Keiichi Koyanagi

A reliable communication switching platform for quick service provisioning

The paper describes key technologies for establishing a highly reliable communication switching platform, particularly from the viewpoint of service provisioning. For this purpose, a mechanism called the NOSES (nonstop service enhanceable software) plug-in is proposed to ensure partial and dynamic modification of switching system software written in a high-level language without interrupting services. Considering the requirements of reliability, excellent software maintainability and easy operation, a precise mechanism for the modification or addition of software is defined. The relationships between the plug-in mechanisms and the dynamic properties modified software are analyzed and measures to extending applicability of the plug-in to executing switching systems are proposed. The NOSES plug-in is sufficiently applicable for many kinds of software modification and is expected to be used widely for such systems.

Hierarchically structured switching software

The paper details a layered hierarchical switching software structure with standardized logical interfaces. The authors also evaluated a pilot project to develop a subscriber switching system which implements ISDN call processing as well as POTS based on this concept. The layered interfaces, named S1 and S2, as well as the software structure are based on a concurrent object-oriented design approach in order to improve program maintainability and extendibility of building-block switching systems based on distributed processing. The approach focuses on quick service provisioning, reducing the total cost and separately developing each software layer. Therefore, the authors created a pilot project to test their assumptions, and compared the results with those of existing switching systems. They also discuss the applicability of this technology to the development of switching software.<<ETX>>

Dynamic program modification in the non-stop software extensible system (NOSES)

This paper presents a mechanism for partially modifying programs written in a high-level language without interrupting service of a switching or communication system. This mechanism is developed as a part of our plan for establishing the non-stop software extensible system (NOSES). This dynamic program modification method covers 100% of bug fixes and most minor feature additions. By considering the relationship of the modification mechanism and the characteristics of the modified program, we clarify conditions for preventing inconsistencies. We also examine the off-line system, the on-line OS kernel, and simple operation interface. Our mechanism is expected to be used widely in switching or communications systems.<<ETX>>

Boundary conditions between current mode and thermal mode second breakdown in epitaxial planar transistors

The dependence of the increase of current in a transistor of n+-p-n-n+type on time is investigated, and current mode second breakdown (CSB)and thermal mode second breakdown (TSB) are discriminated by the duration of the delay time before which second breakdown occurs. The boundary conditions between CSB and TSB in steady state are clarified. The critical voltage between CSB and TSB is determined by the width of the n layer, the immobile charge density of the n layer, and the injected electron density from the emitter to the n layer. The numerical analysis was in qualitative agreement with the experimental results.

Coordinator election using the object model in p2p networks

We propose the ACE (Adaptive Coordinator Election) platform that elects and relocates a coordinator adaptively in P2P networks. In collaborative applications, a coordinator mediates synchronization, consistency, sequencing and delay difference. However, it is difficult to decide a coordinator in applications used in P2P networks because of some characteristics of network, e.g., network instability, and differences in physical networks and devices for participants. The ACE platform elects and relocates a coordinator dynamically according to environmental metrics obtained from participants. Each metric has a priority and weight to allow a coordinator to be chosen according to the purpose of applications. We implemented our platform using the JXTA framework and tested it. The results show the feasibility of adaptive coordinator relocation in P2P networks.

Highly reliable on-line partial file modification for office data provisioning in "NOSES"

The paper presents an on-line software modification technique for use in office data provisioning in the Non-stop Service Enhancible Software (NOSES) system. High reliability and high software-maintainability needed for coping quickly and effectively with diverse customer demands related to system extension. The principal technique is the generation, modification, addition or deletion of office data related to the provision of physical components or logical resources in the executing system file. As an on-line partial program updating technique within the framework of the object oriented paradigm, mechanisms and operation procedure based on TMN are addressed in detail. These technologies are expected to be a basis for quick service provisioning in intelligent networks as well as in transport networks.

Orientation-Aware Indoor Localization Path Loss Prediction Model for Wireless Sensor Networks

There have been a large amount of research and interest in the area of ubiquitous and indoor location aware computing in the past decade. Among several proposed algorithms, fingerprint algorithm stands as one of the most accurate systems for localization. However, there is a lack of theoretical basis and understanding on the orientation of the user. This paper presents a model for orientation-aware indoor location tracking system using a Zigbee based protocol wireless sensor called Suns SPOT (Small Programmable Object Technology). Our experiment shows better accuracy in location tracking when orientation and attenuation factors are considered for the path loss prediction model than the traditional path loss model. Orientation-aware fingerprint algorithm is also examined in our experiment to have a basis of comparison on an empirical algorithm.

Applicability evaluation of service feature enhancement using the partial-file "plug-in" modification technique

This paper evaluates the applicability of the plug-in mechanism of the nonstop service enhanceable software (NOSES) platform. Plug-in is a dynamic partial-file modification technique that does not affect calls in service in a communication switching system. To apply plug-in program modification widely, the static and dynamic properties of the modified software must be considered. The evaluated applicability of plug-in based on case studies and field data was about 60% for service feature additions modifications. Thus, plug-in is effective for file maintenance of switching systems.

Study on a hybrid P2P based DNS

The traditional Domain Name System (DNS), which follows a hierarchical tree structure, is vulnerable to the targeted attacks. Several efforts were proposed to reconstruct DNS as a peer-to-peer network using Distributed Hash Tables (DHT) to improve the system robustness. However, the DHT-based DNS has significantly higher latencies in comparison with traditional DNS. In this paper, we propose a hybrid p2p based DNS by combining the hierarchical tree structure and the flat peer-to-peer structure. The results of simulation show that our system inherits strong robustness from DHT networks and high efficiency from traditional DNS. Even so, we should point out that our system still has lower efficiency compared with traditional DNS.

NOSES object-oriented switching software in C++-non-stop service enhanceable software

NOSES (non-stop service enhanceable software) has been developed applying techniques for realizing high reliability and a low cost by increasing the extent of software reusability. The paper describes these design techniques, in particular those involving the use of the C++ language. The reliability techniques described are call-recovering restart, call-recovering executing file-update, and on-line partial file modification. Software reusability is increased by using customizable platform software. In evaluating these techniques, the resulting increase in the number of instructions per call is estimated, and a method is proposed for measuring the increase in software reusability in an object-oriented design environment.