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  • 51.
    Fiorani, Matteo
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Aleksic, Slavisa
    Casoni, Maurizio
    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).
    Energy-Efficient Elastic Optical Interconnect Architecture for Data Centers2014In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 18, no 9, 1531-1534 p.Article in journal (Refereed)
    Abstract [en]

    To address the urgent need for high-capacity, scalable and energy-efficient data center solutions, we propose a novel data center network architecture realized by combining broadcast-and-select approach with elastic channel spacing technology. We demonstrate that the proposed architecture is able to scale efficiently with the number of servers and offers lower energy consumption at a competitive cost compared to the existing solutions.

  • 52. Fiorani, Matteo
    et al.
    Aleksic, Slavisa
    Monti, Paolo
    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).
    Casoni, Maurizio
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Energy Efficiency of an Integrated Intra-Data-Center and Core Network With Edge Caching2014In: Journal of Optical Communications and Networking, ISSN 1943-0620, Vol. 6, no 4, 421-432 p.Article in journal (Refereed)
    Abstract [en]

    The expected growth of traffic demand may lead to a dramatic increase in the network energy consumption, which needs to be handled in order to guarantee scalability and sustainability of the infrastructure. There are many efforts to improve energy efficiency in communication networks, ranging from the component technology to the architectural and service-level approaches. Because data centers and content delivery networks are responsible for the majority of the energy consumption in the information and communication technology sector, in this paper we address network energy efficiency at the architectural and service levels and propose a unified network architecture that provides both intra-data-center and inter-data-center connectivity together with interconnection toward legacy IP networks. The architecture is well suited for the carrier cloud model, where both data-center and telecom infrastructure are owned and operated by the same entity. It is based on the hybrid optical switching (HOS) concept for achieving high network performance and energy efficiency. Therefore, we refer to it as an integrated HOS network. The main advantage of the integration of core and intra-data-center networks comes from the possibility to avoid the energy-inefficient electronic interfaces between data centers and telecom networks. Our results have verified that the integrated HOS network introduces a higher number of benefits in terms of energy efficiency and network delays compared to the conventional nonintegrated solution. At the service level, recent studies demonstrated that the use of distributed video cache servers can be beneficial in reducing energy consumption of intra-data-center and core networks. However, these studies only take into consideration conventional network solutions based on IP electronic switching, which are characterized by relatively high energy consumption. When a more energy-efficient switching technology, such as HOS, is employed, the advantage of using distributed video cache servers becomes less obvious. In this paper we evaluate the impact of video servers employed at the edge nodes of the integrated HOS network to understand whether edge caching could have any benefit for carrier cloud operators utilizing a HOS network architecture. We have demonstrated that if the distributed video cache servers are not properly dimensioned they may have a negative impact on the benefit obtained by the integrated HOS network.

  • 53.
    Fiorani, Matteo
    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).
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Optical networks for energy-efficient data centers2014Conference paper (Refereed)
    Abstract [en]

    The growing popularity of cloud and multimedia services is increasing the traffic volume that each datacenter (DC) needs to handle. As a consequence, the serious bottlenecks in DC networks in terms of both capacity and energy consumption need to be addressed. DC networks typically consist of edge tier, aggregation tier and core tier, which interconnect different servers within a DC as well as provide the interfaces to the Internet. Current large-scale DC network architectures are based on the fat-tree three-tiers topology [1] and on electronic switches, which are not able to scale to meet future traffic requirements in a sustainable manner. Reducing the power required by the inter- and intra-rack communication inside DCs through use of optical technology opens a way to solve this problem. However, the current optical switching technologies are not able to support the dynamic DC traffic, and hence, new optical interconnect architectures are needed. Several optical switching architectures have been recently proposed to replace the aggregation and core tiers of current DC networks with a high-capacity optical switch [1][2]. However, the largest amount of energy in current DC networks is consumed in the edge tier by the electronic top-of-the-rack (ToR) switches. Therefore, the optical switching in the aggregation-core tier doesn’t solve the problem. Moreover, the majority of the optical DC network architectures proposed so far can be categorized as optical circuit switching or optical packet switching. Unfortunately, there are certain limitations associated with these optical switching technologies for their application in DC networks. Namely, optical circuit switching architectures are not able handle the bursty and highly variable DC traffic while optical packet switching usually makes use of electronic buffers, which limit scalability and increase energy consumption. To reduce the energy consumption in the edge tier, we propose a novel optical broadcast-and-select - rchitecture at the ToR. In this architecture, each server is equipped with an optical network interface (ONI) and is connected to the other servers in the same rack through a N?2 coupler, where N represents the number of servers in the rack. In addition, in order to provide both fine switching granularity and high scalability, we propose the use of the elastic optical networking paradigm [3]. Consequently, each ONI will be equipped with a bandwidth variable transceiver (BVT), which provides the ability to tune wavelength and change dynamically the number of the occupied spectral slots. In this way, the capacity can be varied from 1 Gb/s to 100 Gb/s and beyond on a per-server level. On the other side, the inter-rack communications are handled by a large singlesided optical core switch. One of the commercially available single-sided switches is fabricated using the beam steering technology [4], where the maximum number of switch ports available so far is 192 and a 500-port matrix is under development. Larger single-sided switches can be realized by combining several stages of smaller switch matrices. The results of a preliminary study show that the proposed architecture is able to significantly reduce the energy consumption with respect to other solutions [1][2].

  • 54.
    Fiorani, Matteo
    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).
    Skubic, B.
    Martensson, J.
    Valcarenghi, L.
    Castoldi, P.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Challenges for 5G transport networks2014In: 2014 IEEE International Conference on Advanced Networks and Telecommunication Systems, ANTS 2014, IEEE conference proceedings, 2014Conference paper (Refereed)
    Abstract [en]

    5G mobile communications is seen as the enabler for the networked society where connectivity will be available anywhere and anytime to anyone and anything. The details of 5G are the subject to ongoing research and debate, mostly focused on understanding radio technologies that can enable the 5G vision. So far, less work has been dedicated to the challenges that 5G will pose to the transport network. This paper provides a first analysis of the key challenges to 5G transport in terms of capacity, flexibility and costs, for example. Different use cases are discussed as well as technology options and control plane concepts. © 2014 IEEE.

  • 55.
    Fiorani, Matteo
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab). Kungliga Tekniska högskolan.
    Rostami, Ahmad
    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).
    Abstraction Models for Optical 5G Transport Networks2016In: Journal of Optical Communications and Networking, ISSN 1943-0620, E-ISSN 1943-0639, Vol. 8, no 9, 656-665 p.Article in journal (Refereed)
    Abstract [en]

    The orchestration of radio, transport, and cloud resources is a key enabler for efficient service delivery in 5G networks. Orchestration can be achieved with a hierarchical software-defined networking (SDN) control architecture in which a global orchestrator operates above the domain controllers. In such an architecture, the abstraction of resources between the controllers and the orchestrator plays a fundamental role for the system performance. In order to reduce the orchestrator complexity, the controllers should hide as much detail as possible from the orchestrator. On the other hand, the more details are available to the orchestrator the more optimal resource orchestration strategy can be obtained. In order to assess this trade-off, we recently proposed two transport abstraction models, namely big switch (BiS) and virtual link (VL), for centralized radio access networks (C-RANs) with orchestration of radio and transport resources. We observed that VL can provide a more efficient resource orchestration than BiS at the expense of an increased implementation complexity. The contribution of this paper is twofold. We extend the BiS and VL models to make them applicable to any orchestration scenario. Then, we propose a new transport abstraction model, referred to as optical transport transformation (OTT), that aims at achieving efficient resource orchestration with a reduced implementation complexity. We compare the performance of these new abstraction models in a C-RAN use case in which backhaul and fronthaul traffic are carried over a dense wavelength division multiplexing (DWDM) network. Our results prove that in a C-RAN the best choice for the transport abstraction model depends on the availability and the reachability of the radio resources. If radio resources are scarce compared to transport resources, complex transport abstraction models are not needed and a BiS abstraction is the best choice. On the other hand, if radio resources are widely available and reachable, an OTT model guarantees the best overall performance.

  • 56.
    Fiorani, Matteo
    et al.
    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).
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Transport Abstraction Models for an SDN-Controlled Centralized RAN2015In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 19, no 8, 1406-1409 p.Article in journal (Refereed)
    Abstract [en]

    In a centralized radio access network (C-RAN) scenario the joint coordination of radio (e.g., remote radio units, baseband units) and transport (e.g., optical cross connects) resources can be achieved via software defined networking (SDN) control plane, where a global orchestrator harmonizes the use of resources across all network segments. The more accurate the information about each domain (i.e., the abstraction of wireless and transport resources) is, the better will be the outcome of the orchestration work. This letter presents three transport resources abstraction models along with their corresponding orchestration policies. Their performance are compared showing that there is not a single best abstraction strategy that fits all the cases. If radio resources are scarce compared to transport resources, complex transport abstraction models are not needed. Contrariwise, if enough radio resources are widely available, more detailed abstraction models are required for achieving good network performance, but at the expense of an increased implementation complexity.

  • 57.
    Fiorani, Matteo
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Samadi, Payman
    Shen, Yiwen
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Bergman, Keren
    Flexible Network Architecture and Provisioning Strategy for Geographically Distributed Metro Data Centers2017In: Journal of Optical Communications and Networking, ISSN 1943-0620, E-ISSN 1943-0639, Vol. 9, no 5, 385-392 p.Article in journal (Refereed)
    Abstract [en]

    The fifth generation of mobile networks (5G) is expected to introduce new services with strict end-to-end delay requirements. For this reason, service providers and network operators are increasingly relying on geographically distributed metro data centers (DCs) to bring services closer to end-users and reduce delivery time. The metro DCs frequently exchange data for different purposes, such as backup and load balancing. Some of these data transfers require guaranteed low delays. Meanwhile, efficient use of network resources is necessary to limit the cost of the network infrastructure. To address these issues, in this paper, we propose a converged intra-and inter-DC network architecture and a dynamic provisioning strategy that are able to (i) efficiently support different classes of service, (ii) offer fast data transfers among metro DCs, and (iii) enable efficient utilization of network resources. Simulation results show that the proposed network architecture and provisioning strategy achieve at least two times faster average data transfer between DCs and better network resource utilization compared with conventional solutions. We also present a prototype and an extensive set of experimental results, thus proving the implementation feasibility and effectiveness of the proposed approach.

  • 58.
    Fiorani, Matteo
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Skubic, B.
    Mårtensson, J.
    Valcarenghi, L.
    Castoldi, P.
    Wosinska, L.
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    On the design of 5G transport networks2015In: Photonic network communications, ISSN 1387-974X, E-ISSN 1572-8188, Vol. 30, no 3, 403-415 p.Article in journal (Refereed)
    Abstract [en]

    Future 5G systems will pave the way to a completely new societal paradigm where access to information will be available anywhere, anytime, and to anyone or anything. Most of the ongoing research and debate around 5G systems are focusing on the radio network segment (e.g., how to offer high peak-rates per subscriber, and how to handle a very large number of simultaneously connected devices without compromising on coverage, outage probability, and latency). On the other hand, understanding the impact that 5G systems will have on the transport network (i.e., the segment in charge of the backhaul of radio base stations and/or the fronthaul of remote radio units) is also very important. This paper provides an analysis of the key architectural challenges for the design of a flexible 5G transport infrastructure able to adapt in a cost-efficient way to the plethora of requirements coming from the large number of envisioned future 5G services.

  • 59.
    Fiorani, Matteo
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab). Kungliga Tekniska högskolan.
    Tombaz, S.
    Mårtensson, J.
    Skubic, B.
    Wosinska, L.
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Energy performance of C-RAN with 5G-NX radio networks and optical transport2016In: 2016 IEEE International Conference on Communications, ICC 2016, IEEE conference proceedings, 2016Conference paper (Refereed)
    Abstract [en]

    Each mobile network architecture able to meet the traffic requirements of future 5G services comes with its own set of benefits vs. requirements for the radio and the transport segments. This paper focuses on the energy performance of four mobile network architectures, each one with different splitting options for the baseband processing functions. The radio segment under exam is based on a new radio access technology referred to as 5G-NX, while the transport segment is based on wavelength division multiplexing (WDM). The energy consumption of each mobile network architecture is weighted against (i) the benefits for the radio segment as a function of the level of centralization of the baseband processing resources and (ii) the required transport capacity and consequently the power consumption levels needed to accommodate the backhaul, midhaul, and/or fronthaul traffic generated at each base station. Our results show that a fully centralized radio access network (C-RAN) with centralization of all the baseband functions is not a practical approach for 5G mobile networks, while a partially centralized C-RAN architecture in which the physical layer baseband processing is performed at the base station site represents a promising solution.

  • 60.
    Fiorani, Matteo
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Tombaz, S.
    Mårtensson, J.
    Skubic, Björn
    KTH, School of Information and Communication Technology (ICT).
    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).
    Modeling energy performance of C-RAN with optical transport in 5G network scenarios2016In: Journal of Optical Communications and Networking, ISSN 1943-0620, E-ISSN 1943-0639, Vol. 8, no 11, B21Article in journal (Refereed)
    Abstract [en]

    The deployment of new 5G wireless interfaces based on massive multiantenna transmission and beamforming is expected to have a significant impact on the complexity and power consumption of the transport network. This paper analyzes the energy performance of four radio access network (RAN) architectures, each one utilizing a different option for splitting the baseband processing functions. The radio segment is based on Long-Term Evolution (LTE) and 5G radio access technologies. The transport segment is based on optical wavelength division multiplexing, where coherent and direct detection transmissions are considered. The energy consumption of each RAN architecture is weighted against i) the benefits for the radio segment as a function of the level of centralization of the baseband processing functions and ii) the power consumption levels needed to accommodate the capacity generated at each base station. Results show that, with LTE radio interfaces, the energy consumption of the transport network amounts to only a few percent of the overall network power consumption. As a result, fully centralized LTE radio architectures are a viable option, with energy savings of at least 27% compared with conventional distributed architectures. On the other hand, with advanced 5G radio interfaces, centralized architectures, if not carefully designed, might become impractical due to the excessive energy consumption of the transport network (i.e., as a result of the huge capacity to be accommodated). This aspect can be mitigated via a careful joint design of the radio and the transport network (i.e., leveraging on appropriate optical transmission techniques and compromising where needed on the radio network performance).

  • 61.
    Fiorani, Matteo
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Tombaz, Sibel
    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.
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Casoni, Maurizio
    University of Modena and Reggio Emilia.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Green Backhauling for Rural Areas2014In: Green Backhauling for Rural Areas, IEEE , 2014Conference paper (Refereed)
    Abstract [en]

    Providing wireless broadband access to rural and remote areas is becoming a big challenge for wireless operators, mostly because of the need for a cost-effective and low energy consuming mobile backhaul. However, to the best of our knowledge,energy consumption of different options for backhauling of future rural wireless broadband networks has not been studiedyet. Therefore, in this paper we assess the energy consumption of future rural wireless broadband network deployments andbackhaul technologies. In the wireless segment, two deployment strategies are considered, one with macro base station only,and one with small base stations. In the backhaul segment ,two wireless, i.e., microwave and satellite, and one optical fiber based (i.e., long reach passive optical networks) solutions areconsidered. These options are compared in terms of their abilityto satisfy coverage, capacity and QoS requirements of a numberof rural users in the time span that goes from 2010 until 2021. From the presented results it is possible to conclude that wireless backhaul solutions can significantly increase the energy consumption of the access network. In contrast, the long reach PON based backhaul has much higher energy efficiency and inthe long term might be a better choice for wireless operators.

  • 62.
    Fiorani, Matteo
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Tornatore, M.
    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).
    Mukherjee, B.
    Optical spatial division multiplexing for ultra-high-capacity modular data centers2016In: 2016 Optical Fiber Communications Conference and Exhibition, OFC 2016, Institute of Electrical and Electronics Engineers (IEEE), 2016Conference paper (Refereed)
    Abstract [en]

    We propose and evaluate four optical interconnect architectures based on spatial division multiplexing for ultra-high capacity modular data centers. It is shown in which way the best option depends on the network load and size.

  • 63.
    Fiorani, Matteo
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Tornatore, M.
    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).
    Mukherjee, B.
    Spatial division multiplexing for high capacity optical interconnects in modular data centers2017In: Journal of Optical Communications and Networking, ISSN 1943-0620, E-ISSN 1943-0639, Vol. 9, no 2, A143-A153 p., 7858118Article in journal (Refereed)
    Abstract [en]

    Modular design has recently emerged as an efficient solution to build large data center (DC) facilities. Modular DCs are based on stand-Alone prefabricated modules (i.e., PODs) that can be easily installed and interconnected. PODs can generate a large amount of traffic and thus require an ultra-high-capacity interconnection network. However, current electronic and optical interconnect architectures applied to modular DCs may experience major scalability problems in terms of high energy consumption and cabling complexity. To address these problems, we investigate five optical interconnect architectures based on spatial division multiplexing (SDM), and for each architecture, we propose a resource allocation strategy. We also present an extensive comparison among the SDM architectures in terms of cost and performance (i.e., blocking probability and throughput), with the objective to find the architecture offering the best trade-off between cost and performance for given DC sizes and traffic load values. Our results demonstrate that, in small modular DCs with low traffic load, an architecture based only on SDM is the best option, while in medium DCs with medium traffic load, an architecture based on coupled SDM and flexgrid wavelength division multiplexing (WDM) with spectral flexibility is the best solution. Finally, for large DCs with high traffic load values, the best trade-off between cost and performance is achieved by an SDM architecture that is based on uncoupled SDM and flexgrid WDM.

  • 64. Forzati, Marco
    et al.
    Bianchi, Alberto
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Grobe, Klaus
    Lannoo, Bart
    Machuca, Carmen Mas
    Point, Jean-Charles
    Skubic, Bjorn
    Verbrugge, Sofie
    Weis, Erik
    Wosinska, Lena
    Breuer, Dirk
    Next-Generation Optical Access Seamless Evolution: Concluding Results of the European FP7 Project OASE2015In: Journal of Optical Communications and Networking, ISSN 1943-0620, E-ISSN 1943-0639, Vol. 7, no 2, 109-123 p.Article in journal (Refereed)
    Abstract [en]

    Increasing bandwidth demand drives the need for next-generation optical access (NGOA) networks that can meet future end-user service requirements. This paper gives an overview of NGOA solutions, the enabling optical access network technologies, architecture principles, and related economics and business models. NGOA requirements (including peak and sustainable data rate, reach, cost, node consolidation, and open access) are proposed, and the different solutions are compared against such requirements in different scenarios (in terms of population density and system migration). Unsurprisingly, it is found that different solutions are best suited for different scenarios. The conclusions drawn from such findings allow us to formulate recommendations in terms of technology, strategy, and policy. The paper is based on the main results of the European FP7 OASE Integrated Project that ran between January 1, 2010 and February 28, 2013.

  • 65.
    Furdek, Maria
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Džanko, Matija
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Resilience of optical networks based on architecture on demand nodes2014Conference paper (Refereed)
  • 66.
    Furdek, Maria
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Skorin-Kapov, N
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Shared path protection under the risk of high power jamming2014In: 2014 19th European Conference on Networks and Optical Communications, NOC 2014, 2014, 23-28 p.Conference paper (Refereed)
    Abstract [en]

    Transparent optical networks are sensitive to high-power jamming which can degrade legitimate user signals via out-of-band effects in optical fibers and amplifiers, and in-band crosstalk in optical switches. Jamming signals can be inserted in the network either deliberately as an attack, with the intention to deteriorate service, or accidentally, due to component miscon-figuration. This type of attack/failure can potentially propagate through the network causing high data and revenue losses, requiring tailored survivability approaches which take these harmful effects into consideration. Namely, conventional network survivability approaches which protect transmission in case of component faults might not provide adequate protection from jamming since the working and backup paths of a connection may both be within reach of the same jamming signal, even if they are link/node disjoint. Previously, we proposed the concept of an Attack Group (AG) of an all-optical connection (referred to as a lightpath), comprised of all other lightpaths which potentially can affect it in case they carry a high-power jamming signal. Furthermore, we developed a jamming attack-aware dedicated path protection algorithm which establishes AG-disjoint working and backup paths for each connection. Herein, we extend this work by proposing an approach for Jamming-Aware Shared Path Protection (JA-SPP) to achieve survivability in the presence of jamming signals in a more resource-efficient way. We formulate the JA-SPP problem as an Integer Linear Problem (ILP) to obtain optimal solutions for smaller network instances. Comparison with standard SPP for single component faults (without jamming-awareness) shows that JA-SPP obtains solutions which offer protection from high-power jamming, in addition to single component faults, while using the same amount of resources (in terms of link and wavelength usage) as the standard SPP.

  • 67.
    Furdek, Maria
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Skorin-Kapov, N.
    Zsigmond, S.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Vulnerabilities and security issues in optical networks2014In: Transparent Optical Networks (ICTON), 2014 16th International Conference on, IEEE conference proceedings, 2014, 1-4 p.Conference paper (Refereed)
    Abstract [en]

    The paper provides a comprehensive overview of security issues in state-of-the-art optical networks. It identifies and describes the main vulnerabilities of today’s and future networks and outlines potential methods of attack which could exploit these vulnerabilities.

  • 68.
    Furdek, Marija
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Dzanko, M.
    Matanic, M.
    Boric, I.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Mikac, B.
    Multi-hour network provisioning utilizing function programmable ROADMs2015In: International Conference on Transparent Optical Networks, IEEE Computer Society, 2015, Vol. 2015, 7193722Conference paper (Refereed)
    Abstract [en]

    The study focuses on optimization of optical networks based on function programmable ROADMs implemented by Architecture on Demand (AoD) under a multi-hour traffic scenario. The objective is to minimize the cost and energy consumption by reducing the number of active modules inside the nodes, and to investigate the impact of network reconfiguration frequency to potential savings and lightpath availability. The results indicate that AoD nodes combined with tailored routing can reduce cost and increase availability with no traffic disruptions during transitions between periods.

  • 69.
    Furdek, Marija
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Dzanko, Matija
    Glavica, Patrik
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Can Architecture on Demand nodes with self-healing capabilities improve reliability of optical networks?2014In: Optics InfoBase Conference Papers, 2014Conference paper (Refereed)
    Abstract [en]

    Architecture on Demand (AoD) nodes enable bypass of unneeded node components and support self-healing of node failures. We analyze how AoD impacts network reliability and propose a novel survivable lightpath routing strategy for AoD-based networks.

  • 70.
    Furdek, Marija
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Dzanko, Matija
    Glavica, Patrik
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Mikac, Branko
    Amaya, Norberto
    Zervas, Georgios
    Simeonidou, Dimitra
    Efficient Optical Amplification in Self-Healing Synthetic ROADMs2014In: 2014 International Conference on Optical Network Design and Modeling, ONDM 2014, 2014, 150-155 p.Conference paper (Refereed)
    Abstract [en]

    Optical backbone networks are carrying enormous amount of traffic and therefore, network reliability performance is extremely important to minimize the service interruption time and loss of data. Besides, increasing energy consumption of the ICT sector makes network energy efficiency gain a lot of attention. Reducing the usage of components in the network is a promising strategy to both make network more energy efficient and reliable as it allows N putting idle components into a power-saving, or sleep, mode and (ii) reusing them as redundancy for failure recovery. The new generation of synthetic reconfigurable optical add-drop multiplexers (ROADMs) implemented by Architecture on Demand (AoD) supports the above functionalities by offering unprecedented flexibility and self-healing capabilities. In AoD nodes, components are interconnected via high-port-count optical switch serving as optical backplane, and each connection uses only the components necessary to fulfill the switching and processing requirements. In this paper, we aim at improving optical network availability and reducing power consumption by minimizing the number of optical amplifiers used in AoD nodes. To this end, a decision on the necessity of signal amplification is made for every connection according to the power level at each node. Unnecessary amplifiers are bypassed and put into sleep mode, decreasing the overall power consumption of the network This also reduces the associated risk of connection failure, while reuse of idle amplifiers for failure recovery further improves connection availability. To gain greater insight into the benefits of our approach, we analyze the performance of the NSF and EON network deploying AoD nodes with different optical backplane implementations, i.e. 3D MEMS and piezoelectric optical switch (POS), and compare them with networks deploying hard-wired ROADMs. Simulation results show that deployment of synthetic AoD nodes with POS as optical backplane can reduce the network mean down time and power consumption of EDFAs by up to 63% and 38%, respectively, on average over all test cases.

  • 71.
    Furdek, Marija
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Džanko, Matija
    Skorin-Kapov, Nina
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Planning of optical networks based on programmable ROADMs2015In: Asia Communications and Photonics Conference, ACPC 2015, 2015Conference paper (Refereed)
    Abstract [en]

    Synthetic programmable ROADMs enable great architectural flexibility and offer remarkable opportunities for network optimization. This paper summarizes the benefits and network planning challenges introduced by this technology and outlines optimization approaches to utilize its advantages. © 2015 OSA.

  • 72.
    Furdek, Marija
    et al.
    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).
    Zervas, Georgios
    Alloune, Nabih
    Tremblay, Christine
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Programmable Filterless Network Architecture Based on Optical White Boxes2016In: 20TH INTERNATIONAL CONFERENCE ON OPTICAL NETWORK DESIGN AND MODELING (ONDM 2016), IEEE conference proceedings, 2016Conference paper (Refereed)
    Abstract [en]

    We propose and evaluate a novel architecture enabling high-capacity, resource efficient and agile elastic optical networks. It is based on sliceable bandwidth-variable transponders and optical white box switches which route optical signals without filtering them. Instead of using active filtering components, each node is equipped with an optical white box based on a programmable optical switch that serves as an optical backplane. It provides interconnections between input/output ports and passive splitters and couplers. Due to signal broadcast and the absence of filtering (so-called drop-and-waste transmission), some of the signals appear on unintended links which can lead to an overhead in spectrum usage. To address this issue, we formulate the problem of signal routing, modulation format and spectrum assignment in programmable filterless networks based on optical white boxes as an integer linear program (ILP) with the objective to minimize the total spectrum usage. Simulation results indicate that our proposed solution obtains a beneficial tradeoff between component usage and spectrum consumption, using a drastically lower number of active switching elements than the conventional networks based on hard-wired reconfigurable add/drop multiplexers, and lowering the maximum used frequency slot by up to 48% compared to existing passive filterless networks.

  • 73. Furdek, Marija
    et al.
    Muhammad, Ajmal
    Zervas, Georgios
    Alloune, Nabih
    Tremblay, Christine
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Programmable Filterless Network Architecture Based on Optical White Boxes2016In: 20TH INTERNATIONAL CONFERENCE ON OPTICAL NETWORK DESIGN AND MODELING (ONDM 2016), IEEE conference proceedings, 2016Conference paper (Refereed)
    Abstract [en]

    We propose and evaluate a novel architecture enabling high-capacity, resource efficient and agile elastic optical networks. It is based on sliceable bandwidth-variable transponders and optical white box switches which route optical signals without filtering them. Instead of using active filtering components, each node is equipped with an optical white box based on a programmable optical switch that serves as an optical backplane. It provides interconnections between input/output ports and passive splitters and couplers. Due to signal broadcast and the absence of filtering (so-called drop-and-waste transmission), some of the signals appear on unintended links which can lead to an overhead in spectrum usage. To address this issue, we formulate the problem of signal routing, modulation format and spectrum assignment in programmable filterless networks based on optical white boxes as an integer linear program (ILP) with the objective to minimize the total spectrum usage. Simulation results indicate that our proposed solution obtains a beneficial tradeoff between component usage and spectrum consumption, using a drastically lower number of active switching elements than the conventional networks based on hard-wired reconfigurable add/drop multiplexers, and lowering the maximum used frequency slot by up to 48% compared to existing passive filterless networks.

  • 74.
    Furdek, Marija
    et al.
    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).
    Zervas, Georgios
    Tremblay, Christine
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Performance Evaluation of Programmable Filterless Networks Implemented by Optical White Boxes2016In: 2016 18TH INTERNATIONAL CONFERENCE ON TRANSPARENT OPTICAL NETWORKS (ICTON), IEEE, 2016Conference paper (Refereed)
    Abstract [en]

    To support the immense traffic growth and enable scalable on-demand provisioning of service requests, optical networks must deliver great agility and reconfigurability in a cost-and resource-efficient manner. The progress in elastic coherent transmission [1] has enabled simplifications in the optical network architecture by, for example, replacing the costly wavelength switches in the add/drop part of colorless reconfigurable add/drop multiplexers (ROADMs) with passive couplers. The concept of passive filterless networking further proposes the elimination of wavelength switching in the transport function as well. It is based on completely passive interconnections realized by passive splitters and combiners, essentially forming fiber trees spanning the network nodes [2]. In such networks, transmission follows the Drop&Waste ( or Drop&Continue) scheme where each signal is broadcasted to all branches downstream of the source node in a tree, while a copy of signal continues to propagate downstream of the destination node [3]. Thus, the simplification of the nodal architecture comes at the expense of increased spectrum usage due to the presence of unfiltered signals. Moreover, the broadcasting of signals to inadvertent nodes raises confidentiality issues. An additional drawback stems from the inability of the passive, fixed interconnection of nodes to allow for topology reconfiguration. The optical white boxes, or programmable optical switches (also referred to as architecture-on-demand) can provide unparalleled switching and architectural flexibility [4]. Unlike in conventional ROADMs, optical modules (e.g., passive couplers, amplifiers or WSSs) inside an optical white box are not interconnected in a hard-wired manner, but are selected on demand by a reconfigurable optical backplane (OB), implemented by, e.g., a piezoelectric switch or 3D MEMs. An arbitrary nodal architecture can be configured by setting up the interconnections of the OB as per traffic requirements, and swiftly reconfigured to accommodate changing traffic demands, scale capacity, and ease migration and upgrade. Combining the agile filterless transmission with flexible optical white boxes into a programmable filterless network architecture, recently proposed in [5], integrates the agility of filterless operation with the high flexibility enabled by white boxes. The nodes in a programmable filterless network are equipped with a programmable OB hosting only passive couplers to route the connections. The preliminary study of routing, modulation format and spectrum assignment (RMSA) in programmable filterless networks aimed at spectrum usage minimization [5] shows that they are capable of reducing the amount of unfiltered signals compared to passive filterless networks and can significantly decrease spectrum usage. Due to the moderately-sized switches deployed for the OB, this architecture also offers the potential of diminishing the nodal costs compared to the conventional ROADM-based networks. In addition, when striving to minimize the spectrum usage, connections tend to get routed over fewer splitters as they are the cause of broadcasted, unfiltered signals. This may lead to a decrease in the total number and degree of passive couplers traversed by connections, which can reduce the signal losses and lower the amplification requirements. This talk will outline the operational principles of programmable filterless network architecture and their benefits in terms of spectrum and component usage. We will also present possible technological and optimization approaches to further enhance the performance of white box based filterless networks and the related preliminary results.

  • 75.
    Furdek, Marija
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Skorin-Kapov, Nina
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Attack-aware dedicated path protection in optical networks2016In: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 34, no 4, 1050-1061 p.Article in journal (Refereed)
    Abstract [en]

    Due to the high data rates in optical networks,physical-layer attacks targeting service degradation, such as powerjamming, can potentially lead to large data and revenue losses.Conventional network survivability approaches which establishlink-disjoint working and backup paths to protect from componentfaults may not provide adequate protection for such attacks.Namely, the working and the backup paths, although link-disjoint,might both be affected by a single attack scenario due to specificattack propagation characteristics. To enhance the existing survivabilityapproaches, we utilize the concept of an attack group(AG) which incorporates these characteristics to identify connectionswhich can simultaneously be affected by a single attack. Weapply this concept to dedicated path protection (DPP) and developattack-aware DPP (AA-DPP) approaches which aim to establishAG-disjoint primary and backup paths in a cost-effective manner.We provide a two-step ILP formulation for the routing and wavelengthassignment of the working and backup paths, as well as aheuristic for larger problem instances. Numerical results indicatethat the proposed approaches provide dedicated path protectionschemes with enhanced attack protection without using more resources(i.e., wavelengths, average path lengths) than standardDPPmethods.

  • 76.
    Furdek, Marija
    et al.
    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).
    Goscien, Roza
    Manousakis, Konstantinos
    Aibin, Michal
    Walkowiak, Krzysztof
    Ristov, Sashko
    Gushev, Marjan
    Marzo, Jose L.
    An overview of security challenges in communication networks2016In: PROCEEDINGS OF 2016 8TH INTERNATIONAL WORKSHOP ON RESILIENT NETWORKS DESIGN AND MODELING (RNDM), IEEE, 2016, 43-50 p.Conference paper (Refereed)
    Abstract [en]

    The ongoing transition towards a networked society requires reliable and secure network infrastructure and services. As networks evolve from simple point to point systems towards complex, software-defined, ultra-high capacity and reach, and distributed cloud environments, new security challenges emerge. The EU-funded RECODIS project aims at coordinating and fostering research collaboration in Europe on disaster resiliency in communication networks. One of the disaster types, considered by RECODIS Working Group (WG) 4, are deliberate human-made attacks aimed at gaining unauthorized access to the network or disrupting the service. In order to develop methods for increasing network security in the presence of attacks, it is crucial to first identify the security vulnerabilities and attack methods that exploit them, as well as the capabilities and shortcomings of existing security schemes. To this end, the members of RECODIS WG4 performed a comprehensive overview of attack methods and security approaches from the literature. This overview covers the security vulnerabilities inherent to the underlying physical layer, the implications of software-defined networking to security, and security challenges in cloud networks spanning geographically distributed data centers.

  • 77. 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, 1-4 p.Conference 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.

  • 78. Gong, Yu
    et al.
    Hong, Xuezhi
    Lu, Yang
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. Zhejiang Univ, Peoples R China.
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Passive optical interconnects at top of the rack: offering high energy efficiency for datacenters2015In: Optics Express, ISSN 1094-4087, Vol. 23, no 6, 7957-7970 p.Article in journal (Refereed)
    Abstract [en]

    This paper introduces a new concept, namely passive optical interconnect at top of the rack in the datacenter networks, and investigates several architectures, which use only passive optical components to interconnect different servers. In such a manner, the proposed schemes are able to offer higher bandwidth and significantly improve energy efficiency compared to their electronic counterpart that is based on commodity switches. The proposed passive optical interconnect schemes are experimentally demonstrated in order to validate the transmission performance. Besides, an assessment in terms of energy consumption and cost has also been carried out, which shows our proposed concept can significantly outperform the conventional commodity switches on energy efficiency while keeping the cost in the similar level.

  • 79. Grigoreva, Elena
    et al.
    Wong, Elaine
    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, Optical Network Laboratory (ON Lab).
    Mas Machuca, Carmen
    Energy Consumption and Reliability Performance of Survivable Passive Optical Converged Networks: Public ITS Case Study2017In: Journal of Optical Communications and Networking, ISSN 1943-0620, E-ISSN 1943-0639, Vol. 9, no 4, C98-C107 p.Article in journal (Refereed)
    Abstract [en]

    Access networks are evolving fast by increasing their capacity and coverage area, coping with a larger number of users and variety of terminals. Operators aim at keeping high network performance and quality of service but limiting their capital and operational expenditures by, e.g., minimizing investments and energy consumption using power saving at the network components. To address these challenges this paper evaluates the energy consumption, connection availability, and failure detection time of three protection schemes applicable for converged access networks: disjoint fiber protection, energy-efficient disjoint fiber protection, and reflective disjoint fiber protection. The schemes are assessed by a case study considering a public intelligent transport system (ITS). The studied ITS deploys a dedicated short-range communications radio access network connected to the service server through a protected passive access network. Comparison with unprotected architecture shows that reflective disjoint fiber protection offers low energy consumption and high connection availability, while it significantly reduces the failure detection time and, hence, the connection interruption time.

  • 80. Guerzoni, R.
    et al.
    Vaishnavi, I.
    Perez caparros, D.
    Galis, A.
    Tusa, F.
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Sganbelluri, Andrea
    KTH.
    Biczók, G.
    Sonkoly, B.
    Toka, L.
    Ramos, A.
    Melián, J.
    Dugeon, O.
    Cugini, F.
    Martini, B.
    Iovanna, P.
    Giuliani, G.
    Figueiredo, R.
    Contreras-Murillo, L. M.
    Bernardos, C. J.
    Santana, C.
    Szabo, R.
    Analysis of end-to-end multi-domain management and orchestration frameworks for software defined infrastructures: An architectural survey2017In: Transactions on Emerging Telecommunications Technologies, ISSN 2161-5748, Vol. 28, no 4, e3103Article in journal (Refereed)
    Abstract [en]

    Over the last couple of years, industry operators' associations issued requirements towards an end-to-end management and orchestration plane for 5G networks. Consequently, standard organisations started their activities in this domain. This article provides an analysis and an architectural survey of these initiatives and of the main requirements, proposes descriptions for the key concepts of domain, resource and service slicing, end-to-end orchestration and a reference architecture for the end-to-end orchestration plane. Then, a set of currently available or under development domain orchestration frameworks are mapped to this reference architecture. These frameworks, meant to provide coordination and automated management of cloud and networking resources, network functions and services, fulfil multi-domain (i.e. multi-technology and multi-operator) orchestration requirements, thus enabling the realisation of an end-to-end orchestration plane. Finally, based on the analysis of existing single-domain and multi-domain orchestration components and requirements, this paper presents a functional architecture for the end-to-end management and orchestration plane, paving the way to its full realisation.

  • 81. Hasegawa, Hiroshi
    et al.
    Taniguchi, Y.
    Sato, K.
    Jirattigalachote, Amonrat
    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).
    Design strategies for survivable Grouped Routing Entity (GRE)-based optical networks2013In: Design of Reliable Communication Networks (DRCN), 2013 9th International Conference on the, 2013, 148-154 p.Conference paper (Refereed)
    Abstract [en]

    In bandwidth abundant optical networks, the Grouped Routing Entity (GRE) concept is a cost-efficient alternative used instead of waveband routing. It offers all the benefits of the waveband routing (i.e., reduced number of ports), without using expensive wavelength cross connects (WXCs) required in hierarchical optical networks. In fact in a GRE-based optical network wavelength channel add/drop operations are accomplished via Wavelength Selective Switches (WSS) or with optical couplers. The objective of this paper is to further investigate the benefits of GRE-based optical networks in a scenario where survivability is required. In this paper a dedicated protection scheme is proposed, where wavelength paths are efficiently routed using mostly disjoint working and backup GRE pipes (i.e., working and backup pipes are allowed to share some common nodes along their paths). Numerical experiments demonstrate that significant hardware scale reduction at the switching nodes can be obtained by using the proposed network design algorithm.

  • 82. Ho, Pin-Han
    et al.
    Shen, Gangxiang
    Subramaniam, Suresh
    Mouftah, Hussein T.
    Qiao, Chunming
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Guest Editorial Energy-Efficiency in Optical Networks2014In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 32, no 8, 1521-1523 p.Article in journal (Other academic)
  • 83. Hong, Xuezhi
    et al.
    Gong, Y.
    Yang, Y.
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    AWG based passive optical interconnects for datacenters2014In: Optics InfoBase Conference Papers, OSA - The Optical Society , 2014Conference paper (Refereed)
    Abstract [en]

    We propose a cascaded arrayed waveguide grating based passive optical interconnect scheme for datacenters, which outperforms various existing architectures in terms of scalability and cabling complexity. Proof-of-concept experiments are carried out.

  • 84.
    Hong, Xuezhi
    et al.
    KTH, School of Information and Communication Technology (ICT). South China Normal Univ, Peoples R China.
    Ozolins, Oskars
    Guo, Changjian
    Pang, Xiaodan
    Zhang, Junwei
    Navarro, Jaime Rodrigo
    Kakkar, Aditya
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Westergren, Urban
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Jacobsen, Gunnar
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab). South China Normal Univ, Peoples R China.
    1.55-mu m EML-based DMT Transmission with Nonlinearity-Aware Time Domain Super-Nyquist Image Induced Aliasing2017In: 2017 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC), IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    We experimentally demonstrate a DMT transmission system with 1.55-mu m EML using nonlinearity-aware time domain super-Nyquist image induced aliasing. Compared with linear equalization, the capacity is improved by similar to 16.8%(33.1%) with proposed method for 4(40) km transmission.

  • 85.
    Hong, Xuezhi
    et al.
    KTH. South China Normal University, China.
    Yang, Yi
    Gong, Yu
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab). South China Normal University, China.
    Passive Optical Interconnects Based on Cascading Wavelength Routing Devices for Datacenters: A Cross-Layer Perspective2017In: Journal of Optical Communications and Networking, ISSN 1943-0620, E-ISSN 1943-0639, Vol. 9, no 4, C45-C53 p.Article in journal (Refereed)
    Abstract [en]

    A general passive optical interconnect (POI) architecture based on cascading wavelength routing devices is proposed for datacenters. An analysis shows that with a proper port configuration, the logic topology of the proposed POI is equivalent to a DCell network, which has rich connectivity, leading to a high fault tolerance. Compared with the existing arrayed waveguide grating (AWG)-based architecture, such as H-LION, the proposed architecture has a higher AWG port utilization and lower cabling complexity that result in better scalability. Meanwhile, an impairment-aware scalability analysis is carried out to estimate the impact of in-band crosstalk on the size of the POI. Furthermore, a cross-layer investigation of the proposed POI provides a guideline to select proper physical-layer implementations, including optical interface structure and design of the transceiver, for acceptable network performance. The numerical results reveal that, with a moderate number of shortest paths K and degrees of node D, (a) the bidirectional optical interface is more suitable for large-scale datacenter networks than the unidirectional one, (b) an array of fixed receivers can be replaced by just a small number of tunable receivers with negligible degradation in network performance, and (c) decreasing 50% of the tuning range of the receivers causes only a minor increase of blocking probability, which demonstrates a good balance between the complexity of the transceiver design and network performance.

  • 86. Hong, Y.
    et al.
    Hong, X.
    He, S.
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Flex-grid all-optical interconnect supporting transparent multi-hop connection in data centers2015Conference paper (Refereed)
    Abstract [en]

    In this paper a novel flex-grid all-optical interconnect scheme is proposed for data center, where a transparent multi-hop connection can be realized by using optical bypass rather than going through optical-electric-optical conversions, enhancing energy efficiency for inter-rack communications. Moreover, elastic spectrum allocation is adopted in the proposed scheme to increase the resource utilization and scalability. Transmission performance evaluation has been carried out to verify the feasibility of the proposed scheme.

  • 87. Hong, Y.
    et al.
    Hong, Xuezhi
    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).
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Elastic all-optical multi-hop interconnection in data centers with adaptive spectrum allocation2017In: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 383, 478-484 p.Article in journal (Refereed)
    Abstract [en]

    In this paper, a novel flex-grid all-optical interconnect scheme that supports transparent multi-hop connections in data centers is proposed. An inter-rack all-optical multi-hop connection is realized with an optical loop employed at flex-grid wavelength selective switches (WSSs) in an intermediate rack rather than by relaying through optical-electric-optical (O-E-O) conversions. Compared with the conventional O-E-O based approach, the proposed all-optical scheme is able to off-load the traffic at intermediate racks, leading to a reduction of the power consumption and cost. The transmission performance of the proposed flex-grid multi-hop all-optical interconnect scheme with various modulation formats, including both coherently detected and directly detected approaches, are investigated by Monte-Carlo simulations. To enhance the spectrum efficiency (SE), number-of-hop adaptive bandwidth allocation is introduced. Numerical results show that the SE can be improved by up to 33.3% at 40 Gbps, and by up to 25% at 100 Gbps. The impact of parameters, such as targeted bit error rate (BER) level and insertion loss of components, on the transmission performance of the proposed approach are also explored. The results show that the maximum SE improvement of the adaptive approach over the non-adaptive one is enhanced with the decrease of the targeted BER levels and the component insertion loss.

  • 88. Izquierdo-Zaragoza, J. -L
    et al.
    Furdek, Marija
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Nag, A.
    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).
    Pavon-Marino, P.
    On the dimensioning of survivable optical metro/core networks with dual-homed access2016In: IEEE International Conference on High Performance Switching and Routing, HPSR, IEEE Computer Society, 2016, 7483089Conference paper (Refereed)
    Abstract [en]

    Long-reach passive optical networks (LR-PONs) are able to effectively support the growing demand of traffic originating from residential and business customers. Failures of metro/core (M/C) nodes serving the traffic to/from the access networks covered by LR-PONs, may potentially affect hundreds or thousands of customers. One way of guaranteeing 100% survivability from single-node failures is to apply dual-homing, where each LR-PON is connected to two M/C nodes, and combine it with node-disjoint dedicated-path protection (DPP). In this paper, we present a new approach to provide network survivability against single M/C node failures. Instead of applying dedicated path protection (DPP) strategy, which can require huge amount of extra resources, we combine an unprotected network design with a dynamic multilayer restoration algorithm. Our aim is to determine a suitable amount of resource overbuild (in terms of extra transponders) needed to provide average connection availability close to that guaranteed by DPP. Preliminary results show that dimensioning for the worst-case scenario among a set of predefined M/C node failures, i.e., the one disrupting the highest number of connections, yields to a cost-effective strategy requiring up to 35% less transponders than DPP, while offering the same average connection availability.

  • 89.
    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.

  • 90.
    Jirattigalachote, Amornrat
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Provisioning Strategies for Transparent Optical Networks Considering Transmission Quality, Security, and Energy Efficiency2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The continuous growth of traffic demand driven by the brisk increase in number of Internet users and emerging online services creates new challenges for communication networks. The latest advances in Wavelength Division Multiplexing (WDM) technology make it possible to build Transparent Optical Networks (TONs) which are expected to be able to satisfy this rapidly growing capacity demand. Moreover, with the ability of TONs to transparently carry the optical signal from source to destination, electronic processing of the tremendous amount of data can be avoided and optical-to-electrical-to-optical (O/E/O) conversion at intermediate nodes can be eliminated. Consequently, transparent WDM networks consume relatively low power, compared to their electronic-based IP network counterpart. Furthermore, TONs bring also additional benefits in terms of bit rate, signal format, and protocol transparency. However, the absence of O/E/O processing at intermediate nodes in TONs has also some drawbacks. Without regeneration, the quality of the optical signal transmitted from a source to a destination might be degraded due to the effect of physical-layer impairments induced by the transmission through optical fibers and network components. For this reason, routing approaches specifically tailored to account for the effect of physical-layer impairments are needed to avoid setting up connections that don’t satisfy required signal quality at the receiver. Transparency also makes TONs highly vulnerable to deliberate physical-layer attacks. Malicious attacking signals can cause a severe impact on the traffic and for this reason proactive mechanisms, e.g., network design strategies, able to limit their effect are required. Finally, even though energy consumption of transparent WDM networks is lower than in the case of networks processing the traffic at the nodes in the electronic domain, they have the potential to consume even less power. This can be accomplished by targeting the inefficiencies of the current provisioning strategies applied in WDM networks.

    The work in this thesis addresses the three important aspects mentioned above. In particular, this thesis focuses on routing and wavelength assignment (RWA) strategies specifically devised to target: (i) the lightpath transmission quality, (ii) the network security (i.e., in terms of vulnerability to physical-layer attacks), and (iii) the reduction of the network energy consumption. Our contributions are summarized below.

    A number of Impairment Constraint Based Routing (ICBR) algorithms have been proposed in the literature to consider physical-layer impairments during the connection provisioning phase. Their objective is to prevent the selection of optical connections (referred to as lightpaths) with poor signal quality. These ICBR approaches always assign each connection request the least impaired lightpath and support only a single threshold of transmission quality, used for all connection requests. However, next generation networks are expected to support a variety of services with disparate requirements for transmission quality. To address this issue, in this thesis we propose an ICBR algorithm supporting differentiation of services at the Bit Error Rate (BER) level, referred to as ICBR-Diff. Our approach takes into account the effect of physical-layer impairments during the connection provisioning phase where various BER thresholds are considered for accepting/blocking connection requests, depending on the signal quality requirements of the connection requests. We tested the proposed ICBR-Diff approach in different network scenarios, including also a fiber heterogeneity. It is shown that it can achieve a significant improvement of network performance in terms of connection blocking, compared to previously published non-differentiated RWA and ICBR algorithms. 

    Another important challenge to be considered in TONs is their vulnerability to physical-layer attacks. Deliberate attacking signals, e.g., high-power jamming, can cause severe service disruption or even service denial, due to their ability to propagate in the network. Detecting and locating the source of such attacks is difficult, since monitoring must be done in the optical domain, and it is also very expensive. Several attack-aware RWA algorithms have been proposed in the literature to proactively reduce the disruption caused by high-power jamming attacks. However, even with attack-aware network planning mechanisms, the uncontrollable propagation of the attack still remains an issue. To address this problem, we propose the use of power equalizers inside the network nodes in order to limit the propagation of high-power jamming attacks. Because of the high cost of such equipment, we develop a series of heuristics (incl. Greedy Randomized Adaptive Search Procedure (GRASP)) aiming at minimizing the number of power equalizers needed to reduce the network attack vulnerability to a desired level by optimizing the location of the equalizers. Our simulation results show that the equalizer placement obtained by the proposed GRASP approach allows for 50% reduction of the sites with the power equalizers while offering the same level of attack propagation limitation as it is possible to achieve with all nodes having this additional equipment installed. In turn, this potentially yields a significant cost saving.   

    Energy consumption in TONs has been the target of several studies focusing on the energy-aware and survivable network design problem for both dedicated and shared path protection. However, survivability and energy efficiency in a dynamic provisioning scenario has not been addressed. To fill this gap, in this thesis we focus on the power consumption of survivable WDM network with dynamically provisioned 1:1 dedicated path protected connections. We first investigate the potential energy savings that are achievable by setting all unused protection resources into a lower-power, stand-by state (or sleep mode) during normal network operations. It is shown that in this way the network power consumption can be significantly reduced. Thus, to optimize the energy savings, we propose and evaluate a series of energy-efficient strategies, specifically tailored around the sleep mode functionality. The performance evaluation results reveal the existence of a trade-off between energy saving and connection blocking. Nonetheless, they also show that with the right provisioning strategy it is possible to save a considerable amount of energy with a negligible impact on the connection blocking probability.

    In order to evaluate the performance of our proposed ICBR-Diff and energy-aware RWA algorithms, we develop two custom-made discrete-event simulators. In addition, the Matlab program of GRASP approach for power equalization placement problem is implemented.

  • 91.
    Jirattigalachote, Amornrat
    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).
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Taniguchi, Yuki
    Ban, Toshinori
    Hasegawa, Hiroshi
    Sato, Ken-ichi
    Design of Grouped Routing Entity (GRE)-based Optical Networks with 100% Signal Quality Guarantee2014In: 2014 International Conference on Optical Network Design and Modeling, ONDM 2014, 2014, 174-179 p.Conference paper (Refereed)
    Abstract [en]

    In bandwidth abundant optical networks it is important to develop design strategies that are not only cost effective but also able to account for the inherent characteristics of the optical transmission medium responsible for the signal quality degradation. With this objective in mind, the paper proposes a design algorithm able to determine an appropriate placement of regenerators in Grouped Routing Entity (GRE)-based optical networks. The objective of the algorithm is to guarantee a certain signal quality level to all connections while minimizing the number of fibers and switching ports required in the network The proposed design strategy relies on a physical-layer impairment model, specifically introduced in the paper for this purpose, able to estimate the signal quality of an optical path in a GRE-based optical network Simulation results indicate that compared with a single layer optical path network the proposed design algorithm can reduce at least 87% of the switch ports while the increment in the number of fibers is lower than 10%.

  • 92.
    Jirattigalachote, Amornrat
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Yamada, Yoshiyuki
    Nagoya University.
    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).
    Hasegawa, Hiroshi
    Nagoya University.
    Sato, Ken-ichi
    Nagoya University.
    Impairment-Aware Routing and Waveband Assignment for Efficient Optical Transport Networks2012In: 2012 Optical Fiber Communication Conference and Exposition and the National Fiber Optic Engineers Conference, OFC/NFOEC 2012, 2012, 6192131- p.Conference paper (Refereed)
    Abstract [en]

    We demonstrate the importance of considering physical impairments in waveband-based optical networks. We propose and evaluate an Impairment-Aware waveband-routing and waveband-assignment (IA-RWBA) algorithm achieving significant improvement in both impairment satisfaction rate and total network cost.

  • 93.
    Li, Jun
    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).
    Optical Transport Network Architecture Enabling Ultra-Low Latency for Communications among Base Stations2017In: 2017 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC), IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    We propose a novel transport network architecture for mobile backhauling along with its tailored communication protocol to offer ultra-low latency. Results show that less than 0.5 milliseconds packet delay can be achieved for inter-base-station communications.

  • 94.
    Li, Jun
    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).
    Optical transport network architecture enabling ultra-low latency for communications among base stations2017In: 2017 Optical Fiber Communications Conference and Exhibition, OFC 2017 - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2017, 7937094Conference paper (Refereed)
    Abstract [en]

    We propose a novel transport network architecture for mobile backhauling along with its tailored communication protocol to offer ultra-low latency. Results show that less than 0.5 milliseconds packet delay can be achieved for inter-base-station communications.

  • 95. Li, Shuo
    et al.
    Wang, Meiqian
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Overby, Harald
    Wong, Eric W. M.
    Zukerman, Moshe
    Performance Evaluation of a Bufferless OBS/OPS Network With 1+1 Path Protection2015In: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 27, no 20, 2115-2118 p.Article in journal (Refereed)
    Abstract [en]

    In optical burst/packet switched (OBS/OPS) networks, bursts/packets may be dropped because of equipment failures. A widely used mechanism to protect a connection from a single-trunk-failure event is 1 + 1 path protection. We consider a bufferless OBS/OPS network with two types of users: 1) premium (that receive 1 + 1 protection service) and 2) regular (that do not receive such a service). We propose a fast and accurate approximation to evaluate the performance of such OBS/OPS network. The accuracy and scalability of the approximation and the effect of the proportion of the premium users in the network are discussed.

  • 96. Li, Shuo
    et al.
    Zukerman, Moshe
    Wang, Meiqian
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Wong, Eric W. M.
    Improving throughput and effective utilization in OBS networks2015In: Optical Switching and Networkning Journal, ISSN 1573-4277, E-ISSN 1872-9770, Vol. 18, 222-234 p.Article in journal (Refereed)
    Abstract [en]

    This paper considers two important performance measures that have not received much attention in performance studies of optical burst switching (OBS) networks. The first is the so-called effective utilization which is the proportion of link capacity used by bursts that eventually reach their destinations. The second considers the throughput of individual source-destination pairs that may indicate unfairness and starving connections. Using these performance measures, we evaluate a new proposed contention resolution strategy called EBSL, which is a combination of the Emulated-OBS wavelength reservation scheme, with the two contention resolution strategies - Burst Segmentation and Least Remaining Hop-count First (LRHF). The results show that EBSL can prevent congestion collapse of throughput and effective utilization, and reduce the blocking probability under heavy load conditions. We then add deflection routing to EBSL to further increase the throughput under light and medium traffic load. Finally, we replace LRHF by a fairer version of LRHF in EBSL to provide insights into fairness efficiency and tradeoffs. Overall, we demonstrate that OBS can be enhanced to overcome its known traffic congestion related weaknesses of low throughput, ineffective utilization and unfairness.

  • 97.
    Lin, Rui
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Cheng, Yuxin
    KTH, School of Information and Communication Technology (ICT).
    Guan, Xun
    Tang, Ming
    Liu, Deming
    Chan, Chun-Kit
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Physical-layer network coding for passive optical interconnect in datacenter networks2017In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 25, no 15, 17788-17797 p.Article in journal (Refereed)
    Abstract [en]

    We introduce physical-layer network coding (PLNC) technique in a passive optical interconnect (POI) architecture for datacenter networks. The implementation of the PLNC in the POI at 2.5 Gb/s and 10Gb/s have been experimentally validated while the gains in terms of network layer performances have been investigated by simulation. The results reveal that in order to realize negligible packet drop, the wavelengths usage can be reduced by half while a significant improvement in packet delay especially under high traffic load can be achieved by employing PLNC over POI.

  • 98.
    Lin, Rui
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. Huazhong University of Science and Technology, China.
    Pang, Xiaodan
    Ozolins, Oskars
    Feng, Zhenhua
    Djupsjöbacka, Anders
    Westergren, Urban
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Fotonik och mikrovågsteknik, FMI.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Fotonik och mikrovågsteknik, FMI.
    Jacobsen, Gunnar
    Tang, Ming
    Fu, Songnian
    Liu, Deming
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Experimental Validation of Scalability Improvement for Passive Optical Interconnect by Implementing Digital Equalization2016Conference paper (Refereed)
  • 99.
    Lin, Rui
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Szczerba, K.
    Agrell, E.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Tang, M.
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    To overcome the scalability limitation of passive optical interconnects in datacentres2014In: Optics InfoBase Conference Papers, OSA - The Optical Society , 2014Conference paper (Refereed)
    Abstract [en]

    We propose to add optical amplifier(s) to passive optical interconnect (POI) at top-of-rack in datacentres and validate this approach by introducing impairment constraints into POIs design. It is shown that one amplifier can improve scalability by a factor of 16.

  • 100.
    Lin, Rui
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab). Huazhong University of Sci&Tech (HUST), China.
    Szczerba, K.
    Agrell, E.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Tang, M.
    Liu, D.
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Scalability analysis methodology for passive optical interconnects in data center networks using PAM2017In: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 403, 283-289 p.Article in journal (Refereed)
    Abstract [en]

    A framework is developed for modeling the fundamental impairments in optical datacenter interconnects, i.e., the power loss and the receiver noises. This framework makes it possible, to analyze the trade-offs between data rates, modulation order, and number of ports that can be supported in optical interconnect architectures, while guaranteeing that the required signal-to-noise ratios are satisfied. To the best of our knowledge, this important assessment methodology is not yet available. As a case study, the trade-offs are investigated for three coupler-based top-of-rack interconnect architectures, which suffer from serious insertion loss. The results show that using single-port transceivers with 10 GHz bandwidth, avalanche photodiode detectors, and quadratical pulse amplitude modulation, more than 500 ports can be supported.

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