Nippon Telegraph And Telephone Corporation Research Articles

Search of the Shortest Path in a Communication Network with Fuzzy Cost Functions

A communication network management system takes the measurements of its state variables at specific instants of time, considering them constant in the interval between two consecutive measurements. Nevertheless, this assumption is not true, since these variables evolve in real time. Therefore, uncertainty is inherent in the processing of the measurements during the intervals so that they cannot be efficiently managed using crisp variables. In this paper, we face this problem by modeling the communications network as a type-V fuzzy graph, where both the nodes and the links are described with precision, but the cost of each link is modeled as a triangular fuzzy number. Different fuzzy cost allocation functions and fuzzy optimization strategies are described and applied to the search for the shortest path between two nodes. An experimental study has been conducted using two representative networks: the backbone network of Nippon Telegraph and Telephone Corporation (NTT) and the National Science Foundation’s Network (NFSNET). In these networks, our fuzzy cost functions and strategies have been compared with the well-known crisp equivalents. The optimal search strategies are based on the proposed Fuzzy Dijkstra Algorithm (FDA), which is described deeply. The simulation results demonstrate that in all cases the fuzzy alternatives surpass or equal the crisp equivalents with statistically significant values. Specifically, the so-called Strategy 8 presents the best throughput, as it significantly exceeds the performance of all those evaluated, achieving a Global Mean Delivery Rate (GMDR) close to 1.

Explaining the Growth Potential of a Market Leader and Challenger: Evidence from Japan’s Telecommunications Services Industry

This study examines the growth potential of the market leader and market challenger in Japan’s telecommunications services industry. We focus on Nippon Telegraph and Telephone Corporation (NTT) and KDDI, the market leader and challenger (respectively) in terms of sales revenue, total assets, and market share. Following finance literatures, we use higher values of price–earnings ratio (P/E) and market-to-book-value-of-equity ratio (MV/BV) as the indicators of growth potential. High growth firms have the potential to outperform the overall market over a significant period of time providing a good investment opportunity for retail and institutional investors. This study uses financial data of the NTT and KDDI from the period between 2001 and 2016 and applies several regression models to examine the growth potential of the market leader and market challenger in Japan’s telecommunications services industry. Using the P/E and MV/BV as indicators of growth potential, we show that the market challenger’s growth potential is significantly higher than that of the market leader, even after controlling for firm size, liquidity, profitability, leverage, cash flow, and age.

Cross-sectional association of the number of neighborhood facilities assessed using postal code with objectively measured physical activity: the Saku cohort study.

Objectives The aim of this study was to examine the association between the number of neighborhood facilities that were assessed according to postal code and objectively measured physical activity by using an accelerometer in community-dwelling Japanese people.Methods The participants included 1,274 Japanese people aged 30-84 years from the Saku cohort study. As neighborhood facilities related to physical activity, we extracted information regarding train stations, supermarkets/convenience stores, postal offices/banks, hospitals/clinics, public offices/community centers, cultural facilities/public children's houses, parks, and sports facilities by using each participant's postal code from the online version of the iTownPages directory published by Nippon Telegraph and Telephone Corporation (NTT) and the official homepage of the Saku City Government Office. We measured each participant's physical activity level using an accelerometer, and calculated the average daily step count and the average weekly period of moderate-to-vigorous intensity (≥3 metabolic equivalents of tasks [METs]) physical activity. The association between two selected physical activity-related variables and the numbers of eight types of neighborhood facilities were analyzed by multivariate logistic regression analysis for people aged 30-64 years and for those aged over 65 years.Results On multivariate logistic regression analysis, meeting the 23 METs h/week of moderate-to-vigorous intensity physical activity was significantly and positively associated with the number of supermarkets/convenience stores in the neighborhood in both age groups. In addition, meeting the desired daily step count outlined in the Japanese National Health Promotion guidelines was positively related to the number of postal offices/banks for people aged over 65 years.Conclusion The results of this study suggest that a sufficient number of neighborhood facilities (i.e., stores, banks, and postal offices) is closely associated with the promotion of physical activity.

1MB card announced by NTT

A smart card with a memory capacity of 1MB and that complies with GlobalPlatform V2.1 specifications has been announced by Nippon Telegraph and Telephone Corporation (NTT). Visit www.compseconline.com for the latest computer security industry news

KTN crystal overtakes LiNbO3

Nippon Telegraph and Telephone Corporation (NTT) has successfully prepared KTN crystal (KTa1-xNbxO3) with the highest electro-optic effect ever reported. In addition, NTT has developed a film growth and a lithographic technique for KTN crystal that can be used to fabricate an optical waveguide with excellent optical transmission performance. Visit www.three-fives.com for the latest advanced semiconductor industry news

Exporting Telecommunications Regulation: The U.S.-Japan Negotiations on Interconnection Pricing

Since 1997, the U.S. government has attempted to use the World Trade Organization (WTO) agreement on telecommunications services as a vehicle for exporting American principles of telecommunications regulation to other nations. The United States took the position in 1997 that the WTO telecommunications agreement requires its signatory nations to follow the practices of the Federal Communications Commission (FCC) on telecommunications regulatory policy. Subsequently, the Office of the U.S. Trade Representative (USTR) has sought to influence, under the implicit threat of trade sanctions, Japan's domestic regulatory policy on the pricing of mandatory competitor access to the unbundled elements of the local network belonging to the operating companies of Nippon Telegraph and Telephone Corporation (NTT). In this Article, we examine the substantive difficulties of engrafting the FCC's interconnection policy onto the telecommunications marketplace of another nation. For more than six years, many American experts on telecommunications policy have disagreed whether American consumers have benefited from the very FCC policies that the USTR would have Japanese regulators emulate. The USTR's initiative appears to ignore that the transition to cost-oriented rates for interconnection and retail telecommunications services has been a difficult and unfinished process in the United States; that the cost models used by the FCC to set interconnection prices have significant deficiencies; that actual interconnection prices both within and outside the United States diverge considerably from the estimates of the FCC's cost models; that variations across countries in the prices of inputs have a significant effect on the costs of interconnection; and that, with respect to depreciation in particular, regulators treat this cost differently -- and, from an economic perspective, more reasonably -- in Japan than in the United States. Such substantive economic considerations suggest why the FCC's policy in this area has generated continuous litigation, including two Supreme Court cases since 1996, and consequently is too unresolved at this point in the American experience for the United States to force on its trading partners. Next, we ask whether the USTR has the detailed knowledge required to negotiate trade agreements on interconnection pricing. We question the propriety of using the USTR to influence the domestic regulatory policy of another country on a topic as complex as the efficient pricing of mandatory access to unbundled network elements. The USTR's power to formulate trade policy on this subject resides in officials who are unlikely to possess the economic expertise and resources necessary to evaluate the consumer-welfare implications of the policies that they would have Japan and other nations adopt. For these reasons, the USTR cannot credibly make the interconnection pricing policies of another nation a legitimate concern of U.S. trade policy.

Two-way time transfer through 2.4 Gb/s optical SDH system

An experiment to transfer time and frequency over 2.488 Gb/s synchronous digital hierarchy (SDH) systems using a 175-km commercial optical fiber cable has been set up by Communication Research Laboratory (CRL) and Nippon Telegraph and Telephone Corporation (NTT) Laboratory. We confirm that the frequency stability of the time comparison data is 10/sup -12//square root of tau for averaging times above 10 s. This stability equals that of the cesium frequency standard (HP5071A) used in this experiment. This means that the system can transfer the cesium frequency standard signal without deterioration. The time comparison resolution is of the order of 10/sup -11/ s (square root of time variance). The long-term stability of this system is expected to be better than 1 ns, including the temperature dependence of time information transmitters and receivers. Time comparison results agree well with GPS common-view results. Time accuracy is held to within 32 ns (this includes the anticipated time deviation caused by network elements).

Japanese telecommunications and NTT Corporation: a case in deregulation

The Japanese telecommunications industry has experienced dramatic changes over the past fifteen years. At the end of 1984, both Houses of Japan's Diet passed a set of bills aimed at privatising Nippon Telegraph and Telephone (NTT) Public Corporation and at opening up the market to new facility based carriers and large-scale value added providers. Although parallels can be drawn with the divestiture of AT&T in the USA, and the privatisation of British Telecom in the UK, the resulting degree of competition in the wake of the privatisation of NTT reflects the peculiar institutional and regulatory environment in which the different actors operate and interact. This paper provides the case of NTT in order to understand the changing dynamics of Japan's telecommunication industry and its impact on users, in the context of the global change in the telecommunications industry through deregulation, privatisation and liberalisation. This paper focuses on the major economic grounds for inducing change as well as the accompanying public policy aspects and the assessment of outcomes resting on diverging economic assumptions made by various interested parties in the process. Based on a regulatory economic and institutional analysis framework the paper examines the policy process, which culminated in the enactment of the telecommunication deregulation bills. It analyses the performance of the regulatory bodies such as the Ministry of Posts and Telecommunications (MPT) as well as the behaviour of NTT and non-NTT business interests. In this context, it addresses the following questions: what kind of economic prowess and institutional resources do the latter possess in order to compete effectively with NTT? Does NTT exercise its power over other companies through joint ventures? Has NTT's productive efficiency improved since privatisation? What is the extent of market power that has been exercised by the ex-monopolist? Overall, has the diversity of telecommunication services increased? How have the major telecoms embraced Internet based services? How and when did they engage in a global strategic alliance drive, and how did they position themselves in the international market? Among the major conclusions we cover: 1. Although MPT has laid the foundations for effective internal competition in various telecommunications markets, additional measures must be taken to promote competition even further and to allow Japanese carriers to catch up with competition in domestic and international fields; 2. MPT's posture towards the telecommunication industry is reminiscent of that of MITI in its early years, being overly regulatory and protectionistic through interventionist measures and frequent use of administrative guidance notices; 3. NTT's productive efficiency has substantially improved since the company was privatised and reflects the general improvement of the overall performance of the Japanese telecommunication industry; 4. Since privatisation and authorisation of new entrants, the range of telecommunication services has considerably widened; 5. NTT is still by far the most dominant player and is likely to maintain its market dominance over some long time to come, owing mostly to its extensive R&D investment and facilities. MPT's policy had put NTT far behind other national carriers like BT and the "Baby Bells" in the USA, as the Japanese regulatory environment has been lagging in deregulation. The Appendix contains relevant economic historical details.

The status of Nippon Telegraph and Telephone Corporation (NTT)

The Telecommunications Council, an advisory body of the Ministry of Posts and Telecommunications, presented on 29 February, 1996, a report on the status of NTT. The report proposes a divestiture of NTT, more deregulation, and a positive promotion of interconnection. This paper discusses the central conclusions of the report and provides a personal perspective on the future status of Japan's infocommunications industry.

NTT all-optical switch for ultra-fast processing

Nippon Telegraph and Telephone Corporation (NTT) has developed a surface reflection all-optical switch that uses a semiconductor super-lattice-structure for achieving an ultra-fast switching speed of 250 femtoseconds during which light can move only 0.075 mm in vacuum. The optical switch creates the world's fastest processing speed among semiconductor AND gate devices and features a high on/off ratio (extinction ratio) by large optical non-linearity. Since both signal and control light can be used in a wide range around 1.55-micron band for optical communications, the device can be used for time-division-multiplexing and wavelength-division-multiplexing communications.

Experiences of a software reuse project

Despite the large number of successful software reuse cases reported, there are more than a few negative views that reuse has not yet delivered as expected. This is because of the lack of consensus on the applicative conditions of reuse technology and the size of the benefits that can be expected. This article describes a software reuse project conducted at Nippon Telegraph and Telephone Corporation (NTT) Software Laboratories. Based on this experience, the article discusses such important aspects of software reuse as domain selection and analysis, impediments, incentives, and library tools. It concludes that successful software reuse requires the selection of appropriate domains, systematic development of reusable modules based on domain analysis, and the commitment of senior management.

The fiber-optic subscriber network in Japan

Nippon Telegraph and Telephone Corporation (NTT) has two primary aims regarding the installation of optical fiber cables for subscriber networks as the access network: to provide high-speed broadband services, and to provide narrowband services through optical fiber cables with subscriber-line multiplex technology. Thus, NTT is preparing an infrastructure to support the forthcoming B-ISDN subscriber networks. NTT has been developing technologies for implementing the full-scale construction of fiber-optic subscriber networks. The present article describes the deployment methodology for these networks, their current status, and plans for their future development.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Possible correlation between geoelectric potential change in Izu-Oshima Island and the earthquake swarm off the east Izu Peninsula, Japan

Since May, 1987, we have monitored the geoelectric potential change in Izu-Oshima Island using three long-span dipoles and NTT (Nippon Telegraph and Telephone Corporation) facilities. Occasionally anomalous potential changes, which were different from those induced by geomagnetic variations, have been observed. Their possible correlation with nearby seismic activity has been examined, with the result that the daily number of appearances of one type of anomalous potential change increased shortly before M > 5 events in all three earthquake swarms that have occurred since 1987 in the area off the east Izu Peninsula. Whether or not this correlation is valid and useful for prediction purpose is still not certain.

Recent advances in speech recognition technology at NTT laboratories

This paper introduces recent research activities on speech recognition, ranging from acoustic processing to linguistic processing, at NTT (Nippon Telegraph and Telephone Corporation) Laboratories. These include the proposal of ΔLSP parameters, hierarchical Δcepstral parameters, a new method of utilizing pitch information, automatic speaker adaptation techniques, robust HMM phoneme models, new training algorithms for neural networks, linguistic processing that uses syntactic and semantic knowledge, implementation of prototype continuous speech recognition systems, and an efficient text-independent speaker recognition algorithm.

NNT's research on acoustics for future telecommunication services

This paper describes research on Acoustics at Nippon Telegraph and Telephone Corporation (NTT) aiming at the realization of ideal tele-conference systems, which present participants with an acoustical virtual environment in which they experience the sensation of sharing the same space. Japanese research trends on ‘artificial reality’ and ‘tele-existence’ are mentioned in an appendix.

A Report from Mitaka--INS Model System Experiment Site

Nippon Telegraph and Telephone Corporation (NTT) is now promoting the Information Network System (INS) project, which is expected to be an important part of the basic infrastructure of the coming advanced information society. The purpose of INS is to provide various telecommunication services in a more economical and convenient manner by totally digitalized networks. The INS Model System-a pilot plant-was put into service in September 1984 in Mitaka City, which is adjacent to the Tokyo metropolitan area. This experiment is regarded as a "big" initial step toward the introduction of nationwide INS services. This paper reviews the system as well as service aspect of the experiment, where emphasis is laid on the actual operation status.