• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.5
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• pp.77-83
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• 2012

The importance of mobility management is becoming to be one of the upcomming issues to be addressed to provide the converged services and the convergence of the heterogeneous network environments. In this paper, the new user mobility management scheme which can be utilized to model the user's mobility behaviors for interworking with heterogeneous overlay convergent networks under the time-varying radio propagation environment has been proposed. Thus user mobility management scheme based on user mobility model is considered in order to optimize the dwell time of users in the overlay convergent networks. This Mobile IP user mobility management will be very useful to model the user mobility behaviors and can be used to estimate the signaling traffic and frequency spectrum demands for massive data transfer for the heterogeneous overlay convergent networks.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.38 no.6
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• pp.9-21
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• 2001

This paper defines the mobility and rotatability, and a desired mobility and rotatability that can be achieved by adjusting the distance between two wheels of a mobile robot dynamically. The radii of wheels are assumed to be constant in this paper. If a mobile robot has a fixed axis connecting the two wheels, it may not be able to avoid a sudden obstacle because of the constraint of mobility and rotatability. The focus of this paper is on the instant rotatability with high and stable mobility. That is, by dynamically changing the distance between the two wheels, the mobile robot could get the high rotatability instantly and high mobility with high stability. Supposed that the mobility and rotatability that are defined in this paper are supplied to the design of a mobile robot, it will suggest a theoretical basis on the optimal design of the mobile robot with a given route condition and its states. The experimental data support the validity of the aforementioned mobility and rotatability.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.1
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• pp.78-87
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• 2015

Content-Centric Networking(CCN) is a new networking paradigm to search for the routing information needed to find a data from the content name, unlike conventional IP networks. In CCN, the mobility management, one of the CCN challenges, is consists of consumer mobility and content provider mobility. Among both, in the case of the content provider mobility, it requires too much overhead and time to update routing information on the corresponding routers. In this paper, we propose Popularity-based Pushing CCN(PoPCoN) which considers the content popularity to support effective mobility of content provider in CCN. Our proposed algorithm shortens content download time for the consumer and reduces the network overhead during mobility as compared to the existing approaches.

• Proceedings of the Korea Multimedia Society Conference
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• 2003.11a
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• pp.445-448
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• 2003

During a time when cellular systems are being deployed in massive scale worldwide, international roaming is becoming increasingly important. This paper presents UIM (User Identification Module) for mobility support, authentication, and service portability between different mobile systems. We also introduce network model based on PASM(Portable Authentication and Mobility Service Machine) which will support signaling protocol and user information conversions with database for roaming between different mobile networks. Stored data types and elements in UIM, logical data structure and configuration, and registration procedures are described here in the case of DCN (Digital CDMA (Code Division Multiple Access) Network System) and GSM (Global System for Mobile Communications).

• Journal of Industrial Technology
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• v.26 no.B
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• pp.207-213
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• 2006

Mobility Anchor points are used for the mobility management in HMIPv6 networks. Currently a mobile node selects the MAP farthest away from itself as a new MAP among available candidates when it undertakes a macro hand off. With this technique, however, the traffic tends to be concentrated at a MAP with the largest domain size and the communication cost increases due to the distance between the mobile node and the MAP. In this work, we propose a novel scheme to select a MAP to minimize the communication cost, taking the mobile node's moving speed and data rate into account. To come up with the scheme we analyses the communication analyses the communication cost into the binding update cost and the data packet delivery cost, and derive an equation representing the optimal MAP domain size to minimize the total cost.

• The Journal of the Korea institute of electronic communication sciences
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• v.2 no.2
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• pp.99-105
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• 2007

MANET(Mobile Ad-hoc network) have recently attracted a lot of attention in the research community as well as in industry. Although the previous research mainly focused on various of MANET in routing, we consider, in this paper, how to efficiently support applications such as variable geocasting basd on MANET. The goal of a geocasting protocol is deliver data packet to a group of nodes that are located within a specified geocasting region. Previous research that support geocast service in mobilie computing based on MANET have the non-optimization problem of data delivery path, overhead by frequent reconstruction of the geocast tree, and service disruption problem. In this paper, we propose the mobility pattern based geocast technique using variable service range according to the mobility of destination node and resource reservation to solve this problem. The experimental results show that our proposed mechanism has improved performance of Accessibility & Network Overhead than previous research.

• Journal of information and communication convergence engineering
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• v.11 no.2
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• pp.82-94
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• 2013

In this paper, we propose a novel tunnel-free scheme in a proxy mobile IPv6 (PMIPv6)-based nested network mobility environment; several mobile nodes (MNs) and mobile routers (MRs) compose a hierarchical wireless network topology. Because tunnels created by several MRs overlap and data packets travel along several local mobility anchors (LMAs), the utilization of the wireless section is reduced and the packet forwarding path of the wire-line section is not optimal. In our tunnel-free scheme, the mobile access gateway (MAG) plays an important role in both the wireless and wire-line sections. Using a local binding update, this tunnel-free scheme forwards data packets with a host-based routing table without any tunnel. Establishing a direct tunnel between the MAG and the last LMA, this scheme removes nested tunnels between intermediate LMAs and MRs, and optimizes the forwarding path to the MN in the wire-line section.

• Journal of Communications and Networks
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• v.17 no.6
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• pp.568-581
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• 2015

Predicting locations of users with portable devices such as IP phones, smart-phones, iPads and iPods in public wireless local area networks (WLANs) plays a crucial role in location management and network resource allocation. Many techniques in machine learning and data mining, such as sequential pattern mining and clustering, have been widely used. However, these approaches have two deficiencies. First, because they are based on profiles of individual mobility behaviors, a sequential pattern technique may fail to predict new users or users with movement on novel paths. Second, using similar mobility behaviors in a cluster for predicting the movement of users may cause significant degradation in accuracy owing to indistinguishable regular movement and random movement. In this paper, we propose a novel fusion technique that utilizes mobility rules discovered from multiple similar users by combining clustering and sequential pattern mining. The proposed technique with two algorithms, named the clustering-based-sequential-pattern-mining (CSPM) and sequential-pattern-mining-based-clustering (SPMC), can deal with the lack of information in a personal profile and avoid some noise due to random movements by users. Experimental results show that our approach outperforms existing approaches in terms of efficiency and prediction accuracy.

• The Journal of Bigdata
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• v.7 no.2
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• pp.235-244
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• 2022

The rental history data of public bicycles in Seoul were analyzed to examine how pandemic phenomena such as COVID-19 caused changes in people's micro mobility. Data for 2019 and 2021 were compared and analyzed by dividing them before and after COVID-19. Data were collected from public data portal sites, and data marts were created for in-depth analysis. In order to compare the changes in the two periods, the riding direction type dimension and the rental station type dimension were added, and the derived variables (rotation rate per unit, riding speed) were newly created. There is no significant difference in the average rental time before and after COVID-19, but the average rental distance and average usage speed decreased. Even in the mobility of Ttareungi, you can see the slow rhythm of daily life. On weekdays, the usage rate was the highest during commuting hours even before COVID-19, but it increased rapidly after COVID-19. It can be interpreted that people who are concerned about infection prefer Ttareungi to village buses as a means of micro-mobility. The results of data mart-based visualization and analysis proposed in this study will be able to provide insight into public bicycle operation and policy development. In future studies, it is necessary to combine SNS data such as Twitter and Instagram with public bicycle rental history data. It is expected that the value of related research can be improved by examining the behavior of bike users in various places.

• Journal of Information Technology Services
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• v.20 no.6
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• pp.83-95
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• 2021

In this study, various usage patterns were analyzed after establishing a data mart for micro mobility analysis based on the rental history of public bicycles in Seoul. Rental history data is origin-destination data that includes the rental location and time, and the return location and time. About 1500 rental locations were classified according to the characteristics of the location to create a 'station type' dimension. We also created a 'path type' dimension that displays whether the rental location and return location are the same. In addition, a derived variable called speed, which is obtained by dividing the distance used by the time used, is added, and through this, the characteristics of the riding area and the reason for the rental can be estimated. Meanwhile, administrative district link, administrative neighborhood link, and station type link were created to apply network analysis. Through this analysis, the roles and proportions of administrative districts, public facilities, and private facilities engaged in micro-mobility services were visualized. 49.9% of rentals occur at rental offices near transportation facilities, and half of them occur at rental offices near subway stations. The number of rentals during the evening rush hour is more than double that of the morning rush hour. When the path type is unidirectional, there is a fixed destination, so the distance and time used are short, and the movement speed tends to be high. In the case of round-trip, the purpose of use is exercise or leisure, so the distance and time used are long, and the movement speed is slow. It is expected that the results of the analysis can be used as reference materials for selecting new rental locations, providing convenient services for users, and developing user-specialized products.