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Harai H.,NICT
IEICE Transactions on Communications | Year: 2012

This paper presents recent progress made in the development of an optical packet and circuit integrated network. From the viewpoint of end users, this is a single network that provides both high-speed, inexpensive services and deterministic-delay, low-data-loss services according to the users' usage scenario. From the viewpoint of network service providers, this network provides large switching capacity with low energy requirements, high flexibility, and efficient resource utilization with a simple control mechanism. The network we describe here will contribute to diversification of services, enhanced functional flexibility, and efficient energy consumption, which are included in the twelve design goals of Future Networks announced by ITU-T (International Telecommunication Union - Telecommunication Standardization Sector). We examine the wavebandbased network architecture of the optical packet and circuit integrated network. Use of multi-wavelength optical packet increases the switch throughput while minimizing energy consumption. A rank accounting method provides a solution to the problem of inter-domain signaling for end-to-end lightpath establishment. Moving boundary control for packet and circuit services makes for efficient resource utilization. We also describe related advanced technologies such as waveband switching, elastic lightpaths, automatic locator numbering assignment, and biologically-inspired control of optical integrated network. © 2012 The Institute of Electronics, Information and Communication Engineers. Source


Nishinaga N.,NICT
IEICE Transactions on Communications | Year: 2010

The National Institute of Information and Communications Technology (NICT) vision and five network targets of research and development (R amp; D) of the NeW-Generation Network (NWGN) are presented in this letter. The NWGN is based on new design concepts that look beyond the next generation network (NGN). The NWGN will maintain the sustainability of our prosperous civilization and help resolve various social issues and problems by using information and communication technologies (ICTs). NICT's vision for NWGN is also presented in this letter. Based on this vision, 19 items concerning social issues and future social outlook are analyzed, and the functional requirements of the NWGN are extracted. The requirements are refined and categorized into five network targets that must be developed for realizing the vision. Copyright © 2010 The Institute of Electronics, Information and Communication Engineers. Source


Harai H.,NICT
2013 17th International Conference on Optical Networking Design and Modeling, ONDM 2013 | Year: 2013

An optical packet and circuit integrated (OPCI) network provides both high-speed, inexpensive services and deterministic-delay, low-data-loss services according to the users' usage scenarios, from the viewpoint of end users. From the viewpoint of network service providers, this network provides large switching capacity with low energy consumption, high flexibility, and efficient resource utilization with a simple control mechanism. This paper presents the recent progress made in the development of an OPCI network. We have developed OPCI nodes which are capable of layer 3 switching from/to Ethernet frame to/from optical packet in the optical packet edge part and burst-tolerant optical amplifier and optical buffer with optical fiber delays in 100Gbps optical packet switching part. The OPCI node achieves a packet error rate less than 10 4 and is used as node in a lab-network that has an access to the Internet. A distributed automatic control works in a control plane for the circuit switching part. An address search engine for further power reduction and network management system for shifting from R&D to operation are also described. © 2013 IFIP. Source


Harada H.,NICT
IEICE Transactions on Communications | Year: 2014

This paper summarizes the current status of regulations, standardization efforts and trials around the world regarding white space (WS) communications, especially television band WS (TVWS). After defining WS communication systems configurations and function and the categories of white space database, the TVWS regulations in United States, United Kingdom, and Japan are summarized. Then regarding status of standardization for TVWS devices, IEEE 802 and IEEE 1900 standards are summarized. Finally ongoing pilot projects and trials of WS communications in the world are summarized, and trends and future direction of research on WS communication systems are summarized. Copyright © 2014 The Institute of Electronics, Information and Communication Engineers. Source


Liu J.,Xidian University | Kawamoto Y.,Xidian University | Nishiyama H.,Xidian University | Kato N.,Xidian University | Kadowaki N.,NICT
IEEE Wireless Communications | Year: 2014

In LTE-Advanced networks, besides the overall coverage provided by traditional macrocells, various classes of low-power nodes (e.g., pico eNBs, femto eNBs, and relays) can be distributed throughout the macrocells as a more targeted underlay to further enhance the area's spectral efficiency, alleviate traffic hot zones, and thus improve the end-user experience. Considering the limited backhaul connections within lowpower nodes and the imbalanced traffic distribution among different cells, it is highly possible that some cells are severely congested while adjacent cells are very lightly loaded. Therefore, it is of critical importance to achieve efficient load balancing among multi-tier cells in LTEAdvanced networks. However, available techniques such as smart cell and biasing, although able to alleviate congestion or distribute traffic to some extent, cannot respond or adapt flexibly to the real-time traffic distributions among multi-tier cells. Toward this end, we propose in this article a device-to-device communicationbased load balancing algorithm, which utilizes D2D communications as bridges to flexibly offload traffic among different tier cells and achieve efficient load balancing according to their real-time traffic distributions. Besides identifying the research issues that deserve further study, we also present numerical results to show the performance gains that can be achieved by the proposed algorithm. © 2014 IEEE. Source

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