• Journal of information and communication convergence engineering
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• 제17권2호
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• pp.97-104
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• 2019

Distributed mobility management (DMM) does not use a centralized device. Its mobility functions are distributed among routers; therefore, the mobility services are not limited to the performance and reliability of specific mobility management equipment. The DMM scheme has been studied as a partially distributed architecture, which distributes only a packet delivery domain in combination with the software defined network (SDN) technology that separates the packet delivery and control areas. Particularly, a separated control area is advantageous in introducing a new service, thereby optimizing the network by recognizing the entire network situation and taking an optimal decision. The SDN-based mobility management scheme is studied as a method to optimize the packet delivery path whenever a mobile node moves; however, it results in excessive signaling processing cost. To reduce the high signaling cost, we propose a hybrid distributed mobility management method and analyze its performance mathematically.

• 한국게임학회 논문지
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• 제10권6호
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• pp.57-65
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• 2010

본 논문에서는 6자유도를 갖는 병렬형 기구의 출력 속도 공간에서 성능을 평가할 수 있는 지표를 제안하였다. Manipulability와 condition number에 기반을 둔 성능 지표가 단위계의 볼일치로 인한 물리적 의미의 결함이 없도록 출력공간을 병진속도 공간과 회전속도 공간으로 분리하는 방법을 제안하였다. 각 공간에서 단위 입력에 대용하는 mobility ellipsoid를 정의하여 이를 기반으로 병진운동 출력공간에서 두 종류 성능 지표와 회전운동 공간에서 두 종류의 성능 지표를 제안하였다.

• 마이크로전자및패키징학회지
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• 제28권4호
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• pp.103-107
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• 2021

좁은 밴드갭 반도체 특성을 나타내는 열전소재의 온도에 따른 전자전도 및 열전도 특성은 다수 캐리어 뿐 아니라 소수 캐리어의 전도 거동에 의해 결정된다. 따라서 소수 캐리어의 weighted mobility에 대한 다수 캐리어의 weighted mobility의 비율로 정의되는 weighted mobility ratio는 열전소재의 성능 증대에 매우 중요한 인자이다. 본 논문에서는 열전소재의 전자전도 현상에 대한 이론적인 고찰을 바탕으로 weighted mobility ratio 제어가 열전소재의 성능에 미치는 영향을 규명하여 고성능 Bi-Te계 열전소재 개발에 효과적으로 활용할 수 있는 소재 설계 지침을 제공하고자 한다.

• Journal of Communications and Networks
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• 제16권6호
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• pp.645-655
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• 2014

Latency, an identified element of Internet protocol (IP) mobility protocol execution, can reduce handover performance in mobile networks. Although the performance can be improved by applying an effective network-based IP mobility scheme in place of the traditional host-based alternatives, the existing inter-domain extensions of network-based IP mobility continue to suffer from an extended handover latency. This paper proposes a new inter-domain network-based IP mobility scheme based on node movement prediction. The proposed scheme accelerates the handover by preparing the future domain of the mobile node in a proactive manner. Analytical and simulation-based evaluations confirm improved performance of the proposed scheme in terms of handover latency and packet loss compared with existing schemes.

• 한국경영과학회지
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• 제26권3호
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• pp.53-63
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• 2001

An efficient mobility management for mobile stations plays an important role in mobile communication network. This paper studies the mobility management scheme that combines a distance-based registration(DBR) and a selective paging (SP). We introduce an analytical model based on 2-dimensional random walk mobility model and evaluate the performance of the proposed mobility management scheme using the model to determine the optimal size of location area that results in the minimum signaling traffic on radio channels. Numerical results are provided to demonstrate the performance of the proposed mobility management scheme under various circumstances. These results can be used effectively in design and evaluation of registration methods considering the system circumstances.

• 대한산업공학회지
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• 제29권2호
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• pp.135-144
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• 2003

Traffic performance in a microcellular system is much more affected by cell dwell time and channel holding time in each cell. Cell dwell time of a call is characterized by its mobility pattern, i.e., stochastic changes of moving speed and direction. Cell dwell time provides important information for other analyses on traffic performance such as channel holding time, handover rate, and the average number of handovers per call. In the next generation mobile communication system, the cell size is expected to be much smaller than that of current one to accommodate the increase of user demand and to achieve high bandwidth utilization. As the cell size gets small, traffic performance is much more affected by variable mobility of users, especially by that of pedestrians. In previous work, analytical models are based on simple probability models. They provide sufficient accuracy in a simple second-generation cellular system. However, the role of them is becoming invalid in a picocellular environment where there are rapid change of network traffic conditions and highly random mobility of pedestrians. Unlike in previous work, we propose an improved probability model evolved from so-called Random walk model in order to mathematically formulate variable mobility of pedestrians and analyze the traffic performance. With our model, we can figure out variable characteristics of pedestrian mobility with stochastic correlation. The above-mentioned traffic performance measures are analyzed using our model.

• Journal of information and communication convergence engineering
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• 제9권5호
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• pp.610-614
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• 2011

Nowadays Mobile Ad Hoc Networks (MANETs) are a very popular and emerging technology in the world. MANETs helps mobile nodes to communicate with each other anywhere without using infrastructure. For this purpose we need good routing protocols to establish the network between nodes because mobile nodes can change their topology very fast. Mobile node movements are very important features of the routing protocol. They can have a direct effect on the network performance. In this paper, we are going to discuss random walk and random waypoint mobility models and their effects on routing parameters. Previously, mobility models were used to evaluate network performance under the different routing protocols. Therefore, the network performance will be strongly modeled by the nature of the mobility pattern. The routing protocols must rearrange the changes of accurate routes within the order. Thus, the overheads of traffic routing updates are significantly high. For specific network protocols or applications, these mobility patterns have different impacts.

• 대한산업공학회지
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• 제29권4호
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• pp.292-303
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• 2003

An efficient mobility management for mobile stations plays an important role in mobile communication network. Two basic operations of mobility management are location registration and paging. A zone-based registration (ZBR) is implemented in most of mobile communication systems and we consider the mobility management scheme that combines a zone-based registration and a selective paging (SP). We propose new analytical model that can reflect on the characteristics of the ZBR based on 2-dimensional random walk mobility model and more efficient paging schemes considering the proposed model. We evaluate the performance of the mobility management scheme with our mobility model to determine the optimal size of location area that will result in the minimum signaling traffic on radio channels. Numerical results are provided to demonstrate that our mobility model is useful to evaluate the ZBR more exactly.

• 한국통신학회논문지
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• 제28권6B호
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• pp.563-572
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• 2003

차세대 이동 통신망 환경에 Mobile IP 방식을 적용하였을 경우 빈번히 발생하는 핸드오프로 인한 재등록 과정의 오버헤드 증가와 등록 시의 지연으로 인한 패킷 손실 증가 등의 마이크로 이동성(micro-mobility) 문제가 발생할 수 있다. 본 논문에서는 이 문제의 해결을 위해 IP 기반 무선 액세스 망에서 마이크로 이동성을 효율적으로 지원하는 ANMM(Access Network Mobility Management) 방식을 제안한다. ANMM 방식은 액세스 망 내에서 노드가 이동할 때 발생하는 핸드오프 등록 과정을 액세스 망 자체적으로 처리하여 등록 지연과 시그널링 오버헤드를 감소시킨다. 또한 핸드오프 시의 무선 구간에서의 시그널링을 최소화하여 무선 자원의 낭비를 줄일 수 있다.

• 한국정보과학회논문지:정보통신
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• 제33권1호
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• pp.28-37
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• 2006

최근 새로운 트랜스포트 계층 프로토콜인 SCTP를 기반으로 한 트랜스포트 계층 이동성 지원방안이 제안되었다. 본 논문에서는 이들 트랜스포트 계층 이동성 지원 방안이 지금까지 제안되어 온 대표적인 IPv6 기반 네트워크 계층에서의 이동성 지원 방안들에 비하여 어느 정도의 성능을 보이는지 그 위치를 가늠해 보고, 이들 각 프로토콜이 수반하는 오버헤드를 비교하였다 시뮬레이션 결과를 통하여 트랜스포트 계층에서의 종단 간 이동성 지원 방안이 네트워크 계층 이동성 지원 방안들이 수반하는 오버헤드보다 더 낮은 오버헤드를 가지며 전송 성능이나 핸드오버 지연 측면에서 MIPv6와 유사하거나 더 좋은 성능을 보임을 알 수 있었다.