Takuya Tojo

NTT (Japan)

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Seisho Yasukawa

NTT (Japan)

Makoto Takizawa

Hosei University

Naoki Takaya

University of Tsukuba

Tomoya Enokido

Rissho University

Shingo Okada

NTT (Japan)

Hiromi Hirai

Fukui Prefectural University

Hiroki Baba

Hitotsubashi University

Shiku Hirai

NTT (Japan)

Seisuke Arai

NTT (Japan)

Kimihide Matsumoto

NTT (Japan)

Cooperative Institutions

NTT (Japan)

University of Electro-Communications

Future Earth

The University of Tokyo

Osaka University

Kyoto University

Kyushu University

Waseda University

Hosei University

Universitat Politècnica de Catalunya

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Research toward Realizing a Future Network Architecture

Deleted Journal (2018)

Seisho Yasukawa Hiroaki Sato Takeshi Hirota Takuya Tojo Kenichi Endo

In the 5G (fifth-generation mobile communications) and Internet of Things era, trends such as work on social infrastructure services, the explosive increase in the number of terminals and the amount of network traffic, and the use of artificial intelligence for smart devices and services will have a huge impact on networks, thereby increasing the need for new network architectures.This article analyzes the impact of these trends, examines network requirements, and introduces initiatives to develop the necessary architectures and key technological elements verified by proof of concept.

10.53829/ntr201806fa5

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Citations (4)

An Optimal Allocation Scheme of Database and Applications for Delay Sensitive IoT Services

2015 IEEE Global Communications Conference (GLOBECOM) (2021)

Akio Kawabata Takuya Tojo Bijoy Chand Chatterjee Eiji Oki

In the modern era, we need to deploy several functionalities either on central cloud servers or edge cloud servers to provide Internet of Things (IoT)-based services via a wide-area network. Typically a huge database and several non-real-time functions are deployed on the central cloud servers. On the other hand, real-time functions are deployed on edge cloud servers. For delay-sensitive services, this approach has an issue in completing the analysis with the latest information when the delay between the central and edge cloud servers is large. In this paper, we propose an allocation scheme of database and applications, which minimizes the delay from the latest update of the database to analyze the real-time data from IoT devices. In the proposed scheme, the delay is minimized considering two constraints of each server, which are maximum accommodating capacity of the IoT devices and whether the database function can be deployed. Numerical results observe that the proposed scheme reduces the delay of analysis compared to the conventional scheme. These results indicate that the proposed scheme can configure a low-delay network for delay-sensitive IoT services with data analysis.

Network delay

Database server

10.1109/globecom46510.2021.9685736

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Citations (6)

Multi-level reliability architecture for network slicing in metro networks

Takuya Tojo Tatsuya Matsukawa Shingo Okada Seisuke Arai Seisho Yasukawa

In the 5G era, it is expected that various services will be provided on network slices, which are virtualized network resources. Unlike the uniform service level provided in the current Internet, a network slice has to support multiple service levels for various types of services such as IP telephony, Internet-access and IoT/M2M. Because their requirements are quite different. IP telephony and Internet-access services require high reliability due to their essential role in communication. However, some IoT/M2M services do not necessarily require high reliability since they can tolerate temporary disconnection of networks due to their asynchronous communications. Instead of reliability, they require low-cost connectivity. Therefore, future networks have to support multi-level reliability required by services on a single physical network. In this paper, we propose a multi-level reliability architecture in optical cross-connect based metro networks to satisfy broad service requirements.

Telecommunications service

10.1109/lanman.2017.7972148

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Citations (3)

A passive method for estimating packet loss ratio using TCP Acknowledgment information.

IEICE Technical Report; IEICE Tech. Rep. (2011)

Takuya Tojo Kitada Hiroyuki Kimihide Matsumoto A. Kurokawa

Packet loss

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An Integrated Control of IP and Optical Network for Multi-grade Virtualized Networks

Takuya Tojo Shingo Okada Yoshiyuki Hirata Seisho Yasukawa

In the 5G era, it is expected that various services will be provided on network slices, which are virtualized network resources. A network slice has to support isolation capabilities and multi-grade performance capabilities such as ultra-low-latency and ultra-reliability due to the 5G requirements. IP and optical networks are also required to provide multi-grade property as a part of a network slice. Multi-layer SDN control is beneficial technology to realize the multi-grade network because an integrated control of IP and optical layers enables to combine network technologies across layers. It brings flexibility of service levels in terms of network performance and reliability. In this paper, we propose and demonstrate a multi-grade network which provides various types of virtualized network according to user requirements. Our platform is composed of IP and optical layers and ONOS-based SDN controller. We show on-demand provisioning of a virtualized network with a provisioning tracker that presents current status of provisioning in real-time.

Provisioning

10.1109/netsoft.2018.8459974

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Citations (1)

A study on Gateway Selection Method for Ultra-low Latency Services in IoT Era

IEICE Technical Report; IEICE Tech. Rep. (2015)

Hiromi Hirai Takuya Tojo Matsumoto Minoru Naoki Takaya

Gateway (web page)

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QoS control in group communication

Takuya Tojo Makoto Takizawa

This paper discusses a communication model to exchange multimedia messages in a group of multiple processes. Quality of Service (QoS) required by an application has to be supported. In traditional communication protocols like TCP and RTP, a process can reliably deliver messages to one or more than one process, i.e. one-way transmission. In the group communication, a process sends multimedia messages to multiple processes while receiving multimedia messages from multiple processes in a group. In addition, messages are required to be causally delivered. We discuss how to transmit multimedia messages to each destination process so as to satisfy QoS requirement.

Mobile QoS

10.1109/cw.2002.1180891

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QoS-based synchronous/asynchronous data transmission model in group communication

S. Itaya Takuya Tojo Tomoya Enokido Rozeta Miho Makoto Takizawa

A large-scale network like the Internet is composed of various types of communication channels. Here, each communication channel supports quality of service (QoS) which may be different from others. In group communication, each process sends a message to multiple processes while receiving messages from multiple processes. In addition, messages are required to be causally delivered. In order to realize the atomic and ordered delivery of messages, even if a process with enough QoS channel receives messages, the process has to wait to deliver the messages until another process with lower QoS channel receives the messages. Thus, multimedia data cannot be delivered to processes so as to satisfy the real-time constraint if a slower process is included in a group. In this paper, we discuss group communication protocols by which multimedia messages can be delivered to a process with same time constraint properties which satisfy QoS requirements of multimedia messages.

Mobile QoS

10.1109/aina.2004.1283884

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Citations (6)

Low-Latency Transport Protocol for Multipath Networks

IEICE Technical Report; IEICE Tech. Rep. (2015)

Takuya Tojo Hiromi Hirai Matsumoto Minoru Naoki Takaya

Multipath TCP

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A Study of Effectiveness Evaluation on Proposed Network Slicing methods toward IoT/M2M Era