There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Light-Emitting Diodes. (Monographs in Electrical and Electronic Engineering.) By A. A. Bergh and P. J. Dean. Pp. viii+591. (Clarendon: Oxford; Oxford University: London, 1976.) £22.

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Light-emitting diodes

Singular perturbations and order reduction in control theory - An overview

Singular perturbations and time-scale methods in control theory: Survey 1976-1983

A marriage of optical fibre fabrication technology and LSI microfabrication technology gave birth to fibre-matched silica waveguides on silicon: thick glass layers of high-silica-content glass are deposited on silicon by flame hydrolysis, a method originally developed for fibre preform fabrication. Silica channel waveguides are then formed by photolithographic pattern definition processes followed by reactive ion etching. This ‘high silica (HiS) technology’ offers the possibility of integrating a number of passive functions on a single silicon chip, as well as the possibility of the hybrid integration of both active and passive devices on silicon. This paper reviews the NTT HiS technology and its application to integrated-optic components such as optical beam splitters, optical switches, wavelength-division multi/demultiplexers and optical frequency-division multi/demultiplexers. The clear and simple waveguide structures produced by the HiS technology make it possible to design and fabricate these components with high precision and excellent reproducibility.

Silica waveguides on silicon and their application to integrated-optic components

A description is given of how burst transmission errors affect the quality of service (QOS) of telecommunication services such as data, group three and group four facsimile, and speech. The authors also present characteristics of transmission errors in real networks and show the requirements for in-service monitoring of quality for all services. A method is proposed for estimating error burst duration and error-free interval by in-service monitoring of bit interleaved parity (BIP) violations in a synchronous digital hierarchy (SDH) system. The in-service monitoring capability of the proposed method is also evaluated. >

In-service error monitoring capability in SDH network

PURPOSE:To make the constitution of the photo circuit easy and reduce insertion loss by branching the plural wavelengths transmitted by one optical guide by every one wavelength by the use of a hologram and further coupling the rays of the branched wavelengths separately to plural optical guides. CONSTITUTION:The hologram used here is manufactured by installing, e.g., output waveguides 2, 2', 2'' in the specified positions, emitting the rays having focuses (2a, 2b, 2c) at the ends of the waveguides in the backward direction when using the same as a coupler and sending the rays of the direction opposite from that when used as a coupler from a lens 6 as reference light onto a dry plate 5. The rays consisting of plural wavelengths lambda1, lambda2, lambda3 are sent to the above hologram 5 and the ray of the wavelength of lambda1 out of the rays being emitted is coupled into the optical guides 21, 2'1, 2''1 and lambda2 into the optical guides 22, 2'2, 2''2, the rest being coupled into the optical guides similarly disposed. This makes the constitution of the photo circuit easy and reduces the insertion loss of the branching and distributing device.

Photo branching and distributing device

One of the main issues of mobile IPv6 is handover latency that causes service disruption time. Although plenty of proposals significantly reduce the service disruption time, they suffer from redundant routing that causes packet misordering and excess bandwidth consumption. In this paper, we propose a new scheme that minimizes the redundant routing during the process of inter-domain handover by utilizing forwarding routers. Our proposed scheme consists of forwarding router discovery and proactive handover. Furthermore, we evaluate the proposed scheme in the view of packet misordering and bandwidth consumption, and clarify the effectiveness of the proposed scheme.

/pdf/inter-domain-handover-scheme-based-on-forwarding-router-3jixzurqym.pdf

Inter-domain handover scheme based on forwarding router discovery for mobile IP networks

Metropolitan areas need to be prepared for predicted epicentral earthquakes. During such a disaster, in order to disseminate mitigation information, such as restoration efforts and evacuation procedures, it is important to provide alternative communication systems. In this paper, we discuss the sustainable operation of a mitigation information network. First, we outline use cases and the requirements for a mitigation information network. Next we propose technologies to ensure continuous operation while retaining transmission quality. Using these methods, the system worked for 72 hours with a throughput of more than 2 Mbps. We checked the setup time during a disaster drill and surveyed persons from the disaster countermeasure offices.

Sustainable operation technologies for the mitigation information network in urban area

One of the main issues of mobile IPv6 is handover latency that causes service disruption time. Although plenty of proposals significantly reduce the service disruption time, they suffer from redundant routing that causes packet misordering and bandwidth consumption during the process of inter-domain handover. In this paper, we propose R-MIP, a routing-aware handover scheme for mobile IP, that minimizes the redundant routing during the process of inter-domain handover by utilizing forwarding routers. R-MIP consists of forwarding router discovery and proactive handover. We evaluate R-MIP in the view of packet misordering and bandwidth consumption, and clarify its efficiency. We also evaluate the impact of the forwarding router's capacity since routers have limited resources. By strategically locating forwarding routers, e.g. next to the router that has peering to another domain, the redundant routing caused by inter-domain handover will be efficiently suppressed.

/pdf/a-routing-aware-handover-scheme-for-mobile-ip-uh3pryc2iw.pdf

Koichi Asatani

Papers

In-service error monitoring capability in SDH network

Photo branching and distributing device

Inter-domain handover scheme based on forwarding router discovery for mobile IP networks

Sustainable operation technologies for the mitigation information network in urban area

A routing-aware handover scheme for mobile IP