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Predictive Location Management Strategy Using Two Directional Consecutive LAs a Cellular Network
장인갑(I.K. Chang),홍정식(J.S. Hong),김지표(J.P. Kim),이창훈(C. H. Lie) 한국경영과학회 2008 韓國經營科學會誌 Vol.33 No.3
In this paper, we have presented a dynamic, predictive location update scheme that takes into account each user's mobility patterns, A user's past movement history is used to create two-dimensional transition probability matrix which makes use of two directional consecutive location areas. A mobile terminal utilizes the transition probability to develop a predictive path which consists of several predictive nodes and then the location update is saved as long as a mobile user follows the predictive path. Using continuous-time Markov chain, cost functions of location update and paging are derived and it is shown that the number of predictive nodes can be determined optimally. To evaluate the proposed scheme, simulations are designed and the numerical analysis is carried out. The numerical analysis features user's mobility patterns and regularity, call arrival rates, and cost ratio of location update to paging, Results show that the proposed scheme gives lower total location management cost. compared to the other location update schemes.
구성요소가 서로 종속인 네트워크시스템의 신뢰성모형과 계산알고리즘
홍정식,이창훈 한국경영과학회 1989 한국경영과학회지 Vol.14 No.1
General measure in the reliability is the k-terminal reliability, which is the probability that the specified vertices are connected by the working edges. To compute the k-terminal reliability components are usually assumed to be statistically independent. In this study the modeling and analysis of the k-terminal reliability are investigated when dependency among components is considered. As the size of the network increases, the number of the joint probability parameter to represent the dependency among components is increasing exponentially. To avoid such a difficulty the structured-event-based-reliability model (SERM) is presented. This model uses the combination of the network topology (physical representation) and reliability block diagram (logical representation). This enables us to represent the dependency among components in a network form. Computational algorithms for the k-terminal reliability in SERM are based on the factoring algorithm. Two features of the factoring algorithm are the reliability preserving reduction and the pivoting edge selection strategy. The pivoting edge selection strategy is modified by two different ways to tackle the replicated edges occuring in SERM. Two algorithms are presented according to each modified pivoting strategy and illustrated by numerical examples.
이동 통신망에 있어서 새로운 셀 체류시간 모형화에 따른 최적 이동성 관리
홍정식,장인갑,이창훈 한국경영과학회 2002 한국경영과학회지 Vol.27 No.3
This study investigates two basic operations of mobility management of PCNs (Personal Communication Networks). i.e., the location update and the paging of the mobile terminal. From the realistic consideration that a user either moves through several cells consecutively or stays in a cell with long time, we model the mobility pattern by introducing two types of CRT (Cell Residence Time). Mobility patterns of the mobile terminal are classified into various ways by using the ratios of two types of CRT. Cost analysis is performed for distance-based and movement-based location update schemes combined with blanket polling paging and selective paging scheme. It is demonstrated that in a certain condition of mobility pattern and call arrival pattern, 2-state CRT model produces different optimal threshold and so, is more effective than IID (Independently-Identically-Distributed) CRT model. An analytical model for the new CRT model is compact and easily extendable to the other location update schemes.
홍정식,이해상,홍정완,이창훈,전경표 한국경영과학회 1990 한국경영과학회 학술대회논문집 Vol.- No.1
A conceptual mode of tentative packet handler subsystem (PHS) of TDX-10 is presented. This model is used analyze the capacity of PHS especially when packet bus (PBUS) is bottleneck. In the viewpoint of performance analysis, cyclic server system and token bus LAN are utilized in modeling PHS.
ATM 다중화 장치에 적용된 추계적 유체흐름 모형의 근사분석
윤영하,홍정식,홍정완,이창훈 한국경영과학회 1998 한국경영과학회지 Vol.23 No.4
In this paper. we propose a new approach to solve stochastic fluid flow models applied to the analysis of cell loss of an ATM multiplexer. Existing stochastic fluid flow models have been analyzed by using linear differential equations. In case of large state space. however. analyzing stochastic fluid flow model without numerical errors is not easy. To avoid this numerical errors and to analyze stochastic fluid flow model with large state space. we develope a new computational algorithm. Instead of solving differential equations directly. this approach uses iterative and numerical method without calculating eigenvalues. eigenvectors and boundary coefficients. As a result. approximate solutions and upper and lower bounds are obtained. This approach can be applied to stochastic fluid flow model having general Markov chain structure as well as to the superposition of heterogeneous ON-OFF sources. It can be extended to Markov process having non- exponential sojourn times.