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Masahito TOMIZAWA Yoshiaki YAMABAYASHI
This paper proposes a novel representation scheme for self-healing networks, and estimates the performance of restoration algorithms in terms of survivability. This representation is based on that of ring networks. For an arbitrary topology, the network is partitioned into ring sub-networks which are independent of each other, and we consider an extended network constructed by the concatenation of the ring sub-networks. After the statement of the general case, examples of a self-healing ring and a Digital Cross-connect System(DCS)based network are described.
Hiroji MASUDA Masahito TOMIZAWA Yutaka MIYAMOTO Kazuo HAGIMOTO
We have clarified both theoretically and experimentally the basic performance of distributed Raman amplification (DRA) transmission systems in trunk networks with DSF or SMF spans with limited pump power where the pump power is limited by practical considerations. The gain and noise characteristics of a fiber span with splice loss are accurately determined by employing three approximation models. A novel pumping scheme called band enhanced pumping (BEP) is proposed that improves the DRA gain and optical SNR (OSNR) by 1.5 and 0.55 dB, respectively, compared with those of a conventional pumping scheme, under typical system conditions. We show that a DRA system with a DSF span has OSNRs that are 2.1 and 2.9 dB higher than those of a system with an SMF span at limited pump powers of 200 and 400 mW, respectively, as typical examples.
Shoichiro KUWAHARA Kazushige YONENAGA Yutaka MIYAMOTO Yoshiaki KISAKA Kenji SATO Akira HIRANO Takashi ONO Akihiko MATSUURA Masahito TOMIZAWA Tomoyoshi KATAOKA Yasuhiko TADA Hiromu TOBA Kazuo HAGIMOTO Nobuhiro HIRAYAMA Hirotaka ASAI
The first results of a field trial held in November 2000, of 1 Tbit/s (25 43 Gbit/s) unidirectional Wavelength Division Multiplexing (WDM) transmission, are presented. The field trial used a 43 Gbit/s/channel Optical Transport Network (OTN) interface prototype and standard Single Mode Fibers (SMFs) installed in the Nara area network of NTT West Corporation. The features of this field trial include the accommodation of multiple services such as GbE, STM-16 and OC-48. Error free operation of 25 channels with 100 GHz spacing over a 91 km standard SMF with Forward Error Correction (FEC) is verified for STM-16. A DV stream over IP over Ethernet as a tributary channel was also successfully transmitted.
Takashi ONO Masahito TOMIZAWA Tomoyoshi KATAOKA Akihiko MATSUURA Yoshiaki KISAKA Yutaka MIYAMOTO Kazushige YONENAGA Shoichiro KUWAHARA Yasuhiko TADA Hiromu TOBA
This paper describes the design concept and realized functions of the first Optical Transport Network (OTN) based 43 Gbit/s line terminal. The system requirements of new generation networks are provided, and the functions needed in this line terminal are obtained from the requirements. The line terminal deploys Time Division Multiplexing (TDM) to handle client signals, and provides transparent high quality multiple services such as SONET/SDH and Gigabit Ethernet. The configuration and features of the actually fabricated system are described.
Seiji OKAMOTO Kazushige YONENAGA Kengo HORIKOSHI Mitsuteru YOSHIDA Yutaka MIYAMOTO Masahito TOMIZAWA Takeshi OKAMOTO Hidemi NOGUCHI Jun-ichi ABE Junichiro MATSUI Hisao NAKASHIMA Yuichi AKIYAMA Takeshi HOSHIDA Hiroshi ONAKA Kenya SUGIHARA Soichiro KAMETANI Kazuo KUBO Takashi SUGIHARA
We describe a field experiment of flexible modulation format adaptation on a real-time 400Gbit/s/ch DSP-LSI. This real-time DSP-LSI features OSNR estimation, practical simplified back propagation, and high gain soft-decision forward error correction. With these techniques, we have successfully demonstrated modulation format allocation and transmission of 56-channel 400Gbit/s-2SC-PDM-16QAM and 200Gbit/s-2SC-PDM-QPSK signals in 216km and 3246km standard single mode fiber, respectively.
Masahito TOMIZAWA Yoshiaki KISAKA Takashi ONO Yutaka MIYAMOTO Yasuhiko TADA
This paper proposes a statistical design approach for Non-Return-to-Zero (NRZ) 40 Gbit/s systems with Forward Error Correction (FEC); the approach considers Polarization Mode Dispersion (PMD). We introduce a fluctuating PMD emulator to experimentally clarify FEC performance in PMD-limited systems. By using the proposed design approach, and considering the FEC relaxation effect on PMD, the maximum transmission distance of an NRZ 40 Gbit/s system without PMD compensation is estimated as several hundreds of km depending on the number of cable concatenations per link and the probability threshold of system acceptance.
Masahito TOMIZAWA Shinji MATSUOKA Yoshihiko UEMATSU
This paper provides an architectural study of optical multiple-ring trunk-transmission networks using high-speed Time Division Multiplexing (TDM), and proposes two algorithms for distributed control environments. We propose a path-setup algorithm that uses Token protocol over Section Overhead (SOH) bytes, by which network-nodes communicate with each other to reserve bandwidth. A classified path restoration algorithm is also proposed that offers 3 path classes in terms of restoration performance. Class A paths, the most reliable, never lose any bit even against unpredictable disasters. They are realized by path-duplication at the source node, route diversity,and hitless switching at the destination node. Class B paths are restored by re-routing, where the original path-setup algorithm is reused. Class C paths are the most economical because a failed path is restored by maintenance action.
Akihide SANO Yutaka MIYAMOTO Tomoyoshi KATAOKA Masahito TOMIZAWA Kazuo HAGIMOTO
This paper proposes an automatic dispersion equalization system using extracted clock power monitoring in order to facilitate the field installation of high-speed time-division multiplexed (TDM) systems over existing fiber cables. The proposed scheme adjusts the dispersion of a variable-dispersion equalizer so as to maximize the extracted clock power level. This scheme has a simple configuration, needs no communication channel between the transmitter and the receiver, and is sensitive to parameters such as initial chirping and fiber input power. The clock power dependence on the fiber dispersion is theoretically analyzed assuming that the return-to-zero (RZ) format is used and that pulse broadening is small compared to the bit duration. We show that the clock power is maximized when the dispersion-induced waveform distortion is minimized. Numerical simulations show that the proposed scheme is effective with the non-return-to-zero (NRZ) format and for the case that the optimum total dispersion deviates from zero due to initial and/or self-phase modulation (SPM)-induced chirping. The operation of the proposed automatic equalization system is experimentally confirmed in 20-Gbit/s transmission using both RZ and NRZ formats. Moreover, a 40-Gbit/s transmission experiment over 200 km of dispersion-shifted fiber (DSF) is successfully demonstrated using the proposed equalization scheme.
Masahito TOMIZAWA Yoshiaki YAMABAYASHI Nobuyuki KAWASE Yukio KOBAYASHI
This paper provides an architectural study of optical ring trunk-transmission networks using either Time Division Multiplexing (TDM) or Wavelength Division Multiplexing (WDM). A timeslot arrangement algorithm for distributed controlled TDM rings is proposed that minimizes the number of slots (wavelengths) required in bi-directional ring networks. This algorithm is applied in a straightforward manner to wavelength arrangement in WDM ring networks. The technique, characterized by timeslot (or wavelength) conversion, realizes common add/drop procedures in all Add/Drop Multiplexers (ADMs) when they are connected logically in a mesh topology. A self-healing algorithm is also proposed for network restoration. It offers good performance in terms of protection line-capacity, restoration delay, and survivability against multiple failures.
Yutaka MIYAMOTO Kazushige YONENAGA Akira HIRANO Masahito TOMIZAWA
This paper describes the impact of novel Return-to-Zero (RZ) formas for dense wavelength-division-multiplexing (DWDM) transport systems using 40-Gbit/s channels. The introduction of phase modulation using phase reversal in RZ-signal encoding process dramatically reduces its optical modulation bandwidth and enhances its tolerance against fiber nonlinearities. By using proposed RZ formats, DWDM transmission performance in 40-Gbit/s channels can be enhanced with high spectral efficiency compared with conventional Non-Return-to-Zero (NRZ) and Return-to-Zero (RZ) formats.
Fukutaro HAMAOKA Takeo SASAI Kohei SAITO Takayuki KOBAYASHI Asuka MATSUSHITA Masanori NAKAMURA Hiroki TANIGUCHI Shoichiro KUWAHARA Hiroki KAWAHARA Takeshi SEKI Josuke OZAKI Yoshihiro OGISO Hideki MAEDA Yoshiaki KISAKA Masahito TOMIZAWA
We demonstrated 1-Tb/s-class transmissions of field-deployed large-core low-loss fiber links, which is compliant with ITU-T G.654.E, using our newly developed real-time transponder consisting of a state-of-the-art 16-nm complementary metal-oxide-semiconductor (CMOS) based digital signal processing application-specific integrated circuit (DSP-ASIC) and an indium phosphide (InP) based high-bandwidth coherent driver modulator (HB-CDM). In this field experiment, we have achieved record transmission distances of 1122km for net data-rate 1-Tb/s transmission with dual polarization-division multiplexed (PDM) 32 quadrature amplitude modulation (QAM) signals, and of 336.6 km for net data-rate 1.2-Tb/s transmission with dual PDM-64QAM signals. This is the first demonstration of applying hybrid erbium-doped fiber amplifier (EDFA) and backward-distributed Raman amplifier were applied to terrestrial G.654.E fiber links. We also confirmed the stability of signal performance over field fiber transmission in wavelength division multiplexed (WDM) condition. The Q-factor fluctuations respectively were only less than or equal to 0.052dB and 0.07dB for PDM-32QAM and PDM-64QAM signals within continuous measurements for 60 minutes.