• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.8B
• /
• pp.762-770
• /
• 2004

With rapid advances in wireless communication technologies and with the advent of the smaller and high-performance mobile handsets nowadays, many researches are actively performed for providing seamless communications while mobile nodes are roaming around. As real-time application programs are more prevalent, it is very important to manage mobility of mobile nodes efficiently. In this paper, we propose a localized mobility support scheme that is based on the Mobile IPv6 by IETF. The proposed scheme enhances functionalities in mobile nodes and only uses signaling messages of Mobile IPv6. The performance of the proposed scheme is evaluated through analytical model and simulations. According to the results of the evaluation, the proposed scheme provides better performance than Mobile IPv6 in terms of packet losses and TCP throughput by localizing the binding update messages inside the foreign domain during handoffs and reducing binding update time.

• Journal of Internet Computing and Services
• /
• v.3 no.2
• /
• pp.27-37
• /
• 2002

This paper analyzes problems of existing Mobile IP and redesigns component functions, and proposes handover method using LRS and BCS for handover performance improvement. When mobile node moves another domain, the proposed BCS recognizes its mobility. So, BCS manages mobile node's binding information and serves micro mobility. When handover occurs among domains, micro mobility enables using LRS, As BCS and LRS have buffering function, they can reduce packet loss by forwarding the buffered datagram. It's designed component is implemented in LINUX environment. And then, handover performance was evaluated by simulation. The results of proposed handover method are better than existing method in both transmission delay time and packet loss.

• ETRI Journal
• /
• v.37 no.6
• /
• pp.1065-1076
• /
• 2015

Network densification is regarded as the dominant driver for wireless evolution into the era of 5G. However, in this context, interference-limited dense small cell deployments are facing technical challenges in mobility management. The recently announced results from an LTE field test conducted in a dense urban area show a handover failure (HOF) rate of over 21%. A major cause of HOFs is the transmission failure of handover command (HO CMD) messages. In this paper, we propose two enhancements to HO performance in LTE networks - radio link failure-proactive HO, which helps with the reliable transmission of HO CMD messages while the user equipment is under a poor radio link condition, and Early Handover Preparation with Ping-Pong Avoidance (EHOPPPA) HO, which assures reliable transmission of HO CMD under a good radio link condition. We analyze the HO performance of EHOPPPA HO theoretically, and perform simulations to compare the performance of the proposed schemes with that of standard LTE HO. We show that they can decrease the HOF rate to nearly zero through an analysis, and based on the simulation results, by over 70%, without increasing the ping-pong probability.

• Physical Therapy Korea
• /
• v.22 no.4
• /
• pp.27-33
• /
• 2015

The purpose of this study was to find which spatiotemporal gait parameters gained from stroke patients could be predictive factors for the gait part of Tinetti Performance-Oriented Mobility Assessment (POMA-G). Two hundred forty-six stroke patients were recruited for this study. They participated in two assessments, the POMA-G and computerized spatiotemporal gait analysis. To analyze the relationship between the POMA-G and spatiotemporal parameters, we used Pearson's correlation coefficients. In addition, multiple linear regression analyses (stepwise method) were used to predict the spatiotemporal gait parameters that correlated most with the POMA-G. The results show that the gait velocity (r=.67, p<.01), cadence (r=.66, p<.01), step length of the affected side (r=.49, p<.01), step length of the non-affected side (r=.53, p<.01), swing percentage of the non-affected side (r=.47, p<.01), and single support percentage of the affected side (r=.53, p<.01) as well as the double support percentage of the non-affected side (r=-.42, p<.01) and the step-length asymmetry (r=-.64, p<.01) correlated with POMA-G. The gait velocity, step-length asymmetry, cadence, and single support percentage of the affected side explained 67%, 2%, 2%, and 1% of the variance in the POMA-G, respectively. In conclusion, gait velocity would be the most predictive factor for the POMA-G.

• Journal of Communications and Networks
• /
• v.14 no.1
• /
• pp.91-103
• /
• 2012

Network mobility (NEMO) based on mobile IP version 6 has been proposed for networks that move as a whole. Route optimization is one of the most important topics in the field of NEMO. The current NEMO basic support protocol defines only the basic working mode for NEMO, and the route optimization problem is not mentioned. Some optimization schemes have been proposed in recent years, but they have limitations. A new NEMO route optimization scheme-involving a combination of the optimized route cache protocol (ORC) and reverse routing header (RRH) and the use of a quota mechanism for optimized sessions (OwR)-is proposed. This scheme focuses on balanced performance in different aspects. It combines the ORC and RRH schemes, and some improvements are made in the session selection mechanism to avoid blindness during route optimization. Simulation results for OwR show great similarity with those for ORC and RRH. Generally speaking, the OwR's performance is at least as good as that of the RRH, and besides, the OwR scheme is capable of setting up optimal routing for a certain number of sessions, so the performance can be improved and the cost of optimal routing in nested NEMO can be decreased.

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

• 제어로봇시스템학회:학술대회논문집
• /
• 2004.08a
• /
• pp.1435-1439
• /
• 2004

Most recently, CP(Cellular Phone) has been one of the most important technologies in the IT(Information Tech-nology) field, and it is situated in a position of great importance industrially and economically. To produce the best CP in the world, a new technological concept and its advanced implementation technique is required, due to the extreme level of competition in the world market. The RT(Robot Technology) has been developed as the next generation of a future technology. Current robots require advanced technology, such as soft computing, human-friendly interface, interaction technique, speech recognition, object recognition etc. unlike the industrial robots of the past. Therefore, this paper explains conceptual research for development of the RCP(Robotic Cellular Phone), a new technological concept, in which a synergy effect is generated by the merging of IT & RT. RCP infra consists of $RCP^{Mobility}$ $RCP^{Interaction}$, $RCP^{Integration}$ technologies. For $RCP^{Mobility}$, human-friendly motion automation and personal service with walking and arming ability are developed. $RCP^{Interaction}$ ability is achieved by modeling an emotion-generating engine and $RCP^{Integration}$ that recognizes environmental and self conditions is developed. By joining intelligent algorithms and CP communication network with the three base modules, a RCP system is constructed. Especially, the RCP mobility system is focused in this paper. $RCP^{Mobility}$ is to apply a mobility technology, which is popular robot technology, to CP and combine human-friendly motion and navigation function to CP. It develops a new technological application system of auto-charging and real-world entertainment function etc. This technology can make a CP companion pet robot. It is an automation of human-friendly motions such as opening and closing of CPs, rotation of antenna, manipulation and wheel-walking. It's target is the implementation of wheel and manipulator functions that can give service to humans with human-friendly motion. So, this paper presents the definition, the basic theory and experiment results of the RCP mobility system. We confirm a good performance of the RCP mobility system through the experiment results.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.53 no.8
• /
• pp.13-18
• /
• 2016

In Internet of Things (IoT) environment, a variety of smart devices are connected to Internet through various network technologies such as 4G/5G, WiBro, Bluetooth, etc. in order to provide the remote monitoring service such as smart healthcare service, etc. Most standard mobility management protocols based on IETF Mobile IP may not be suitable for Internet of Things (IoT) environments due to constrained power, constrained CPU processing and memory capacity, and large signalling overhead which are inherently accompanied by various devices in IoT environments. In this article, we propose a new mobility management protocol CoMP (CoAP-based Mobility Managemenbt Protocol) for reliable mobility management in IoT environments. The architecture and algorithm to achieve both reliability and simplicity for IoT mobility management are proposed. Finally, performance has been evaluated by both mathematical analysis and simulation.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.26 no.2
• /
• pp.153-159
• /
• 2016

In this paper, a mechanism of an omni-directional personal mobility which can drive diagonally is proposed. Mobility is a prerequisite involved in basic human life and activities. Personal mobility vehicle is a new mobility method which overcome the limits of automobiles. However, personal mobilities with four wheeled structure still have limitations. The proposed personal mobility vehicle can overcome the limitations of mobility because its rear wheels can be steered omni-directionally. In addition, the handicapped can drive it through a narrow road such as an alleyway or corridor and avoid obstacles on the traveling route. The proposed mechanism of personal mobility and the steering performance are tested by experiments, and the feasibility of diagonal driving is verified.

• Journal of Internet Computing and Services
• /
• v.21 no.4
• /
• pp.1-8
• /
• 2020

In order to reach Ultra-Reliable Low-Latency communication, one of 5G aims, Multi-access Edge Computing paradigm was born. The idea of this paradigm is to bring cloud computing technologies closer to the network edge. User services are hosted in multiple Edge Clouds, deployed at the edge of the network distributedly, to reduce the service latency. For mobile users, migrating their services to the most proper Edge Clouds for maintaining a Quality of Service is a non-convex problem. The service migration problem becomes more complex in high mobility scenarios. The goal of the study is to observe how user mobility affects the selection of Edge Cloud during a fixed mobility path. Mobility-Aware Service Migration (MASM) is proposed to optimize service migration based on two main parameters: routing cost and service migration cost, during a high mobility scenario. The performance of the proposed algorithm is compared with an existing greedy algorithm.