K. Kitayama

Osaka University, Suika, Ōsaka, Japan

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Publications (427)379.54 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Mode-division multiplexing (MDM) over wavelength division multiplexed (WDM) networks is studied, particularly for the deployment of metro area networks (MAN) using two-mode fibers (TMF). Full C-band differential mode group delay (DMGD)-compensated TMF links are adopted for decreasing the computational complexity of real-time multiple-input multiple-output (MIMO) signal processing. The effect of modal crosstalk to the maximum delay spread of the channel is validated through numerical simulations. Finally, the 2×2 MIMO channel state information (CSI) of a 102.6-km DMGD-compensated TMF link is experimentally estimated for mode path provisioning based upon routing and mode assignment (RMA) in MDM networks. The results confirm close-to-zero total DMGD value over the entire C-band.
  • Yue-Cai Huang · Yuki Yoshida · Salah Ibrahim · Ryo Takahashi · Atsushi Hiramatsu · Ken-ichi Kitayama
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    ABSTRACT: In OPS-based data center networks, setting up temporal OCS paths for high-reliability-required large data transmissions is preferred. However, inappropriate OCS path selection could severely affect the original OPS traffic, which is because OCS path may break the network topology and cause OPS packet circulations. We propose to hold bypassing routes for every link of the OCS path when it is established. Then, the OPS packets could bypass the OCS links by being deflected to the bypassing routes. Therefore, this method facilitates the coexistence of OCS in OPS-based data center networks. Simulations demonstrate the benefit achieved by our proposal compared to no-bypassing-route scenarios.
    photonics in switching 2015; 09/2015
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    ABSTRACT: A multi-domain optical infrastructure with end-to-end Ethernet transport capability can deliver Ethernet services over a large scale and provide a promising solution for inter data center networks (DCN) communication. The already existed metro and core networks should be evolved both in data plane and control plane towards to support the heterogeneous and dynamic Ethernet traffic environment. In this paper, we report the work carried out in the ICT STRAUSS project to provide Ethernet connections for intra-DCN and inter-DCN over metro and core networks. The key technologies for intra- and inter- DCN communications are reported with experimental validation.
    EuCNC 2015; 07/2015
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    ABSTRACT: We present the performance of fixed-length, variable-capacity (FL-VC) packets in optical packet-switching (OPS) networks. We show how FL-VC achieves an effective balance between implementation feasibility and performance of the applications using the network. Focusing on metropolitan area networks and real-world file distributions, we also show that an adequate selection of packet duration leads to nearly optimal application throughput with respect to conventional variable-length, fixed-bit-rate packets (VL-FBR), and that this optimal packet duration is robust against changes in the workload. Finally, we show that a single fiber delay line per OPS switch managed by a first-fit scheduler can increase throughput to levels similar to those obtained by random access buffers.
    Journal of Optical Communications and Networking 07/2015; 7(7):609-617. DOI:10.1364/JOCN.7.000609 · 1.55 Impact Factor
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    The 19th International Conference on Optical Networks Design and Modelling (ONDM 2015); 05/2015
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    ABSTRACT: In this study, we demonstrate coherent OFDMA-PON uplink transmission experimentally using three optical network units including a 3-Gbaud real-time transmitter prototype. Cooperative digital signal processing at the ONUs and an optical line terminal enable no-guard-band subcarrier-based multiple access with free-running up to 100-kHz-linewidth external cavity lasers over a 40-km fiber link. In addition, we demonstrate the OFDMA-PON uplink with multiformatted and unequally-allocated subcarriers over up to 65-km link to verify the bandwidth flexibility of the proposed uplink. We then extend the experimental results to cases with >3 ONUs via numerical simulation.
    Journal of Lightwave Technology 04/2015; 33(8):1-1. DOI:10.1109/JLT.2015.2390221 · 2.86 Impact Factor
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    ABSTRACT: We present an energy-efficient, low-latency, torus-topology intra-datacenter network with the deployment of 100-Gb/s hybrid optoelectronic routers, where OPS, OCS and virtual OCS are all supported on a single hardware platform enabled by smart flow management. 1..Introductionn The rapid growth in internet, mobile, and cloud services has been boosting the size and service diversity of data centers (DCs), whereas current DC networks with hierarchical topologies i.e., fat-tree, are failing to cope with the demand due to performance insufficiencies e.g., poor flexibility, high latency, and more importantly because of the lack of scalability and serious power issues. To tackle these problems, optical technologies have been introduced into DC networks in different approaches such as the combination of conventional electrical packet switching (EPS) and optical circuit switching (OCS) [1], an optical packet switching (OPS) approach based on large-scale all-optical switches [2], and more recently the combination of OPS and OCS [3]. Regarding the pure OPS solution that relies on all-optical switches, low latency and good connectivity can be provided but the centralized approach restricts the scalability and redundancy, whereas for the hybrid approaches of EPS/OCS or OPS/OCS, different hardware platforms with different sets of control are required. On other hand, we have previously proposed a torus-topology DC network based on the deployment of hybrid optoelectronic routers (HOPRs), where both OPS and OCS are simultaneously supported on a unified hardware platform equipped with an OpenFlow controller. An upgraded HOPR for the new DC network is currently being developed to support 100-Gbps optical packets with a significant reduction in power consumption and latency compared to the previously developed HOPR [4] that can support 10-Gb/s optical packets. In this paper, we describe the operating mechanism of the new Torus DC network that relies on HOPRs, and we also review the latest updates on the 100-Gb/s underlying technologies.
    Optical Fiber Communication Conference and Exposition (OFC 2015); 03/2015
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    ABSTRACT: We review our work on an intra-data center (DC) network based on co-deployment of optical packet switching (OPS) and optical circuit switching (OCS), conducted within the framework of a five-year-long national R&D program in Japan (similar to March 2016). For the starter, preceding works relevant to optical switching technologies in intra-DC networks are briefly reviewed. Next, we present the architecture of our torus-topology OPS and agile OCS intra-DC network, together with a new flow management concept, where instantaneous optical path on-demand, so-called Express Path is established. Then, our hybrid optoelectronic packet router (HOPR), which handles 100 Gbps (25 Gbps x 4-wavelength) optical packets and its enabling device and sub-system technologies are presented. The HOPR aims at a high energy-efficiency of 0.09 [W/Gbps] and low-latency of 100 ns regime. Next, we provide the contention resolution strategies in the OPS and agile OCS network and present the performance analysis with the simulation results. It is followed by the discussions on the power consumption of intra-DC networks. We compare the power consumption and the throughput of a conventional fat-tree topology with the N-dimensional torus topology. Finally, for further power saving, we propose a new scheme, which shuts off HOPR buffers according to the server operation status.
    Journal of Lightwave Technology 03/2015; 33(5):1-1. DOI:10.1109/JLT.2015.2394384 · 2.86 Impact Factor
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    ABSTRACT: A multidomain and multitechnology optical network orchestration is demonstrated in an international testbed located in Japan, the U.K., and Spain. The application-based network operations architecture is proposed as a carrier software-defined network solution for provisioning end-to-end optical transport services through a multidomain multitechnology network scenario, consisting of a 46-108 Gb/s variable-capacity Open-Flow-capable optical packet switching network and a programmable, flexi-grid elastic optical path network.
    Journal of Lightwave Technology 02/2015; 33(3):609-617. DOI:10.1109/JLT.2014.2351852 · 2.86 Impact Factor
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    ABSTRACT: We demonstrate a power-efficient coherent interleaved frequency domain multiple access passive optical network (IFDMA-PON) uplink system. The digital signal processing circuits for coherent IFDMA-based quadrature phase-shift keying (PSK) are implemented on 40-nm field programmable gate arrays. By employing polar-coordinate transformed mapping of the PSK signal, the power consumption of the optical network unit is reduced to one-tenth that of conventional orthogonal frequency-division multiple access-PON systems. The transmission of a 6 Gb/s real-time coherent IFDMA-PON uplink signal across 20 km of single mode fiber is demonstrated for the first time.
    IEEE Photonics Technology Letters 01/2015; 27(1):81-84. DOI:10.1109/LPT.2014.2362172 · 2.18 Impact Factor
  • Takahiro Kodama · Koji Morita · Gabriella Cincotti · Ken-ichi Kitayama
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    ABSTRACT: Photonic analog-to-digital conversion and optical quantization are demonstrated, based on the spectral shifts of orthogonal frequency division multiplexing subcarriers and a frequency-packed arrayed waveguide grating. The system is extremely low-energy consuming since the spectral shifts are small and generated by cross-phase modulation, using a linear-slope high-speed and low-jitter pulse train generated by a mode locked laser diode. The feasibility of a 2, 3 and 4-bit optical quantization scheme is demonstrated.
    Optics Express 11/2014; 22(23). DOI:10.1364/OE.22.028719 · 3.49 Impact Factor
  • Ken-ichi Kitayama · Akihiro Maruta · Yuki Yoshida
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    ABSTRACT: Current status and the future perspective of digital coherent technology for optical fiber and radio-over-fiber (RoF) transmission systems will be reviewed. For the starter, we will review two key digital coherent techniques; the coherent receiver and compensation techniques for the fiber nonlinearity-induced impairments. Next, we will present a commercial deployment of 100 G digital coherent long-haul optical fiber transmission system and the R&D challenge to 400 G and beyond transmission systems. Finally, we will turn our focus on digital coherent RoF transmission systems. We will introduce an ongoing government-funded R&D program in Japan, entitled “Agile deployment capability of highly resilient optical and radio seamless communication systems.” It was initiated after the disaster in Japan in March 2011, aiming at optical fiber and millimeter-wave-band radio seamless transmission system. It would be a good use case of cutting-edge radio-over-fiber technology for an immediate social need.
    Journal of Lightwave Technology 10/2014; 32(20):3411-3420. DOI:10.1109/JLT.2014.2310461 · 2.86 Impact Factor
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    ABSTRACT: A vision of the photonic network in 2020 is presented, which envisages a “smart photonic cloud.” A smart photonic cloud is defined as a universal network platform without any physical or logical constraint that provides flexible connectivity for machine-to-machine communication such as networked high-performance computing or intra- and inter-data center networks. The key requirements for the network in the Big Data era include an ultralarge capacity with low power consumption, low latency, as well as flexibility on demand to the changes in the configuration and bandwidth of the optical path. To cope with the growing demand for network virtualization, novel photonic layer virtualization will be proposed, which differs from the conventional approach in terms of the number of slices and the dynamic range of the bandwidth of each slice. First, the objectives and the guiding principle of the vision will be addressed. Next, three “Ss” will be presented that represent the key enabling technologies, namely scale-free photonics, smart photonic networking, and a synthetic transport platform. A key engine with which to realize the above three enabling technologies is the photonic network processor (P-NP), which can define versatile functionality of switches and transmission systems by software. The P-NP takes advantage of the rapid progress made on digital signal processing for coherent optical transmission systems, and it consists of pools of optical frontends, digital signal processors, L1/L2 switches, which are either electrically or optically interconnected based on silicon photonic technology. Finally, a multifunctional optical cross-connect and a bit-rate-flexible optical transponder are presented as examples of P-NP applications.
    Journal of Lightwave Technology 08/2014; 32(16):2760-2770. DOI:10.1109/JLT.2014.2324651 · 2.86 Impact Factor
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    ABSTRACT: Cloud applications and the global delivery of Ethernet services require a scalable, reliable, virtualizable and cost/energy efficient optical transport infrastructure able to support data rates beyond 100 Gb/s. The ICT STRAUSS project addresses the requirement of future optical infrastructures for Ethernet transport beyond 100 Gb/s, by combining two network switching technologies, namely Optical Packet Switching (OPS) and flexible Optical Circuit Switching (OCS). In this paper, cost/energy-efficient solutions and technology enablers are presented, specifically dealing with data plane aspects, such as the design and development of sliceable bandwidth variable transponders (S-BVT), fixed-length variable-capacity OPS, flexi-grid optical switching nodes and OPS/OCS integrated interface.
    2014 European Conference on Networks and Communications (EuCNC); 06/2014
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    ABSTRACT: Modeling and performance analysis of optical packet switching (OPS) data center networks (DCN) with flow management is presented. Hybrid optoelectronic packet routers (HOPR) are introduced in the data center network, which combines optical switching fabric and electronic buffers with 100 Gbit/s (25 Gbit/s x 4 wavelengths) links. A novel " Express Path " , an instant wavelength path on demand, is proposed to enable the flows bypassing label processors at intermediate nodes, whereas ordinary packets are switched with deflection routing algorithm for contention resolution. This architecture thus guarantees end-to-end Quality-of-Service of traffic on express path as well as reduces the latency and the power consumption. First, the combined architecture of flows on the express paths and ordinary packet switching is modeled. Next, through the numerical simulations of serve-to-server traffic in 4-dimensional (4-D) (=up to 4096-node) torus topology, the performance in terms of the throughput, packet dropping probability and the end-to-end delay will be discussed, in comparison with ordinary-packet-only OPS architecture.
    The 18th International Conference on Optical Network Design and Modeling – ONDM; 05/2014
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    ABSTRACT: A novel hybrid all-optical mode-division multiplexing and code division multiplexing architecture for flexible and scalable access networks is presented. We successfully demonstrate, for the first time, an asynchronous on-off keying modulation, 2 mode x 4 code x 10 Gbps transmission over 42-km link, using a set of single-mode and two-mode fibers, without dispersion compensation. The four phase-shift keyed optical codes are generated at a single wavelength, by a multiport encoder/decoder, and we use an optical mode multiplexer/demultiplexer in the remote node and at the central office. We also experimentally evaluate the mode crosstalk tolerance considering different access span distances for the LP<sub>01</sub> and LP<sub>11</sub> modes.
    Optics Express 05/2014; 22(10):12060-12069. DOI:10.1364/OE.22.012060 · 3.49 Impact Factor
  • Giampiero Contestabile · Akihiro Maruta · Ken-Ichi Kitayama
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    ABSTRACT: We report an extensive experimental characterization of four wave mixing (FWM) in InAs/InGaAsP/InP columnar quantum dot semiconductor optical amplifiers (QD-SOAs). This paper includes a characterization of the QD-SOA and of the single and double pump FWM performance. The double pump case is studied in both the orthogonal and parallel pumps configurations. Unprecedented ultrabroadband and efficient wavelength conversion are found including, for the two pumps case, 100-nm conversion span in the telecom bands around 1550 nm (S/C/L bands) with positive conversion efficiency and more than 30-dB output optical signal-to-noise ratio.
    IEEE Journal of Quantum Electronics 04/2014; 50(5). DOI:10.1109/JQE.2014.2313063 · 2.11 Impact Factor
  • Daisuke Hisano · Akihiro Maruta · Ken-Ichi Kitayama
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    ABSTRACT: We report experimental demonstration of synchronization detection using semiconductor optical amplifier (SOA). We show the feasibility with which the timing of the signal can be actually monitored and with little impact on signal light. When return-to-zero ON-OFF-keyed signal light and a probe light are launched into SOA, error-free operation at 10.7 Gb/s is demonstrated with small power penalty as compared with the case which the probe light is not launched, then the amplified signal can be directly used for the following all-optical processing circuit.
    IEEE Photonics Technology Letters 04/2014; 26(10). DOI:10.1109/LPT.2014.2312379 · 2.18 Impact Factor
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    ABSTRACT: A cost-effective time-sliceable IM/DD OFDM transceiver using low-complex DSP is experimentally investigated. Slicing capabilities are tested for concurrently serving 12.5GHz channels running at up to 10Gb/s variable bandwidth optical routes covering up to 185km.
    Optical Fiber Communication Conference; 03/2014
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    ABSTRACT: Coherent IFDMA-PON uplink system with 3 multiplexed ONUs is demonstrated experimentally. With a prototype of ONU transmitter and OLT receiver and two offline ONU transmitters, almost no penalty between all of subcarrier assignments was confirmed.
    Optical Fiber Communication Conference; 03/2014

Publication Stats

4k Citations
379.54 Total Impact Points


  • 1999–2015
    • Osaka University
      • • Division of Electrical, Electronic and Information Engineering
      • • Graduate School of Engineering
      Suika, Ōsaka, Japan
  • 2009–2010
    • Scuola Superiore Sant'Anna
      Pisa, Tuscany, Italy
    • National Institute of Information and Communications Technology
      • Advanced ICT Research Institute
      Edo, Tōkyō, Japan
  • 2006–2010
    • Università Degli Studi Roma Tre
      • Department of Applied Electronics
      Roma, Latium, Italy
    • Doshisha University
      Kioto, Kyōto, Japan
  • 2007
    • Osaka City University
      • Graduate School of Engineering
      Ōsaka, Ōsaka, Japan
  • 1998–2006
    • Oki Electric Industry Co., Ltd.
      Edo, Tōkyō, Japan
    • University of Duisburg-Essen
      • Zentrum für Halbleitertechnik und Optoelektronik
      Essen, North Rhine-Westphalia, Germany
    • Fujikura Ltd.
      Edo, Tōkyō, Japan
  • 2000
    • University of Western Australia
      • School of Electrical, Electronic and Computer Engineering
      Perth, Western Australia, Australia
  • 1997
    • Nagaoka University of Technology
      Нагаока, Niigata, Japan