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  • 1.
    Abdollahi, Kamran
    et al.
    Computer and Science Department Iran University of Science and Technology Tehran, Iran.
    Shams Shafigh, Alireza
    Computer and Science Department Iran University of Science and Technology Tehran, Iran.
    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.
    Improving Performance of On Demand Multicast Routing by deleting lost join query packet2010In: Proceedings of The Sixth Advanced International Conference on Telecommunications - AICT 2010, IEEE conference proceedings, 2010, p. 316-322Conference paper (Refereed)
    Abstract [en]

    A Mobile ad hoc network is a collection of wireless nodes that dynamically organize themselves to form a network without the need for any fixed infrastructure or centralized administration. The network topology dynamically changes frequently in an unpredictable manner since nodes are free to move. Support for multicasting is essential in such environment as it is considered to be an efficient way to deliver information from source nodes to many client nodes. A problem with multicast routing algorithms is their efficiency as their forwarding structure determines the overall network resource consumption makes them significantly less efficient than unicast routing algorithms. In this research, we improve the performance of the popular ODMRP multicast routing protocol by restricting the domain of join query packets, which have been lost. This is achieved by augmenting the join query packets with minimum extra information (one field), which denotes the number of the visited node from previous forwarding group. Simulation results show, that our mechanisms significantly reduce the control traffic and thus the overall latency and power consumption in the network.

  • 2.
    Agapi, Mesodiakaki
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Zola, Enrica
    UPC BarcelonaTECH, Barcelona Spain.
    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.
    Joint User Association and Backhaul Routing for Green 5G Mesh Millimeter Wave Backhaul Networks2017In: Proceedings Of The 20Th Acm International Conference On Modelling, Analysis And Simulation Of Wireless And Mobile Systems, ASSOC COMPUTING MACHINERY, , 2017, p. 179-186Conference paper (Refereed)
    Abstract [en]

    With the advance of fifth generation (5G) networks, network density needs to grow significantly in order to meet the required capacity demands. A massive deployment of small cells may lead to a high cost for providing. ber connectivity to each node. Consequently, many small cells are expected to be connected through wireless links to the umbrella eNodeB, leading to a mesh backhaul topology. This backhaul solution will most probably be composed of high capacity point-to-point links, typically operating in the millimeter wave (mmWave) frequency band due to its massive bandwidth availability. In this paper, we propose a mathematical model that jointly solves the user association and backhaul routing problem in the aforementioned context, aiming at the energy efficiency maximization of the network. Our study considers the energy consumption of both the access and backhaul links, while taking into account the capacity constraints of all the nodes as well as the fulfillment of the service-level agreements (SLAs). Due to the high complexity of the optimal solution, we also propose an energy efficient heuristic algorithm (Joint), which solves the discussed joint problem, while inducing low complexity in the system. We numerically evaluate the algorithm performance by comparing it not only with the optimal solution but also with reference approaches under different traffic load scenarios and backhaul parameters. Our results demonstrate that Joint outperforms the state-of-the-art, while being able to find good solutions, close to optimal, in short time.

  • 3.
    Agapi, Mesodiakaki
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Zola, Enrica
    Univ Politecn Cataluna, Dept Network Engn, Barcelona, 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: 2017 IEEE 18th International Symposium on A World of Wireless, Mobile and Multimedia Networks (WoWMoM), IEEE, 2017Chapter in book (Other academic)
    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 BIT network reliability. In this context, the joint problem of user association and HI 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 BIT 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.

  • 4. Ali Yahiya, Tara
    et al.
    Chaouchi, Hakima
    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.
    Pujolle, Guy
    Seamless Interworking of WLAN and WMAN Wireless Networks2006Conference paper (Refereed)
    Abstract [en]

    Future network environments will be heterogeneous and mobile terminals will have the opportunity to dynamically select among many different access technologies. Therefore, it is important to provide service continuity in case of vertical handovers when terminals change the access technology. Two important wireless access technologies are WLAN (Wireless Local Access Networks) and WMAN (Wireless Metropolitan Access Networks) networks. In this paper, we address several challenges related to a seamless integration of those technologies. We highlight important aspects for designing a WLAN/WMAN interworking architecture and we address important Quality of Service (QoS) issues for such interworked systems like degree of QoS support provided by the technologies, QoS mapping and signalling for vertical handover. By formulating several interworking scenarios, where WLAN users with ongoing voice, video and data sessions hand over to WMAN, we study QoS and performance issues and analyse feasibility of seamless session continuity through simulations

  • 5.
    Alizadeh Noghani, Kyoomars
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Hernandez Benet, Cristian
    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).
    Antonio, Marotta
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Jestin, Patrick
    Ericsson AB, Sweden.
    Srivastava, Vivek V.
    Ericsson AB, Sweden.
    Automating Ethernet VPN deployment in SDN-based Data Centers2017In: 2017 Fourth International Conference on Software Defined Systems (SDS)., IEEE, 2017, p. 61-66Conference paper (Refereed)
    Abstract [en]

    Layer 2 Virtual Private Network (L2VPN) is widely deployed in both service provider networks and enterprises. However, legacy L2VPN solutions have scalability limitations in the context of Data Center (DC) interconnection and networking which require new approaches that address the requirements of service providers for virtual private cloud services. Recently, Ethernet VPN (EVPN) has been proposed to address many of those concerns and vendors started to deploy EVPN based solutions in DC edge routers. However, manual configuration leads to a time-consuming, error-prone configuration and high operational costs. Automating the EVPN deployment from cloud platforms such as OpenStack enhances both the deployment and flexibility of EVPN Instances (EVIs). This paper proposes a Software Defined Network (SDN) based framework that automates the EVPN deployment and management inside SDN-based DCs using OpenStack and OpenDaylight (ODL). We implemented and extended several modules inside ODL controller to manage and interact with EVIs and an interface to OpenStack that allows the deployment and configuration of EVIs. We conclude with scalability analysis of our solution.

  • 6.
    Alizadeh Noghani, Kyoomars
    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).
    SDN Enhanced Ethernet VPN for Data Center Interconnect2017In: 2017 IEEE 6th International Conference on Cloud Networking (CloudNet) / [ed] Maga, D, IEEE, 2017, p. 77-82Conference paper (Refereed)
    Abstract [en]

    Ethernet Virtual Private Network (EVPN) is an emerging technology that addresses the networking challenges presented by geo-distributed Data Centers (DCs). One of the major advantages of EVPN over legacy layer 2 VPN solutions is providing All-Active (A-A) mode of operation so that the traffic can truly be multi-homed on Provider Edge (PE) routers. However, A-A mode of operation introduces new challenges. In the case where the Customer Edge (CE) router is multi-homed to one or more PE routers, it is necessary that only one of the PE routers should forward Broadcast, Unknown unicast, and Multicast (BUM) traffic into the DC. The PE router that assumes the primary role for forwarding BUM traffic to the CE device is called the Designated Forwarder (DF). The proposed solution to select the DF in the EVPN standard is based on a distributed algorithm which has a number of drawbacks such as unfairness and intermittent behavior. In this paper, we introduce a Software-Defined Networking (SDN) based architecture for EVPN support, where the SDN controller interacts with EVPN control plane. We demonstrate how our solution mitigates existing problems for DF selection which leads to improved EVPN performance.

  • 7.
    Alizadeh Noghani, Kyoomars
    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).
    Sankar Gopannan, Prem
    Ericsson, USA.
    EVPN/SDN Assisted Live VM Migration between Geo-Distributed Data Centers2018In: 4th IEEE Conference on Network Softwarization (NetSoft), 2018, p. 105-113Conference paper (Refereed)
    Abstract [en]

    Live Virtual Machine (VM) migration has significantly improved the flexibility of modern Data Centers (DC). However, seamless live migration of a VM between geo-distributed DCs faces several challenges due to difficulties in preserving the network configuration after the migration paired with a large network convergence time. Although SDN-based approaches can speed up network convergence time, these techniques have two limitations. First, they typically react to the new topology by installing new flow rules once the migration is finished. Second, because the WAN is typically not under SDN control, they result in sub-optimal routing thus severely degrading the network performance once the VM is attached at the new location.

    In this paper, we identify networking challenges for VM migration across geo-distributed DCs. Based on those observations, we design a novel long-haul VM migration scheme that overcomes those limitations. First, instead of reactively restoring connectivity after the migration, our SDN-based approach proactively restores flows across the WAN towards the new location with the help of EVPN and VXLAN overlay technologies. Second, the SDN controller accelerates the network convergence by announcing the migration to other controllers using MP-BGP control plane messages. Finally, the SDN controller resolves the sub-optimal routing problem that arises as a result of migration implementing a distributed anycast gateway. We implement our approach as extensions to the OpenDaylight controller. Our evaluation shows that our approach outperforms existing approaches in reducing the downtime by 400 ms and increasing the application performance up to 12 times.

  • 8.
    Antonio, Marotta
    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.

  • 9.
    Antonio, Marotta
    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.

  • 10.
    Avallone, Stefano
    et al.
    Univ Naples Federico II, Dept Comp Engn, I-80125 Naples, Italy.
    Di Stasi, Giovanni
    Univ Naples Federico II, Dept Comp Engn, I-80125 Naples, Italy.
    Kassler, Andreas
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    A Traffic-Aware Channel and Rate Re-Assignment Algorithm for Wireless Mesh Networks.2013In: IEEE Transactions on Mobile Computing, ISSN 1536-1233, E-ISSN 1558-0660, Vol. 12, no 7, p. 1335-1348Article in journal (Refereed)
  • 11.
    Bayer, Nico
    et al.
    Deutsche Telekom/T-Systems, Darmstadt, Germany.
    Cavalcanti de Castro, Marcel
    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.
    Kassler, Andreas
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Koucheryavy, Yevgeni
    Tampere University of Technolo, Finland.
    Mitoraj, Piotr
    Tampere University of Technology, Finland.
    Staehle, Dirk
    University of Würzburg, Germany.
    VoIP service performance optimization in pre-IEEE 802.11s Wireless Mesh Networks2008In: Proceedings of the IEEE International Conference on Circuits andSystems for Communications (ICCSC) 2008, IEEE conference proceedings, 2008, p. 75-79Conference paper (Refereed)
    Abstract [en]

    802.11-based wireless mesh networks are seen as a means for providing last mile connections to next generation networks. Due to the low deployment cost and the mature technology used, they are scalable, easy to implement and robust. With an increasing coverage of wireless networks, VoIP becomes a cheaper alternative for traditional and cellular telephony. In this paper, we carry out a feasibility study of VoIP in a dual radio mesh environment. Heading towards 802.11s, we present the design of a mesh testbed and methodology for performing the measurements. Additionally, we address the problem that small voice packets introduce a high overhead leading to a low voice capacity of 802.11 based mesh networks. In order to alleviate this problem and increase the voice capacity, a novel packet aggregation mechanism is presented and evaluated using the ns-2 simulator.

  • 12.
    Bellalta, Boris
    et al.
    Department of Information and Communication Technologies, Universitat Pompeu Fabra, Barcelona 08018, Spain.
    Bononi, Luciano
    Department of Computer Science and Engineering, University of Bologna, 40127 Bologna, Italy.
    Bruno, Raffaele
    Institute for Informatics and Telematics (IIT), Italian National Research Council (CNR), Pisa 56124, Italy.
    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.
    Next generation IEEE 802.11 Wireless Local Area Networks: Current status, future directions and open challenges2016In: Computer Communications, ISSN 0140-3664, E-ISSN 1873-703X, Vol. 75, p. 1-25Article in journal (Refereed)
    Abstract [en]

    A new generation of Wireless Local Area Networks (WLANs) will make its appearance in the market in the forthcoming years based on the amendments to the IEEE 802.11 standards that have recently been approved or are under development. Examples of the most expected ones are IEEE 802.11aa (Robust Audio Video Transport Streaming), IEEE 802.11ac (Very-high throughput at < 6 GHz), IEEE 802.11af (TV White Spaces) and IEEE 802.11ah (Machine-to-Machine communications) specifications. The aim of this survey is to provide a comprehensive overview of these novel technical features and the related open technical challenges that will drive the future WLAN evolution. In contrast to other IEEE 802.11 surveys, this is a use case oriented study. Specifically, we first describe the three key scenarios in which next-generation WLANs will have to operate. We then review the most relevant amendments for each of these use cases focusing on the additional functionalities and the new technologies they include, such as multi-user MIMO techniques, groupcast communications, dynamic channel bonding, spectrum databases and channel sensing, enhanced power saving mechanisms and efficient small data transmissions. We also discuss the related work to highlight the key issues that must still be addressed. Finally, we review emerging trends that can influence the design of future WLANs, with special focus on software-defined MACs and the internet-working with cellular systems.

  • 13.
    Benet, Cristian Hernandez
    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.
    Zola, Enrica
    Univ Politecn Cataluna, C Jordi Girona 1-3, Barcelona, Spain..
    Predicting expected TCP throughput using genetic algorithm2016In: Computer Networks, ISSN 1389-1286, E-ISSN 1872-7069, Vol. 108, p. 307-322Article in journal (Refereed)
    Abstract [en]

    Predicting the expected throughput of TCP is important for several aspects such as e.g. determining handover criteria for future multihomed mobile nodes or determining the expected throughput of a given MPTCP subflow for load-balancing reasons. However, this is challenging due to time varying behavior of the underlying network characteristics. In this paper, we present a genetic-algorithm-based prediction model for estimating TCP throughput values. Our approach tries to find the best matching combination of mathematical functions that approximate a given time series that accounts for the TCP throughput samples using genetic algorithm. Based on collected historical datapoints about measured TCP throughput samples, our algorithm estimates expected throughput over time. We evaluate the quality of the prediction using different selection and diversity strategies for creating new chromosomes. Also, we explore the use of different fitness functions in order to evaluate the goodness of a chromosome. The goal is to show how different tuning on the genetic algorithm may have an impact on the prediction. Using extensive simulations over several TCP throughput traces, we find that the genetic algorithm successfully finds reasonable matching mathematical functions that allow to describe the TCP sampled throughput values with good fidelity. We also explore the effectiveness of predicting time series throughput samples for a given prediction horizon and estimate the prediction error and confidence. 

  • 14.
    Bozakov, Zdravko
    et al.
    Dell EMC, Ireland.
    Mangiante, Simone
    Dell EMC, Ireland.
    Hernandez Benet, Cristian
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Brunström, Anna
    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.
    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).
    Buckley, Donagh
    Dell EMC, Ireland.
    A NEAT framework for enhanced end-host integration in SDN environments2017In: 2017 IEEE Conference on Network Function Virtualization and Software Defined Networks (NFV-SDN), IEEE, 2017Conference paper (Refereed)
    Abstract [en]

    SDN aims to facilitate the management of increasingly complex, dynamic network environments and optimize the use of the resources available therein with minimal operator intervention. To this end, SDN controllers maintain a global view of the network topology and its state. However, the extraction of information about network flows and other network metrics remains a non-trivial challenge. Network applications exhibit a wide range of properties, posing diverse, often conflicting, demands towards the network. As these requirements are typically not known, controllers must rely on error-prone heuristics to extract them. In this work, we develop a framework which allows applications deployed in an SDN environment to explicitly express their requirements to the network. Conversely, it allows network controllers to deploy policies on end-hosts and to supply applications with information about network paths, salient servers and other relevant metrics. The proposed approach opens the door for fine grained, application-aware resource optimization strategies in SDNs

  • 15.
    Brajdic, Agata
    et al.
    Fac. of EE & Comput., Univ. of Zagreb, Zagreb, Croatia .
    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.
    Matijasevic, Maja
    Quality of Experience based optimization of heterogeneous multimedia sessions in IMS2011In: Proceedings of Baltic Congress on Future Internet Communications, IEEE conference proceedings, 2011, p. 25-32Conference paper (Refereed)
    Abstract [en]

    For delivering multimedia services over (wireless) networks it is important that the mechanisms which negotiate and optimize content delivery under resource constraints take into account user perceived quality in order to improve user satisfaction. Within the scope of the IP Multimedia Subsystem (IMS) architecture a novel application server may be added which handles multi-user multi-flow Quality of Experience (QoE) negotiation and adaptation for heterogeneous user sessions. Based on a mathematical model, which takes into account the characteristics of audio, video and data sessions for QoE optimization, we develop several optimization algorithms to be used by the application server to maximize overall user defined QoE parameters for all ongoing multimedia sessions, subject to network resource constraints. Our results show that a greedy based approach provides a reasonable compromise in terms of run-time and sub-optimality for the overall QoE based resource allocations.

  • 16. Brolin, Jonas
    et al.
    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.
    Hedegren, Mikael
    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.
    Implementing Packet Aggregation in the Linux Kernel2008Conference paper (Refereed)
    Abstract [en]

    In multi-hop wireless mesh networks (WMN) Voice over IP (VoIP) suffers from large overhead created by the IP/UDP/RTP/MAC header and time due to collisions. As a result the VoIP capacity of WMNs is small. As shown in [1] a 3 hop WMN at a data rate of 2Mbit/s can only support 3 concurrent VoIP flows. [1], [2] and [3] propose the use of packet aggregation in order to reduce the overhead and thus increase the capacity. The idea behind packet aggregation is to combine multiple small packets into a single larger one, reducing overhead and collision probability in multi-hop environment. This paper presents insights into an implementation of an aggregation scheme in the Linux Kernel and its experimental evaluation

  • 17.
    Brunström, Anna
    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.
    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.
    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.
    Palazzo, S
    DR11.2: Intermediate report on resource management issues and routing/forwarding schemes for opportunistic networks2009Report (Refereed)
  • 18.
    Brunström, Anna
    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.
    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.
    Lavén, Andreas
    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.
    Galluccio, L
    NEWCOM++ DR11.3: Final report on the activities and results of WPR112010Report (Other academic)
    Abstract [en]

    This document is the last deliverable of WPR.11 and presents an overview of the final activities carried out within the NEWCOM++ Workpackage WPR.11 during the last 18 months. We provide a description of the most consolidated Joint Research Activities (JRAs) and the main results so far obtained. We also address some considerations on the future activities which are expected to continue at the end of NEWCOM++

  • 19.
    Cardellini, Valeria
    et al.
    University of Rome Tor Vergata, Rome, Italy.
    Galinac Grbac, Tihana
    Facylty of Engineering, University or Rijeka, Rijeka, Croatia .
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Kathiravelu, Pradeeban
    INESC-ID Lisboa, Instituto Superior Técnico, Universidade de Lisboa, Portugal.
    Lo Presti, Francesco
    University or Rome tor Vergata, Rome, Italy.
    Marotta, Antonio
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Nardelli, Matteo
    University of Rome Tor Vergata, Rome, Italy.
    Luís, Veiga
    INESC-ID Lisboa/Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal.
    Integrating SDN and NFV with QoS-Aware Service Composition Cardellini2018In: Autonomous Control for a Reliable Internet of Services: Methods, Models, Approaches, Techniques, Algorithms, and Tools / [ed] Ivan Ganchev, Robert D. van der Mei and J.L. van den Berg, Cham, Switzerland: Springer, 2018, 1, p. 212-240Chapter in book (Refereed)
    Abstract [en]

    Traditional networks are transformed to enable full integrationof heterogeneous hardware and software functions, that are configuredat runtime, with minimal time to market, and are provided to theirend users on “as a service” principle. Therefore, a countless number ofpossibilities for further innovation and exploitation opens up. NetworkFunction Virtualization (NFV) and Software-Defined Networking (SDN)are two key enablers for such a new flexible, scalable, and service-orientednetwork architecture. This chapter provides an overview of QoS-awarestrategies that can be used over the levels of the network abstractionaiming to fully exploit the new network opportunities. Specifically, wepresent three use cases of integrating SDN and NFV with QoS-awareservice composition, ranging from the energy efficient placement of virtualnetwork functions inside modern data centers, to the deployment ofdata stream processing applications using SDN to control the networkpaths, to exploiting SDN for context-aware service compositions.

  • 20.
    Castro C, Marcel
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Prasad, Durga M
    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.
    Avallone, Stefano
    Peer-to-Peer Selection and Channel Assignment for Wireless Mesh Networks2011Conference paper (Refereed)
    Abstract [en]

    Wireless mesh networks are an emerging paradigm for future broadband wireless access networks, with manyapplication areas ranging from content distribution over community networking and providing backhaul networking for sensor devices. In wireless mesh networks, clients connect to wireless routers which are equipped with one or more wireless cards and relay the packets over the wireless links towards internetgateways or the destination. Peer-to-Peer applications are an important class of applications which contributes nowadays to the majority of internet traffic. Therefore, it is important to provide high capacity in the mesh network to support them. However, the capacity of wireless mesh networks depends on many factors such as network topology and size, traffic volume and pattern, interfaces per node and channel assignment scheme used, modulation schemes, routing approaches, etc. In this paper, we develop an analytical framework which allows to estimate theachievable capacity of a wireless mesh network when peer-to-peer applications download many flows simultaneously. The model is based on the collision domain concept and incorporates various channel assignment, replication and peer selection strategies. We investigate the achievable capacity for various scenarios and study the impact of different parameters such as the number of channels or radios used

  • 21.
    Castro, Marcel C.
    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.
    Kassler, Andreas
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Vaidya, Nitin H.
    QoS-Aware Channel Scheduling for Multi-Radio/Multi-Channel Wireless Mesh Networks2009In: Proceedings of the Fourth ACM International Workshop on Wireless Network Testbeds, Experimental evaluation and Characterization (WiNTECH 09), New York: ACM , 2009Conference paper (Refereed)
    Abstract [en]

    In non-static multi-radio/multi-channel wireless mesh networks architectures such as Net-X, mesh nodes need to switch channels in order to communicate with different neighbors. Present channel schedulers do not consider the requirements of real time traffic such as voice over IP. Thus the resulting quality is low. We propose a novel channel scheduler for the Net-X platform that takes into account packet priorities. We evaluate the algorithm on the KAUMesh testbed. Our algorithm outperforms the standard round-robin scheduler both in terms of average delay and jitter.

  • 22.
    Castro, Marcel
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Gallucio, Laura
    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.
    Rametta, Corrado
    Opportunistic P2P Communications in Delay Tolerant Rural Scenarios2011In: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. Januari, article id 892038Article in journal (Refereed)
    Abstract [en]

    Opportunistic networking represents a promising paradigm for support of communications, specifically in infrastructure-less scenarios such as remote areas communications. In principle in opportunistic environments, we would like to make available all the applications thought for traditional wired and wireless networks like file sharing and content distribution. In this paper we present a delay tolerant scenario for file sharing applications in rural areas where an opportunistic approach is exploited. In order to support communications, we compare two peer-to-peer (P2P) schemes initially conceived for wireless networks and prove their applicability and usefulness to a DTN scenario where replication of resources can be used to improve the lookup performance and the network can be occasionally connected by mean of a data mule. Simulation results show the suitability of the schemes and allow to derive interesting design guidelines on the convenience and applicability of such approaches

  • 23.
    Castro, Marcel
    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.
    Avallone, Stefano
    Uni Napoli.
    BestPeer: A Load-aware Multi-path Peer Selection for Wireless Mesh Networks2012In: 2012 IEEE International Symposium on a World of Wireless, Mobile and Multimedia Networks (WoWMoM), IEEE Press, 2012Conference paper (Refereed)
    Abstract [en]

    In this paper we study the interactions between peer selection, routing and channel assignment while deploying Peer-to-Peer (P2P) systems over multi-channel multi-radio Wireless Mesh Networks (WMNs). In particular we propose Bestpeer, a novel peer selection algorithm for WMNs which incorporates a cross-layer path load metric and integrates multi-path load balancing capability throughout the P2P download process in order to achieve faster resource disseminations. By comparing Bestpeer with BitTorrent through extensive simulations, we show that we can reduce the time to disseminate a resource by up to 40 %. The key mechanism used by Bestpeer to increase performance in WMNs is the effective exploitation of cross-layer information made available from the routing and channel assignment during the peer selection process in order to balance the load along high capacity paths

  • 24.
    Castro, Marcel
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Villanueva, Eva
    Ruiz, Iraide
    Sargento, Susana
    Kassler, Andreas
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Performance Evaluation of Structured P2P over Wireless Multi-hop Networks2008In: SENSORCOMM '08 Proceedings of the 2008 Second International Conference on Sensor Technologies and Applications, IEEE conference proceedings, 2008, p. 796-801Conference paper (Refereed)
    Abstract [en]

    Internet connected wireless multi-hop networks are an interesting alternative for providing broadband wireless access. In order for the network to be transparent, the same services need to be available as in standard infrastructure wireless deployments. However, there is a significant challenge in providing services such as authentication, name resolution, VoIP over multi-hop mesh networks as dedicated servers implementing those services might be not available. Therefore, deploying overlay networks in the mesh to decentralize those services and move towards a Peer-to-Peer paradigm is an interesting approach. However, the multi-hop nature of wireless mesh networks and the restrictions in resource availability might cause problems when deploying overlay networks on top of such environments. In this paper, we investigate the overhead and trade-offs when deploying a structured overlay solution such as the Bamboo DHT over wireless multi-hop mesh networks. We provide various simulation results characterizing the overhead of management and control traffic and give recommendations for performance improvement.

  • 25.
    Cavalcanti de Castro, Marcel
    et al.
    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.
    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.
    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.
    Capacity Increase for Voice over IP Traffic through Packet Aggregation in Wireless Multihop Mesh Networks2007Conference paper (Refereed)
    Abstract [en]

    Recently, Voice over IP (VoIP) has become an important service for the future internet. However, for ubiquitous wireless VoIP services, greater coverage will be necessary as promised by the advent of e.g. 802.11 WLAN based wireless meshed networks. Unfortunately, the transmission of small (voice) packets imposes high overhead which leads to low capacity for VoIP over 802.11 based multihop meshed networks. In this work, we present a novel packet aggregation mechanism that significantly enhances capacity of VoIP in wireless meshed networks while still maintaining satisfactory voice quality. Extensive experiments using network simulation ns-2 confirm that our packet aggregation algorithm can lead to a significantly increase in the number of supported concurrent VoIP flows over a variety of different hop numbers while reducing the MAC layer contention

  • 26.
    Cavalcanti de Castro, Marcel
    et al.
    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.
    Galluccio, L
    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.
    Palazzo, S
    Rametta, C
    On the comparison between performance of DHT-based protocols for opportunistic networks2010In: Proceedings of Future Network and MobileSummit 2010, IIMC , 2010Conference paper (Refereed)
    Abstract [en]

    Opportunistic networks represent a new frontier for networking research as due to node mobility the network might become disconnected. Such intermittent connectivity imposes challenges to protocol design, especially when information access might require the availability of updated information about resources shared by mobile nodes. An opportunistic network can be seen as a peer-to-peer network where resources should be located in a distributed way. Numerous solutions for P2P resource management have been proposed in the last years. Among the different approaches being considered, Distributed Hash Table (DHT) based schemes offer the advantages of a distributed approach which can be tuned to network scalability. In this paper we consider two well known P2P DHT-based solutions for wireless networks denoted as Bamboo and Georoy, and compare their performance in a multihop wireless scenario. We evaluate scalability and key lookup behavior for different network sizes. The results allow us to gain insights into protocol behavior which allows to select for a given network configuration the appropriate scheme.

  • 27.
    Cavalcanti de Castro, Marcel
    et al.
    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.
    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.
    Challenges of SIP in Internet Connected MANETs2007Conference paper (Refereed)
    Abstract [en]

    Mobile Ad Hoc networking has been considered as one of the most important technologies to support future Ubiquitous and Pervasive Computing Scenarios and internet connected MANETs will be an integral part of future wireless networks. For providing multimedia services and Voice over IP in such environment, support for Session Initiation Protocol (SIP) is essential. A MANET is a decentralized collection of autonomous nodes but a SIP infrastructure requires centralized proxies and registrar servers. In this paper, we study the implications of using standard SIP architecture in internet connected MANETs. We analyze performance limitations of SIP service scalability when centralized proxies/registrars located in the access network are used by MANET nodes. We also present and compare an alternative approach to provide SIP services in internet connected MANETs in order to minimize the impact of such performance limitations

  • 28.
    Cavalcanti de Castro, Marcel
    et al.
    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.
    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.
    On the Interaction Between Peer Selection, Routing and Channel Assignment2011Conference paper (Other (popular science, discussion, etc.))
  • 29.
    Cavalcanti de Castro, Marcel
    et al.
    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.
    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.
    Optimizing SIP service provisioning in internet connected MANETs (Invited Paper)2006Conference paper (Other (popular science, discussion, etc.))
    Abstract [en]

    Recently, Mobile Ad-hoc Networks (MANETs) have gained a lot of attraction because they are flexible, self-configurable and fast to deploy. Systems beyond 4G are likely to consist of a combination of heterogeneous wireless technologies and naturally might comprise MANETs as one component. In order to provide multimedia services such as Voice over IP in such environment, support for Session Initiation Protocol (SIP) is essential. A MANET is a decentralized collection of autonomous nodes but a SIP infrastructure requires centralized proxies and registrar servers. In this paper, we first study the implications of using standard SIP architecture in internet connected MANETs. We analyze limitations of SIP service scalability when centralized proxies/registrars located in the Access Network are used by MANET nodes. Finally, we present alternative approaches to provide SIP services in such environment to avoid such limitations

  • 30.
    Cavalcanti de Castro, Marcel
    et al.
    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.
    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.
    SIP based Service Provisioning for hybrid MANETs2007Conference paper (Refereed)
    Abstract [en]

    Traditional Voice over IP (VoIP) systems is based on client/server architecture, which is not applicable to Mobile Ad Hoc Networks (MANETs), which are a decentralized collection of autonomous nodes. However, internet connectivity for MANETs becomes important as internet connected MANETs can serve as hot spot extension in 4G scenarios. Here, MANET nodes can reach any wired node thus potentially registering with SIP proxies in the fixed network becomes a viable solution. In order to study the implications of using VoIP systems in internet connected MANETs we present in this paper simulation result of SIP service scalability when centralized proxies/registrars located in the Access Network are used by MANET nodes. Alternative approaches to provide SIP services in such environment are also discussed to improve performance

  • 31.
    Cavalcanti de Castro, Marcel
    et al.
    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.
    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.
    SIP in hybrid MANETs - A gateway based approach2006Conference paper (Refereed)
    Abstract [en]

    Mobile Ad Hoc networking has been considered as one of the most important technologies to support future Ubiquitous and Pervasive Computing Scenarios and internet connected MANETs will be an integral part of future wireless networks. For providing multimedia services and Voice over IP in such environment, support for Session Initiation Protocol (SIP) is essential. A MANET is a decentralized collection of autonomous nodes but a SIP infrastructure requires centralized proxies and registrar servers. In this paper, we study the implications of using standard SIP architecture in internet connected MANETs. We analyze performance limitations of SIP service scalability when centralized proxies/registrars located in the Access Network are used by MANET nodes. We also present and compare an alternative approach to provide SIP services in internet connected MANETs in order to minimize the impact of such performance limitations

  • 32.
    Cavalcanti de Castro, Marcel
    et al.
    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.
    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.
    Avallone, Stefano
    Measuring the Impact of ACI in Cognitive Multi-Radio Mesh Networks2010Conference paper (Refereed)
    Abstract

    In this paper we address the impact of ACI on dynamic spectrum allocation in multi-radio systems. In particular, we present the benefits of dynamic spectrum allocation by adapting channel bandwidth and distance in order to mitigate ACI in multi-radio mesh networks. Based on our measurement campaign in an indoor mesh testbed, which we extended in order to use adaptive channel width, we evaluate the performance in terms of network throughput. We show that by using channel bandwidth adaptation and antenna separation, the impact of ACI can be significantly reduced. The performed experiments give important insights into ACI in multi-radio cognitive systems which help to develop e.g. better channel assignment algorithms or capacity estimation methods

  • 33.
    Cavalcanti de Castro, Marcel
    et al.
    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.
    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.
    Castro, Marcel C
    Chiasserini, Carla-Fabiana
    Casetti, Claudio
    Korpeoglu, Ibrahim
    Peer-to-Peer Overlay in Mobile Ad-hoc Networks2009In: Handbook of Peer-to-Peer Networking / [ed] X. Shen, H. Yu and J. Buford and M. Akon, New York: Springer , 2009Chapter in book (Other academic)
    Abstract

    Wireless multi-hop networks such as mobile ad-hoc (MANET) or wireless

    mesh networks (WMN) have attracted big research efforts during the last years

    as they have huge potential in several areas such as military communications, fast

    infrastructure replacement during emergency operations, extension of hotspots or

    as an alternative communication system. Due to various reasons, such as characteristics

    of wireless links, multi-hop forwarding operation, and mobility of nodes,

    performance of traditional peer-to-peer applications is rather low in such networks.

    In this book chapter, we provide a comprehensive and in-depth survey on recent research

    on various approaches to provide peer-to-peer services in wireless multi-hop

    networks. The causes and problems for low performance of traditional approaches

    are discussed. Various representative alternative approaches to couple interactions

    between the peer-to-peer overlay and the network layer are examined and compared.

    Some open questions are discussed to stimulate further research in this area

  • 34.
    Cavalcanti de Castro, Marcel
    et al.
    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.
    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.
    Kliot, Gabriel
    Friedman, Roy
    Kummer, Raphäel
    Kropf, Peter
    Felber, Pascal
    Minimizing DHT Routing Stretch in MANETs2009Conference paper (Refereed)
  • 35.
    Chow, Lawrence
    et al.
    Stanford Univ, Stanford, CA 94305 USA.
    Collins, Bradley
    Stanford Univ, Stanford, CA 94305 USA.
    Bambos, Nicholas
    Stanford Univ, Stanford, CA 94305 USA.
    Dely, Peter
    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.
    Peylo, Christoph
    Deutsch Telekom Labs, Berlin, Germany.
    Einsiedler, Hans
    Deutsch Telekom Labs, Berlin, Germany.
    Bayer, Nico
    Deutsch Telekom Labs, Berlin, Germany.
    Channel Aware Rebuffering for Wireless Media Streaming with Handoff Control2013In: 2013 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM), IEEE Press, 2013, p. 4434-4439Conference paper (Refereed)
    Abstract [en]

    Packet/frame 'rebuffering' in wireless video streaming typically considers only connectivity from the mobile terminal to its network access point (AP). However, in the presence of multiple APs with the possibility of handoffs, the overall wireless environment should be considered. We develop a model capturing joint rebuffering & handoff dynamics in wireless video streaming, and design a new channel-aware joint rebuffering & handoff control scheme, aiming to minimize the long-run average cost of video jitters and freezes. We first characterize the optimal control in the general case of multiple wireless APs/channels and multiple states per channel. Subsequently, we evaluate the system performance in key important cases, using experimental traces of wireless channel data. We explore the relationship between optimal rebuffering thresholds and overall channel dynamics, and evaluate the associated joint handoff control. The performance results demonstrate the importance of jointly managing rebuffering and handoff controls to achieve high-performance wireless video streaming.

  • 36.
    Chow, Lawrence
    et al.
    Stanford University.
    Collins, Bradley
    Stanford University.
    Bambos, Nick
    Stanford University.
    Peylo, Christoph
    Telekom Innovation Laboratories.
    Einsiedler, Hans
    Telekom Innovation Laboratories.
    Bayer, Nico
    Telekom Innovation Laboratories.
    Dely, Peter
    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.
    Playout-Buffer Aware Hand-Off Control for Wireless Video Streaming2012In: 2012 IEEE Global Communications Conference (GLOBECOM 2012): Proceedings of a meeting held 3-7 December 2012, Anaheim, California, USA, IEEE conference proceedings, 2012, p. 5237-5242Conference paper (Refereed)
    Abstract [en]

    Wireless hand-off control typically considers only connectivity strength from the mobile terminal to alternative access points. In wireless video streaming, however, where video freezing must be avoided at the mobile terminal, the playout buffer level should also be considered by hand-off control. In this paper, we first develop a model capturing hand-off dynamics under video streaming, and design a new playout buffer aware hand-off control. It aims to avert a video freeze for as long as possible, maximizing the expected time until freezing. We compute the optimal control in the general case of multiple access points and multiple connectivity strength states per channel. The optimal hand-off control is then computationally probed in specific relevant cases. It is demonstrated that there is a certain playout buffer threshold level - a buffer tipping point - above which a hand-off should be attempted. Of course, this tipping point depends on the access point to mobile channel statistics

  • 37.
    Coutinho, Nuno
    et al.
    Universidade de Aveiro, Portugal.
    Matos, Ricardo
    Universidade de Aveiro, Portugal.
    Marques, Carlos
    Universidade de Aveiro, Portugal.
    Reis, Andre
    Universidade de Aveiro, Portugal.
    Sargento, Susana
    Universidade de Aveiro, Portugal.
    Chakareski, Jacob
    University of Alabama, United States.
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Dynamic Dual-Reinforcement-Learning Routing Strategies for Quality of Experience-aware Wireless Mesh Networking2015In: Computer Networks, ISSN 1389-1286, E-ISSN 1872-7069, Vol. 88, no 269, article id 285Article in journal (Refereed)
    Abstract [sv]

    The impact of transmission impairments such as loss and latency on user perceived quality(QoE) depends on the service type. In a real network, multiple service types such as audio,video, and data coexist. This makes resource management inherently complex and difficultto orchestrate. In this paper, we propose an autonomous Quality of Experience managementapproach for multiservice wireless mesh networks, where individual mesh nodes apply rein-forcement learning methods to dynamically adjust their routing strategies in order to maxi-mize the user perceived QoE for each flow. Within the forwarding nodes, we develop a novelpacket dropping strategy that takes into account the impact on QoE. Finally, a novel sourcerate adaptation mechanism is designed that takes into account the expected QoE in order tomatch the sending rate with the available network capacity. An evaluation of our mechanismsusing simulations demonstrates that our approach is superior to the standard approaches,AODV and OLSR, and effectively balances the user perceived QoE between the service flows.

  • 38.
    Curado, Marilia
    et al.
    Univ Coimbra, Dept Informat Engn, P-3000 Coimbra, Portugal.;Univ Coimbra, Ctr Informat & Syst, Lab Commun & Telemat, P-3000 Coimbra, Portugal..
    Ganchev, Ivan
    TRC, Limerick, Ireland.;Plovdiv Univ Paisii Hilendarski, Plovdiv, Bulgaria..
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Koucheryavy, Yevgeni
    TUT, Dept Elect & Commun Engn, Pretoria, South Africa..
    Guest editorial: Special issue on mobile wireless networks2016In: Computer Networks, ISSN 1389-1286, E-ISSN 1872-7069, Vol. 107, p. 145-147Article in journal (Refereed)
  • 39.
    Dely, Peter
    et al.
    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.
    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.
    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.
    Moldsvor, Arild
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Soukhakian, Sina
    Practical Considerations for Channel Assignment in Wireless Mesh Networks2010In: GLOBECOM Workshops (GC Wkshps), 2010 IEEE, IEEE , 2010, p. 763-767Conference paper (Refereed)
    Abstract [en]

    Abstract--- In multi-radio wireless mesh networks (WMNs) several radios can operate within one node simultaneously on different channels. Due to frequency selective fading and varying output powers of WLAN cards the received signal strength on channels in the U-NII band can differ by several dB. Furthermore, power leakage from neighboring channels in the frequency spectrum can cause adjacent channel interference (ACI). Using a IEEE 802.11a testbed, we experimentally evaluate the achievable throughput of a multi-radio mesh network in a string topology under the impact of ACI and channel heterogeneity. Our results show that for low PHY rates the channel separation is a good indicator for throughput. However, for high PHY rates the propagation properties of a specific channel also need to be considered. Based on the results we provide recommendations for designing channel assignment algorithms for IEEE 802.11-based WMNs

  • 40.
    Dely, Peter
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    D’Andreagiovanni, Fabio
    Konrad-Zuse-Zentrum für Informationstechnik Berlin (ZIB), Germany.
    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.
    Fair Optimization of Mesh-Connected WLAN Hotspots2015In: Wireless Communications & Mobile Computing, ISSN 1530-8669, E-ISSN 1530-8677, Vol. 15, no 5, p. 924-946Article in journal (Refereed)
    Abstract [en]

    In Wireless mesh networks mesh access points (MAPs) forward traffic wirelessly towards users or Internet gateways. A user device usually connects to the MAP with the strongest signal, as such MAP should guarantee the best quality of service. However, this connection policy may lead to: (i) unfairness towards users that are distant from gateways; (ii) uneven distribution of users to MAPs; and (iii) inefficient use of network paths. We present a new model and solution approach to the problem of assigning users to MAPs and routing the data within the mesh network with the objective of providing max–min fair throughput. The problem is formulated as a mixed-integer linear programming problem (MILP). Because of the inherent complexity of the problem, real size instances cannot be solved to optimality within the time limits for online optimization. Therefore, we propose an original heuristic solution algorithm for the resulting MILP. Both numerical comparisons and network simulations demonstrate the effectiveness of the proposed heuristic. For random networks, the heuristic achieves 98% of the optimal solution. Network simulations show that in medium-sized networks, the number of users with at least 1Mbit/s minimum end-to-end rate increases by 550% when compared with the classical signal-strength based association.

  • 41.
    Dely, Peter
    et al.
    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.
    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.
    Adaptive Aggregierung von VoIP Paketen in Wireless Mesh Networks2008Conference paper (Refereed)
  • 42.
    Dely, Peter
    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.
    Architecture and Algorithms for User Association and Routing in Wireless Mesh Networks2011Conference paper (Other (popular science, discussion, etc.))
  • 43.
    Dely, Peter
    et al.
    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.
    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.
    KAUMesh Demo: A MultiRadio MultiChannel Mesh Testbed2009Other (Other (popular science, discussion, etc.))
    Abstract [en]

    In this demo, we will present KAUMesh, an experimental Wireless Broadband Mesh Network based on 802.11a/b/g WLAN devices that has been deployed at the Karlstad University Campus. KAUMesh comprises currently 20 mesh nodes, which are permanently installed to cover large areas inside the new House 21. Standard 802.11b/g based clients can be used to connect to the mesh as they would to any given normal WLAN access point. KAUMesh features multiple gateways that connect the mesh network towards the internet. By deploying multiple radio cards in mesh nodes, KAUMesh is able to fully exploit available spectrum in the mesh backbone. One radio card interface is used for transparent client access, using typically 802.11b/g mode. The mesh backhaul connectivity is established using multiple radio interfaces per mesh node. The interfaces involved in the backhaul use a hybrid channel assignment mechanism, which rebalances channel usage according to user demand. As the hybrid channel assignment involves channel switching, a novel scheduling approach for making the channel switching QoS aware has been developed. KAUMesh also supports 802.11e standard on the mesh interface to provide service differentiation on the mesh backhaul

  • 44.
    Dely, Peter
    et al.
    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.
    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.
    On Packet Aggregation for VoIP in Wireless Meshed Networks2007Conference paper (Refereed)
  • 45.
    Dely, Peter
    et al.
    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.
    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.
    Bayer, Nico
    Telekom Innovation Laboratories.
    Einsiedler, Hans
    Telekom Innovation Laboratories.
    Method and System for Centralized Control of User Associations in Wireless Mesh Networks2012Patent (Other (popular science, discussion, etc.))
  • 46.
    Dely, Peter
    et al.
    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.
    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.
    Bayer, Nico
    Telekom Innovation Laboratories.
    Einsiedler, Hans
    Telekom Innovation Laboratories.
    Peylo, Christoph
    Telekom Innovation Laboratories.
    Optimization of WLAN associations considering handover costs2012In: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. 255Article in journal (Refereed)
    Abstract [en]

    In Wireless Local Area Network (WLAN) hotspots the coverage areas of Access Points (APs) often overlap considerably. Current state of the art optimization models find the optimal AP for each user station by balancing the load across the network. Recent studies have shown that in typical commercial WLAN hotspots the median connection duration is short. In such dynamic network settings the mentioned optimization models might cause many handovers between APs to accommodate for user arrivals or mobility. We introduce a new mixed integer linear optimization problem that allows to optimize handovers but takes into account the costs of handovers such as signaling and communication interruption. Using our model and extensive numeric simulations we show that disregarding the handover costs leads to low performance. Based on this insight we design a new optimization scheme that uses estimates of future station arrivals and mobility patterns. We show that our scheme outperforms current optimization mechanisms and is robust against estimation errors

  • 47.
    Dely, Peter
    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.
    Bayer, Nico
    Telekom Innovation Laboratories.
    Einsiedler, Hans
    Telekom Innovation Laboratories.
    Peylo, Christoph
    Telekom Innovation Laboratories.
    Chow, Lawrence
    Stanford University.
    Collins, Bradley
    Stanford University.
    Bambos, Nicholas
    Stanford University.
    Daniel, Mellado
    Miguel, Sanchez
    A Software Defined Networking Approach for Handover Management with Real-Time Video in WLANs2012Conference paper (Refereed)
  • 48.
    Dely, Peter
    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.
    Bayer, Nico
    Telekom Innovation Laboratories.
    Einsiedler, Hans
    Telekom Innovation Laboratories.
    Sivchenko, Dmitry
    Method and system for deriving an aggregation delay for packet aggregation in a wireless network2011Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    System and method for deriving an aggregation delay for a packet aggregation in a wireless network comprising a controller for deriving an optimal aggregation delay at a network node depending on information relating to the channel quality related parameters at the network node in the wireless network.

  • 49.
    Dely, Peter
    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.
    Bayer, Nico
    Einsiedler, Hans-Joachim
    Sivchenko, Dmitry
    FUZPAG: A Fuzzy-Controlled Packet Aggregation Scheme for Wireless Mesh Networks2010In: Proceedings of the International Conference on Fuzzy Systems and Knowledge Discovery (FSKD'10), IEEE , 2010, p. 778-782Conference paper (Refereed)
    Abstract [en]

    Wireless mesh networks (WMNs) are wireless multi-hop backhaul networks in which mesh routers relay traffic on behalf of clients or other routers. Due to large MAC layer overhead, applications such as Voice over IP, which send many small packets, show poor performance in WMNs. Packet aggregation increases the capacity of IEEE 802.11-based WMNs by aggregating small packets into larger ones and thereby reducing overhead. In order to have enough packets to aggregate, packets need to be delayed and buffered. Current aggregation mechanisms use fixed buffer delays or do not take into account the delay characteristics of the saturated IEEE 802.11 MAC layer. In this work, we present FUZPAG, a novel packet aggregation architecture for IEEE 802.11-based wireless mesh networks. It uses fuzzy control to determine the optimum aggregation buffer delay under the current channel utilization. By cooperation among neighboring nodes FUZPAG distributes the buffer delay in a fair way. We implemented and evaluated the system in a wireless mesh testbed. For different network topologies we show that FUZPAG outperforms standard aggregation in terms of end-to-end latency under a wide range of traffic patterns.

  • 50.
    Dely, Peter
    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.
    Bayer, Nico
    Sivchenko, Dmitry
    An Experimental Comparison of Burst Packet Transmission Schemes in IEEE 802.11-based Wireless Mesh Networks2010In: Proceedings of IEEE Global Telecommunications Conference (GLOBECOM) 2010, IEEE , 2010, p. 1-5Conference paper (Refereed)
    Abstract [en]

    Wireless mesh networks (WMNs) are wireless multihop networks comprised of mesh routers, which relay traffic on behalf of clients and other nodes. Using the standard IEEE 802.11 distributed coordination function (DCF) as MAC layer, a node needs to contend for the medium each time it wants to transmit a packet. This creates high overhead in particular for small packets and leads to poor performance for real-time applications such as Voice over IP (VoIP) or online gaming. Burst packet transmission can increase the efficiency. For example, with the Transmission Opportunity limit (TXOPlimit) in IEEE 802.11e, a station may transfer several packets without contending for the channel in between. Similarly, IP packet aggregation combines several IP packets together and sends them as one MAC Service Data Unit. Originally, both schemes have been developed for singlehop networks only. Thus the impact on WMNs is unclear if the packets need to contend over multiple hops. In this paper, we use measurements from a 9-node WMN testbed to compare TXOPs and IP packet aggregation for VoIP in terms of fairness, network capacity and quality of user experience. We show that for low networks loads, both TXOPs and IP packet aggregation increase the VoIP quality compared to IEEE 802.11 DCF. However, in highly loaded networks IP packet aggregation outperforms the other schemes.

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