Change search
Refine search result
12 1 - 50 of 89
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Abtahi, Farzad
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Khanmohamadi, Sahar
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Mantelet, G.
    Archambault, E.
    Tremblay, C.
    Bélanger, M. P.
    Optimal Design of Cost- and Energy-Efficient Scalable Passive Optical Backbone Networks2012In: 2012 Asia Communications And Photonics Conference (ACP), 2012, p. AS3D.4-Conference paper (Refereed)
    Abstract [en]

    We propose an optimization model minimizing number of wavelengths in passive optical backbone networks and obtaining the same resource usage as in networks based on active switching while reducing both cost and power consumption.

  • 2.
    Agnihotri, Mohit
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Chirikov, R.
    Militano, F.
    Cavdar, C.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Topology Formation in mesh networks considering Role Suitability2016In: 2016 IEEE Wireless Communications and Networking Conference Workshops, WCNCW 2016, Institute of Electrical and Electronics Engineers (IEEE), 2016, p. 421-427Conference paper (Refereed)
    Abstract [en]

    The paper studies various mesh topology formation techniques that can be used to aid the development of large-scale capillary networks. The work focuses on how mesh networks can be established using Bluetooth Low Energy exploiting the heterogeneous characteristics of the devices in the network. A novel algorithm called Topology Formation considering Role Suitability (TFRS) is proposed aiming to maximize the network lifetime. The algorithm employs a newly introduced metric called role suitability metric (RSM) to assign the best role among master, relay and slave to a participating device. The RSM metric is computed from device characteristics including, but not limited to, energy, mobility and computational capability. We use system-level simulation to evaluate the performance of the proposed algorithm against a reference under a homogeneous deployment scenario consisting of heterogeneous devices. Results show that the network lifetime can be improved significantly when the topology is formed considering the device characteristics for both master role selection and relay selection. TFRS can achieve 20% to 40% higher network lifetime depending on the deployment characteristics over the reference algorithm.

  • 3.
    Agnihotri, Mohit
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Chirikov, R.
    Militano, F.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Topology formation in mesh networks considering role suitability2016In: IEEE Wireless Communications and Networking Conference, WCNC, IEEE, 2016Conference paper (Refereed)
    Abstract [en]

    The paper studies various mesh topology formation techniques that can be used to aid the development of large-scale capillary networks. The work focuses on how mesh networks can be established using Bluetooth Low Energy exploiting the heterogeneous characteristics of the devices in the network. A novel algorithm called Topology Formation considering Role Suitability (TFRS) is proposed aiming to maximize the network lifetime. The algorithm employs a newly introduced metric called role suitability metric (RSM) to assign the best role among master, relay and slave to a participating device. The RSM metric is computed from device characteristics including, but not limited to, energy, mobility and computational capability. We use systemlevel simulation to evaluate the performance of the proposed algorithm against a reference under a homogeneous deployment scenario consisting of heterogeneous devices. Results show that the network lifetime can be improved significantly when the topology is formed considering the device characteristics for both master role selection and relay selection. TFRS can achieve 20% to 40% higher network lifetime depending on the deployment characteristics over the reference algorithm.

  • 4.
    Ahmed, Ashraf Awadelkarim Widaa
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Chatzimichail, Konstantinos
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Markendahl, Jan
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Techno-economics of Green Mobile Networks Considering Backhauling2014In: European Wireless 2014; 20th European Wireless Conference; Proceedings of, Barcelona: VDE Verlag GmbH, 2014, p. 1-6Conference paper (Refereed)
    Abstract [en]

    In this paper we consider a comparative analysis of different deployment solutions in terms of total cost of ownership (TCO) and impact of energy efficiency as a cost parameter, i.e. mobile operator's electric bill. Different deployment options for the wireless segment of the network are considered: macro only versus heterogeneous networks with femto cells to support indoor traffic demand. In addition to the wireless segment different technologies for the backhauling segment are also considered: microwave versus fiber (10G-PON). Considering different user traffic intensities in an urban area and different environments such as business and residential areas, the impact of energy consumption on the TCO has been analyzed. The scope of the paper is extended to compare different backhaul technologies considering the annual increase in the traffic demand up to year 2020. The obtained results indicate that the impact of electric bill becomes more significant over the TCO especially after year 2018. Moreover, the heterogeneous deployment strategy utilizing indoor femto-cells achieves significant savings in terms of electric bill and TCO compared to the macro only solution. However, the saving ratio varies according to the adopted backhauling technology.

  • 5.
    Ahmed, Ashraf Awadelkarim Widaa
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Markendahl, Jan
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Interplay Between Cost,Capacity and Power Consumption in Heterogeneous Mobile Networks2014In: 2014 21st International Conference on Telecommunications, ICT 2014, Lisbon: IEEE Press, 2014, , p. 5p. 98-102Conference paper (Refereed)
    Abstract [en]

    Mobile operators nowadays tend to deploy dense heterogeneous layers of 3G and 4G networks in outdoor and indoor environments by adding more macrocells and small cells (e.g. microcells, picocells and femtocells) in response to the increasing demand for coverage and capacity. Another main driver and enabler behind this tendency is the phenomenon that around 80% of power consumption in mobile communication networks stems from the radio base stations. This situation makes mobile operators opt for the use of lowpower radio base stations to provide better coverage, capacity and an environmentally-friendly operation. In this paper the interplay between the deployment costs, targeted QoS and power consumptions have been studied considering two deployment options for the provisioning of the required mobile broadband coverage and capacity; namely the heterogeneous network (HetNet) option versus the homogenous macrocell deployment option. The main findings indicate that, the perceived saving in the total cost of ownership (TCO) resulting from offloading percentage of network traffic to indoor smallcell, in the case of HetNet, is bounded by the mobile subscriber density per area, their usage patterns, the adopted backhaul solution and the used spectrum resources. In general, a quite paying cost and power saving can be achieved by the heterogonous deployment solution for scenarios with high demand levels especially when there is a need to use the spectrum resources more efficiently.

  • 6.
    Ahmed, Ashraf Awadelkarim Widaa
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Markendahl, Jan
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Ghanbari, Amirhossein
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Study on the effects of backhual solutions on indoor mobile deployment "macrocell vs. femtocell"2013In: 2013 IEEE 24th International Symposium on Personal Indoor and Mobile Radio Communications (PIMRC), IEEE conference proceedings, 2013, p. 2444-2448Conference paper (Refereed)
    Abstract [en]

    The deployment of low cost and low power base stations has been recognized in recent years as a promising cost-efficient solution and energy-efficient strategy. In this paper the femtocell and macrocell deployment options have been compared in the context of indoor mobile broadband deployment, with focus on the effect of different backhauling solutions in power consumption and the total deployment cost. This study has been based on the deployment of mobile broadband services within an area of one square kilometers in a new densely populated business district where the different user demands, spectrum bandwidths, backhaul technologies and radio access technologies are taken into account. Moreover, various deployment scenarios reflecting the business perspectives of mobile operators have been looked into as well. The main findings reached indicate that backhaul solutions contribute differently to cost and power consumption depending on the employed deployment strategy. However, contributions to the total power consumption and to the CapEx and OpEx elements of the total deployment cost elements turned to be more significant in the case of femtocell deployment scenarios than in the case of macrocell ones. It is worthy of notice that the femtocell deployment is more cost-efficient, especially in high demand situation when new macro sites are needed to be deployed.

  • 7.
    Ahmed, Jawwad
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    A Dynamic Bulk Provisioning Framework for Concurrent Optimization in PCE-Based WDM Networks2012In: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 30, no 14, p. 2229-2239Article in journal (Refereed)
    Abstract [en]

    A centralized network control and management plane, such as the one based on a path computation element (PCE), is highly beneficial in terms of resource optimization in wavelength division multiplexing optical networks. Benefits of centralized provisioning are even more evident when connection requests are provisioned in batches, i.e., they allow a better use of network resources via concurrent optimization. In this study, a dynamic bulk provisioning framework is presented with the objective of optimizing the use of network resources that also presents, as an additional benefit, the ability to yield a reduction of the control plane overhead. The rationale behind the proposed framework is based on a mechanism in which the PCE client is allowed to bundle and simultaneously send multiple labeled switch path (LSP) requests to the PCE where, in turn, several bundles can be concurrently processed together as a single bulk. From the network deployment perspective, a PCE-based network architecture is proposed to practically realize this approach. For dynamic bulk provisioning of optical LSP requests, a time-efficient integer linear programming (ILP) model (LSP BP ILP) is presented to minimize the request blocking, the network resource consumption, and the network congestion. In addition, a heuristic based on a greedy randomized adaptive search procedure (GRASP), namely LSP_BP_GRASP, is also proposed as a scalable alternative. The presented results demonstrate significant advantages of the proposed PCE bulk provisioning framework based on concurrent optimization in terms of reduced blocking probability and control overhead when compared with conventional dynamic connection provisioning approaches processing a single connection request at a time.

  • 8.
    Ahmed, Jawwad
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    An Optimal Model for LSP Bundle Provisioning in PCE-based WDM Networks2011In: 2011 Optical Fiber Communication Conference and Exposition and the National Fiber Optic Engineers Conference, OFC/NFOEC 2011, Washington: Optical Society of America , 2011Conference paper (Refereed)
    Abstract [en]

    A time-efficient resource optimization model for dynamic concurrent provisioning of connection requests at PCE is proposed. It is shown that a significant performance improvement can be achieved without noticeable increase in connection setup-time.

  • 9.
    Ahmed, Jawwad
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Bulk provisioning of LSP requests with shared path protection in a PCE-based WDM network2011In: ONDM 2011 - 15th Conference on Optical Network Design and Modeling, 2011Conference paper (Refereed)
    Abstract [en]

    The Path Computation Element (PCE) is a network entity utilized for network path computation operations, especially useful in optical networks based on wavelength division multiplexing (WDM). In the PCE paradigm, the communication between a node and the PCE is specified by the Path Computation Element Communication Protocol (PCEP). According to PCEP protocol, multiple LSP (Label Switched Path) requests can be bundled together before being sent to the PCE in order to reduce the control overhead. Multiple bundles received by the PCE can then be provisioned at once as a single bulk. Enabling bulk provisioning of LSP requests at the PCE in a concurrent manner can bring significant improvements in terms of higher network resource utilization and control plane overhead reduction. However, these advantages come at a cost of a longer connection setup-time and of an instantaneous increase in the network load, which may lead to a degradation of the network performance, e.g. blocking probability. In this study pros and cons of bulk provisioning are explored in shared path protection (SPP) by comparing sequential and concurrent path computation strategies. An efficient meta-heuristic named GRASP-SPP-BP (Greedy Random Adoptive Search Procedure for Shared Path Protection with Bulk Provisioning) is proposed for concurrent provisioning of primary and shared backup path pairs. GRASP-SPP-BP minimizes the backup resource consumption while requiring minimal path computation time. The presented results demonstrate that, in a SPP network scenario, a significant reduction in the PCEP control overhead, network blocking probability and backup resource consumption can be achieved via LSP bulk provisioning at the PCE with the proposed GRASP-SPP-BP approach.

  • 10.
    Ahmed, Jawwad
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Hybrid Survivability Schemes Achieving High Connection Availability With a Reduced Amount of Backup Resources2013In: Journal of Optical Communications and Networking, ISSN 1943-0620, E-ISSN 1943-0639, Vol. 5, no 10, p. A152-A161Article in journal (Refereed)
    Abstract [en]

    Maximizing connection availability in WDM networks is critical because even small disruptions can cause huge data losses. However, there is a trade-off between the level of network survivability and the cost related to the backup resources to be provided. The 100% survivability can be achieved by dedicated path protection with multiple pre-reserved protection paths for each provisioned connection, i.e., DPP (1:N). Unfortunately, the blocking probability performance of DPP (1:N) is negatively affected by the large number of pre-reserved backup wavelengths standing-by unutilized. On the other hand, path restoration (PR)-based solutions ensure good blocking performance at the expense of lower connection availability.

    The work in this paper aims at finding hybrid network survivability strategies that combine the benefits of both techniques (i.e., high availability with low blocking rate). More specifically, the paper focuses on a double link failure scenario and proposes two strategies. The first one, couples dedicated path protection DPP (1:1) with path restoration (referred to as DPP + PR) to minimize the number of dropped connections. The second scheme adds up the concept of backup reprovisioning (BR), referred to as DPP + BR + PR, in order to further increase the connection availability achieved by DPP + PR. Integer Linear Programming (ILP) models for the implementation of the proposed schemes are formulated. Extensive performance evaluation conducted in a PCE-based WDM network scenario shows that DPP + BR + PR and DPP + PR can significantly lower the blocking probability value compared to DPP (1:2) without compromising too much in terms of connection availability.

  • 11.
    Ahmed, Jawwad
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Survivability strategies for PCE-based WDM networks offering high reliability performance2013In: 2013 Optical Fiber Communication Conference and Exposition and the National Fiber Optic Engineers Conference, OFC/NFOEC 2013, Optical Society of America, 2013, p. 6532695-Conference paper (Refereed)
    Abstract [en]

    Two approaches based on backup reprovisioning and path restoration are proposed for dynamic failure recovery in survivable, PCE-based, WDM networks. Results show that proposed schemes can achieve high connection availability in double link failure scenarios.

  • 12.
    Alabbasi, Abdulrahman
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Delay-Aware Green Hybrid CRAN2017In: 2017 15th International Symposium on Modeling and Optimization in Mobile, Ad Hoc, and Wireless Networks, WiOpt 201727 June 2017, IEEE conference proceedings, 2017, article id 7959942Conference paper (Refereed)
    Abstract [en]

    As a potential candidate architecture for 5G systems,cloud radio access network (CRAN) enhances the system’s capacityby centralizing the processing and coordination at the centralcloud. However, this centralization imposes stringent bandwidthand delay requirements on the fronthaul segment of the networkthat connects the centralized baseband processing units (BBUs)to the radio units (RUs). Hence, hybrid CRAN is proposed toalleviate the fronthaul bandwidth requirement. The concept ofhybrid CRAN supports the proposal of splitting/virtualizing theBBU functions processing between the central cloud (centraloffice that has large processing capacity and efficiency) and theedge cloud (an aggregation node which is closer to the user,but usually has less efficiency in processing). In our previouswork, we have studied the impact of different split points onthe system’s energy and fronthaul bandwidth consumption. Inthis study, we analyze the delay performance of the end user’srequest. We propose an end-to-end (from the central cloud tothe end user) delay model (per user’s request) for differentfunction split points. In this model, different delay requirementsenforce different function splits, hence affect the system’s energyconsumption. Therefore, we propose several research directionsto incorporate the proposed delay model in the problem ofminimizing energy and bandwidth consumption in the network.We found that the required function split decision, to achieveminimum delay, is significantly affected by the processing powerefficiency ratio between processing units of edge cloud and centralcloud. High processing efficiency ratio ( 1) leads to significantdelay improvement when processing more base band functionsat the edge cloud.

  • 13.
    Alabbasi, Abdulrahman
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Shihada, Basem
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    On Energy Efficiency of Prioritized IoT Systems2017In: Globecom 2017 - 2017 IEEE Global Communications Conference, IEEE, 2017Conference paper (Refereed)
    Abstract [en]

    The inevitable deployment of 5G and the Internet of Things (IoT) sheds the light on the importance of the energy efficiency (EE) performance of Device-to- Device (DD) communication systems. In this work, we address a potential IoT application, where different prioritized DD system, i.e., Low-Priority (LP) and High-Priority (HP) systems, co-exist and share the spectrum. We maximize the EE of each system by proposing two schemes. The first scheme optimizes the individual transmission power and the spatial density of each system. The second scheme optimizes the transmission power ratio of both systems and the spatial density of each one. We also construct and analytically solve a multi- objective optimization problem that combines and jointly maximizes both HP and LP EE performance. Unique structures of the addressed problems are verified. Via numerical results we show that the system which dominates the overall EE (combined EEs of both HP and LP) is the system corresponding to the lowest power for low/high power ratio (between HP and LP systems). However, if the power ratio is close to one, the dominating EE corresponds to the system with higher weight.

  • 14.
    Andersson, Göran
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Västberg, Anders
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth. KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Devlic, Alisa
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth. KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Energy efficient heterogeneous network deployment with cell DTX2016In: 2016 IEEE International Conference on Communications (ICC),, IEEE, 2016, p. 1-6Conference paper (Refereed)
    Abstract [en]

    This paper evaluates different means of reducing power consumption of macro base stations (BS) and heterogeneous mobile network deployments (HetNet) considering the time dimension. These approaches are based on the same idea of reducing the load of heavily loaded macro cells and putting them to discontinuous transmission (DTX) mode during the time of inactivity by either (1) macro cell densification or (2) offloading traffic to small cells. Activity factor of a BS is defined as the fraction of time the BS is transmitting over a fixed time period. It is shown that by macro cell layer network densification, the average daily area power consumption can be reduced by up to 73 % with the use of cell DTX. However, reducing the activity factor by macro layer densification is not cost effective, as already demonstrated in previous studies. Alternatively, by adding small cells and enabling their DTX capability, power consumption can be reduced by up to 29 %. Adding small cells is especially effective in terms of energy savings, when users are distributed around hot spots, where additional coverage and capacity is required.

  • 15. Ansari, A.
    et al.
    Jaumard, B.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Energy optimization of a cellular network with minimum bit-rate guarantee2017In: 2017 15th International Symposium on Modeling and Optimization in Mobile, Ad Hoc, and Wireless Networks, WiOpt 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, article id 7959933Conference paper (Refereed)
    Abstract [en]

    Energy optimization in cellular networks has been studied using different perspectives in the literature: sleep patterns, network interference, association of users and base stations, resource allocation of resources (bandwidth and power), etc. All these means have been discussed individually in previous works. However, none of the existing works has succeeded in proposing an exact mathematical model that takes into account several of these parameters simultaneously. In this article, we propose a first exact modelling of several network parameters and their interaction in order to minimize the energy consumption in a LTE cellular network. The optimization model guarantees to satisfy all the users with a minimum quality of service (data rate). Its exact solution allows energy savings of up to 50% in a moderately loaded network, which leads to energy savings up to twice that of the heuristic proposed by Piunti et al., (2015). Various numerical results are presented on hexagonal and randomly generated cellular networks.

  • 16.
    Azari, Amin
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Cavdar, Cicek
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Performance Evaluation and Optimization of LPWA IoT Networks: A Stochastic Geometry Approach2018Conference paper (Refereed)
    Abstract [en]

    Leveraging grant-free radio access for enabling lowpowerwide-area (LPWA) Internet of Things (IoT) connectivityhas attracted lots of attention in recent years. Regarding lack ofresearch on LPWA IoT networks, this work is devoted to reliabilitymodeling, battery-lifetime analysis, and operation-controlof such networks. We derive the interplay amongst density ofthe access points, communication bandwidth, volume of trafficfrom heterogeneous sources, and quality of service (QoS) incommunications. The presented analytical framework comprisesmodeling of interference from heterogeneous sources with correlateddeployment locations and time-frequency asynchronousradio-resource usage patterns. The derived expressions representthe operation regions and rates in which, energy and costresources of devices and the access network, respectively, couldbe traded to achieve a given level of QoS in communications. Forexample, our expressions indicate the expected increase in QoSby increasing number of transmitted replicas, transmit power,density of the access points, and communication bandwidth.Our results further shed light on scalability of such networksand figure out the bounds up to which, scaling resources cancompensate the increase in traffic volume and QoS demand.Finally, we present an energy-optimized operation control policyfor IoT devices. The simulation results confirm tightness of thederived analytical expressions, and indicate usefulness of themin planning and operation control of IoT networks.

  • 17.
    Azari, Amin
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Cavdar, Cicek
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Self-organized Low-power IoT Networks: A Distributed Learning Approach2018Conference paper (Refereed)
    Abstract [en]

    Enabling large-scale energy-efficient Internet-ofthings(IoT) connectivity is an essential step towards realizationof networked society. While legacy wide-area wireless systemsare highly dependent on network-side coordination, the level ofconsumed energy in signaling, as well as the expected increase inthe number of IoT devices, makes such centralized approachesinfeasible in future. Here, we address this problem by selfcoordinationfor IoT networks through learning from pastcommunications. To this end, we first study low-complexity distributedlearning approaches applicable in IoT communications.Then, we present a learning solution to adapt communicationparameters of devices to the environment for maximizing energyefficiency and reliability in data transmissions. Furthermore,leveraging tools from stochastic geometry, we evaluate theperformance of proposed distributed learning solution againstthe centralized coordination. Finally, we analyze the interplayamongst energy efficiency, reliability of communications againstnoise and interference over data channel, and reliability againstadversarial interference over data and feedback channels. Thesimulation results indicate that compared to the state of the artapproaches, both energy efficiency and reliability in IoT communicationscould be significantly improved using the proposedlearning approach. These promising results, which are achievedusing lightweight learning, make our solution favorable in manylow-cost low-power IoT applications.

  • 18.
    Azari, Amin
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Cavdar, Cicek
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Ozger, Mustafa
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Serving Non-Scheduled URLLC Traffic: Challenges and Learning-Powered StrategiesManuscript (preprint) (Other academic)
    Abstract [en]

    Supporting ultra-reliable low-latency communications (URLLC) is a major challenge of 5G wireless networks. Whilst enabling URLLC is essential for realizing many promising 5G applications, the design of communications' solutions for serving such unseen type of traffic with stringent delay and reliability requirements is in its infancy. In prior studies, physical and MAC layer solutions for assuring the end-to-end delay requirement of scheduled URLLC traffic have been investigated. However, there is lack of study on enabling non-scheduled transmission of urgent URLLC traffic, especially in coexistence with the scheduled URLLC traffic. This study at first sheds light into the coexistence design challenges, especially the radio resource management (RRM) problem. It also leverages recent advances in machine learning (ML) to exploit spatial/temporal correlation in user behaviors and use of radio  resources, and proposes a distributed risk-aware ML solution for RRM. The proposed solution benefits from hybrid orthogonal/non-orthogonal radio resource slicing, and proactively regulates the spectrum needed for satisfying delay/reliability requirement of each traffic type. A case study is introduced to investigate the potential of the proposed RRM in serving coexisting URLLC traffic types. The results further provide insights on the interplay between the reliabilities of coexisting traffic, uncertainties in users' demands and channel conditions, and amount of required radio resources.

  • 19.
    Azari, Amin
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Masoudi, Meysam
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Cavdar, Cicek
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Optimized Resource Provisioning and Operation Control for Low-power Wide-area IoT NetworksManuscript (preprint) (Other academic)
    Abstract [en]

    Grant-free radio access is a promising solution for reducing energy consumption and access delay in low power wide-area (LPWA) Internet of Things (IoT) networks. This work is devoted to reliability modeling, battery-lifetime analysis, resource provisioning, and operation control for grantfreeIoT networks. Our modeling captures correlation in devices’locations, benefits from 3D (time/frequency/code) interference analysis, and enables coexistence analysis of multi-type IoT technologies. We derive the interplay amongst density of the access points, communication bandwidth, traffic volume, and quality of service (QoS) of communications. Deriving the interplay enables scalability analysis, i.e. it figures out the required increase in device's energy consumption (or access network’s resources) for compensating the increase in traffic volume or QoS demand. Our major contribution consists in deriving traffic loads and respective exchange rates in which, energy and cost resources of devices and the access network, respectively, could be traded to achieve a given level of QoS. We further indicate operation regions in which scaling a parameter turns from being a friend into a foe. Finally, we present energy- and cost-optimized operation control and resource provisioning strategies, respectively. The simulation results confirm tightness of the analytical expressions, and indicate the usefulness of them in planning and operation control of IoT networks.

  • 20.
    Azari, Amin
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Popovski, Petar
    Stefanovic, Cedomir
    Cavdar, Cicek
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Grant-Free Radio Access for Cellular IoTManuscript (preprint) (Other academic)
    Abstract [en]

    Radio resource management (RRM) is a major factor affecting the delay, reliability, and energy consumption of Internet of Things (IoT) communications. This article is focused on grant-free access, a class of techniques suited to support massive IoT connectivity. Within the proposed scheme, the IoT devices transmit multiple replicas of the same packet. In addition to that, the receiver makes use of the random timing and frequency offsets in order to carry out Successive Interference Cancellation (SIC). The system performance is investigated by using a model based on stochastic geometry, leading to closed-form expressions for the key performance indicators, such as reliability and battery lifetime. The framework allows optimization of the number of replicas per device. This results in overall improvement of the energy consumption, delay and reliability, at the expense of more complex processing at the Base Station. The evaluation results indicate that the proposed data transmission and reception schemes can significantly prolong battery lifetime of IoT devices by removing the need for connection establishment and reducing the number of retransmissions. The obtained results also indicate existence of traffic-load regions, where grant-free radio access outperforms the grant-based one, which is used in LTE and NB-IoT systems. These results pave the way for enabling intelligent grant-based/free operation mode switching in 5G networks.

  • 21.
    Bui, Minh N.
    et al.
    Concordia University.
    Jaumard, Brigitte
    Concordia University.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Mukherjee, Biswanath
    University of California - Davis.
    Design of a survivable VPN topology over a service provider network2013In: 2013 9th International Conference on the Design of Reliable Communication Networks (DRCN), IEEE conference proceedings, 2013, p. 71-78Conference paper (Refereed)
    Abstract [en]

    Survivability in IP-over-WDM networks has alreadybeen extensively discussed in a series of studies. Up to date,most of the studies assume single-hop working routing of trafficrequests. In this paper, we study the multi layer survivable designof a logical topology in the context of multiple-hop workingrouting for IP layer traffic requests. The design problem iscomposed of two problems which are simultaneously solved:(i) Finding the most efficient or economical multi-hop routingof the IP traffic flows with different bandwidth granularitiesover the logical topology, which involves some traffic grooming,(ii) Ensuring that the logical topology is survivable throughoutan appropriate mapping of the logical links over the physicaltopology, if such a mapping exists.In order to solve such a complex multi layer resilient networkdesign problem, we propose a column generation ILP model. Itallows exploiting the natural decomposition of the problem andhelps devising a scalable solution scheme.We conducted numerical experiments on a German networkwith 50 nodes and 88 physical links. Not only we could solve muchlarger data instances than those published in the literature, butalso observe than multi-hop routing allows a saving of up to 10%of the number of lightpaths, depending on the traffic load.

  • 22. Buysse, Jens
    et al.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    De Leenheer, M.
    Dhoedt, B.
    Develder, Chris
    Improving energy efficiency in optical cloud networks by exploiting anycast routing2011In: ACP. Asia Communications and Photonics Conference and Exhibition, 2011, IEEE conference proceedings, 2011, p. 1-6Conference paper (Refereed)
    Abstract [en]

    Exploiting anycast routing significantly reduces optical network and server energy usage. In this work we present a case study showing that intelligently selecting destinations and routes thereto, while switching off unused (network) elements, cuts power consumption by around 20% and saves network resources by 29%.

  • 23.
    Cavdar, Cicek
    et al.
    Istanbul Technical University.
    Buzluca, F.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Energy-Efficient Design of Survivable WDM Networks with Shared Backup2010In: Global Telecommunications Conference (GLOBECOM 2010), 2010 IEEE, 2010, p. 1-5Conference paper (Refereed)
    Abstract [en]

    In recent years, energy-efficient design of optical WDM networks has become increasingly important as efforts to reduce the operational expenditure (Opex) and the carbon footprint of the internet are prioritized. In this paper we focus on energy- efficient survivable network design where backup resources are shared for efficient capacity consumption. However there is a trade-off between energy-efficiency and survivability. Survivable network design strategies lead to lightly loaded links in order to minimize the risk in case of a failure and to increase the shareability of backup resources. On the contrary, energy-efficient network design strategies tend to increase the load in a set of links as a consequence of concentrating the traffic in order to be able to switch off as much network resources as possible. In this study, we present a novel method to simultaneously minimize Capex and Opex while providing an energy-efficient, shared backup protected network, under the assumption of backup capacity in sleep mode. For the first time we propose an ILP formulation for the energy-efficient shared backup protection problem. By exploiting the sleep mode for the backup resources, we observe that the ILP solution of our mathematical model brings up to 40% gain in energy efficiency in comparison to energy-unaware shared backup protection approach.

  • 24. Cavdar, Cicek
    et al.
    Buzluca, Feza
    Key Points of a Scheme Design Problem for Multilayer Survivability in Optical Networks2004Conference paper (Refereed)
  • 25.
    Cavdar, Cicek
    et al.
    Computer Engineering Department, Istanbul Technical University.
    Buzluca, Feza
    Computer Engineering Department, Istanbul Technical University.
    Tornatore, Massimo
    Computer Science Department, University of California.
    Mukherjee, Biswanath
    Computer Science Department, University of California.
    Dynamic Scheduling of Survivable Connections with Delay Tolerance in WDM Networks2009In: Proceedings: IEEE INFOCOM, 2009Conference paper (Refereed)
    Abstract [en]

    In optical wavelength-division multiplexing (WDM) networks, recent technological progress is enabling dynamic optical transport in which leasable circuits (connections) can be set up and released for a specific duration of time, providing large capacity to bandwidth-hungry applications. Set-up times can be flexible or fixed, depending on the type of the application. Since the interruption of a high-speed optical connection could lead to huge loss of data, such connections need to be protected against failures. We study the problem of dynamic provisioning of user-controlled connection requests that have specified holding times and particular delay tolerances with shared path protection. The metric of delay tolerance is a measure of customer patience, and it is defined as the time a connection request can be held until it is set up. A connection that cannot be established at the instant of its request could potentially be set up in the remaining duration of its delay tolerance. We show that a reduction of up to 50 percent can be achieved on blocking probability by exploiting delay tolerance in networks without using extra backup capacity. In this study we explore different queuing policies for impatient customers. Different dynamic scheduling algorithms are applied and compared by giving priority to connections according to their arrival rates, delay tolerances and holding times alternatively.

  • 26.
    Cavdar, Cicek
    et al.
    Istanbul Technical University.
    Gencata, Aysegul
    Mukherjee, Biswanath
    CATZ: Time-zone-aware Bandwidth Allocation in Layer 1 VPNs2007In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 45, no 4, p. 60-66Article in journal (Refereed)
    Abstract [en]

    The layer 1 virtual private network framework has emerged from the need to enable the dynamic coexistence of multiple circuit-switched client networks over a common physical network infrastructure. Such a VPN could be set up for an enterprise with offices across a wide geographical area (e.g., around the world or by a global ISP). Additionally, emerging IP over optical WDM technologies let IP traffic be carried directly over the optical WDM layer. Thus, different VPNs can share a common optical WDM core, and may demand different amounts of bandwidth at different time periods. This type of operation would require dynamic and reconfigurable allocation of bandwidth. This article evaluates the state of the art in layer I VPNs in the context of globally deployable optical networks and cost-efficient dynamic bandwidth usage. While exploiting the dynamism of IP traffic in a global network in which the nodes are located in different time zones, we study different bandwidth allocation methods for setting up a worldwide layer 1 VPN. We propose and investigate the characteristics of a cost-efficient bandwidth provisioning and reconfiguration algorithm, called Capacity Allocation Using Time Zones (CATZ).

  • 27.
    Cavdar, Cicek
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Ruiz, M.
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Velasco, L.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Design of green optical networks with signal quality guarantee2012In: IEEE International Conference on Communications, IEEE , 2012, p. 3025-3030Conference paper (Refereed)
    Abstract [en]

    Energy consumption of communication networks is growing very fast due to the rapidly increasing traffic demand. Consequently, design of green communication networks gained a lot of attention. In this paper we focus on optical Wavelength Division Multiplexing (WDM) networks, able to support this growing traffic demand. Several energy-aware routing and wavelength assignment (EA-RWA) techniques have been proposed for WDM networks in order to minimize their operational cost. These techniques aim at minimizing the number of active links by packing the traffic as much as possible, thus avoiding the use of lightly loaded links. As a result, EA-RWA techniques may lead to longer routes and to a high utilization on some specific links. This has a detrimental effect on the signal quality of the optical connections, i.e., lightpaths. In this study we quantify the impact of power consumption minimization on the optical signal quality. and address this problem by proposing a combined impairment and energy-aware RWA (IEA-RWA) approach. Towards this goal we developed a complete mathematical model that incorporates both linear and non-linear physical impairments together with an energy efficiency objective. The IEA-RWA problem is formulized as a Mixed Integer Linear Programming (MILP) model where both energy efficiency and signal quality considerations are jointly optimized. By comparing the proposed IEA-RWA approach with existing RWA (IA-RWA and EA-RWA) schemes, we demonstrate that our solution allows for a reduction of energy consumption close to the one obtained by EA-RWA approaches, while still guaranteeing a sufficient level of the optical signal quality.

  • 28.
    Cavdar, Cicek
    et al.
    Department of Computer Science, University of California.
    Song, Lei
    Tornatore, Massimo
    Dept. of Electronics and Information, Politecnico di Milano.
    Mukherjee, Biswanath
    Holding-Time-Aware and Availability-Guaranteed Connection Provisioning in Optical WDM Mesh Networks2007In: 2007 International Symposium on High Capacity Optical Networks and Enabling Technologies, HONET, 2007, p. 243-249Conference paper (Refereed)
    Abstract [en]

    In optical wavelength-division multiplexing (WDM) networks, the progress in new technologies is paving the road towards dynamic optical transport networks in which leasable circuits can be set up and released on a short-term basis while providing huge capacities to bandwidth-hungry applications. Since interruption of a high-speed optical connection means a huge loss of data information, such connections need to be protected against failures. On the other hand, the explosive growth of different traffic types such as data, voice and video requires differentiated services besides availability-guaranteed bandwidth. Therefore, future network carriers need to meet strict SLA (Service Level Agreement) guidelines, thus guaranteeing a level of service, as well as achieving efficient resource utilization. Unprotected, shared-path, and dedicated-path protection techniques can be used to meet the differentiated availability requirements. Recently, among the other Service Level Specifications (SLSs), many new applications are identified by a predictable or known-in-advance holding-time. So, for dynamic provisioning of availabitity-guaranteed connections in an optical mesh network, we investigate a new algorithm which exploits the knowledge of connection holding times to accomplish minimum backup capacity allocation as compared to the previous holding-time-unaware approach.

  • 29.
    Cavdar, Cicek
    et al.
    Dept. of Computer Engineering, Istanbul Technical University.
    Tornatore, Massimo
    Dept. of Computer Science, University of California, Davis.
    Buzluca, Feza
    Availability-Guaranteed Connection Provisioning with Delay Tolerance in Optical WDM Mesh Networks2009In: OFC: 2009 CONFERENCE ON OPTICAL FIBER COMMUNICATION, VOLS 1-5, 2009, p. 986-988Conference paper (Refereed)
    Abstract [en]

    We propose a novel dynamic provisioning scheme exploiting a new user-centric SLA metric, called delay tolerance, in availability-guaranteed shared-path-protected optical WDM networks. Significant reduction in blocking probability is achieved without sacrificing additional resources.

  • 30.
    Cavdar, Cicek
    et al.
    University of California; Istanbul Technical University.
    Tornatore, Massimo
    Buzluca, Feza
    Mukherjee, Biswanath
    Shared-Path Protection With Delay Tolerance (SDT) in Optical WDM Mesh Networks2010In: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 28, no 14, p. 2068-2076Article in journal (Refereed)
    Abstract [en]

    Optical wavelength-division-multiplexing (WDM) networks have emerged as an ideal backbone for the dynamic transport of bandwidth-intensive applications. Most emerging applications require end-to-end survivable connections to be set up for specific time durations that have sliding or fixed setup times (such as IPTV, grid computing backup storage). It is critical for the development of future network infrastructure that user-centric, dynamic, and end-to-end management and control mechanisms are devised to bridge the gap between the transport capacity and the needs of new applications at the customer edges. In this paper, we study the problem of dynamic provisioning of user-controlled connection requests that have specified holding times and delay tolerances. Delay tolerance is a measure of customer patience, and it is defined as the duration a connection request can be held until it is set up. A connection that cannot be established at the instant of its request could potentially be set up in the remaining duration of its delay tolerance. In this study, different dynamic scheduling algorithms are developed and compared by giving priority to connections according to their arrival rates, delay tolerances, and holding times. Using a mathematical model for impatient requests and simulation experiments, we show that delay tolerance flexibility in the traffic model provides a reduction of up to 50% on blocking probability, without the use of extra backup capacity.

  • 31.
    Cavdar, Cicek
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Yayimli, A.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    How to cut the electric bill in optical WDM networks with time-zones and time-of-use prices2011In: European Conference on Optical Communication, ECOC, Geneva, 2011Conference paper (Refereed)
    Abstract [en]

    We investigate the benefit of utilizing electric price difference between time intervals of the day for networks covering multiple time-zones. We show that by exploiting this time-and-price variation electric bill can be significantly reduced.

  • 32.
    Cavdar, Cicek
    et al.
    Dept. of Computer Science, Univ. of California.
    Yayimli, Aysegul Gencata
    Dept. of Computer Engineering, Istanbul Technical Univ..
    Mukherjee, Biswanath
    Dept. of Computer Science, Univ. of California.
    Multi-Layer Resilient Design for Layer-1 VPNs2008In: 2008 CONFERENCE ON OPTICAL FIBER COMMUNICATION/NATIONAL FIBER OPTIC ENGINEERS CONFERENCE, 2008, p. 2857-2859Conference paper (Refereed)
    Abstract [en]

    We define the multi-layer resilient layer-1 VPN design problem, where the traffic matrix is given, and an optimal survivable VPN is designed by formulating the problem, first time, as an integer linear program.

  • 33.
    Cavdar, Cicek
    et al.
    Istanbul Technical University.
    Yayimli, Aysegul Gencata
    Networks Research Lab., University of California.
    Rai, Smita
    Mukherjee, Biswanath
    Time-Zone-Aware Traffic Grooming in IP-over-WDM networks2007In: 2007 High-Speed Networks Workshop, HSNW, 2007, p. 31-35Conference paper (Refereed)
    Abstract [en]

    We present an efficient algorithm to optimize routing and grooming in IP-over-WDM networks where traffic is generated by backbone nodes located in different time zones in a global network. We analyze the performance of our algorithm, called RUTZ (Routing Using Time Zones), according to the cost and link utilization as well as observed significant improvements compared to traditional grooming approaches. The cost gain and link utilization in RUTZ gets closer to the dynamic on-demand cost assignment method which adjusts the provisioned bandwidth according to user demands on an hourly basis. In a global network, the daily traffic profile in a backbone link shifts as the time changes, and the peak and valley move as the sun moves. If time-zone dynamism is predictable, traffic can be groomed and routes can be calculated in an efficient manner without making periodic (e.g., hourly) changes in bandwidth allocation. In this study we present an intelligent routing and grooming algorithm which exploits this dimension of dynamism in IP traffic.

  • 34.
    Cavdar, Cicek
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Yayimli, Aysegul
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Cutting the Electric Bill by Routing and Wavelength Assignment with Time-zones and Time-of-use Prices2011In: Proceedings of SPIE: Network Architectures, Management, and Applications IX, SPIE , 2011Conference paper (Refereed)
    Abstract [en]

    We consider an energy-aware WDM core network, where the electric prices direr according to time intervals of the day, referred to as time-of-use rates. Since a large backbone network may have nodes scattered over several time zones, we exploit the time-of-use rates to lower the electric bill of the network provider. By using an ILP formulation of the bill minimization problem, we investigate the gain of total electric bill over two approaches where capacity and energy are optimized under different network traffic load conditions.

  • 35.
    Dinc, Ergin
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Vondra, Michal
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Multi-user Beamforming and Ground Station Deployment for 5G Direct Air-to-Ground Communication2017In: Globecom 2017 - 2017 IEEE Global Communications Conference, Institute of Electrical and Electronics Engineers (IEEE), 2017Conference paper (Refereed)
    Abstract [en]

    On-board of aircraft is one of the last venues without high-speed connectivity, which makes it an important problem to address for both industry and academia. To this end, direct air-to-ground communications (DA2GC), where communication link is provided via direct link between aircraft and ground station, is a promising solution to provide high capacity and low latency backhaul capacity for aircraft. In this paper, we investigate the ground station deployment problem to provide 1.2 Gbps average backhaul capacity for each aircraft. The feasible operation points for the key network parameters: the number of ground stations, antenna array size, transmit power and bandwidth, are calculated. In addition, we propose a multi-user beamforming algorithm for dual-polarized hybrid DA2GC antenna arrays, and derive a tractable expression for the DA2GC cell throughput.

  • 36.
    Dinc, Ergin
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Vondra, Michal
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Seamless Gate-to-Gate Connectivity Concept: Onboard LTE, Wi-Fi and LAA2017In: 2017 IEEE 86th Vehicular Technology Conference  (VTC-FALL), Institute of Electrical and Electronics Engineers (IEEE), 2017Conference paper (Refereed)
    Abstract [en]

    Aircraft is one of the last venues with no highspeed connectivity, which makes it an important research issue to address for both industry and academia. This paper introduces seamless gate-to-gate connectivity concept so that passengers can stay connected in all phases of the flight. The backhaul capacity is provided via direct air-to-ground communications links. Passengers can utilize both LTE andWi-Fi access technologies on-board. In order to avoid interference with licensed ground LTE network, in-cabin LTE users will be served in the unlicensed spectrum via license assisted access (LAA) functionality when the aircraft is close to the ground. In this paper, we determine the altitude threshold for switching to LAA in order to provide seamless LTE connectivity. According to our analysis the myth about the 3 km threshold for the interference with the terrestrial network is not anymore valid. In addition, throughput and user data rates for LTE and Wi-Fi networks are investigated in different flight phases. We have found out that in-cabin LTE network can serve 80-240 users between 5-15 Mbps data rates, and Wi-Fi network can provide peak data rates of 14 Mbps in the worst-case scenario.

  • 37.
    Dinc, Ergin
    et al.
    KTH, School of Information and Communication Technology (ICT).
    Vondra, Michal
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Hofmann, Sandra
    Schupke, Dominic
    Prytz, Mikael
    Bovelli, Sergio
    Frodigh, Magnus
    Zander, Jens
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    In-Flight Broadband Connectivity: Architectures and Business Models for High Capacity Air-to-Ground Communications2017In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 55, no 9, p. 142-149Article in journal (Refereed)
    Abstract [en]

    In-Flight Broadband Connectivity (IFBC) is a significant open market for mobile network operators, considering that more than 3.3 billion passengers were served by airlines in 2015. On-board broadband services are provided via air-to-ground (A2G) connectivity through direct A2G communication (DA2GC) and satellite A2G communication (SA2GC). Available on-board connectivity systems have significant limitations: high latency in SA2GC and low capacity in DA2GC. The customer expectancy is multi-Mb/s connections in every seat, which leads to capacity requirements of Gb/s to the aircraft. Creation of high capacity IFBC requires a collaborative interaction between different industry partners. For this reason, we investigate A2G architectures in terms of economic and technical perspectives, and propose business models by identifying new roles and positioning them in the A2G business ecosystem. In addition, we provide an extensive summary of the state-of-the-art and future improvements for A2G communications.

  • 38. Dolfi, M.
    et al.
    Morosi, S.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Del Re, E.
    Energy efficient optimization of a sleep mode strategy in heterogeneous cellular networks2017In: EuCNC 2017 - European Conference on Networks and Communications, Institute of Electrical and Electronics Engineers (IEEE), 2017, article id 7980740Conference paper (Refereed)
    Abstract [en]

    As base stations (BS) are responsible for the large amount of energy consumed in cellular networks, energy efficient BS sleep mode techniques have the potential to save a significant amount of energy. However, assuming that BSs are able to alternate between sleeping and active states as frequently as possible may have a negative impact on network reliability, shortening BS lifetime. In this paper we propose a multiobjective optimization framework aimed at minimizing the power consumption and number of BS sleep mode switchings in heterogeneous cellular networks (HetNet), by jointly considering Quality of Service (QoS) requirements. We focus on the HetNet scenario in which macro and micro cells coexist. The Mixed Integer Quadratic Programming (MIQP) optimization technique is used to minimize the power consumption together with the number of BS sleep mode operations of both macro and micro cells. The trade-off between power consumption, sleep mode switchings and performance of the network is shown for different energy saving solutions. Results show that the proposed optimization can guarantee QoS target throughput for users and significant reduction of 50% for macro and 73% for micro BS respectively daily number of switchings, while still achieving 8% savings in terms of daily energy consumption.

  • 39.
    Ergin, Dinc
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Vondra, Michal
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Hofmann, Sandra
    Schupke, Dominic
    Prytz, Mikael
    Bovelli, Sergio
    Frodigh, Magnus
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    In-Flight Broadband Connectivity: Architectures and Business Models for High Capacity Air-to-Ground Communications2017In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896Article in journal (Refereed)
    Abstract [en]

    In-flight broadband connectivity (IFBC) is a significant open market for mobile network operators considering more than 3.3 billion passengers being served by airlines in2015. On-board broadband services are provided via air-to-ground(A2G) connectivity through direct A2G communications(DA2GC) and satellite A2G communications (SA2GC). Available on-board connectivity systems have significant limitations: high latency in SA2GC and low capacity in DA2GC. The customer expectancy is multi-Mbps connections in every seat which leads to capacity requirements of Gbps to the aircraft. Creation of high capacity IFBC requires a collaborative interaction between different industrial partners. For this reason, we investigate A2Garchitectures in terms of economic and technical perspectives, and propose business models by identifying new roles and positioning them in the A2G business ecosystem. In addition, we provide an extensive summary of the state-of-the-art and future improvements for A2G communications.

  • 40. Gencata, Aysegul
    et al.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Energy-aware virtual topology reconfiguration under dynamic traffic2012In: 14th International Conference on Transparent Optical Networks (ICTON), 2012, IEEE conference proceedings, 2012, p. 1-4Conference paper (Refereed)
    Abstract [en]

    In an IP over WDM network architecture, IP traffic is carried over a virtual topology (VT), composed of optical transparent channels called lightpaths. We propose an energy-efficient dynamic VT adaptation method with sleep mode, which allows changing only one lightpath connectivity at a time by dynamically monitoring the IP packet traffic load on each lightpath. In order to assure the connectivity of future traffic increase a high-load threshold is used. When the packet traffic load on a specific lightpath becomes higher than a threshold, a new lightpath is added to the virtual topology. However this congestion avoidance policy increases the power consumption by activating transponders in the network. Therefore at the same time lightly loaded lightpaths are eliminated in the virtual topology by using a low-load threshold. Energy-efficient virtual topology adaptation is achieved by traffic offloading considering both lightly loaded and heavily loaded links in the network. In this regard, high- and low-load threshold values need to be carefully determined in order to both gain power and ensure load balancing with keeping the stability of virtual connectivity at a reasonable level. We have analysed the power consumption of the network during 48-hours for different values of low- and high-load thresholds together with the impact of different threshold values on the stability of the virtual topology. We have shown that there is a trade-off between number of changes in the virtual topology and the energy-efficiency. Experimental results demonstrate that a good compromise can be achieved by adjusting the high- and low-load thresholds carefully.

  • 41. Gu, Feng
    et al.
    Xie, Chongyang
    Peng, Min
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture, Communication Systems, CoS.
    Khan, S.
    Ghani, N.
    Advance reservation for virtual overlay network services2011In: 13th International Conference on Transparent Optical Networks (ICTON), 2011, IEEE conference proceedings, 2011, p. 1-4Conference paper (Refereed)
    Abstract [en]

    Network advance reservation is an area of growing interest and focus today. However most proposed solutions in this field have only focused on the scheduling of point-to-point client connections. Now as applications and user communities continue to expand, there is a growing need to extend advance reservation support for multipoint services. To address this concern, a heuristic solution is presented for virtual overlay network scheduling. The scheme uses graph-theoretic schemes and is analyzed in detail using network simulation.

  • 42. Gu, Feng
    et al.
    Xie, Chongyang
    Peng, Min
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Khan, Samee
    Ghani, Nasir
    Virtual Overlay Network Scheduling2011In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 15, no 8, p. 893-895Article in journal (Refereed)
    Abstract [en]

    As applications continue to expand, there is a growing need to provide advance reservation scheduling for higher-end virtual overlay network services. Hence this work presents an optimization formulation for this problem and studies several heuristic solutions using network simulation.

  • 43.
    Hossain, M. M. A.
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Jantti, R.
    Traffic offloading based energy saving market for cellular operators2017In: 2017 IEEE International Conference on Communications Workshops, ICC Workshops 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, p. 97-102, article id 7962640Conference paper (Refereed)
    Abstract [en]

    Larger share of total energy consumed by mobile network operators (MNOs) is wasted to ensure seamless coverage. Three to six MNOs covering the same geographical area results in even more energy waste. Division of scarce resource, i.e., spectrum into small chunks also deteriorates the overall performance. With exponential growth of the traffic and insignificant marginal revenue, it is time for the regulators and MNOs to resort to new ideas in order to reduce operational cost and devise appropriate mechanisms to ensure business as well as environmental sustainability. In this paper, we propose a double auction based energy saving market where MNOs share coverage and spectrum to save energy. In this market each MNO submits bid and asks to an independent auctioneer simultaneously. The bid is the offer to offload its total traffic to some other MNO along with releasing its own spectrum to be used by the latter. Similarly, the ask is the offer by a MNO to accept excess load along with the spectrum. The auctioneer matches the bids and asks, determines the trading price and makes the offloading decisions to minimize the total energy consumption. We show that even though the information is hidden among the MNOs, this mechanism allows the MNOs to save significant percentage of energy.

  • 44. Hossain, M. M. A.
    et al.
    Jantti, R.
    Cavdar, Çiçek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Energy saving market for mobile operators2015In: 2015 IEEE International Conference on Communication Workshop, ICCW 2015, IEEE conference proceedings, 2015, p. 2856-2861Conference paper (Refereed)
    Abstract [en]

    Ensuring seamless coverage accounts for the lion's share of the energy consumed in a mobile network. Overlapping coverage of three to five mobile network operators (MNOs) results in enormous amount of energy waste which is avoidable. The traffic demands of the mobile networks vary significantly throughout the day. As the offered load for all networks are not same at a given time and the differences in energy consumption at different loads are significant, multi-MNO capacity/coverage sharing can dramatically reduce energy consumption of mobile networks and provide the MNOs a cost effective means to cope with the exponential growth of traffic. In this paper, we propose an energy saving market for a multi-MNO network scenario. As the competing MNOs are not comfortable with information sharing, we propose a double auction clearinghouse market mechanism where MNOs sell and buy capacity in order to minimize energy consumption. In our setting, each MNO proposes its bids and asks simultaneously for buying and selling multi-unit capacities respectively to an independent auctioneer, i.e., clearinghouse and ends up either as a buyer or as a seller in each round. We show that the mechanism allows the MNOs to save significant percentage of energy cost throughout a wide range of network load. Different than other energy saving features such as cell sleep or antenna muting which can not be enabled at heavy traffic load, dynamic capacity sharing allows MNOs to handle traffic bursts with energy saving opportunity.

  • 45.
    Hossain, M. M. Aftab
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Cavdar, Cicek
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Bjornson, Emil
    Linkoping Univ, Dept Elect Engn, S-58183 Linkoping, Sweden..
    Jantti, Riku
    Aalto Univ, Sch Elect Engn, Espoo 02150, Finland..
    Energy Saving Game for Massive MIMO: Coping With Daily Load Variation2018In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 67, no 3, p. 2301-2313Article in journal (Refereed)
    Abstract [en]

    Massive MIMO (MM) is one of the leading technologies that can cater for very high capacity demand. However, energy consumption of MM systems needs to be load adaptive in order to cope with the significant temporal load variations (TLV) over a day. In this paper, we propose a game-theoretic model for studying load adaptive multicell massive MIMO system where each base station (BS) adapts the number of antennas to the TLV in order to maximize the downlink energy efficiency (EE). The utility function considered here is defined as the number of bits transferred per Joule of energy. In order to incorporate the TLV, the load at each BS is modeled as an M/G/m/m state dependent queue under the assumption that the network is dimensioned to serve a maximum number of users at the peak load. The EE maximization problem is formulated in a game theoretic framework where the number of antennas to be used by a BS is determined through the best response iteration. This load adaptive system achieves around 24% higher EE and saves around 40% energy compared to a baseline system where the BSs always run with the fixed number of antennas that is most energy efficient at the peak load and that can be switched OFF when there is no traffic.

  • 46. Hossain, M. M. Aftab
    et al.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Bjornson, Emil
    Jantti, Riku
    Energy-Efficient Load-Adaptive Massive MIMO2015In: 2015 IEEE GLOBECOM WORKSHOPS (GC WKSHPS), 2015Conference paper (Refereed)
    Abstract [en]

    Massive MIMO is a promising technique to meet the exponential growth of global mobile data traffic demand. However, contrary to the current systems, energy consumption of next generation networks is required to be load adaptive as the network load varies significantly throughout the day. In this paper, we propose a load adaptive massive MIMO system that varies the number of antennas following the daily load profile (DLP) in order to maximize the downlink energy efficiency (EE). A multi- cell system is considered where each base station (BS) is equipped with a large number of antennas to serve many single antenna users. In order to incorporate DLP, each BS is modeled as an M/G/m/m state dependent queue under the assumption that the network is dimensioned to serve a maximum number of users at the peak load. For a given number of users in a cell, the optimum number of active antennas maximizing EE is derived. The EE maximization problem is formulated in a game theoretic framework where the number of antennas to be used by a BS is determined through best response iteration. This load adaptive system achieves overall 19% higher EE compared to a baseline system where the BSs always run with the fixed number of antennas that is most energy efficient at peak load and that can be switched-off when there is no traffic.

  • 47.
    Hossain, M. M. Aftab
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Jantti, Riku
    Aalto Univ, Sch Elect Engn, Espoo, Finland..
    Dynamic capacity sharing based energy saving market for MNOs2017In: Globecom 2017 - 2017 IEEE Global Communications Conference, Institute of Electrical and Electronics Engineers (IEEE), 2017Conference paper (Refereed)
    Abstract [en]

    As the larger share of total energy consumed by mobile network operators (MNOs) is wasted in order to ensure coverage, three to five MNOs covering the same geographical area results in enormous energy waste. In order to cater for the data tsunami with almost zero marginal revenue, required densification of cells are not sustainable from both Capex and Opex perspective. Even with densification of networks, it is hard to satisfy the performance requirement of the cell edge users due to interference. However, the performance can be upgraded as well as energy can be saved by the offloading of the cell edge users to other MNOs if regulator and MNOs resort to appropriate mechanism. In our previous work, we proposed a double auction based energy saving market mechanism where MNOs participate in bidding to share coverage and capacity in order to save energy, especially during low to medium load. Unlike previous work, in this paper we use this mechanism that involve cell level bidding, i.e., cells bid for each user which not only allows total offloading of the cells at the low load but also offloading of cell edge users among the MNOs during high load. As a result, the energy saving potential becomes very high also at high load conditions along with improvement in performance of cell edge users.

  • 48.
    Hossain, M. M. Aftab
    et al.
    AALTO.
    Jantti, Riku
    AALTO.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Dimensioning of PA for massive MIMO system with load adaptive number of antennas2014In: Globecom Workshops (GC Wkshps), 2014, 2014, p. 1102-1108Conference paper (Refereed)
    Abstract [en]

    This paper takes into consideration the non-ideal efficiency characteristics of realistic power amplifiers (PAs) along with the daily traffic profile in order to investigate the impact of power amplifier dimensioning on the energy efficiency of load adaptive massive MIMO system. A multicellular system has been considered where each base station (BS) is equipped with large number of antennas to serve many single antenna users. For a given number of users in a cell, the optimum number of active antennas maximizing energy efficiency (EE) has been derived where total BS downlink power is assumed to be fixed. Under the same assumption, the power amplifiers have been dimensioned in a way that maximize network energy efficiency not only for a for a single time snapshot but over twenty four hours of operation while considering dynamic efficiency characteristics of the PAs. In order to incorporate this daily load profile, each BS has been modeled as an M/G/c/c state dependent queue under the assumption that the network is dimensioned to serve a maximum number of users at a time corresponding to 100% cell traffic load. This load adaptive system along with the optimized PA dimensioning achieves 30% higher energy efficinecy compared to a base line system where the BSs always run with a fixed number of active antennas which are most energy efficient while serving 100% traffic load.

  • 49.
    Jalalinia, Shabnam S.
    et al.
    KTH, School of Information and Communication Technology (ICT).
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Green and resilient design of telecom networks with shared backup resources2017In: OPTICAL SWITCHING AND NETWORKING, ISSN 1573-4277, Vol. 23, p. 97-107Article in journal (Refereed)
    Abstract [en]

    Backbone telecommunication network infrastructures are deployed with redundant resources taking into account the backup capacity for protection in order to be resilient against link failures, and serving extremely large amount of data transmission resulting in increasing power consumption. In this study, the interplay between green and resilient network design, and flow routing mechanisms is analyzed. We propose Mixed Integer Linear Programming (MILP) models to obtain optimum solutions under various objectives: Minimizing consumption of (I) Capacity, (II) Capacity+ Power, and (III) Power. Two different shared backup protection (SBP) schemes (1) SBP-ind (failure independent) and (2) SBP-dep (failure dependent) are compared with dedicated path protection (DPP). It is assumed that network links utilized by only backup paths can be put into sleep mode. It is observed that when power consumption is minimized, the backup sharing decreases in SBP and, in the extreme case, it behaves similar to DPP. The models are generalized and valid for both IP traffic flow routing and lightpath routing. It is shown that for a sample network topology, to save e.g., 32.33% power, capacity consumption increases significantly, e.g., in SBP-ind up to 127.53%. In order to achieve a compromise between power and capacity consumption, we propose a multi-objective approach. All the MILP models are run and results are presented for a small scale European network topology as well as a larger scale sample US network topology. For larger problem instances ILP solutions are not scalable. Therefore, a novel energy efficient and survivable routing and network design algorithm, called energy-aware shared path protection (EASPP), addressing the trade-off caused by conflicting objectives of green and resilient network planning is proposed. Moreover this study presents a complete picture of various survivability mechanisms when power consumption is minimized together with the capacity consumption.

  • 50.
    Jalalinia, Shabnam Sadat
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Survivable Green Optical Backbone Networkswith Shared Path Protection2012In: Optical Fiber Communication Conference Los Angeles, California March 4, 2012    Energy Efficient Network and Technology (OM2G), Optical Society of America, 2012Conference paper (Refereed)
    Abstract [en]

    We propose a novel energy-efficient and survivable routing algorithm addressing the trade-off caused by conflicting objectives of energy saving and survivability, i.e. energy-efficient routing tends to pack while survivable strategies try to spread the traffic.

12 1 - 50 of 89
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf