenet, Filip De Turck, Prosper Chemouil, Flavio Esposito, Olivier Festor, Walter Cerroni, Stefano Secci, IEEE, 2019Conference paper (Refereed)
    Abstract [en]

    Network Function Virtualization (NFV) is anemerging technology to consolidate network functions onto highvolume storages, servers and switches located anywhere in thenetwork. Virtual Network Functions (VNFs) are chainedtogether to provide a specific network service. Therefore, aneffective service chain placement strategy is required tooptimize the resource allocation and consequently to reduce theoperating cost of the substrate network. To this end, we proposefour genetic-based algorithms using roulette wheel andtournament selection techniques in order to place service chainsconsidering two different placement strategies. Since mappingof service chains sequentially (One-at-a-time strategy) may leadto suboptimal placement, we also propose Simultaneous strategythat places all service chains at the same time to improveperformance. Our goal in this work is to reduce deployment costof VNFs while satisfying constraints. We consider Geantnetwork as the substrate network along with its characteristicsextracted from SndLib. The proposed algorithms are able toplace service chains with any type of service graph. Theperformance benefits of the proposed algorithms arehighlighted through extensive simulations.

  • 121.
    Kim, Wooseong
    et al.
    UCLA, USA.
    Gerla, Mario
    UCLA, USA.
    Oh, Soon Y.
    Lee, Kevin
    Cisco Syst, San Jose, CA USA.
    Kassler, Andreas
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    CoRoute: A New Cognitive Anypath Vehicular Routing2011In: Wireless Communications & Mobile Computing, ISSN 1530-8669, E-ISSN 1530-8677, Vol. 11, no 12, p. 1588-1602Article in journal (Refereed)
    Abstract [en]

    Vehicular communications promise to bring us safer driving and better traffic control. Dedicated short range communications and IEEE 802.11p are now well established standards for vehicular communications. Channels for those systems, however, are of limited capacity and are dedicated to safety applications. Thus, they are not sufficient to support the broad range of services envisioned in VANETs. It is anticipated that vehicles will utilize Wi-Fi (802.11 a/b/g) to acquire more capacity. Unfortunately, the Wi-Fi channels in urban areas are already quite heavily subscribed by residential customers. To evade the residential load, in this paper, we propose CoVanet, a cognitive vehicular ad hoc network architecture that allows vehicle radios to access the Wi-Fi channels ‘opportunistically’, finding least loaded channels. In CoVanet, network topology and channel environment change frequently because of high node mobility. The main contribution of this work is a cognitive ad hoc vehicular routing protocol (CoRoute). CoRoute is a hybrid that utilizes both geographical location and sensed channel information to establish stable, minimum delay routes to the destination. Simulation results show that CoRoute is robust to mobility and to external interference and improves packet delivery ratio on average by 70% with respect to routing without cognitive radios

  • 122.
    Kim, Wooseong
    et al.
    Department of Computer Science, University of California, Los Angeles, USA.
    Kassler, Andreas
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    Di Felice, Marco
    Department of Computer Science, University of Bologna, Italy.
    Gerla, Mario
    Department of Computer Science, University of California, Los Angeles, USA.
    Cognitive Multi-Radio Mesh Networks on ISM Bands: A Cross-Layer Architecture2010In: Proceedings of the 29th IEEE International Performance Computing and Communications Conference, IEEE , 2010, p. 34-41Conference paper (Refereed)
    Abstract [en]

    A wireless mesh network (WMN) has been popularly researched as a wireless backbone for Internet access with off-the-shelf and inexpensive equipments. Nowadays, several applications like contents sharing, multicast video streaming, vehicular networks encourage to build mesh networks in urban areas. However, the deployment of WMNs in unlicensed bands of dense urban areas imposes many challenges. While previous research has mostly focused on optimal channel allocation under inter or intra-flow interferences within mesh nodes, the practical deployment of WMNs also requires to consider the interference caused by external entities such as residential access points that do not belong to the WMN. To address this issue, we propose Urban-X which is a first attempt towards a new architecture for Multi-Radio Cognitive Mesh Networks. Based on a cross-layer scheme, we develop novel routing and forwarding schemes reflecting the residential traffic state of external users. Through an extensive simulation analysis using the ns-2 simulator, we demonstrate the feasibility of our routing scheme and we show its robustness to the variations of channel environment and external traffics.

  • 123.
    Kim, Wooseong
    et al.
    Department of Computer Science, University of California, Los Angeles, USA.
    Kassler, Andreas
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    Di Felice, Marco
    Department of Computer Science, University of Bologna, Bologna, Italy.
    Gerla, Mario
    Department of Computer Science, University of California, Los Angeles, USA.
    Urban-X: Towards Distributed Channel Assignment in Cognitive Multi-Radio Mesh Networks2010In: 2010 IFIP Wireless Days (WD), IEEE conference proceedings, 2010, p. 1-5Conference paper (Refereed)
    Abstract [en]

    Researches about multi-radio mesh networks have mostly focused on channel allocation under internal interference. However, the deployment of WMNs in unlicensed bands of dense urban areas imposes many challenges regarding co-existence with residential access points. In this paper, we propose Urban-X, which is a first attempt towards a new architecture for MultiRadio Cognitive Mesh Networks. We develop a novel channel assignment that reflects channel and residential traffic state of external users to maximize network throughput. We evaluate our approach using an enhancement of the ns-2 simulator. Urban-X demonstrate the feasibility of our approach and show robustness to variation of channel environment and external user traffic.

  • 124.
    Kim, Wooseong
    et al.
    University of Computer Science, University of California, Los Angeles, USA.
    Kassler, Andreas
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    Di Felice, Marco
    Department of Computer Science, University of Bologna, Italy.
    Gerla, Mario
    University of Computer Science, University of California, Los Angeles, USA.
    Bononi, Luciano
    Department of Computer Science, University of Bologna, Italy.
    Urban-X: A Self-Organizing Cognitive Wireless Mesh Network for Dense City Environments2011In: Proceedings of the Wired/Wireless Internet Communications (WWIC) / [ed] Xavier Masip-Bruin, Dominique Verchere, Vassilis Tsaoussidis & MarceloYannuzzi, Springer Berlin/Heidelberg, 2011, p. 398-409Conference paper (Refereed)
    Abstract [en]

    The practical deployment of Wireless Mesh Networks (WMNs) using unlicensed ISM band within dense urban scenarios is difficult due to the increasing number of wireless devices operating in those licensed exempt frequencies. For this reason, current research on WMN is directed towards novel and more flexible network paradigms which would allow the WMN to dynamically adapt to the environmental interference conditions. Here, we propose Urban-X, which is a novel cross-layer architecture for self-organizing WMNs over urban scenarios. Urban-X combines elements from classical Multi-Radio Multi-Channel (MC-MR) technology with novel Dynamic Spectrum Access (DSA) mechanisms. The self-organizing behavior is achieved through a novel distributed channel assignment scheme, an adaptive multi-path routing scheme and a flexible layer 2.5 channel and path scheduler algorithm. Based on the current interference on each channel, Urban-X performs channel allocation among the nodes of the WMN, updates the available paths towards the gateways and distributes the internal traffic among the paths/channels in order to maximize the network throughput while minimizing interference to the external networks. Simulation results demonstrate the effectiveness of our cross-layer approach in terms of increased throughput compared to traditional routing schemes for WMNs, and its adaptiveness to the variation in channel conditions and external user traffic.

  • 125.
    Koslowski, Konstantin
    et al.
    Fraunhofer Heinrich Hertz Inst, Germany.
    Santos, Ricardo
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Keusgen, Wilhelm
    Fraunhofer Heinrich Hertz Inst, Germany.
    Haustein, Thomas
    Fraunhofer Heinrich Hertz Inst, Germany.
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Sakaguchi, Kei
    Tokyo Institute of Technology, Japan.
    Ogawa, Hiroaki
    Tokyo Institute of Technology, Japan.
    Nakamura, Makoto
    Tokyo Institute of Technology, Japan.
    Tao, Yu
    Tokyo Institute of Technology, Japan.
    SDN Orchestration to Optimize Meshed Millimeter-Wave Backhaul Networks for MEC-enhanced eMBB Use Cases2018In: 2018 13th IEEE International Symposium on Broadband Multimedia Systems and Broadcasting (BMSB), IEEE, 2018Conference paper (Refereed)
    Abstract [en]

    This paper presents a novel concept for enhanced mobile broadband (eMBB) communication using millimeter-wave radio technologies enhanced by mobile edge computing to support a new class of applications requiring low latency and high data rates at the same time. The concept developed in the joint European/Japanese collaboration project 5G-MiEdge [1] builds on meshed backhaul topologies using millimeter wave links with beam forming capabilities and smart routing units for dynamic route, link and power management to be orchestrated by SDN. It is shown that dynamic changes in the topology at run time can be realized without experiencing losses in latency or throughput.

  • 126.
    Lavén, Andreas
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Brunstrom, Anna
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Performance Evaluation of the Anypath Routing and Forwarding Mechanism AP-OLSR2013In: MSWiM '13 Proceedings of the 16th ACM international conference on Modeling, analysis & simulation of wireless and mobile systems, Association for Computing Machinery (ACM), 2013, p. 81-90Conference paper (Other academic)
    Abstract [en]

    Wireless mesh networks (WMNs) consist of several small routers relaying packets wirelessly toward the destination or the Internet. A dense deployment enables the rapid creation of wireless access networks at a reasonable cost. The capacity of a wireless mesh network can be increased by using a diverse set of channels to allow simultaneous transmissions without causing interference. An interesting approach is to use one fixed wireless network interface for receiving and at least one switchable interface for sending. However, such a channel assignment suffers from switching overhead.

    In order to minimize the channel switching latency, we have developed a novel packet routing and forwarding strategy, AP-OLSR, which uses multiple next hop candidates tuned to different channels. When forwarding a packet, nodes pick the neighbor which is on a channel that gives a good balance between local switching overhead and global path quality.

    In this paper, we present a thorough evaluation of AP-OLSR with scenarios involving both single and multiple gateways, as well as single and competing flows. The evaluation shows that AP-OLSR can improve performance in both latency and throughput.

  • 127.
    Lavén, Andreas
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Kassler, Andreas
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    Multi-Channel Anypath Routing in Wireless Mesh Networks2010In: Proceedings of IEEE Globecom 2010, IEEE Press, 2010, p. 196-201Conference paper (Refereed)
    Abstract [en]

    Recently, wireless mesh networks have been proposed as a mechanism to provide alternative broadband wireless internet access. The usage of multiple radios transmitting at diverse frequency bands allows a significant increase in the capacity of such networks. However, popular Hybrid Channel Assignment strategies, which use a fixed interface for receiving and a switchable interface for transmitting to neighbor nodes, suffer from large delay and jitter due to the accumulated switching overhead over multiple hops. In this paper, we propose a novel routing mechanism for such hybrid multi-radio multichannel mesh networks based on the anypath paradigm. In our approach, the routing layer maintains for each destination at each hop a set of candidate forwarders, where each neighbor is tuned to a different channel. A novel layer 2.5 forwarding and scheduling algorithm decides then for each packet individually, which actual neighbor to forward the packet to, in order to minimize the overall delay. We implemented the selected approach using extensions to OLSR. An evaluation in KAUMesh test bed shows for specific scenarios that AP-OLSR reduces average delay with up to 70% compared to standard OLSR while also reducing both average and maximum jitter by 60% and 45% respectively.

  • 128.
    Lavén, Andreas
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Brunstrom, Anna
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Latency Aware Anypath Routing and Channel Scheduling for Multi-Radio Wireless Mesh Networks2014In: IEEE WCNC'14 Track 3 (Mobile and Wireless Networks), IEEE, 2014Conference paper (Refereed)
    Abstract [en]

    Wireless mesh network (WMN), radio nodes that form a mesh topology, is an interesting architectural candidate for the future wireless Internet. A dense access network can rapidly be deployed at a reasonable cost because there is no need to wire the mesh access points. However, WMNs typically do not perform well with latency-sensitive data traffic, such as Voice over IP (VoIP), due to restricted bandwidth. In this paper, we present the design, implementation and evaluation of LA-APOLSR for hybrid WMNs, where mesh nodes have two radios; a fixed radio for receiving and a switchable radio which rapidly changes channels to send to neighbor nodes. The key novelty of our approach is to use anypath routing for latency-sensitive traffic while normal traffic is treated using single path routing. Also, we develop a novel queuing strategy which prioritizes latency-sensitive traffic. A detailed evaluation using KAUMesh, an in-house multi-radio wireless mesh testbed, shows a reduction in latency and packet loss for VoIP traffic without negatively impacting competing TCP background traffic.

  • 129.
    Marotta, Antonio
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013). University of Naples Federico II.
    Avallone, Stefano
    University of Naples Federico II.
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013). Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    A Joint Power Efficient Server and Network Consolidation approach for virtualized data centers2018In: Computer Networks, ISSN 1389-1286, E-ISSN 1872-7069, Vol. 130, p. 65-80Article in journal (Refereed)
    Abstract [en]

    Cloud computing and virtualization are enabling technologies for designing energy-aware resource management mechanisms in virtualized data centers. Indeed, one of the main challenges of big data centers is to decrease the power consumption, both to cut costs and to reduce the environmental impact. To this extent, Virtual Machine (VM) consolidation is often used to smartly reallocate the VMs with the objective of reducing the power consumption, by exploiting the VM live migration. The consolidation problem consists in finding the set of migrations that allow to keep turned on the minimum number of servers needed to host all the VMs. However, most of the proposed consolidation approaches do not consider the network related consumption, which represents about 10–20% of the total energy consumed by IT equipment in real data centers. This paper proposes a novel joint server and network consolidation model that takes into account the power efficiency of both the switches forwarding the traffic and the servers hosting the VMs. It powers down switch ports and routes traffic along the most energy efficient path towards the least energy consuming server under QoS constraints. Since the model is complex, a fast Simulated Annealing based Resource Consolidation algorithm (SARC) is proposed. Our numerical results demonstrate that our approach is able to save on average 50% of the network related power consumption compared to a network unaware consolidation.

  • 130.
    Marotta, Antonio
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    D’Andreagiovanni, Fabio
    Sorbonne Universités, Université de Technologie de Compiègne, France.
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Zola, Enrica
    Universitat Politècnica de Catalunya, C. Barcelona, Spain.
    On the energy cost of robustness for green virtual network function placement in 5G virtualized infrastructures2017In: Computer Networks, ISSN 1389-1286, E-ISSN 1872-7069, Vol. 125, p. 64-75Article in journal (Refereed)
    Abstract [en]

    Next generation 5G networks will rely on virtualized Data Centers (vDC) to host virtualized network functions on commodity servers. Such Network Function Virtualization (NFV) will lead to significant savings in terms of infrastructure cost and reduced management complexity. However, green strategies for networking and computing inside data centers, such as server consolidation or energy aware routing, should not negatively impact the quality and service level agreements expected from network operators. In this paper, we study how robust strategies that place virtual network functions (VNF) inside vDC impact the energy savings and the protection level against resource demand uncertainty. We propose novel optimization models that allow the minimization of the energy of the computing and network infrastructure which is hosting a set of service chains that implement the VNFs. The model explicitly provides for robustness to unknown or imprecisely formulated resource demand variations, powers down unused routers, switch ports and servers, and calculates the energy optimal VNF placement and network embedding also considering latency constraints on the service chains. We propose both exact and heuristic methods. Our experiments were carried out using the virtualized Evolved Packet Core (vEPC), which allows us to quantitatively assess the trade-off between energy cost, robustness and the protection level of the solutions against demand uncertainty. Our heuristic is able to converge to a good solution in a very short time, in comparison to the exact solver, which is not able to output better results in a longer run as demonstrated by our numerical evaluation. We also study the degree of robustness of a solution for a given protection level and the cost of additional energy needed because of the usage of more computing and network elements.

  • 131.
    Marotta, Antonio
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Kassler, Andreas
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT. Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    A Power Efficient and Robust Virtual Network Functions Placement Problem2016In: Teletraffic Congress (ITC 28), 2016 28th International, IEEE, 2016Conference paper (Refereed)
  • 132.
    Marotta, Antonio
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Kassler, Andreas
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Green Virtual Network Functions Placement Under Uncertainty Constraints2016In: , 2016Conference paper (Refereed)
  • 133.
    Marotta, Antonio
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Zola, Enrica
    Universitat Politècnica de Catalunya, Barcelona, Spain.
    D'Andreagiovanni, Fabio
    Sorbonne Universités, Université de Technologie de Compiègne, France.
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013). Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    A fast robust optimization-based heuristic for the deployment of green virtual network functions2017In: Journal of Network and Computer Applications, ISSN 1084-8045, E-ISSN 1095-8592, Vol. 95, p. 45-53Article in journal (Refereed)
    Abstract [en]

    Network Function Virtualization (NFV) has attracted a lot of attention in the telecommunication field because it allows to virtualize core-business network functions on top of a NFV Infrastructure. Typically, virtual network functions (VNFs) can be represented as chains of Virtual Machines (VMs) or containers that exchange network traffic which are deployed inside datacenters on commodity hardware. In order to achieve cost efficiency, network operators aim at minimizing the power consumption of their NFV infrastructure. This can be achieved by using the minimum set of physical servers and networking equipment that are able to provide the quality of service required by the virtual functions in terms of computing, memory, disk and network related parameters. However, it is very difficult to predict precisely the resource demands required by the VNFs to execute their tasks. In this work, we apply the theory of robust optimization to deal with such parameter uncertainty. We model the problem of robust VNF placement and network embedding under resource demand uncertainty and network latency constraints using robust mixed integer optimization techniques. For online optimization, we develop fast solution heuristics. By using the virtualized Evolved Packet Core as use case, we perform a comprehensive evaluation in terms of performance, solution time and complexity and show that our heuristic can calculate robust solutions for large instances under one second.

  • 134. Meng Lim, Teck
    et al.
    Chong Seet, Boon
    Sung Lee, Bu
    Kiat Yeo, Chai
    Kassler, Andreas
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    Pervasive Communication for Commuters in Public Buses2005Conference paper (Refereed)
    Abstract [en]

    Using inter-vehicular communications as a mobile backbone has been a area of active research in recent years. We propose an pervasive mobile communication network that utilises our BUSNet to provide Internet access for the public transportation system such as Buses, Taxi and Trains. These vehicles act as the wireless backbone which connects to the Internet. Thus, users of cellular network can have a faster and lower cost pervasive mobile communication when they use public transports. Unique to our ad hoc to Internet architecture is a a lightweight Access Router discovery protocol, an eventdriven neighbouring Access Router discovery protocol, and a distributed location service with privacy protection that is works in conjunction with Internet Protocol Mobility. Additionally, we proposed two information discovery protocols that use the properties of the movement of buses and Access Routers to provide information for possible advance services, prediction and Quality-of-Service

  • 135.
    Mesodiakaki, Agapi
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Kassler, Andreas
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Enrica, Zola
    UPC.
    Mattias, Ferndahl
    Gothic AB.
    Tao, Cai
    HWSE.
    Energy Efficient Line-of-Sight Millimeter Wave Small Cell Backhaul: 60, 70, 80 or 140 GHz?2016In: World of Wireless, Mobile and Multimedia Networks (WoWMoM), 2016 IEEE 17th International Symposium on A, IEEE, 2016Conference paper (Refereed)
  • 136.
    Mesodiakaki, Agapi
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Zola, Enrica
    Dept. of Network Engineering, UPC - BarcelonaTECH, Spain.
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    User Association in 5G Heterogeneous Networks with Mesh Millimeter Wave Backhaul Links2017In: 18th IEEE International Symposium on a World of Wireless, Mobile and Multimedia Networks (WoWMoM), IEEE, 2017Conference paper (Refereed)
    Abstract [en]

    Fifth generation (5G) wireless networks will target at energy and spectrum efficient solutions to cope with the increasing demands in capacity and energy efficiency. To achieve this joint goal, dense networks of small cells (SCs) are expected to overlay the existing macro cells. In parallel, for the SC connection to the core network, a promising solution lies in a mesh network of high capacity millimeter wave backhaul (BH) links. In the considered 5G architecture, each SC is able to forward its BH traffic to the core network through alternative paths, thus offering high BH network reliability. In this context, the joint problem of user association and BH routing becomes challenging. In this paper, we focus on this problem targeting at energy and spectrum efficient solutions. A low-complexity algorithm is proposed, which bases its user association and BH routing decision i) on minimizing the spectrum resources to guarantee the user rate, so as to provide high spectrum efficiency, and ii) on minimizing both the access network and BH route power consumption to provide high energy efficiency. Our results show that our solution provides better trade-offs between energy and spectrum efficiency than the state-of-the-art in 3GPP scenarios.

  • 137.
    Mesodiakaki, Agapi
    et al.
    Department of Informatics, Aristotle University of Thessaloniki, Greece.
    Zola, Enrica
    UPC-BarcelonaTECH, Barcelona, Spain.
    Santos, Ricardo
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Optimal User Association, Backhaul Routing and Switching off in 5G Heterogeneous Networks with Mesh Millimeter Wave Backhaul Links2018In: Ad hoc networks, ISSN 1570-8705, E-ISSN 1570-8713, Vol. 78, p. 99-114Article in journal (Refereed)
    Abstract [en]

    Next generation, i.e., fifth generation (5G), cellular networks will provide a significant higher capacity per area to support the ever-increasing traffic demands. In order to achieve that, many small cells need to be deployed that are connected using a combination of optical fiber links and millimeter-wave (mmWave) backhaul architecture to forward heterogeneous traffic over mesh topologies. In this paper, we present a general optimization framework for the design of policies that optimally solve the problem of where to associate a user, over which links to route its traffic towards which mesh gateway, and which base stations and backhaul links to switch off in order to minimize the energy cost for the network operator and still satisfy the user demands. We develop an optimal policy based on mixed integer linear programming (MILP) which considers different user distribution and traffic demands over multiple time periods. We develop also a fast iterative two-phase solution heuristic, which associates users and calculates backhaul routes to maximize energy savings. Our strategies optimize the backhaul network configuration at each timeslot based on the current demands and user locations. We discuss the application of our policies to backhaul management of mmWave cellular networks in light of current trend of network softwarization (Software-Defined Networking, SDN). Finally, we present extensive numerical simulations of our proposed policies, which show how the algorithms can efficiently trade-off energy consumption with required capacity, while satisfying flow demand requirements.

  • 138.
    Nasim, Robayet
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    A Robust Tabu Search Heuristic for VM Consolidation under Demand Uncertainity in Virtualized Datacenters2017In: CCGrid '17 Proceedings of the 17th IEEE/ACM International Symposium on Cluster, Cloud and Grid Computing, IEEE, 2017, p. 170-180Conference paper (Refereed)
    Abstract [en]

    In virtualized datacenters (vDCs), dynamic consolidation of virtual machines (VMs) is used as one of the most common techniques to achieve both energy- and resource- utilization efficiency. Live migrations of VMs are used for dynamic consolidation but due to dynamic resource demand variation of VMs may lead to frequent and non-optimal migrations. Assuming deterministic workload of the VMs may ensure the most energy/resource efficient VM allocations but eventually may lead to significant resource contention or under-utilization if the workload varies significantly over time. On the other hand, adopting a conservative approach by allocating VMs depending on their peak demand may lead to low utilization, if the peak occurs infrequently or for a short period of time. Therefore, in this work we design a robust VM migration scheme that strikes a balance between protection for resource contention and additional energy costs due to powering on more servers while considering uncertainties on VMs resource demands. We use the theory of Gamma-robustness and derive a robust Mixed Integer Linear programming (MILP) formulation. Due to the complexity, the problem is hard to solve for online optimization and we propose a novel heuristic based on Tabu search. Using several scenarios, we show that that the proposed heuristic can achieve near optimal solution qualities in a short time and scales well with the instance sizes. Moreover, we quantitatively analyze the trade-off between energy cost versus protection level and robustness.

  • 139.
    Nasim, Robayet
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Deploying OpenStack: Virtual Infrastructure or Dedicated Hardware2014In: Computer Software and Applications Conference Workshops (COMPSACW), 2014 IEEE 38th International, IEEE, 2014, p. 84-89Conference paper (Refereed)
    Abstract [en]

    Cloud computing is a computing model through which resources such as - infrastructure, applications or software are offered as services to the users. Cloud computing offers the opportunity of virtualization through deploying multiple virtual machines (VMs) on single physical machine, which increases resource utilization and reduces power consumption. The main benefit of a virtualized technology relies on its on-demand resource allocation strategy and flexible management. OpenStack is one of the promising open source solutions which offers infrastructure as a service. This paper covers how underlying infrastructure for deployment affects the performance of OpenStack. The aim is to provide a comparative view on the performance of OpenStack while deploying it over a virtual environment versus using dedicated hardware. We conduct three basic tests on both environments to check CPU performance, data transfer rate, and bandwidth. The results show that OpenStack over dedicated hardware performs much better than OpenStack over virtualized environment.

  • 140.
    Nasim, Robayet
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Kassler, Andreas
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    Distributed Architectures for Intelligent Transport Systems: A Survey2012In: 2012 Second Symposium on Network Cloud Computing and Applications (NCCA), IEEE Press, 2012, p. 130-136Conference paper (Refereed)
    Abstract [en]

    Recently Intelligent Transport Systems (ITS) have acted as an efficient solution for improving the operational performance of traffic systems, reducing traffic congestion, and increasing safety for the travelers. But due to the inclusion of different distributed transport departments, heterogeneous devices, and diverse data sources, the architecture of ITS has become complex and costly. For an efficient and cost-effective architecture, ITS need to have easy and effective mechanisms for interacting among different transport subsystems. Recent technologies such as – service-oriented architectures (SOA), cloud or grid computing, provide a way of building a reliable and loosely-coupled distributed system. This paper surveys the promising solutions for distributed architectures of ITS and discusses opportunities and challenges in the context of ITS for public transport.

  • 141.
    Nasim, Robayet
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Kassler, Andreas
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Network-centric Performance Improvement for Live VM Migration2015In: 2015 IEEE 8th International Conference on Cloud Computing, IEEE, 2015, p. 106-113Conference paper (Refereed)
    Abstract [en]

    Live Virtual Machine (VM) migrations are an important tool that is used in modern datacenters in order to e.g. consolidate server racks for maintenance or optimize VM placements across physical hosts. However, live VM migration causes a lot of network stress due to the potential large volume of data that is transmitted between the physical hosts, which may negatively impact other latency sensitive VM to VM traffic. As VM downtime and the time to migrate depend on the allocated resources for migration traffic, it is important to manage the network resources for live VM migration traffic. In this work, we improve the performance for both live VM migration traffic and VM to VM communication using three strategies. First, we take advantage out of the path diversity available in modern datacenters and utilize multipath TCP (MPTCP) for live VM traffic. Second, we implement flexible use of queue management strategies such as FQ_CODEL or Hierarchy Token Bucket (HTB). Finally, we orchestrate the process into OpenStack Neutron and connect it together with an SDN control application, which runs on OpenDaylight. An extensive evaluation in our OpenStack testbed using different VM workload patterns and VM sizes shows, that FQ_CODEL can bring down VM to VM latency during ongoing migrations while MPTCP effectively aggregates bandwidth of multiple paths to reduce live VM migration latency and downtime.

  • 142.
    Nasim, Robayet
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    The Impact of Underlying Infrastructure on Performance of Private Cloud Deployments2014Conference paper (Refereed)
  • 143.
    Nasim, Robayet
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Kassler, Andreas
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Žarko, Ivana Podnar
    Croatia.
    Antonic, Aleksandar
    Croatia.
    Mobile Publish/Subscribe System for Intelligent Transport Systems over a Cloud Environment2014In: 2014 International Conference on Cloud and Autonomic Computing (ICCAC 2014): Proceedings of a meeting held 8-12 September 2014, London, United Kingdom, IEEE, 2014, p. 187-195Conference paper (Refereed)
    Abstract [en]

    With the advent of Smart Cities, public transport authorities are more and more interested in Intelligent Transport System (ITS) applications that allow to process a large amount of static and real time data in order to make public transport smarter. However, deploying such applications in a large scale distributed environment is challenging and requires an automated, scalable, flexible, elastic, loosely-coupled communication models in order to dynamically link information providers and consumers. To this end, Publish/Subscribe (Pub/Sub) systems offer an asynchronous, dynamic, decoupled interaction scheme that is perfectly suitable for developing up-to-date, large-scale distributed applications within the ITS domain. In addition, cloud computing offers computational resources as services to utility driven model regardless of considering geographical locations in a scalable, elastic, fault tolerant and cost-effective way. In this work, we build an ITS application “Real-time Public Transit Tracking” on top of a Mobile Pub/Sub System (MoPS), and deploy it over an open source cloud platform, OpenStack, in order to achieve high performance and flexible management. We conduct a set of experiments to evaluate the performance of the implemented ITS application in terms of scalability, resource usage, and efficiency of the underlying matching algorithm under automated mobility of the subscribers. Our experimental results show that the ITS application can handle a large number of subscribers and publishers with proper reliability and negligible notification delay under real-time constraints. Further, we present a measurement study to characterize the impact of different workloads on the performance of OpenStack.

  • 144.
    Nasim, Robayet
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Taheri, Javid
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Optimizing Virtual Machine Consolidation in Virtualized Datacenters Using Resource Sensitivity2016In: Cloud Computing Technology and Science (CloudCom), 2016 IEEE International Conference on, IEEE, 2016, p. 168-175Conference paper (Refereed)
    Abstract [en]

    In virtualized datacenters (vDCs), dynamic consolidation of virtual machines (VMs) is used to achieve both energy-efficiency and load balancing among different physical machines (PMs). Using VM live migrations, we can consolidate VMs on a smaller number of hosts to power down unused PMs and save energy. Most migration schemes are however oblivious to the characteristics of services that run inside VMs, and thus may lead to migrations where VMs competing for the same resource type are packed on the same PM. As a result, VMs may suffer from significant resource contention and noticeable degradation in their performance. Using resource sensitivity values of VMs (ie, quantitative measures to reflect how much a VM is sensitive to its requested resources such as CPU, Mem, and Disk), we have designed a novel VM consolidation approach to optimize placement of VMs on available PMs. We validated our approach using five well-known applications/benchmarks with various resource demand signatures: varying from pure CPU/Mem/Disk-intensive to mixtures of them. Our extensive numerical evaluation illustrates that, for the same power consumption, our approach improve the performance of cloud services by 9 - 12\%, on average, when compared with current sensitivity oblivious approaches.

  • 145.
    Nasim, Robayet
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Zola, Enrica
    Universitat Politècnica de Catalunya (UPC), Spain..
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Robust Optimization for Energy-Efficient Virtual Machine Consolidation in Modern Datacenters2018In: Cluster Computing, ISSN 1386-7857, E-ISSN 1573-7543, Vol. 21, no 3, p. 1681-1709Article in journal (Refereed)
    Abstract [en]

    Energy efficient Virtual Machine (VM) consolidation in modern data centers is typically optimized using methods such as Mixed Integer Programming, which typically require precise input to the model. Unfortunately, many parameters are uncertain or very difficult to predict precisely in the real world. As a consequence, a once calculated solution may be highly infeasible in practice. In this paper, we use methods from robust optimization theory in order to quantify the impact of uncertainty in modern data centers. We study the impact of different parameter uncertainties on the energy efficiency and overbooking ratios such as e.g. VM resource demands, migration related overhead or the power consumption model of the servers used. We also show that setting aside additional resource to cope with uncertainty of workload influences the overbooking ratio of the servers and the energy consumption. We show that, by using our model, Cloud operators can calculate a more robust migration schedule leading to higher total energy consumption. A more risky operator may well choose a more opportunistic schedule leading to lower energy consumption but also higher risk of SLA violation.

  • 146. O'Droma, Máirtín
    et al.
    Rupp, Markus
    Koucheryavy, Yevgeni
    Kassler, Andreas
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    Advances in Quality and Performance Assessment for Future Wireless Communication Services2010In: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. 2010, p. 1-3Article in journal (Refereed)
  • 147. Ossipov, Evgeny
    et al.
    Kassler, AndreasKarlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.Bohnert, Thomas MichaelMasip-Bruin, Xavier
    Wired/Wireless Internet Communications: 8th International Conference, WWIC 20102010Conference proceedings (editor) (Refereed)
  • 148.
    Pieskä, Marcus
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Reducing the Latency of TCP for 5G mmWave Links2017Conference paper (Refereed)
    Abstract [en]

    Abstract: Recently, 5G systems started to explore the usage of mmWave bands both for access and backhaul due to the extremely large portion of bandwidth available. Cellular systems operating at such frequencies would achieve a significantly higher capacity than current systems. Due to the propagation characteristics at those frequency bands, highly directional links may frequently switch between Line-of-sight and outage if the beam is blocked by obstacles. Such intermittent connectivity combined with high throughput however causes TCP to perform very badly. In this paper, we study the performance of several TCP variants in intermittend mmWave links. We focus on latency aspects as 5G systems should be designed for very low latency. We use ns-3 in emulation mode (DCE) and experiment with real Linux TCP implementations. Unfortunately, all TCP variants that we evaluated, increase the latency tremendously when the mmWave link characteristics switch from Line-of-sight to non Line-of-sight. In addition, when applying bufferbloat solutions such as CoDel, the latency can be controlled at the expense of low throughput. Based on our findings, we develop a method which transparently tunes the receive window of the TCP connections both for upload and download to effectively maintain low latency while at the same time achieving high capacity.

  • 149.
    Pieskä, Marcus
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    TCP Performance over 5G mmWave Links - Tradeoff between Capacity and Latency2017In: 2017 IEEE 13th International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob), IEEE, 2017, p. 385-394Conference paper (Refereed)
    Abstract [en]

    Recently, 5G systems started to explore the usage of mmWave bands both for access and backhaul. Cellular systems operating at such frequencies would achieve a significantly higher capacity than current systems due to the large frequency block available. Due to the propagation characteristics, highly directional mmWave links may frequently switch between Line-of-sight, Non Line-of-sight and outage if the beam is blocked by obstacles. Such intermittent connectivity combined with high throughput causes TCP to perform very badly. In this paper, we study the performance of several TCP variants over intermittent mmWave links. We focus on latency aspects, use ns-3 with extensions for mmWave links and evaluate the TCP performance with real Linux TCP stacks using the Direct Code Execution (DCE) framework. We also investigate the benefit of bufferbloat solutions such as CoDel, with different TCP variants. We investigate the impact of CoDels configuration parameters and different RTTs on TCP throughput, fairness and queueing delay. The problem of slow recovery of TCP after NLOS periods is less pronounced when multiple flows coexist under CoDel only if some of the flows have very short RTTs. However, under presence of NLOS, the fairness between different flows with different RTT values is reduced.

  • 150.
    Pieskä, Marcus
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Kassler, Andreas
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT. Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Lundqvist, Henrik
    Huawei, Stockholm.
    Cai, Tao
    Huawei, stockholm.
    Improving TCP Fairness over Latency Controlled 5G mmWave Communication Links2018In: WSA 2018; 22nd International ITG Workshop on Smart Antennas, 2018Conference paper (Refereed)
    Abstract [en]

    In order to increase the capacity of 5G networks, using mmWave band communication links both for access and backhaul are an important alternative due to the large spectrum portion available at those frequency bands. However, mmWave bands exhibit special propagation characteristics which require the usage of highly directional and beam-steerable antennas in order to cope with the significantly higher path loss. Using such links in urban scenarios may lead to frequent blocking events due to moving pedestrians or cars, which may result in the links dynamically changing their characteristics from Line-of-Sight (LOS) to Non Line-of- Sight (NLOS) or outage (OUT). Due to the immediate significant variation in available capacity when changing the link states, TCP connections may experience rapid spikes in end-to-end latency and severe bufferbloat may build up. Although bufferbloat solutions such as CoDel can be deployed to control the delay, they significantly impact capacity and fairness between different TCP flows sharing the same mmWave link. In this paper, we study this fairness issue when running multiple TCP connections over fluctuating mmWave links and deploying AQM schemes to control the latency. We study the effect of length and severity of the NLOS episode upon fairness and latency. Finally, we develop an algorithm that tunes the AQM parameters in order to increase fairness across flows having different RTTs while at the same time reduce their latency.

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