• 한국통신학회논문지
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• 제26권12B호
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• pp.1686-1694
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• 2001

본 논문에서는 Hot-spot 마이크로셀을 가진 계층적 CDMA 셀룰러 시스템에서 여러 가지 자원 공유 방식들 중 스펙트럼 공유 방식에 대한 용량을 역방향 링크와 순방향 링크 대해 분석한다. 용량 분석은 마이크로셀 반경 및 마이크로셀의 위치 및 매크로셀에 대한 마이크로셀의 전력 비를 고려하여 몬테카를로 시뮬레이션을 통해 수행된다. 시뮬레이션 결과로부터 스펙트럼 공유 방식의 용량을 각 링크에 대해 이러한 영향들을 분석하였고, 일반적인 설계 접근방식을 제시하였다. 또한 각 링크에 대해 스펙트럼 공유 방식의 성능을 용량 평면도를 통해 분석하였다

• 한국통신학회논문지
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• 제22권3호
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• pp.571-579
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• 1997

There are some transmission types on the reverse link of wideband DS-CDMA cellular system. The configurations of logical channels on the reverse link may be different dependent upon the transmission methods of reverse pilot or control signaling. In this paper, we present three transmission types on the wideband DS-CDMA reverse link; no-pilot system, pilot-channel aided system and pilot-symbol aided system. And we compare the performance of three systems in terms of capacity and cell coverage. The pilot-symbol aided system is shown to have the better performance than the pilot-channel aided system in both capacity and cell coverage.

• 한국통신학회논문지
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• 제24권12A호
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• pp.1868-1875
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• 1999

무선 망에서 단말기를 호출하기 위한 일차 페이징 지역인 LAI 의 설계는 페이징 채널의 트래픽 생성과 매우 밀접한 관련이 있다. 이 논문에서는 페이징 채널을 통과하는 호 제어 및 부가 기능 메시지를 통해 IS-95 CDMA 표준에 따른 페이징 채널이 용량을 실제 운용 상황에서 발생하는 트래픽 자료를 바탕으로 분석하고자 한다. 이 분석은 페이징 채널이 처리할 수 있는 LAI 의 적정 용량(Engineered Capacity)을 통하여, 기지제어국 및 기지국 시스템의 용량에 따른 망 계획의 중요한 기준을 제공한다.

• 한국컴퓨터정보학회논문지
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• 제22권8호
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• pp.41-46
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• 2017

In this paper, we investigate the D2D Transmitter(Tx) and Receiver(Rx) pair assignment problem in the cellular system where D2D users share the uplink resource of the cellular system. Sharing the uplink resource of the cellular system may cause interference to the cellular system, though it is beneficial to improve the D2D user Capacity. Therefore, to protect the cellular users, D2D transmit power should be carefully controlled. In this work, we focus on optimal Tx-Rx assignment in such a way that the total transmit power of users is minimized. First, we consider the optimum Tx-Rx assignment in general and the corresponding complexity. Then, we propose an iterative D2D Tx-Rx assignment algorithm with low complexity that can minimize total transmit power of users. Finally, we present the numerical examples that show the complexity and the convergence to the unique transmit power level.

• Journal of Communications and Networks
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• 제11권5호
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• pp.464-472
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• 2009

In this paper, we propose a packet scheduling algorithm for cellular relay networks by considering relay selection, variation of channel quality, and packet delay. In the networks, mobile users are equipped with not only cellular but also user relaying radio interfaces, where base station exploits adaptive high speed downlink channel. Our proposed algorithm selects a user with good cellular channel condition as a relay station for other users with bad cellular channel condition but can get access to relay link with good quality. This can achieve flexible packet scheduling by adjusting transmission rates of cellular link. Packets are scheduled for transmission depending on scheduling indexes which are calculated based on user's achieved transmission rate, packet utility, and proportional fairness of their throughput. The performance results obtained by using computer simulation show that the proposed scheduling algorithm is able to achieve high network capacity, low packet loss, and good fairness in terms of received throughput of mobile users.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1982-1985
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• 2003

Future cellular networks will mainly be driven by, high quality channels, high band with utilization, low power consumption and efficient network management. For a given channel allocation, the capacity and quality of communication of cellular radio systems using CDMA(Code Division Multiple Access) can be increased by using a transmitter power control scheme to combat the near-far problem. Centralized power control schemes or distributed ones to maximize the minimum signal-to-interference in each user of CDMA wireless network have been investigated. This paper has proposed a distributed power control algorithm, which employs an adaptive search scheme, in order to solve quickly the linear systems of equations for power update in CDMA cellular radio systems. The simulation results show that the proposed scheme has faster convergence rate than the typical bang-bang type of distributed power control algorithm, which has been much used as a reference algorithm in IS-95A and W-CDMA communication network.

• 산업경영시스템학회지
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• 제29권3호
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• pp.111-118
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• 2006

This paper presents design and development of a simulator evaluates the performance of a hierarchical cellular system. The proposed hierarchical cellular simulator, consisting of macro, micro, and pico cells, applies the wrap-around technique to reduce simulation time. The simulator is implemented as object oriented class models by using the C++ language in a PC environment. The resulting application can evaluate the interference, SIR(Signal to Interference Ratio), and capacity of a hierarchical cellular system in various configurations. Moreover, it can be used in other applications such as power control, call admission control, hand over scheme.

• 아시안잔디학회지
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• 제10권3호
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• pp.247-262
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• 1996

In this study, the distribution of dictyostelid cellular slime molds was investigated from F, H and $A_1$ horizon of pinus, oak forests in Mt. Puk'an, Mt. Nam and Mt. Kwanak. The relationship of cellular slime molds with other soil microorganisms and abiotic factors were analyzed. The six species were isolated as follows: Polysphondlium pallidurn, Dictyostelium purpureum, D. mucoroides, D. crassicaule, D. capitatum, D. implicatum. The dominant species in pinus forests was P. pallidum, and in oak forests it was D. macro ides. In Mt. Nam, D. mucoroides and P. pallidum were isolated at only oak forest. The Correlations of slime mold abundance with bacteria were significant. Even though positive correlations of cellular slime molds with actinomycetes or fungi were not significant, correlations between soil microorganisms were analyzed. Correlation coefficients were high in Mt. Kwanak(r=0.5921) and Mt. Nam(r=0.7243) at significant level P<0.01. There were significant correlations between total slime molds and abiotic factors. It supports that cellular slime molds are limited by foods in nature. In low level of pH, water content and organic matter, that community diversity is more affected by bacteria whose organic degradation capacity is regulated by interactions of soil microorgaisms. Key words: Cellular slime molds, Soil microorganisms, Correlations, Abiotic factors.

• 한국전자파학회논문지
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• 제21권10호
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• pp.1194-1199
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• 2010

본 논문에서는 빔 성형(beamforming) 기술을 사용하는 릴레이 기반 셀룰러 네트웍에서, 순방향 링크 채널 상태에 대한 제한된 피드백 정보를 이용하여, 동시에 전송되는 송신기과 수신기 사이의 직접 링크(direct link)와 중계기(relay station)와 수신기 사이의 중계 링크(relaying link) 간의 간섭을 효과적으로 억제하는 간섭 회피(interference avoidance) 빔 성형 기술을 제안한다. 이를 위해 송신기는 빔 성형을 사용하여 한정된 공간으로만 직접링크 신호 전력을 전송하고, 송신기의 간섭 전력이 도달하지 않는 공간 영역에 위치한 릴레이들의 relaying을 허용함으로써, 효과적으로 직접 링크와 중계 링크간 간섭을 억제할 수 있는 충돌 회피(collision avoidance) 스케줄링 기술을 제안한다. 시뮬레이션을 통해 제안하는 간섭 회피 빔 성형 기술이 중계 링크의 전송 용량을 보장하면서 동시에 전송되는 직접 링크 전송 용량을 최대화 할 수 있음을 보인다.

• Journal of Microbiology and Biotechnology
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• 제26권8호
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• pp.1367-1374
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• 2016

The present study evaluated the total phenolic and flavonoid contents as well as total antioxidant capacity (TAC) of three cultivars of Actinidia arguta Planch. kiwi berries; cv. Mansoo (Mansoo), cv. Chiak (Chiak), and cv. Haeyeon (Haeyeon). In addition, the anti-inflammatory effects of the three cultivars of kiwi berries were investigated using a lipopolysaccharide (LPS)-stimulated RAW 264.7 murine macrophage cell line. Mansoo had the highest total phenolic content and TAC among the three cultivars, whereas Chiak had the highest total flavonoid content. The total antioxidant capacities of the kiwi berry extracts were more strongly correlated with total phenolic content than with total flavonoid content. The kiwi berry extracts suppressed the secretion of pro-inflammatory cytokines, including interleukin-6 and tumor necrosis factor-α, from LPS-stimulated RAW 264.7 cells. The release of nitrite, an indirect indicator of nitric oxide, was also ameliorated by pre-treatment with the kiwi berry extracts in a dose-dependent manner. Cellular-based measurements of antioxidant capacity exhibited that the kiwi berry extracts had cellular antioxidant capacities. Such cellular antioxidant effects are possibly attributed to their direct antioxidant capacity or to the inhibition of reactive oxygen species generation via anti-inflammatory effects. Our findings suggest that kiwi berries are potential antioxidant and anti-inflammatory agents.