• Journal of IKEEE
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• v.13 no.4
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• pp.75-81
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• 2009

The cellular system in the next generation decreases the range of transmission of a signal as well as increases the rate of transmission adapting the method of multi-hop relaying with the relay. However, the fact of decreasing the range of transmission with the method of multi-hop relaying means increasing interferential amount in the outer cell; therefore, the deployment of the relay can affect to the function of the cellular system. In this thesis, the deployment of the relay is determined for the maximum rate of transmission, based on the transmission power of the relay and the variation of interferential amount. The condition to determine the deployment of the relay is analyzed with the mathematical model; in addition, its performance is verified through the result of a simulation. Based on the analysis of this thesis, the established deployment and transmission power of the relay to minimize the average outage probability exist. Furthermore, the relay contributes to enlargement of capacity of cells, decreasing the average outage probability in the situation of less severe interference between cells with reuse of frequency. However, the relay should be restrained in use in the situation of severe interference between cells due to the fact that the outage probability of inter-cells can be increased.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.3A
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• pp.254-266
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• 2006

Recently, researches about downlink resource allocation algorithms applying SDMA to enhance the system throughput and cell coverage have begun. Most OFDM/SDMA based resource allocation algorithms have some limitations such that those only concentrate on maximizing the system throughput or can be applied in single cell environment. In this paper, we propose an OFDM/SDMA based downlink resource allocation algorithm which considers high layer QoS parameters suitable for the required data traffic and it also minimizes the system throughput loss and considers inter-cell interference from adjacent cells. so it can be adopted in multi-cell environment. We manifest the performance of the proposed algorithm in Ped A and SCME MIMO Channel Model.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2010.09a
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• pp.283-285
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• 2010

도시 계획의 중요성이 부각되면서 다양한 도시 통합 모델의 개발이 이루어져왔으나 기존 모델들은 거시적 측면의 토지이용의 변화만 다루는 한계점이 있다. 본 논문은 토지이용 변화뿐만 아니라 다양한 사회 경제 지표를 반영하여 미시적인 분석이 가능한 UrbanSim 모델을 사용하여 사례연구를 통한 국내 도입 가능성과 시사점을 도출하고자 하였다. 이를 위해 수치지적도, 건축물 대장, 개별 공시지가 등 다양한 시공간 데이터를 이용하여 $150{\times}150m$ 그리드 셀 기반의 입력 데이터베이스를 구축하고 UrbanSim의 Land Price Model에 적용하였다. 향후 보다 현실적인 모델 수행을 위한 다중 스케일 및 Synthetic 데이터 구축 방안과 접근성 측면의 교통 통합 모델로 확장이 요구된다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.12A
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• pp.958-963
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• 2003

Increasing throughput using high order data modulations in the WCDMA downlink requires the elimination of multipath interferences. For this reason, Kenichi Higuchi proposed a multipath interference canceller in WCDMA downlink. However, this paper considers the downlink signal models that only contains code channels for which code information is known to the receiver. WCDMA systems contain code channels for other active users whose code information is unknown to the receiver and these code channels degrade the performance of the multipath interference canceller. Thus, this paper proposes a multipath interference mitigation scheme which removes multipath interference induced by all the code channels within a cell. Simulation results show that the proposed scheme outperforms both the RAKE receiver and the multipath interference canceller in the WCDMA downlink.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.9A
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• pp.714-721
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• 2005

In this parer, we analyze the preamble model in the OFDMA/TDD(OFDM-FDMA/Time Division Duplexing). Besides, under AWGN, ITU-R M.1225 Ped-B and Veh-A channel environments, we analyze capabilities of symbol timing & carrier frequency offset and performance of cell searching capabilities applied to OFDM/TDD system through computer simulation. The performance using Detection Probability, False Alarm Probability, Missing Probability, Mean Acquisition Time and MSE(Mean Square Error) is analyzed. Especially, in the case of symbol timing offset estimation, the preamble structure and its algorithm with enhanced performance are proposed and then compared with existing ones.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37B no.10
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• pp.956-964
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• 2012

An opportunistic interference alignment based on dynamic cell selection is proposed. Since the proposed method can switch the desired signal space and the interference space of received signals, an additional selective diversity gain increases. The performance analysis using probabilistic models provides a mathematical expression for the sum-rate capacity. Simulation examples show that the proposed method achieves the higher sum-rate capacity than that of the conventional opportunistic interference alignment.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.7
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• pp.693-701
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• 2002

In this paper, we analyze the coverage of asynchronous IMT(International Mobile Telecommunication)-2000 reverse link with a MUD(Multi-User Detector) system. The MUD system is utilized to increase the coverage of reverse link. Also we have considered a propagation loss model and an interference effect. Because it is very difficult that we have calculated the interference accurately, so a fractional cell loading factor(F) is used in this paper. We make use of a MUD efficiency($\beta$) to analyze the performance; this efficiency is presented the MAI of reduction. A simulation utilizes Hata's model, we calculated the coverage according to voice and data services. In this paper, we have assumed that the frequency of carrier has 800 MHz or 1.9 GHz, and a bandwidth is decided 3.84 MHz. We have predicted the performance of actual system by the analysis of capacity and coverage.

• Journal of KIISE:Information Networking
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• v.32 no.6
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• pp.651-658
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• 2005

Mobile communication has become more pervasive and it is considered as one of main concerns oi conferencing, multi-user games and etc. in mobile environment. These applications need to secure communication in group. Most of the published protocols are based on model which consists of a stationary base station and a cluster of mobile devices. In this paper, we have focused on the extended model of which participants are several base stations and mobile devices in different cells. We present a new group key protocol among mobile devices in different cells and analyze its security And we also look at how password authentication can be used to our group key agreement protocol. The mobile device's computing load may be reduced by using password authentication.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.81-81
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• 2017

최근 발생하는 태풍 또는 국지성호우는 단기간에 많은 양의 강우를 동반하고 있으며, 이로인한 내수침수 및 외수범람 피해가 빈번히 발생하고 있다. 이와 같은 홍수피해를 저감하기 위한 하나의 대책으로 내수 또는 외수로 인한 피해를 미리 예측하고 대비하는 방법이 필요하다. 피해를 미리 예측하기 위한 기존의 모델들은 지표유출, 지하유출, 침투, 증발산 등 다양한 강우-유출 알고리즘에 의해 홍수범람모의를 분석하게 된다. 따라서 그 모의시간이 길게 나타나 재난상황을 대처하는 데 문제가 있다. 본 연구에서는 홍수로 인한 제내지의 침수 확산 경로 빠른 시간 안에 모의하기 위하여 여러 가지 알고리즘을 단순화시킨 홍수범람 모형을 개발하였다. 개발된 분포형 홍수범람 모형인 SIMOD(Simplified Inundation MODel)는 홍수가 발생된 시점에서 그리드화된 주변셀로의 홍수전의를 위하여 주변셀과의 경사를 이용하여 차등 분배하는 다중흐름방향법(Multi Direction Method, MDM)과, 하나의 낮은 고도의 셀에서 수위가 높아져 인접셀보다 수위가 증가하면 그 수위는 인접 셀들과 균등해 진다는 가정인 평수가정법(Flat-Water Assumption, FWA)인 두 가지 알고리즘을 이용한다. 개발된 모형의 적합성을 확인하기 위하여 상용 모형인 FLO-2D를 이용하여 각 모의시간별 침수면적과 모형의 구동시간을 비교하였다. 비교결과 초기 1시간을 제외하고 홍수피해 면적이 10% 전후로 나타나 SIMOD의 적용성이 확인되었다. 모의 구동시간의 경우 32시간 모의시 SIMOD는 10분 안에 결과가 나오는 반면 FLO-2D는 1시간 이상 소요되는 것으로 나타났다. 또한 대피계획을 수립하기 위하여 제방붕괴시나리오를 이용한 제내지 침수모의를 실시하였다. 대상지역은 금호강하류 성서산업단지 유역으로 계획홍수위는 200년 빈도 홍수위를 기준으로 하였으며 폭 35m, 높이 7m의 제방파제로 인한 외수위 유입을 가정하여 제내지의 시간별 침수면적 모의하였다. 모의된 결과를 이용하여 시간대별 대피경로를 산정함으로써 홍수로 인한 대피 계획 수립에 적용 가능함을 확인하였다.

• The Transactions of the Korea Information Processing Society
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• v.6 no.1
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• pp.167-174
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• 1999

In this paper, we propose the adaptive separated-queueing ATM switching model for the effective processing of the various types of multimedia traffic by virtue of ATM switching network with multiple outlets which is the essential part of B-ISDN. This proposed model employs the dynamically separated buffering mechanism in the processing of two classes of cell, realtime service traffic and non-realtime service traffic, at the output buffer to enhance the overall QoS(Quality of Service). The adopted ATM switch architecture has Batcher-banyan based network, but it uses different topologies and control techniques 6to resolve the cell contention. For the performance evaluation of our proposed method, we have done both analytical modeling and simulation. The both results show that our proposed queueing strategy is quite appropriate to the ATM switch with multiple outlets and can quarantee the QoS requirements of the incoming multimedia traffic.