| 1. |
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| 2. |
- Callegati, F., et al.
(författare)
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Research on Optical Core Networks in the e-Photon/ONe Network of Excellence
- 2006
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Ingår i: 25TH IEEE INTERNATIONAL CONFERENCE ON COMPUTER COMMUNICATIONS, VOLS 1-7, PROCEEDINGS IEEE INFOCOM 2006. ; , s. 2987-2991
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Konferensbidrag (refereegranskat)abstract
- This papers reports the advances in optical core networks research coordinated in the framework of the e- photon/ONe and e-photon/ONe+ networks of excellence.
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| 3. |
- Liu, Li, et al.
(författare)
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New Progress in VLBI tracking of GNSS satellites at GFZ
- 2014
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Ingår i: IVS 2014 General Meeting Proceedings "VGOS: The New VLBI Network", Edited by Dirk Behrend, Karen D. Baver, and Kyla L. Armstrong, Science Press (Beijing). - 9787030429742 ; , s. 456-460
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 4. |
- Mas-Machuca, Carmen, et al.
(författare)
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Reliable Control and Data Planes for Softwarized Networks
- 2020
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Ingår i: Guide to Disaster-Resilient Communication Networks. - : Springer. - 9783030446840 - 9783030446857 - 9783030446871 ; , s. 243-270
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Bokkapitel (refereegranskat)abstract
- Driven by the requirement of increasing performance and flexibility, networks are being softwarized by paradigms such as software-defined networking (SDN) and network function virtualization (NFV). These solutions reduce the complexity and the specialization of hardware devices, by extracting the inherently distributed control plane of forwarding network elements such as switches and routers, to a logically centralized control plane (referred as controller in SDN). The control plane acts as a broker between the network applications (e.g. monitoring, traffic engineering) and the data plane (i.e. physical network infrastructure). For scalability and robustness, the logically centralized control plane is implemented by physically distributing different controllers throughout the network. This chapter presents different solutions to increase the reliability of both planes: data and control planes. The reliability of the data plane can be increased by considering survivable virtual network embedding solutions. This chapter proposes a survivable embedding against single and double failures at either links or nodes. Furthermore, in order to provide a programmable and resilient data plane, BPFabric has been proposed for SDN which supports high performance functions suitable for detecting attacks. On the other hand, the reliability of the control plane applied to SDN can be addressed by considering enhanced controller placement solutions providing redundancy against uncorrelated as well as targeted failures while coping with latency and capacity requirements. Furthermore, a solution to increase the security and robustness of the control channel is also addressed in this chapter.
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| 5. |
- Wang, X., et al.
(författare)
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Virtualized Cloud Radio Access Network for 5G Transport
- 2017
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Ingår i: IEEE Communications Magazine. - : Institute of Electrical and Electronics Engineers (IEEE). - 0163-6804 .- 1558-1896. ; 55:9, s. 202-209
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Tidskriftsartikel (refereegranskat)abstract
- Current radio access networks (RANs) need to evolve to handle diverse service requirements coming from the growing number of connected devices and increasing data rates for the upcoming 5G era. Incremental improvements on traditional distributed RANs cannot satisfy these requirements, so the novel and disruptive concept of a cloud RAN (CRAN) has been proposed to decouple digital units (DUs) and radio units (RUs) of base stations (BSs), and centralize DUs into a central office, where virtualization and cloud computing technologies are leveraged to move DUs into the cloud. However, separating RUs and DUs requires low-latency and high-bandwidth connectivity links, called "fronthaul," as opposed to traditional backhaul links. Hence, design of the 5G transport network, that is, the part of the network that carries mobile data traffic between BSs and the core network and data centers, is key to meet the new 5G mobile service requirements and effectively transport the fronthaul traffic. Today, consensus is yet to be achieved on how the fronthaul traffic will be transported between RUs and DUs, and how virtualization of network resources will occur from a radio network segment to the centralized baseband processing units. In this article, we present a new 5G architecture, called virtualized cloud radio access network (V-CRAN), moving toward a cell-less 5G network architecture. We leverage the concept of a virtualized BS (V-BS) that can be optimally formed by exploiting several enabling technologies such as software defined radio (SDR) and coordinated multipoint (CoMP) transmission/reception. A V-BS can be formed on a per-cell basis or per-user basis by allocating virtualized resources on demand. For the fronthaul solution, our approach exploits the passive optical network (PON), where a wavelength can be dynamically assigned and shared to form a virtualized passive optical network (VPON). Several use cases of the V-CRAN are presented to show how network architecture evolution can enhance system throughput, energy efficiency, and mobility management.
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| 6. |
- Callegati, F., et al.
(författare)
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Research in Optical Transport Networks : The e-Photon/ONe+ Experience
- 2007
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Ingår i: ICTON 2007. ; , s. 3-6
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Konferensbidrag (refereegranskat)abstract
- This paper reports the view of the e-Photon/ONe community regarding the research directions in optical transport networks. Results stemming from joint international research activities in the framework of the project are summarized. This summary presents, necessarily, little details, but wants to draw the attention of the reader towards the most advanced research activities ongoing on the broad topics of optical core networks, from wavelength routed network, to optical burst switching and optical packet switching.
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| 7. |
- Colman-Meixner, C., et al.
(författare)
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Resilient cloud network mapping with virtualized BBU placement for cloud-RAN
- 2017
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Ingår i: 2016 IEEE International Conference on Advanced Networks and Telecommunications Systems, ANTS 2016. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781509021932
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Konferensbidrag (refereegranskat)abstract
- Cloud Radio Access Network (C-RAN) will improve mobile radio coordination and resource efficiency by allowing baseband processing unit (BBU) functions to be virtualized and centralized, i.e., deployed in a BBU hotel. We consider a BBU hoteling scheme based on the concept of access cloud network (ACN). An ACN consists of virtualized BBUs (vBBUs) placed in metro cloud data centers (metro DCs). A vBBU is connected to a set of remote radio heads (RRHs). ACN resiliency against network and processing failures is critical for C-RAN deployments. Hence, in this study, we propose three protection approaches: 1+1 ACN protection, 1+1 ACN and vBBU protection, and partial ACN protection. Simulation results show that both 1+1 ACN and 1+1 ACN and vBBU protection requires large capacity for backup to provide 100% survivability for singlelink and single-DC failures. As a result, we suggest a partial ACN protection approach which provides degraded services with only 8% additional network resources.
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| 8. |
- Fiorani, Matteo, et al.
(författare)
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Optical spatial division multiplexing for ultra-high-capacity modular data centers
- 2016
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Ingår i: 2016 Optical Fiber Communications Conference and Exhibition, OFC 2016. - Washington, D.C. : Institute of Electrical and Electronics Engineers (IEEE). - 9781943580071
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 9. |
- Fiorani, Matteo, et al.
(författare)
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Spatial division multiplexing for high capacity optical interconnects in modular data centers
- 2017
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Ingår i: Journal of Optical Communications and Networking. - : Optical Society of America. - 1943-0620 .- 1943-0639. ; 9:2, s. A143-A153
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 10. |
- Tornatore, M., et al.
(författare)
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Guest Editorial Latest Advances in Optical Networks for 5G Communications and beyond
- 2021
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Ingår i: IEEE Journal on Selected Areas in Communications. - 0733-8716 .- 1558-0008. ; 39:9, s. 2667-2671
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Forskningsöversikt (refereegranskat)abstract
- This Special Issue contains a collection of outstanding papers covering several recent advances in optical networks for 5G communications and beyond. Papers are organized into four categories: network resource planning; optical access networks; optical fronthaul solutions; and autonomous and data-driven network management. In this introduction, a brief overview of the field is given, followed by a summary of the seventeen papers of this Special Issue, and a discussion of future directions in the field.
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| 11. |
- Wang, X., et al.
(författare)
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Handover reduction in virtualized cloud radio access networks using TWDM-PON fronthaul
- 2016
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Ingår i: Journal of Optical Communications and Networking. - : Institute of Electrical and Electronics Engineers (IEEE). - 1943-0620 .- 1943-0639. ; 8:12, s. B124-B134
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Tidskriftsartikel (refereegranskat)abstract
- To meet challenging 5G capacity requirements, operators are densifying their cellular networks by deploying additional small cells to cover hot spots, and such an increase in the number and density of cells may result in excessive numbers of handovers. In this study, we propose a handover reduction mechanism implemented in a cloud radio access network (CRAN) by exploiting the high capacity of an optical access network serving as a "fronthaul." CRAN has been proposed as a 5G radio access network architecture, where the digital unit (DU) of a conventional base station (BS) is separated from the radio unit (RU) and moved to the "cloud" (DU-cloud) for better mobility management and cost saving. Separating RUs and DUs requires a low-latency and high-bandwidth 5G transport network to handle "fronthaul" traffic, for which optical access is an excellent choice. Here, we present a new 5G architecture, called virtualized-CRAN (V-CRAN), moving toward a cell-less 5G mobile network architecture. We leverage the concept of a "virtualized-BS" (V-BS) that can be formed by exploiting several enabling technologies such as software-defined radio and coordinated multipoint transmission/reception. A V-BS can be formed on a per-user basis by allocating virtualized resources on demand so that common signals can be jointly transmitted from multiple RUs to the user without triggering handover. We first model the handover reduction optimization problem for a scenario where future mobility information is known, and then propose a suite of algorithms for a scenario where future information is unknown. Simulation results show that V-CRAN can enhance the throughput of users at the cell-edge, as well as significantly reduce the number of handovers, handover delay, and failure rate.
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| 12. |
- Wang, X., et al.
(författare)
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Joint allocation of radio and optical resources in virtualized cloud RAN with CoMP
- 2017
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Ingår i: 2016 IEEE Global Communications Conference, GLOBECOM 2016 - Proceedings. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781509013289
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Konferensbidrag (refereegranskat)abstract
- 5G Radio Access Networks (RANs) are supposed to increase their capacity by 1000x to handle growing number of connected devices and increasing data rates. The concept of cloud-RAN (CRAN) has been recently proposed to decouple digital units (DUs) and radio units (RUs) of base stations (BSs), and centralize DUs into central offices. CRAN can ease the implementation of advanced radio coordination techniques, e.g., Coordinated Multi-Point (CoMP) Transmission/Reception, to enhance its system throughput. However, separating DUs and RUs, and implementing CoMP in CRAN require low-latency and high-bandwidth connectivity links, called "fronthaul". Today, consensus has not yet been achieved on how BSs, fronthaul, and central offices will be orchestrated to enhance the system throughput. In this study, we present a CRAN over Passive Optical Network (PON) architecture called virtualized-CRAN (V-CRAN). V-CRAN leverages the concept of virtualized PON (VPON) that can dynamically associate any RU to any DU so that several RUs can be coordinated by the same DU, and the concept of virtualized BS (V-BS) that can jointly transmit common signals from multiple RUs to a user. We propose a novel mathematical model based on constraint programming for joint allocation of radio, optical network, and baseband processing resources to enhance RAN throughput, and we solve it by optimally forming VPONs and V-BSs. Comprehensive simulations show that V-CRAN can enhance the system throughput and the efficiency of resource utilization.
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| 13. |
- Yan, Li, 1988, et al.
(författare)
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Network performance trade-off in optical spatial division multiplexing data centers
- 2017
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Ingår i: 2017 Optical Fiber Communications Conference and Exhibition, OFC 2017 - Proceedings. - : Institute of Electrical and Electronics Engineers Inc.. - 9781943580231 ; Part F40-OFC 2017, s. W3D.5-
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Konferensbidrag (refereegranskat)abstract
- 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.
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