The accommodation of machine-to-machine (M2M) terminals in mobile networks is important; therefore, future network architecture supporting M2M services is of intense interest to mobile network operators. We propose an implemental architecture of a virtualized evolved packet core (vEPC) to accommodate M2M services. The proposed architecture deploys dedicated vEPCs based on the functional requirements of services. Every vEPC is optimized by eliminating EPC components or replacing standardized interface protocols with internal application interworking. We confirm the validity of the proposed architecture by experimentally evaluating CPU resource consumption. We also confirm that the proposed architecture reduces CPU time consumption by up to 27% by reducing signaling message volume, and improved performance is observed independently with M2M terminal mobility or communication characteristics.

Core network

10.1109/wcnc.2015.7127743

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Citations (21)

<b>Policies and Tax Systems for Regulating Vacant Houses</b>

Urban and Regional Planning Review (2022)

Hiroki Baba Ana Ruiz-Varona Yasushi Asami

An increased number of vacant houses have been found in Spain and Japan in recent years, specifically in de-growth areas. This article explores the extent to which these two countries have promoted policies and tax systems to counteract this phenomenon. According to existing research, tax systems sometimes work as factors that encourage the increase of vacant houses. However, the systems in the two countries in question are dissimilar. We apply the divergence perspective for developing housing system typologies, and analyse vacant housing policy measures from the administrative perspective of Japan’s centralised unitary and Spain’s decentralised unitary state.

Divergence (linguistics)

Phenomenon

Tax Policy

10.14398/urpr.9.153

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The relationship of single-family detached house prices with neighborhood walkability and disaster risk

PLoS ONE (2023)

Hongjik Kim Hiroki Baba Chihiro Shimizu Kimihiro Hino

People's preferences regarding their neighborhood environment can vary depending on their socioeconomic status and the cities where they live. This study aims to discern the relationship between neighborhood environment factors and single-family detached house sales by sale price and by central and noncentral cities. We analyzed sale prices in the Tokyo Metropolitan Area from 2015 to 2020. The neighborhood environment was assessed using flood/sediment risk and neighborhood walkability measured by net residential density, intersection density, and facility density (walking opportunity). Flood and sediment risk is a major concern that restricts the available land and is included as a negative aspect of the neighborhood environment, taking the topographic features into consideration. A comparison of the results showed that the preference for neighborhood walkability varies by socioeconomic status as well as by target cities. For most facility types, the number of walking opportunities within walking distance from houses was found to be positively related to the sale price of single-family detached houses in all quantiles. The relationship of house price with population and intersection density was found to vary depending on the price level, with a negative relationship with the sale price of relatively more expensive houses being exhibited. People who considered buying houses with relatively higher sale prices were found to devalue houses located in flood/sediment-hazardous areas more. However, it was also found that the negative relationship was slightly mitigated in the highest quantile of sale prices for houses in areas with a moderate flood risk (maximum flooding depth: 3-5 m). Plains near rivers with amenities offer high walkability but pose a flood risk, resulting in a trade-off between flood risk and neighborhood walkability. The findings suggest the use of indices representing diverse preferences in accordance with the target socioeconomic status when policymakers assess the neighborhood environment.

Walkability

Megacity

10.1371/journal.pone.0292657

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スマートメータを利用した空き家期間と地域特性との関係分析

Theory and Applications of GIS (2022)

Hiroki Baba Yuki Akiyama Chihiro Shimizu

The problem of vacant housing in Japan is becoming more and more pronounced. However, a uniform view of vacant houses will not solve the problem, and duration of vacancy can be an important indicator to understand the characteristics of vacancies. This study focused on the geographic distribution of vacant houses considering the duration of vacancies with the use of smart meters, and analyzed the relationship with neighborhood characteristics. The main finding indicates that there is a structural difference between vacant houses and neighborhood characteristics depending on urban areas. Some variables had statistically significant correlations regardless of the duration of vacancies, others changed their significance or the magnitude of estimated coefficients depending on the duration of vacancies. Moreover, this study demonstrates the usefulness of smart meter data, which has not been utilized in urban and housing studies.

10.5638/thagis.30.39

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Citations (3)

A study on the function placement method for ultra-low latency mobile services

IEICE technical report. Speech (2015)

Hiromi Hirai Hiroki Baba Minoru Matsumoto Katsunori Noritake

Source

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Accuracy of vacant housing detection models: An empirical evaluation using municipal and national census datasets

Transactions in GIS (2022)

Kanta Sayuda Euijung Hong Yuki Akiyama Hiroki Baba Tomoya Tokudomi

Abstract In Japan, the rise in vacant housing has created the need to develop quick, effective, and inexpensive methods to detect the spatial distribution of vacant housing at the municipal level. However, due to incomplete and inaccessible data, the change in the accuracy of the vacant housing detection model must be evaluated while accounting for the limited data. Therefore, this study compares the performance of vacant housing detection models for different data combinations (Basic Resident Register; building registration, water usage, and national census) by considering Wakayama City, Japan, as the case study setting. Three main findings emerged: (1) the contribution of the data to the accuracy varies with the combination of datasets and metrics; (2) even if specific municipal data are unavailable, it is possible to acquire a similar accuracy by combining other data; and (3) the missing value contributes to the vacant housing detection rather than the feature value itself.

Feature (linguistics)

Value (mathematics)

10.1111/tgis.12992

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Citations (3)

Relationship between building demolition sites and urban planning measure considering local characteristics

Deleted Journal (2018)

Hiroki Baba Kimihiro Hino

本研究は、ドイツにおいて建物除却跡地利用が都市計画的にどのように統制されているのかを明らかにすることを目的とした。そのため、ベルリン市東部の住宅団地を例にとり、建物除却跡地利用について現地調査を行い、立地特性を踏まえて現況跡地利用と都市計画的枠組みとの対応関係を明らかにした。結果、建物除却が早期に計画されている土地では建物・ガレージとしての積極的利用が多くなされ、現況跡地利用と将来方針に大きな乖離がないことから、都市計画的な誘導が有効に行われていると考えられる。今後、跡地利用の統制絵要因である公有地の払い下げの条件や、近年策定された統合的基本構想と建物除却跡地との関連を明らかにしたい。

10.11361/reportscpij.17.2_103

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An Evaluation of Efficient Mobility and Bearer control mechanism for Low Mobility Terminals

IEICE Technical Report; IEICE Tech. Rep. (2013)

Hiroki Baba Minoru Matsumoto Seisho Yasukawa Katsunori Noritake

Social Mobility

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Citations (1)