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  • 201.
    Udalcovs, Aleksejs
    et al.
    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).
    Bobrovs, V.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Power efficiency of WDM networks using various modulation formats with spectral efficiency limited by linear crosstalk2014In: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 318, 31-36 p.Article in journal (Refereed)
    Abstract [en]

    Small channel spacing in WDM systems offers very good spectral efficiency, but may reduce the transparent optical reach because of interchannel crosstalk. In turn, an increase in the network power consumption can be expected, due to the need for signal regeneration. This paper explores the trade-off between spectral efficiency, transparent optical reach, and power consumption. The results confirm that using the most energy efficient transponder (i.e., in terms of W/bps) does not always guarantee the lowest overall network power consumption. This is especially true over long point-to-point distances (i.e., multiple transmission fiber spans) where, in order to ensure stringent quality of transmission levels together with high spectral efficiency, the optical signal needs to be regenerated many times.

  • 202. Udalcovs, Aleksejs
    et al.
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Bobrovs, Vjaceslavs
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Ivanovs, Girts
    Spectral and energy efficiency considerations in mixed-line rate WDM networks with signal quality guarantee2013In: ICTON 2013: 15th International Conference on Transparent Optical Networks, 2013, 1-7 p.Conference paper (Refereed)
    Abstract [en]

    Mixed-Line Rate (MLR) is a cost efficient solution to cope with the rapidly increasing and heterogeneous Internet traffic. In a MLR-based scenario wavelength channels are organized in groups (i.e., sub-bands), each of which consisting of channels operating at the same rate, e.g., it is possible to have on the same fiber link subbands operating at 10 Gbps, 40 Gbps, and 100 Gbps. In order to increase spectral efficiency one can reduce not only the channel spacing within a sub-band but also the frequency spacing between sub-bands operating at different rates, i.e., the sub-band spacing. On the other hand smaller sub-band spacing may: (i) negatively impact the transparent optical reach of wavelength channels due to the higher inter-channel crosstalk levels, and consequently (ii) increase the network power consumption because of the need of more signal regeneration. This paper aims at assessing the trade-off between spectral efficiency and the power consumption in a WDM transport network, when a certain quality of transmission needs to be guaranteed at the receiving node. This is accomplished by evaluating a number of spectral efficient MLR solutions, where the number of wavelength channels allocated to each sub-band is varied while keeping the required Bit Error Rate (BER) level at the receiving node fixed. Results show that the width of each sub-band plays a central role in determining the power consumption of an end-to-end connection.

  • 203.
    Urban, Patryk
    et al.
    Ericsson.
    Getaneh, Agerekibre
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Weid, Jean Pierre von der
    Temporão, Guilherme Penello
    Vall-llosera, Gemma
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Detection of Fiber Faults in Passive Optical Networks2013In: Journal of Optical Communications and Networking, ISSN 1943-0620, E-ISSN 1943-0639, Vol. 5, no 11, 1111-1121 p.Article in journal (Refereed)
    Abstract [en]

    Wider deployment of fiber in the last mile is driven by increased customer needs for broadband communication services. This deployment requires solutions that reduce operational expenditures for the operator. A cost-efficient fully reliable and accurate monitoring solution supporting fault detection, identification, and localization in different fiber access architectures will be essential. In this article, we present a fast, automatic, and precise monitoring method applicable to both power-splitter- and wavelength-router-based passive optical networks through the combined techniques of optical time domain reflectometry and optical transceiver monitoring. The description of the architecture, components, and process flow is followed by tests on setups with live data transmission.

  • 204.
    Valcarenghi, Luca
    et al.
    Scuola Superiore Sant'Anna.
    Chincoli, Michele
    Scuola Superiore Sant'Anna.
    Castoldi, Piero
    Scuola Superiore Sant'Anna.
    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).
    Improving energy efficiency in TDMA passive optical networks from theory to practice2012In: Photonics In Switching, 2012Conference paper (Other academic)
    Abstract [en]

     Passive optical networks are currently the major contributor to fixed optical networks energy consumption. Within PON, almost 65% of their energy consumption is due to the customer premises equipments (i.e., the ONUs).Standardisation authorities, industries and researchers are proposing several methods for decreasing ONU energy consumption. Cyclic sleep or fast sleep is one of the proposed methods that is based on cycles of sleep and waking periods. However, cyclic sleep, while decreasing ONU energy consumption, causes an increase in the delay experienced by the transmitted data. Based on the requested Quality of Service (QoS) such additional delay can be more or less detrimental for the carried service. Therefore, it is essential to optimally select when to sleep and for how long, based also on the services subscribed by the ONU.This presentation will outline a method for maximizing energy savings while providing services with delay guaranteed. The method exploits service-based variable sleep periods. Simulation results prove the method effectiveness with both Poisson and heavy-tailed traffic. The presentation will also provide an overview of the testbed implementation of the proposed approach

  • 205.
    Valcarenghi, Luca
    et al.
    Scuola Superiore Sant'Anna.
    Chincoli, Michele
    Scuola Superiore Sant'Anna.
    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).
    Castoldi, Piero
    Scuola Superiore Sant'Anna.
    Energy efficient PONs with service delay guarantees2012In: 2012 Sustainable Internet and ICT for Sustainability, SustainIT 2012, IFIP , 2012, 1-8 p.Conference paper (Refereed)
    Abstract [en]

    Passive Optical access Networks (PONs) are currently the major contributor to the energy consumption budget of fixed optical networks. In PON, the largest part of the energy consumption is due to the equipments at the customer premises. This paper proposes a method for maximizing energy savings while providing services with delay guarantees (i.e., frame delivery time and frame delay variation). The method combines service-based variable sleep period and a queueing theory model to compute the optimal sleep time. Simulation results prove the effectiveness of the method for a Poisson frame arrival process.

  • 206. Van, Dung Pham
    et al.
    Fiorani, Matteo
    Wosinska, Lena
    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).
    Adaptive Open-Shop Scheduling for Optical Interconnection Networks2017In: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 35, no 13, 2503-2513 p.Article in journal (Refereed)
    Abstract [en]

    This paper deals with resource management in optical interconnection networks. It first proposes an optical resource management framework as a platform to develop and evaluate efficient solutions for multipoint-to-multipoint optical communication systems with a centralized controller. The paper then focuses on studying the optical resource scheduling (ORS) problem as a core element in the framework by applying the classical open-shop scheduling theory. The ORS problem can therefore be solved by adopting the existing preemptive and nonpreemptive open-shop scheduling algorithms. In an optical network with nonnegligible reconfiguration delay, a preemptive algorithm may incur high reconfiguration overhead resulting in worse performance compared to the nonpreemptive strategy. Motivated by this fact, this paper proposes an adaptive open-shop scheduling (AOS) algorithm that dynamically decides the optimal scheduling strategy according to traffic condition and system parameters, such as reconfiguration delay, nonpreemptive approximation ratio, and number of involved optical interfaces. The solution is assessed by means of an analytical model that allows to quantify the network performance in terms of packet delay and potential energy savings obtained by the sleep mode operation. As a possible application scenario, the inter- and intrarack optical interconnection networks in data centres are considered. Analytical results demonstrate how the proposed AOS outperforms the nonpreemptive and preemptive scheduling strategies for typical configurations used in data center networks. In addition, the reconfiguration delay and wake-up time of optical devices are identified as performance-determining factors.

  • 207.
    Van, Dung Pham
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Fiorani, Matteo
    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).
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Resource management for optical interconnects in data centre networks2017In: 2016 IEEE Global Communications Conference, GLOBECOM 2016 - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2017, 7842226Conference paper (Refereed)
    Abstract [en]

    This paper deals with resource management in data centre networks that feature optical interconnects. It first proposes an optical resource management framework as a platform to develop different solutions for multipoint-to-multipoint optical communication systems with a centralized controller. The paper takes optical intra-rack communications as an example application scenario of the framework and studies the intra-rack scheduling (IRS) problem using a theoretical approach. The problem is mapped into the classical open-shop scheduling problem, in which the optical interfaces are viewed as the jobs and the wavelengths used for communication among the interfaces are viewed as the machines. The IRS problem can therefore be solved by adopting the existing preemptive and/or non-preemptive open-shop scheduling algorithms. In a realistic intra-rack communication scenario with non-negligible network reconfiguration time, it is important to understand whether the preemptive or non-preemptive strategy provides better performance under given traffic conditions and system configurations. To address the question, this paper presents a performance analysis that allows to quantitatively compare the two scheduling strategies in terms of packet delay and potential energy savings obtained from sleep mode implementation. Analytical results reveal that the non-preemptive strategy outperforms the preemptive one for typical configurations used in data centre networks. In addition, the tuning and wake-up times of optical transceivers are shown to be key performance-determining factors. The proposed framework and obtained findings are not limited to the considered intra-rack communication scenario, but can be applied to any centralized optical switching systems featuring multipoint-to-multipoint transmissions with non-negligible reconfiguration time.

  • 208.
    Van, Dung pham
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Rimal, B. P.
    Maier, M.
    Fiber optic vs. wireless sensors in energy-efficient integrated FiWi smart grid networks: An energy-delay and TCO comparison2016In: Proceedings - IEEE INFOCOM, IEEE, 2016Conference paper (Refereed)
    Abstract [en]

    This paper aims at designing an ecoconscious future-proof sensor enhanced fiber-wireless (SFiWi) network based on EPON, WLAN, wireless sensor (WS), and fiber optic sensor (FOS) technologies as a shared communications infrastructure for broadband access and smart grids. A total cost of ownership (TCO) model is developed to help utilities decide whether to deploy WSs or FOSs in different scenarios and estimate sensor-related costs. To prolong battery life of wireless devices and maximize the overall energy efficiency, a novel energy conservation scheme for SFiWi networks (ECO-SFiWi) is proposed. ECO-SFiWi designs the whole network in three TDMA layers to enhance network performance, while scheduling network components to sleep outside their transmission slots. A comprehensive energy saving model accounting for both optical backhaul and wireless front-end components and a delay analysis based on M/G/1 queuing are presented. Results reveal that with their extremely long lifetime and ability to sustain in harsh environments, FOSs are superior to WSs when advanced interrogation techniques are deployed to reduce their total cost. ECO-SFiWi achieves more than 89% of energy savings, while maintaining low delay for both broadband and smart grid traffic in typical scenarios. FPGA hardware emulation and analytical results match well verifying the effectiveness of ECO-SFiWi.

  • 209.
    Van, Dung Pham
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Rimal, Bhaskar Prasad
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Maier, Martin
    Power-Saving Methods for Internet of Things over Converged Fiber-Wireless Access Networks2016In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 54, no 11, 166-175 p.Article in journal (Refereed)
    Abstract [en]

    The IoT has been emerging as the next big leap in the information and communication technology sector. Providing a unified communication platform to support billions of smart connected devices seamlessly alongside existing voice and Internet services is vitally challenging. This article leverages converged fiber-wireless (FiWi) access networks to design a shared communication infrastructure for supporting both IoT applications and traditional services. Given the paramount importance of energy efficiency in both IoT and access networks, the article discusses the possibilities and potential challenges of designing and implementing power-saving mechanisms to prolong battery life of IoT devices while reducing energy consumption of the optical backhaul network. In-depth technical guidelines are provided through end-to-end power-saving solutions proposed for typical IoT deployment scenarios.

  • 210.
    Van, Dung Pham
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab). Institut National de la Recherche Scientifique (INRS), Canada.
    Rimal, Bhaskar Prasad
    Maier, Martin
    Valcarenghi, Luca
    Design, Analysis, and Hardware Emulation of a Novel Energy Conservation Scheme for Sensor Enhanced FiWi Networks (ECO-SFiWi)2016In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 34, no 5, 1645-1662 p.Article in journal (Refereed)
    Abstract [en]

    Fiber-wireless sensor networks (Fi-WSNs) composed of a hybrid fiber-wireless (FiWi) network enhanced with sensors will play a key role in supporting machine-to-machine (M2M) communications to enable a wide range of Internet of Things (IoT) applications, of which smart grids represent an important real-world example. This paper explores opportunities of designing an energy-efficient Fi-WSN based on EPON/10G-EPON, WLAN, wireless sensors, and passive fiber optic sensors as a shared communications infrastructure for broadband services and smart grids. A novel energy conservation scheme for sensor enhanced FiWi networks (ECO-SFiWi) is proposed to reduce the overall energy consumption. ECO-SFiWi maximizes energy efficiency by leveraging TDMA to schedule power-saving modes of EPON's optical network units, wireless stations, and wireless sensors and incorporate them into EPON's bandwidth allocation algorithm. To study the performance, a comprehensive energy saving model and a delay analysis of both FiWi traffic and sensor data based on M/G/1 queue modeling are presented. FPGA-based hardware emulation and demonstration are performed to verify the effectiveness of the proposed solution. Results provide deep insights into the tradeoff between energy savings and frame delays. Noticeably, ECO-SFiWi achieves significant amounts of energy saving, while maintaining low delay for FiWi traffic and sensor data under typical deployment scenarios.

  • 211. Vardakas, J. S.
    et al.
    Monroy, I. T.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Agapiou, G.
    Brenot, R.
    Pleros, N.
    Verikoukis, C.
    Towards high capacity and low latency backhauling in 5G: The 5G STEP-FWD vision2017In: 2017 19th International Conference on Transparent Optical Networks (ICTON), IEEE Computer Society, 2017, 8025130Conference paper (Refereed)
    Abstract [en]

    This paper presents the vision of the 5G STEP-FWD project, funded by the European Commission, with the objective to propose a novel optical-wireless networking solution for the provision of high speed connectivity to end users. The features of the new architecture, based on the utilization of Ultra-Dense Wavelength Division Multiplexing Passive Optical Networks as the backhaul network, providing access to hyper dense mmWave networks, are presented in detail. Moreover, the research challenges to meet the 5G requirements in terms of low latency, spectral and energy efficiency are highlighted, followed by the description of way the project 5G STEP-FWD is going to address them.

  • 212. Velasco, L.
    et al.
    Jirattigalachote, Amornrat
    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).
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Junyent, G.
    Statistical Approach for Fast Impairment-Aware Provisioning in Dynamic All-Optical Networks2012In: Journal of Optical Communications and Networking, ISSN 1943-0620, E-ISSN 1943-0639, Vol. 4, no 2, 130-141 p.Article in journal (Refereed)
    Abstract [en]

    Physical layer impairments (PLIs) need to be considered in the routing and wavelength assignment (RWA) process of all-optical networks to ensure the provisioning of good quality optical connections (i.e., lightpaths). A convenient way to model the impact of PLIs on the signal quality is to use the so-called Q-factor. In a dynamic provisioning environment, impairment-aware RWA (IA-RWA) algorithms include Q-factor evaluation in their on-line decisions on whether to accept a connection request or not. The Q-factor can be computed in either an approximated or an exact way. IA-RWA algorithms using an approximated Q-factor estimation (i.e., worst case) can be very fast and allow for a short setup delay. However, connection request blocking can be unnecessarily high because of the worst-case assumption for the Q-factor parameters. In contrast, an exact Q-factor computation results in a better blocking performance at the expense of a longer setup delay, mainly due to the time spent for the Q-factor computation itself. Moreover, an exact Q-factor approach requires extensions of the generalized multi-protocol label switching suite. To overcome these problems, we propose a statistical approach for fast impairment-aware RWA (SAFIR) computation. The evaluation results reveal that SAFIR improves the blocking probability performance compared to the worst-case scenario without adding extra computational complexity and, consequently, without increasing the connection setup delay.

  • 213. Verplaetse, Michiel
    et al.
    Lin, Rui
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Van Kerrebrouck, Joris
    Ozolins, Oskars
    De Keulenaer, Timothy
    Pang, Xiaodan
    Pierco, Ramses
    Vaernewyck, Renato
    Vyncke, Arno
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT).
    Westergren, Urban
    KTH, School of Information and Communication Technology (ICT).
    Jacobsen, Gunnar
    KTH, School of Information and Communication Technology (ICT). Acreo Swedish ICT AB, Sweden.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT).
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Torfs, Guy
    Bauwelinck, Johan
    Yin, Xin
    Real-Time 100 Gb/s Transmission Using Three-Level Electrical Duobinary Modulation for Short-Reach Optical Interconnects2017In: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 35, no 7, 1313-1319 p.Article in journal (Refereed)
    Abstract [en]

    Electrical duobinary modulation is considered as a promising way to realize high capacity because of the low bandwidth requirement on the optical/electrical components and high tolerance toward chromatic dispersion. In this paper, we demonstrate a 100 Gb/s electrical duobinary transmission over 2 km standard single-mode fiber reaching a bit error rate under 7% HD-FEC threshold with the use of PRBS7. This link is tested in real-time without any form of digital signal processing. In-house developed SiGe BiCMOS transmitter and receiver ICs are used to drive an electroabsorption modulated laser and decode the received signal from a PIN-photodiode. The performance of 50 and 70 Gb/s nonreturn-to-zero and electrical duobinary transmission are investigated for comparison.

  • 214.
    Wang, Kun
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab). RISE Acreo.
    Mas Machuca, Carmen (Contributor)
    Technical University of Munich.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Brunnström, Kjell (Contributor)
    RISE Acreo.
    Chen, Jiajia (Contributor)
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Migration Strategies for FTTx Solutions based on Active Optical Networks2016In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 54, no 2, 78-85 p.Article in journal (Refereed)
    Abstract [en]

    AON, one of the most deployed fiber access solutions in Europe, needs to be upgraded in order to satisfy the ever growing bandwidth demand driven by new applications and services. Meanwhile, network providers want to reduce both capital expenditures and operational expenditures to ensure that there is profit coming from their investments. This article proposes several migration strategies for AON from the data plane, topology, and control plane perspectives, and investigates their impact on the total cost of ownership.

  • 215.
    Wang, Kun
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab). RISE Acreo.
    Migration Towards Next Generation Optical Access and Transport Networks2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    By 2020 there will be 50 billion connected devices over the Internet. With the fast-increasing data traffic demand in both fixed and mobile networks, network operators need to migrate networks towards next generation solutions. The network migration requires the enormous investment in equipment and infrastructure, while the revenues are not expected to grow significantly. Therefore, one of the main challenges for network operators is to find out a proper cost-effective optical network solution that can match future high capacity demand and flexibly support multiple network services on a common network infrastructure.

    The first part of the thesis addresses the Active Optical Network (AON) and its migration strategies towards Next Generation Optical Access (NGOA) solutions. Several migration strategies are proposed from the perspective of network topology, data plane and control plane. A general methodology for Techno-Economic analysis has been developed and applied to the Total Cost of Ownership (TCO) calculation of different NGOA solutions. The thesis provides a complete cost evaluation of AON migration paths, which can be used by network operators to assess the economic feasibility of network migration.

    A converged Optical Transport Network (OTN) that can serve both fixed and mobile network services is beneficial from the cost-saving perspective. However, the different types of services, require different network performance. The second part of the thesis focuses on the investigation of the converged OTN that can be flexibly and timely adjusted to satisfy varying service conditions. A programmable OTN featured with Wavelength Division Multiplexing (WDM) in the data plane and Software Defined Networking (SDN) in control plane has been proposed. To demonstrate the benefits of the converged OTN, the thesis also provides a multi-domain orchestration architecture for the multiple network services.  The resource orchestration, across three network domains: OTN, mobile network and cloud, enables agile service creation and optimized resource allocation among the multiple domains.

  • 216.
    Wang, Kun
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab). RISE Acreo.
    Wosinska, Lena (Contributor)
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Urban, Patryk J. (Contributor)
    Ericsson.
    Gavler, Anders (Contributor)
    RISE Acreo.
    Brunnström, Kjell (Contributor)
    RISE Acreo.
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Techno-Economic Analysis of Active Optical Network Migration Toward Next-Generation Optical Access2017In: Journal of Optical Communications and Networking, ISSN 1943-0620, E-ISSN 1943-0639, Vol. 9, no 4, 327-341 p.Article in journal (Refereed)
    Abstract [en]

    Active optical networks (AONs) have been one of the most deployed fiber access solutions in Europe. However, with the increasing traffic demand, the capacity of the existing AONs is becoming insufficient. For the legacy AONs, there are two major variants of architectures, namely, point-to-point and active star. Considering the different characteristics of these two AON architectures, this paper proposes and analyzes several migration paths toward next-generation optical access (NGOA) networks offering a minimum 300 Mbit/s sustainable bit rate and 1 Gbit/s peak bit rate to every end customer. Furthermore, this paper provides detailed descriptions of the network cost modeling and the processes for AON migration. The total cost of ownership (TCO) is evaluated for the proposed migration paths, taking into account different migration starting times, customer penetration, node consolidation, and business roles in the fiber access networks. The migration from AON to NGOA can be economically feasible. The results indicate that a network provider plays a key business role and is responsible for the major part of the TCO for AON migration. Moreover, performing node consolidation during AON migration can be beneficial from a cost point of view, especially in rural areas.

  • 217.
    Wang, Kun
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab). RISE Acreo.
    Larsen, Claus Popp
    Gavler, Anders
    RISE Acreo.
    Lannoo, Bart
    Chiaroni, Dominique
    Popov, Mikhail
    A Comparative Model and Techno-Economic Analysis of Next Generation AON Ethernet and TDM PON2010In: Network Architectures, Management, and Applications VIII, Optical Society of America, 2010Conference paper (Refereed)
    Abstract [en]

    A global reference model covering next generation active and passive networks has been developed for techno-economic evaluations, and an extensive techno-economic analysis with a focus on CAPEX has been performed for 10G TDM PON and 1G AON - both capable of delivering 1Gbit/s to end-users. Two major cases have been considered: urban and rural at green field deployment. The results show that AON is less expensive than PON solution in urban case while in rural case 10G TDM PON is more competitive.

  • 218.
    Wang, Meiqian
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Furdek, Marija
    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).
    Restoration with service degradation and relocation in optical cloud networks2015In: Asia Communications and Photonics Conference, ACPC 2015, 2015Conference paper (Refereed)
    Abstract [en]

    The paper studies the improvement of cloud service restoration by combining the service degradation and relocation concepts. Results demonstrate that it is possible to achieve improvements in both cloud service availability and restorability performance. © 2015 OSA.

  • 219.
    Wang, Meiqian
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Furdek, Marija
    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.
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Wavelength overprovisioning strategies for enhanced optical path restoration2016In: International Conference on Transparent Optical Networks, IEEE Computer Society, 2016Conference paper (Refereed)
    Abstract [en]

    This paper proposes two wavelength overprovisioning strategies that can be used to improve the performance of path restoration in optical core networks under dynamic traffic conditions while considering single fiber link failure scenarios. The study presented in the paper shows that with the two proposed schemes it is possible to achieve nearly the same level of average connection availability and restorability typical of dedicated path protection schemes (i.e., 100%) with, on the other hand, better blocking probability performance.

  • 220. Wiatr, P.
    et al.
    Forchheimer, R.
    Furdek, Marija
    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).
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Yuan, D.
    Hierarchical optical interconnects saving spectrum resources in data center networks2017In: Optics InfoBase Conference Papers, Optics Info Base, Optical Society of America, 2017, Vol. Part F53Conference paper (Refereed)
    Abstract [en]

    This paper presents a hierarchical interconnect architecture for optical data center networks composed of specially designed couplers allowing for significant reduction of required spectral resources.

  • 221.
    Wiatr, Pawel
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Energy Saving vs. Performance: Trade-offs in Optical Networks2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The energy consumption of communication networks is continuously growing. Many energy saving approaches have been proposed at the device, system, and network level. The most promising way to address this problem is to utilize photonic technologies as much as possible thanks to their low energy consumption per bit performance. Moreover, several approaches have been proposed to further reduce the energy consumption in optical networks. One popular technique exploits low power modes (e.g., sleep or doze mode) for devices that are not used. However, sleep mode based approaches may affect the way optical connections (i.e., lightpaths) are routed, or alter the characteristics of some devices. This in turn may have a detrimental impact on crucial network/device performance parameters. In other words a green approach may introduce additional delay, change the level of resource utilization in the network, or even impact the lifetime of a device, resulting in increased network operational cost. This thesis provides a study that carefully assesses, in both access and core networks, the trade-off between the benefits of sleep-based energy-efficient schemes and their possible side-effects.

    In fiber access networks putting a device into sleep mode and waking it up can introduce a significant energy overhead. Already proposed energy-efficient approaches reduce this overhead by aggregating as much as possible the traffic before a transmission. However, aggregating data may cause an additional delay that in some cases might not be acceptable. This thesis investigates the trade-off between energy saving and additional packet delay in the case of a LTE backhaul network based on wavelength division multiplexing passive optical network (WDM-PON). The thesis proposes a novel energy-efficient approach based on the dozing concept able to precisely control when a transmitter needs to wake up in order to maximize the time spent in sleep mode, while assuring that packet transmissions are completed before a given deadline. The proposed scheme is also able to exploit possibly diverse traffic delay requirements to further improve energy saving performance.

    In optical core networks, one way to decrease the energy consumption is to minimize the number of used active devices by aggregating the lightpaths on the lowest possible number of active fiber links. Routing strategies based on this intuition are beneficial in terms of energy saving, but on the other hand may impact the network performance (e.g., blocking probability) by affecting length of the lightpaths and link occupancy distribution. This trade-off is evaluated in the thesis with the help of a specially designed routing and wavelength assignment (RWA) strategy referred to as weighted power aware lightpath routing (WPA-LR). The WPA-LR strategy permits the fine tuning between the minimization of two objectives: energy consumption and network resource (i.e., wavelength) utilization. Evaluation results confirm that energy efficiency and network performance are conflicting objectives. However, the proposed WPA-LR strategy offers energy minimization with acceptable impact on the network performance.

    The thesis also investigates the impact that sleep-based energy-efficient strategies have on the lifetime of a number of optical network devices, in both access and core networks. In fact, utilizing a sleep mode functionality may change the operational conditions of the device which can impact the device lifetime. This is a crucial aspect to consider because it may directly affect the network operational cost related to fault management. The thesis provides a methodology to assess under which conditions and for which devices an energy-efficient scheme may lead to overall cost benefit vs. a (possible) increase of reparation cost. It was found that in access networks and with business customers a small lifetime variation in optical line terminals (OLTs) or in optical network units (ONUs) can lead to significant cost increase that cannot be covered by the profits coming from the energy saving. In core networks erbium doped fiber amplifiers (EDFAs) are the most vulnerable devices in terms of impact on their lifetime. For this reason it was found that the usage of green routing algorithms based on putting EDFAs into sleep mode may not always be economically beneficial.

    In conclusion this thesis provides a different perspective on sleep mode based energy-efficient algorithms where the potential benefit in terms of energy saving is weighted against the impact of a possible degradation of the network performance and devices lifetime. On the other hand these performance degradations can be controlled and limited by the proposed algorithms.

  • 222.
    Wiatr, Pawel
    et al.
    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).
    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).
    Energy efficiency and reliability tradeoff in optical core networks2014In: Optical Fiber Communication Conference, OFC 2014, Optical Society of America, 2014Conference paper (Refereed)
    Abstract [en]

    We assess the highest allowable reliability performance degradation of active components caused by applying energy-efficient mechanisms. EDFAs are identified as the most critical devices where energy saving might not cover the potential additional reparation cost.

  • 223.
    Wiatr, Pawel
    et al.
    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).
    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).
    Energy Efficiency Versus Reliability Performance in Optical Backbone Networks2015In: Journal of Optical Communications and Networking, ISSN 1943-0620, E-ISSN 1943-0639, Vol. 7, no 3, A482-A491 p.Article in journal (Refereed)
    Abstract [en]

    Improving the energy efficiency in telecommunication networks has been one of the main research topics of the past few years. As a result, many energy efficient algorithms have been proposed, some focusing on maximizing only the energy savings, others considering also the impact that green strategies have on other network performance metrics, e.g., delay, utilization of network resources, and blocking probability. The aim of this paper is to provide new insight on the impact of energy efficient strategies, i.e., investigating the trade-off between green network operations and the reliability performance of optical backbone devices. The study is motivated by the intuition that energy efficient strategies are usually based on putting unutilized devices in power saving (sleep) mode, which can have some side effects (e.g., frequent on/sleep switching, and/or high fiber link utilization) that may affect the working conditions of a device. To better understand these phenomena, this paper presents a number of models aimed at estimating the reliability performance changes of a device as a function of its average working temperature, of its temperature variations, and of its average occupancy. These models are then used to carry out a study both at the component and at the network levels. The study at the component level shows that erbium-doped fiber amplifiers (EDFAs) are critical devices, i.e., their achievable energy savings might not cover the additional reparation costs resulting from their reliability performance degradation. Similar findings are reached also with the network level study. In summary, it can be concluded that the use of energy efficient routing algorithms based on setting EDFAs in sleep mode may not always be beneficial.

  • 224.
    Wiatr, Pawel
    et al.
    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).
    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).
    Energy saving in access networks: Gain or loss from the cost perspective?2013In: 2013 15th International Conference on Transparent Optical Networks (ICTON), IEEE conference proceedings, 2013, 6603014- p.Conference paper (Refereed)
    Abstract [en]

    Energy consumption in telecommunication networks has become a significant problem during the last few years. Many energy efficient mechanisms have been proposed and evaluated with respect to their impact on the overall network performance (e.g., delay, blocking probability, quality of transmission). Most of these mechanisms are based on the sleep mode functionality, i.e., a "low power" state of network devices that can be utilized in low traffic conditions. On the other hand, a frequent switching between a working and a sleeping state may increase the probability of failures in a device, which in turn makes the operational cost related to fault reparation higher. This paper discusses how sleep mode-based energy saving mechanisms can impact the reliability performance of network equipment by pointing out several physical phenomena that may lead to an increase of the failure rate. In order to quantify such effects we propose a methodology that estimates to what extent energy savings can be maximized without exceeding the extra reparation cost caused by the degradation of the reliability performance of network equipment due to frequent switching on and off. We perform a number of simulative studies focused on an optical access segment and show that the cost saved by reducing the energy consumption (i.e., as the result of a power efficient mechanism) may be easily overcome by the extra expenses related to reparation of network equipment and service interruption for business users.

  • 225.
    Wiatr, Pawel
    et al.
    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).
    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).
    Green WDM-PONs: Exploiting traffic diversity to guarantee packet delay limitation2013In: 2013 17th International Conference On Optical Networking Design And Modeling (ONDM), IEEE , 2013, 229-234 p.Conference paper (Refereed)
    Abstract [en]

    In this paper we propose a scheme tailored for WDM-PONs, which employs dozing mode in transceivers not only at the user side but also at the central office. The objective is to reduce the energy consumption while minimizing the impact on the total packet delay. The proposed scheme is able to take into account the diverse delay requirement of multiple traffic classes by adapting the wakeup time of the transmitter. Simulation results confirm that the proposed scheme can significantly improve the power efficiency in WDM-PONs while maintaining the maximum packet delay at an acceptable level, in particular in cases where multiple traffic classes are considered.

  • 226.
    Wiatr, Pawel
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101). 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), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101). 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), Optics and Photonics (Closed 20120101). KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Power Savings versus Network Performance in Dynamically Provisioned WDM Networks2012In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 50, no 5, 48-55 p.Article in journal (Refereed)
    Abstract [en]

    The role of the ICT sector in our daily life is causing a significant growth of the power consumed by the network equipment. In this context, transparent WDM networks represent a promising solution for reducing the power consumption of telecom networks. For this reason transparent WDM networks attract a lot of interest and several power-aware routing and wavelength assignment algorithms are available in the literature. These approaches, however, seem to consider power minimization as the only parameter to be optimized. Little or no attention is given to other important network aspects, e. g., connection requests blocking. Such approaches may not always be advisable, especially in core WDM networks where high performance levels must be considered in the first place. This article aims at providing a different insight to the PA-routing problem. It follows the intuition that in some cases relaxing the power minimization constraint can have beneficial effects on the overall network performance, especially on the blocking probability. A novel approach, referred to as Weighted Power-Aware Lightpath Routing (WPA-LR), is proposed and evaluated using two continental core networks. Our results confirm the presence of a trade-off between power savings and blocking probability.

  • 227. Wong, E.
    et al.
    Machuca, C. M.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Survivable architectures for power-savings capable converged access networks2016In: 2016 IEEE International Conference on Communications, ICC 2016, IEEE conference proceedings, 2016, 365-371 p., 7510719Conference paper (Refereed)
    Abstract [en]

    The reliance on the loss-of-signal (LOS) of upstream transmissions to indicate fiber/component failure is potentially unsuitable in networks that implement sleep/doze mode operation. In such networks, the transition into sleep/doze mode would result in no signal transmission, and when used in conjunction with conventional LOS to indicate network failure, would result in erroneous triggering of false alarm and subsequently protection switching. Recently, converged access networks using a hybrid passive optical architecture, have been favored as a low-cost and high-bandwidth solution to deliver high-bandwidth applications to both fixed access and mobile users. These networks are referred to as Hybrid PON Converged Access Networks. Protection against fiber/equipment failures in these networks is critical considering the customer base, network span, and traffic supported. This paper proposes four survivable architectures for such converged access networks. These architectures combine rapid fault detection and protection switching against high impact failures but without the need to rely on upstream transmissions for LOS detection. A comparison of the four architectures across three different area densities under three deployment scenarios, is presented. Guidance for selecting the best protection architecture to be deployed, considering area densities and deployment scenarios, is provided.

  • 228. Wong, Elaine
    et al.
    Machuca, Carmen Mas
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Survivable Hybrid Passive Optical Converged Network Architectures Based on Reflective Monitoring2016In: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 34, no 18, 4317-4328 p.Article in journal (Refereed)
    Abstract [en]

    Hybrid passive optical converged access networks (HPCANs) are recognized as a cost-efficient and high-bandwidth solution to address the exponentially increasing demands of both fixed access and mobile users. HPCANs are expected to support high client count with different bandwidth requirements, long network spans, and high traffic. In that respect, survivability of such networks against fiber/equipment failures is a critical deployment feature. Consequently, rapid fault detection and subsequent restoration of services to users are gaining importance. Four survivable architectures that are compliant with the aforementioned HPCAN specifications are presented in this work. These architectures do not need to rely on upstream transmissions for loss-of-signal (LOS) activation, thereby making them suitable for use with sleep/doze mode transceivers for power saving. In networks that implement sleep/doze upstream transceivers, the transition into sleep/doze mode would result in no upstream signal transmission. If using conventional LOS activation rather than our proposed architectures to indicate equipment/fiber failure in the network, the absence of upstream transmission would result in erroneous triggering of false LOS alarm and subsequently unnecessary protection switching. We compare the four survivable HPCAN architectures against an unprotected HPCAN using illustrative examples of three different population densities, namely covering dense urban, urban, and rural areas, and three different deployment scenarios, namely brownfield, duct reuse, and greenfield. We perform detailed evaluations of connection availability, failure impact factor, yearly network energy consumption, and total network cost. Results from this study provide guidance for the choice of the best survivable HPCAN architecture to serve each of the three considered area densities under each of the three deployment scenarios.

  • 229.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Optical network architectures for datacenters2017In: Optics InfoBase Conference Papers, Optics Info Base, Optical Society of America, 2017, Vol. Part F53Conference paper (Refereed)
    Abstract [en]

    The talk will highlight challenges related to dramatically growing datacenter traffic. The advantages of using photonic technology in intra-datacenter networks will be discussed and a crosslayer view of network architecture design will be presented.

  • 230.
    Wosinska, Lena
    et al.
    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).
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Next Generation Optical Access Network Architectures: What is the Best Option?2013Conference paper (Other academic)
  • 231.
    Wosinska, Lena
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Furdek, Marija
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Dzanko, Matija
    Reliability Performance of Optical Networks Based on Programmable ROADMs2016In: 2016 18TH INTERNATIONAL CONFERENCE ON TRANSPARENT OPTICAL NETWORKS (ICTON), IEEE, 2016Conference paper (Refereed)
  • 232.
    Wosinska, Lena
    et al.
    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).
    Fiorani, Matteo
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Dreier, Dennis
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    Silveira, Semida
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    ICT Infrastructure for Smart Cities: Curitiba, Brazil2015Conference paper (Other academic)
  • 233. Wu, Jing
    et al.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Jin, Yaohui
    Araki, Soichiro
    Guest editorial2013In: Telecommunications Systems, ISSN 1018-4864, E-ISSN 1572-9451, Vol. 54, no 2, 111-112 p.Article in journal (Refereed)
  • 234. Wu, Jing
    et al.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Machuca, Carmen Mas
    Tzanakaki, Anna
    Hasegawa, Hiroshi
    Untitled2014In: Optical Switching and Networkning Journal, ISSN 1573-4277, E-ISSN 1872-9770, Vol. 11, 53-54 p.Article in journal (Refereed)
  • 235. Wu, Jing
    et al.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Shen, Gangxiang
    Spadaro, Salvatore
    Advances in optical networks control and management2013In: Optical Switching and Networkning Journal, ISSN 1573-4277, E-ISSN 1872-9770, Vol. 10, no 1, 1-2 p.Article in journal (Other academic)
  • 236. Wu, Jing
    et al.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Shen, Gangxiang
    Spadaro, Salvatore
    Optical Networks Control and Management2014In: Journal of Network and Systems Management, ISSN 1064-7570, E-ISSN 1573-7705, Vol. 22, no 3, 434-436 p.Article in journal (Refereed)
  • 237. Wu, Jing
    et al.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Tzanakaki, Anna
    Shen, Gangxiang
    Forward of special issue on "Optical Network Architectures, Systems and Applications"2015In: Telecommunications Systems, ISSN 1018-4864, E-ISSN 1572-9451, Vol. 60, no 3, 347-347 p.Article in journal (Other academic)
  • 238. Xu, Z.
    et al.
    Archambault, E.
    Tremblay, C.
    Chen, Jiajia
    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).
    Belanger, M. P.
    Littlewood, P.
    1+1 dedicated optical-layer protection strategy for filterless optical networks2014In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 18, no 1, 98-101 p.Article in journal (Refereed)
    Abstract [en]

    We propose a dedicated optical-layer protection strategy for filterless optical networks offering a 100% protection ratio by introducing a limited number of wavelength selective components at selected intermediate nodes. A comparison with conventional active photonic switching networks is presented. The results show that the proposed 1+1 protection for filterless networks exhibits a clear cost advantage at similar wavelength usage compared to active switching solutions.

  • 239. Xu, Zhenyu
    et al.
    Tremblay, Christine
    Archambault, Emile
    Furdek, Marija
    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).
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Belanger, Michel P.
    Littlewood, Paul
    Flexible Bandwidth Allocation in Filterless Optical Networks2015In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 19, no 4, 565-568 p.Article in journal (Refereed)
    Abstract [en]

    We introduce the new concept of an elastic filterless optical network and propose an efficient heuristic algorithm for solving the static routing and spectrum assignment problem. Our simulation results obtained for different network topologies under multi-period traffic show increasing bandwidth savings with the growth of traffic load compared to a fixed-grid scenario. We also show the benefits of periodical spectrum defragmentation.

  • 240.
    Yaghoubi, Forough
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Agile, Resilient and Cost-efficient Mobile Backhaul Networks2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The exponentially increasing traffic demand for mobile services requires innovative solutions in both access and backhaul segments of 5th generation (5G) mobile networks. Although, heterogeneous networks (HetNets) are a promising solution for the wireless access, the backhaul segment has received considerably less attention and falls short in meeting the stringent requirements of 5G in terms of capacity and availability.

    HetNets together with mobility requirements motivate the use of microwave backhauling that supports fiber-like capacity with millimeter-wave communications. However, higher carrier frequencies are subject to weather disturbances like rain that may substantially degrade the network throughput. To mitigate this effect, we develop a fast and accurate rain detection algorithm that triggers a network-layer strategy, i.e., rerouting. The results show that with small detection error the network throughput increases while posing small overhead on the network.

    The rain impact can be alleviated by centralized rerouting under the software defined networking paradigm. However, careless reconfiguration may impose inconsistency that leads to a significant temporary congestion and limits the gain of rerouting. We propose a consistency-aware rerouting framework by considering the cost of reconfiguration. At each time, the centralized controller may either take a rerouting or no-rerouting decision in order to minimize the total data loss. We use a predictive control algorithm to provide such an online sequence of decisions. Compared to the regular rerouting, our proposed approach reduces the throughput loss and substantially decreases the number of reconfigurations.

    In the thesis we also study which backhaul option is the best from a techno-economic perspective. We develop a comprehensive framework to calculate the total cost of ownership of the backhaul segment and analyze the profitability in terms of cash flow and net present value. The results highlight the importance of selecting proper backhaul solution to increase profitability.

  • 241.
    Yaghoubi, Forough
    et al.
    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).
    Rostami, Ahmad
    Ericsson AB.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Mitigation of rain impact on microwave backhaul networks2016Conference paper (Refereed)
    Abstract [en]

    Microwave backhaul networks are a cost-efficient option to support increasing capacity demands of mobile networks. However, inherent vulnerability of wireless backhauling to random fluctuations of the wireless channel complicates the design of reliable backhaul links. Long-lasting channel fluctuations such as rain fading may bring significant network performance degradation, and therefore, need to be carefully treated. This paper proposes a novel rain detection algorithm utilizing both temporal and spatial correlation of link status, aiming at efficiently distinguishing between long-term and shortterm channel fading. With this distinction, a central controller decides whether network-wide strategies, such as rerouting, are required to mitigate the effects of rain. The accuracy of the proposed detection method is evaluated by measuring false alarm and misdetection probabilities. Numerical results show high rain detection accuracy of the proposed algorithm. Consequently, the impact of imperfect rain detection on the network throughput performance and on the overhead imposed to the central controller becomes negligible.

  • 242.
    Yaghoubi, Forough
    et al.
    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).
    Rostami, Ahmad
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Mitigation of Rain Impact on Microwave Backhaul Networks2016In: 2016 IEEE International Conference on Communications Workshops (ICC), Institute of Electrical and Electronics Engineers (IEEE), 2016, 134-139 p.Conference paper (Refereed)
    Abstract [en]

    Microwave backhaul networks are a cost-efficient option to support increasing capacity demands of mobile networks. However, inherent vulnerability of wireless backhauling to random fluctuations of the wireless channel complicates the design of reliable backhaul links. Long-lasting channel fluctuations such as rain fading may bring significant network performance degradation, and therefore, need to be carefully treated. This paper proposes a novel rain detection algorithm utilizing both temporal and spatial correlation of link status, aiming at efficiently distinguishing between long-term and short-term channel fading. With this distinction, a central controller decides whether network-wide strategies, such as rerouting, are required to mitigate the effects of rain. The accuracy of the proposed detection method is evaluated by measuring false alarm and misdetection probabilities. Numerical results show high rain detection accuracy of the proposed algorithm. Consequently, the impact of imperfect rain detection on the network throughput performance and on the overhead imposed to the central controller becomes negligible.

  • 243.
    Yaghoubi, Forough
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Furdek, Marija
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Rostami, Ahmad
    Ericsson AB.
    Öhlén, Peter
    Ericsson AB.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Consistency-aware Weather Disruption-tolerant Routing in SDNbased Wireless Mesh Networks2017In: IEEE TNSM Special Issue on Advances in Management of Softwarized NetworksArticle in journal (Other academic)
    Abstract [en]

    Although, wireless solutions continue to be a dominant enabling technology in the future backhaul  segment, they are susceptible to weather disturbances that may substantially degrade network throughput, or delay, compromising the 5G requirements.  These  effects  can  be  alleviated  by centralized rerouting realized by software defined networking (SDN) architecture. However, careless frequent reconfigurations may lead to inconsistencies in network states due to asynchrony between different switches, which may create  congestion and limit the gain of frequent rerouting.  In  this  paper, we focus on the rerouting process during rain disturbance considering the minimum total congestion imposed  during  the  update  of  routing  tables as a switching cost. At each time sample, the central controller has the possibility to adopt the optimal routes at a switching cost or to keep using previous routes at the expense of a throughput loss due to route sub- optimality. To find optimal solutions with minimal data loss in a static scenario, we formulate a dynamic programming problem that utilizes perfect knowledge of the rain attenuation for the whole rain period (off-line policy with full knowledge). For dynamic scenarios where the future rain attenuation data cannot be known, we propose an online consistency-aware rerouting algorithm, called optimal control action with prediction (OCAP), which uses the temporal correlation of rain fading to estimate the future rain attenuation. Simulation results on synthetic and real networks validate the efficiency of our OCAP algorithm, substantially reducing congestion and increasing network throughput with a fewer number of rerouting actions compared to benchmarks approaches.

  • 244.
    Yaghoubi, Forough
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Mahloo, Mozghan
    Ericsson AB.
    Wosinska, Lena
    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).
    Farias, Fabricio de Souza
    Universidade Federal do Pará.
    Costa, João Crisóstomo Weyl Albuquerque
    Universidade Federal do Pará.
    A Techno-Economic Framework for 5G Transport Networks2017Article in journal (Other academic)
    Abstract [en]

    Wireless heterogeneous networks (HetNets) are a cost- and an energy-efficient alternative to provide high capacity to end users in the future 5G communication systems. However, the transport segment of a radio access network (RAN) poses a big challenge in terms of cost and energy consumption. In fact, if not planned properly its resulting high cost might limit the benefits of using small cells and impact the revenues of mobile network operators. Therefore, it is essential to be able to properly assess the economic viability of different transport techonolgies as well as their impact on the cost and profitability of a HetNets deployment (i.e., RAN + transport).

    This paper first presents a general and comprehensive techno-economic framework able to assess not only the total cost of ownership (TCO) but also the business viability of a HetNets deployment. It then applies it to the specific case study of a backhaul-based transport segment. In the evaluation work two technology options for the transport network are considered (i.e., microwave and fiber) assuming both a homogeneous (i.e., macro cells only) and a HetNet deployments. Our results demonstrate the importance of selecting the right technology and deployment strategy in order not to impact the economic benefits of a HetNet deployment. Moreover, the results also reveal that a deployment solution with the lowest TCO does not always lead to the highest profit.  

  • 245.
    Yaghoubi, Forough
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Rostami, Ahmad
    Ericsson AB.
    Chen, Jiajia
    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).
    Öhlén, Peter
    Ericsson AB.
    Mitigation of rain impact on microwave networks2016Patent (Other (popular science, discussion, etc.))
  • 246. Yan, Li
    et al.
    Fiorani, Matteo
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Muhammad, Ajmal
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Tornatore, Massimo
    Agrell, Erik
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Network Performance Trade-Off in Optical Spatial Division Multiplexing Data Centers2017In: 2017 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC), IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    We propose close-to-optimal network resource allocation algorithms for modular data centers using optical spatial division multiplexing. A trade-off between the number of established connections and throughput is identified and quantified.

  • 247. Yang, Y.
    et al.
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Network performance analysis of an AWG-based passive optical interconnect for datacenters2014In: Optics InfoBase Conference Papers, OSA - The Optical Society , 2014Conference paper (Refereed)
    Abstract [en]

    AWG-based passive optical interconnects (POIs) are considered a high-capacity and energy-efficient solution for datacenter networks. We concentrate on a cascaded AWG-based POI and analyze network performance to gain insights on efficiency of such an architecture.

  • 248.
    Yang, Yanpeng
    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.
    Sung, Ki Won
    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.
    Wosinska, Lena
    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).
    Hybrid Fiber and Microwave Protection for Mobile Backhauling2014In: Journal of Optical Communications and Networking, ISSN 1943-0620, E-ISSN 1943-0639, Vol. 6, no 10, 869-878 p.Article in journal (Refereed)
    Abstract [en]

    Several studies have shown that optical-fiber-based backhauling offers a future proof solution to handle rapidly increasing traffic in wireless access networks and outperforms other existing backhauling technologies, such as microwave and copper, in terms of capacity, scalability, and sustainability. However, the deployment cost of fiber infrastructure is relatively high and it may be difficult to provide a cost efficient and flexible protection strategy for a fiber backhauling network. Considering that protection is very important to avoid service interruption in a high-capacity mobile backhauling network, in this paper we propose a hybrid fiber and microwave protection scheme for mobile backhauling based on a passive optical network (PON). The proposed reliable architecture is compatible with any wavelength division multiplexing (WDM)based PON, e. g., pure WDM PON and a hybrid time and wavelength division multiplexing (TWDM) PON, offering high flexibility and relatively low deployment cost. The backup for the feeder fiber is provided by dual homing, while the protection of the distribution section can be established via a microwave connection between two base stations in case high reliability performance is required, e. g., for macrocells covering large service areas. We have carried out an extensive assessment of our approach in terms of connection availability, failure impact, complexity, and flexibility in providing resiliency. We also show a comparison with other existing solutions. The evaluation results confirm that our scheme can achieve relatively high flexibility and reliability performance while maintaining low complexity compared with the existing approaches.

  • 249. Ye, Yabin
    et al.
    Jimenez Arribas, Felipe
    Elmirghani, Jaafar
    Idzikowski, Filip
    Lopez Vizcaino, Jorge
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Musumeci, Francesco
    Pattavina, Achille
    Van Heddeghem, Ward
    Energy-Efficient Resilient Optical Networks: Challenges and Trade-offs2015In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 53, no 2, 144-150 p.Article in journal (Refereed)
    Abstract [en]

    Energy efficiency and resilience are two well established research topics in optical transport networks. However, their overall objectives (i.e., power minimization and resource utilization/availability maximization) conflict. In fact, provisioning schemes optimized for best resilience performance are in most cases not energy-efficient in their operations, and vice versa. However, very few works in the literature consider the interesting issues that may arise when energy efficiency and resilience are combined in the same networking solution. The objective of this article is to identify a number of research challenges and trade-offs for the design of energy-efficient and resilient optical transport networks from the perspective of long-term traffic forecasts, short-term traffic dynamics, and service level agreement requirements. We support the challenges with justifying numbers based on lessons learned from our previous work. The article also discusses suitable metrics for energy efficiency and resilience evaluation, in addition to a number of steps that need to be taken at the standardization level to incorporate energy efficiency into already existing and well established protocols.

  • 250. Yin, X.
    et al.
    Verplaetse, M.
    Breyne, L.
    Van Kerrebrouck, J.
    De Keulenaer, T.
    Vyncke, A.
    Pierco, R.
    Vaernewyck, R.
    Spiga, S.
    Amann, M. -C
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Van Steenberge, Geert
    KTH.
    Torfs, G.
    Bauwelinck, J.
    Towards efficient 100 Gb/s serial rate optical interconnects: A duobinary way2017In: 6th IEEE Photonics Society Optical Interconnects Conference, OI 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, 33-34 p., 7965517Conference paper (Refereed)
    Abstract [en]

    Recent advances in integrated opto-electronic devices and front end circuits have made it possible to efficiently transmit very high data rates over optical links for HPC/datacenter applications. This paper reviews our current progress towards serial 100-Gb/s optical interconnects, with emphasis on electrical duobinary (EDB) modulation.

23456 201 - 250 of 255
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