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[Author] Toshinori TSUBOI(16hit)

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  • Economical Unified Platform Using ATM Transport System to Carry both STM and ATM Signals

    Ryoichi IWASE  Koji WATANABE  Yoshihiko UEMATSU  Hiroshi OHTA  Mitsugu HIRAKI  Yukiharu KANAYAMA  Toshinori TSUBOI  

     
    PAPER-Switching and Communication Processing

      Vol:
    E83-B No:2
      Page(s):
    353-361

    This paper describes the roles and benefits of an ATM transport network composed of ATM transport systems, such as ATM cross-connect systems and/or ATM add-drop multiplexers. The ATM transport network is an economical way of providing the ATM public network and a virtual path service for enterprise users. This paper exemplifies the effectiveness of a VP grooming function in the ATM transport system by comparing it to the network costs with direct fiber connection, an alternative to VP grooming. Main and junction module architecture for the ATM cross-connect system is proposed to realize an economical network that supports small to large traffic. For implementing a large-scale cross-connect switch, a cell congestion control method that employs re-arrangement control and a concentration network is proposed. Implementation of multiple service classes and VP protection switching in the ATM cross-connect system are mentioned. We also describe an SDH signal transmission method based on ATM cells, that offers a cost effective and reliable transport network.

  • Development of Gigabit Ethernet Optical Switched Access Network System Using Optical Packet Switches

    Takumi NOMURA  Hiromi UEDA  Takashi KURIYAMA  Toshinori TSUBOI  Hiroyuki KASAI  

     
    PAPER

      Vol:
    E91-B No:8
      Page(s):
    2485-2493

    We have already proposed a Gigabit Ethernet-Optical Switched Access Network (GE-OSAN) architecture that realizes longer transmission distances and achieves higher security than the conventional Passive Optical Network (PON). To confirm the technical feasibility of the architecture, we introduce here a GE-OSAN prototype system for downstream transmission. We present the Optical Switching Module (OSM), which uses (Pb,La)(Zr,Ti)O3 (PLZT) optical packet switches, and show that it realizes switching within 10 ns of the designed position in the Inter-Frame Gap (IFG). We also introduce an Optical Network Unit (ONU) with optical burst receiver that uses off-the-shelf commercial devices to reduce its cost; two types of an optical to electrical signal (O/E) converter are implemented for performance comparison. After testing both of them, we select the one that satisfies our acquisition time requirement of 64 ns.

  • Discovery Method for Ethernet Optical Switched Access Network

    Hiromi UEDA  Toshinori TSUBOI  Hiroyuki KASAI  

     
    PAPER

      Vol:
    E93-B No:2
      Page(s):
    263-271

    An Optical Line Terminal (OLT) needs to find and register newly connected Optical Network Units (ONUs) in the proposed Ethernet Optical Switched Access Network (E-OSAN) as well as the Ethernet Passive Optical Network (E-PON). In this discovery process, OLT measures round trip time (RTT) between OLT and each ONU and then assigns a Logical Link Identification (LLID) to each ONU. For E-OSAN, the conventional discovery method takes up to N discovery periods for OLT to register all ONUs, where N denotes the number of switch ports of the Optical Switching Module (OSM). This paper proposes an efficient method that completes discovery in just one period. This paper also evaluates the maximum ranging completion time of the proposed discovery method in a comparison with E-PON.

  • A Failure-Resistant ATM Transport Method for the Transmission of High-Quality Real-Time Signals

    Yukiharu KANAYAMA  Kazuhiro FUJIHARA  Toshinori TSUBOI  

     
    PAPER-Traffic Control and Network Management

      Vol:
    E83-B No:2
      Page(s):
    293-298

    This paper proposes a new failure-resistant ATM transport method for real-time applications (FRAT-RA). This method can prevent not only cell loss but also cell delay variation (CDV) even when a network failure occurs. First, a general overview of the existing fault-resistant method is briefly described and its problems for real-time applications are discussed. Next, the proposed FRAT-RA method is described in detail. Finally, evaluation results on the CDV of FRAT-RA and its QoS improvement are presented. The results show that failure-resistant and high-quality transmission of real-time signals can be achieved with FRAT-RA.

  • ATM VP-Based Economical Transport Network Architecture for Multi-Reliability and Broadband Integrated Service Infrastructure

    Yoshihiko UEMATSU  Hiroshi OHTA  Ryoichi IWASE  Koji WATANABE  Masayuki MATSUDA  Seiichi TAKAGI  Toshinori TSUBOI  

     
    PAPER-Traffic Control and Network Management

      Vol:
    E83-B No:2
      Page(s):
    299-306

    The ATM Virtual Path(VP)-based transport network is a candidate for the future multi-reliability and broadband integrated service infrastructure. This paper compares the performance attributes of the VP transport network with those of the conventional SDH network and future optical path-based transport network. This paper shows that the VP-based network is superior in terms of path-grooming efficiency and connection capability, and will still play an important role when WDM technologies are introduced to carrier networks. This paper also describes the recently fabricated VP Cross Connect(VP-XC) system configuration and the VP Automatic Protection Switching(APS) performance of the XC.

  • Nonorthogonal CSK/CDMA with Received-Power Adaptive Access Control Scheme

    Nobuyoshi KOMURO  Hiromasa HABUCHI  Toshinori TSUBOI  

     
    PAPER-Communication Theory

      Vol:
    E91-A No:10
      Page(s):
    2779-2786

    The measurements for Multiple Access Interference (MAI) problems and the improvement of the data rate are key issues on the advanced wireless networks. In this paper, the nonorthogonal Code Shift Keying Code Division Multiple Access (CSK/CDMA) with received-power adaptive access control scheme is proposed. In our system, a user who is ready to send measures the received power from other users, and then the user decides whether to transmit or refrain from transmission according to the received power and a pre-decided threshold. Not only overcoming the MAI problems, but our system also improve the throughput performance. The throughput performance of the proposed system is evaluated by theoretical analysis. Consequently, the nonorthogonal CSK/CDMA system improves by applying received-power adaptive access control. It was also found that the throughput performance of the nonorthogonal CSK/CDMA system is better than that of the orthogonal CSK/CDMA system at any Eb/N0. We conclude that the nonorthogonal CSK/CDMA system with received-power adaptive access control scheme is expected to be effective in advanced wireless networks.

  • Performance Improvement for IEEE 802.11 Distributed Coordination Function (DCF)

    Kiyoshi TAKAHASHI  Toshinori TSUBOI  

     
    PAPER-Wireless Communication Technologies

      Vol:
    E89-B No:5
      Page(s):
    1605-1612

    The medium access control (MAC) protocol is the main determiner of the system throughput in Wireless Local Area Networks (WLANs). The MAC technique of the IEEE 802.11 protocol is called Distributed Coordination Function (DCF). DCF is based on a carrier sense multiple access with collision avoidance (CSMA/CA) scheme with binary slotted exponential backoff. Each station generates a random backoff interval before transmitting a packet to minimize the probability of collision with packets being transmitted by other stations. However, when the number of stations increases, the system throughput decreases. This paper proposes a new backoff algorithm that uses finish tags. The proposed algorithm uses the finish tag of each station to control the backoff intervals so as to improve system throughput. The finish tag is updated when a packet reaches the front of its flow, and it is attached to the packet just prior to transmission. When a station receives packets with older finish tags, its backoff time interval is increased. For this reason, the more the stations there are, the larger the backoff time becomes. Simulations confirm that the proposal improves system throughput of a IEEE 802.11 network under saturation conditions.

  • ATM Superpacket Network for Responsive Mega-Data Delivery Service

    Hisaya HADAMA  Takashi SHIMIZU  Masayoshi NABESHIMA  Toshinori TSUBOI  

     
    PAPER-Communication Networks and Services

      Vol:
    E81-B No:5
      Page(s):
    1041-1050

    This paper shows new techniques to construct a service network which realizes responsive large-size data transmission for widely distributed mass users. We set our service target as transferring mega-byte scale data from a server to a client within one second. ATM is recognized as a powerful technology with which to construct a wide area network infrastructure that supports multiple bandwidth services. Our fundamental principles in developing such a service network are as follows: a) The bandwidth sharing mechanism should be of the best effort rather than resource reservation type. This is because only best effort schemes remove bandwidth reservation/release overheads. b) More than a 100 Mb/s data transmission rate should be supported throughout data transfer. c) Data transfer should be completed within the round trip through the network (or a small multiple thereof). This is necessary to minimize the effect of transmission time in large-scale networks. d) The user network interface should be simply defined to allow independent evolution of both network and terminal technologies. e) Congestion control must block the spread of congestion within the network. Based on these principles, we propose the "ATM superpacket network (ATM-SN)" as the service network to realize our target service. Key techniques are as follows. (1) Best effort and cut-through transmission of superpackets whose length reaches ten mega-bytes. (2) Network nodes with large-capacity buffer memories that prevent superpacket collisions. (3) Superpacket admission control at network nodes to prevent cell overflow. (4) Superpacket-based congestion control. Our proposal assumes the existence of a high-quality ATM infrastructure that can provide a large bandwidth with a high-quality DBR cell transmission capability (cell loss ratio is less than 10E-7) and small bit error ratios (less than 10E-10). First, we detail our proposal of the ATM-SN. Next, we propose a superpacket-based congestion control technique coupled with a simple Usage Parameter Control function. We then show the evaluation results of those key techniques to confirm the effectiveness of the superpacket network.

  • A Novel MAC Protocol for QoS in Ad Hoc Wireless Networks

    Kiyoshi TAKAHASHI  Takuya TERASAWA  Toshinori TSUBOI  

     
    PAPER-Wireless Communication Technologies

      Vol:
    E91-B No:10
      Page(s):
    3297-3306

    We propose a medium access control (MAC) protocol for real-time applications in one-hop ad-hoc wireless networks. It is a distributed mechanism that takes account of priority and has a bounded packet delay. Nodes use energy signals to contend for the right to access the channel. Nodes, which have a packet to transmit, send energy signals or listen to the channel based on their binary frame. The node that has sent energy signals and has not heard any energy signals wins the right to access the channel. We use two schemes to determine the binary frame: at the beginning of a session, a node determines it based on its priority level and a random number; after successful transmission, based on a count of successful packet transmissions. With the first scheme, in order to reduce contention losses, the nodes that had won the right to access the channel but failed in transmission have priority over the other nodes. With the second scheme, the node that has the largest count, the one that has been waiting the longest, can send a packet without risking collision. The protocol provides higher probability of successful transmission and a limit on maximum packet delay. An analysis of the protocol provides conditions for the protocol to be stable. We evaluate the performance of the proposed protocol using simulations of a network with a mixed population of data and real-time nodes, whose source is constant bit rate (CBR) and a two state Markov on/off process.

  • Interference Drop Scheme: Enhancing QoS Provision in Multi-Hop Ad Hoc Networks

    Chang-Yi LUO  Nobuyoshi KOMURO  Kiyoshi TAKAHASHI  Hiroyuki KASAI  Hiromi UEDA  Toshinori TSUBOI  

     
    PAPER-Network

      Vol:
    E93-B No:8
      Page(s):
    2088-2096

    Ad hoc networking uses wireless technologies to construct networks with no physical infrastructure and so are expected to provide instant networking in areas such as disaster recovery sites and inter-vehicle communication. Unlike conventional wired networks services, services in ad hoc networks are easily disrupted by the frequent changes in traffic and topology. Therefore, solutions to assure the Quality of Services (QoS) in ad hoc networks are different from the conventional ones used in wired networks. In this paper, we propose a new queue management scheme, Interference Drop Scheme (IDS) for ad hoc networks. In the conventional queue management approaches such as FIFO (First-in First-out) and RED (Random Early Detection), a queue is usually managed by a queue length limit. FIFO discards packets according to the queue limit, and RED discards packets in an early and random fashion. IDS, on the other hand, manages the queue according to wireless interference time, which increases as the number of contentions in the MAC layer increases. When there are many MAC contentions, IDS discards TCP data packets. By observing the interference time and discarding TCP data packets, our simulation results show that IDS improves TCP performance and reduces QoS violations in UDP in ad hoc networks with chain, grid, and random topologies. Our simulation results also demonstrate that wireless interference time is a better metric than queue length limit for queue management in multi-hop ad hoc networks.

  • Proposal of Novel Optical Burst Signal Receiver for ONU in Optical Switched Access Network

    Hiromi UEDA  Keita HAMASAKI  Takashi KURIYAMA  Toshinori TSUBOI  Hiroyuki KASAI  

     
    PAPER-Fiber-Optic Transmission for Communications

      Vol:
    E95-B No:3
      Page(s):
    819-831

    To realize economical optical burst signal receivers for the Optical Network Unit (ONU) of the Ethernet Optical Switched Access Network (E-OSAN), we previously implemented optical burst receivers with AC-coupling and DC-coupling using off-the-shelf components, and showed that the former offers better performance. This paper proposes a new optical burst signal receiver that uses the transfer function, Gn(s) = 1-Hn(s), where Hn(s) denotes a Bessel filter transfer function of order n. We also present a method for designing the proposed receiver and clarify that it has better performance than the conventional AC-coupling one. We then present an LCR circuit synthesis of Gn(s), which is necessary to actually implement a burst receiver based on the proposal.

  • An Efficient ATM Network Architecture with a Dynamic Bandwidth Estimation and Allocation Scheme

    Atsushi HORIKAWA  Yasuyuki OKUMURA  Toshinori TSUBOI  

     
    PAPER-Communication Networks and Services

      Vol:
    E81-B No:8
      Page(s):
    1674-1680

    An important issue in accelerating the introduction of ATM networks is to offer more convenient access to the customer and a more efficient ATM system architecture. Regarding the first point, ATM network customers are currently inconvenienced by the need to declare traffic parameters, such as peak and average cell rates to the network provider before using the network. However, it is difficult for a customer to predict traffic parameters. This paper proposes a new ATM system with a dynamic bandwidth estimation and allocation scheme. This eliminates the need for traffic parameter declaration, and realizes more convenient ATM service. The proposed ATM system is a ring network. Bandwidth estimation is carried out by the "Network Server" located on the ring network. The estimation is achieved by observing the parameters closely related to media access control (MAC) protocols of LAN/MAN systems. Based on an estimation of customer traffic, the "Network Server" effectively allocates the bandwidth to each customer. This realizes a more efficient ATM network.

  • Efficient TCP with Pacing for Multi-Hop Ad Hoc Networks

    Chang-Yi LUO  Nobuyoshi KOMURO  Kiyoshi TAKAHASHI  Toshinori TSUBOI  

     
    PAPER-Network

      Vol:
    E93-B No:3
      Page(s):
    581-589

    In multi-hop ad hoc wireless networks, it is well known that TCP suffers severe performance degradation. This is due to its window-based approach to transmission control, which injects traffic bursts into the network. These bursts increase the frequency of contention in the MAC layer which forces the dropping of some packets. This paper proposes an efficient TCP with pacing, Paced TCP, to alleviate MAC contention and thus achieve better performance than the traditional TCP variants. Our design approach is a TCP that probe the available bandwidth of the network without affecting the stability of the network. Simulations show that Paced TCP not only achieves better performance but is also friendly to UDP traffic.

  • Design of Optical Switching Module for Gigabit Ethernet Optical Switched Access Network

    Takumi NOMURA  Hiromi UEDA  Chikashi ITOH  Hiroaki KUROKAWA  Toshinori TSUBOI  Hiroyuki KASAI  

     
    PAPER-Fiber-Optic Transmission for Communications

      Vol:
    E89-B No:11
      Page(s):
    3021-3031

    This paper introduces the design of an Optical Switching Module (OSM) for our newly proposed Gigabit Ethernet Optical Switched Access Network (GE-OSAN) architecture that uses the Multi-Point Control Protocol (MPCP), defined in IEEE 802.3ah. We outline the GE-OSAN architecture to clarify OSM's role in the network. We offer an OSM configuration that has the basic functions needed to realize downstream and upstream high-speed data services in GE-OSAN. We clarify the OSM optical switching time that allows GE-OSAN to achieve the same throughput as GE-PON. Our survey of currently available optical switches identifies the optical packet switches that can meet this switching time requirement. We evaluate OSM insertion loss with these switches. We propose an OSM configuration that has a regeneration function as well as the basic ones to realize wider network configurations that can lead to a reduction in overall system costs. In addition, we present OSM configurations that have broadcast and multicast functions as well as the basic ones so that GE-OSAN can support broadcast and multicast video services to equal and exceed GE-PON.

  • Technical Features and Approaches on Optical Access Networks for Various Applications Open Access

    Toshinori TSUBOI  Tomohiro TANIGUCHI  Tetsuya YOKOTANI  

     
    INVITED PAPER-Fiber-Optic Transmission for Communications

      Pubricized:
    2017/03/22
      Vol:
    E100-B No:9
      Page(s):
    1606-1613

    This paper describes optical access networks focusing on passive optical network (PON) technologies from a technical point of view. Optical access networks have been applied to fiber-to-the-home as a driving force of broadband services and their use will continue growing in the near future. They will be applied as an aggregate component of broadband wireless networks. This paper also addresses solutions for their application.

  • New Optical Access Network Architecture Using Optical Packet Switches

    Hiromi UEDA  Takumi NOMURA  Kunitetsu MAKINO  Toshinori TSUBOI  Hiroaki KUROKAWA  Hiroyuki KASAI  

     
    PAPER-Fiber-Optic Transmission for Communications

      Vol:
    E89-B No:3
      Page(s):
    724-730

    This paper proposes a new optical access network architecture that differs from those of conventional Point-to-Point (PP) and Passive Optical Networks (PON). The proposed architecture, Optical Switched Access Network (OSAN), uses Optical Switching Modules (OSMs) that connect an Optical Line Terminal (OLT) to Optical Network Units (ONUs) in a virtual point to point configuration so that it offers the merits of both PP and PON while overcoming their demerits. Each OSM optically switches packets of variable length one by one under electrical control. To allow the elimination of optical buffers from OSM, OSAN uses the Multi-Point Control Protocol (MPCP) defined in IEEE 802.3ah. We evaluate the transmission distances between OLT and ONUs, and consider a network synchronization scheme and discovery mechanism that supports MPCP.