• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2002.11a
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• pp.15-20
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• 2002

광대역의 멀티미디어 서비스를 제공하기 위해서는 전송채널 채널용량에 대한 분석은 필수적이라 할 수 있다. 지금까지 CATV망의 채널대역폭은 대규모 전송망과 소규모 전송망에서 동일한 대역폭을 이용하여 전송하였다. 소규모 전송망에서 광대역 멀티미디어 및 타 미디어 방송서비스를 제공하기 위해 현재의 사용 대역폭은 부족한 상황이다. 이 논문은 우리나라 CATV 구내 전송망 구조를 분석하고, 구내 전송망에서 주로 사용되는 동축케이블의 크기에 따른 최대 허용 주파수와 주파수 대역에 따른 동축케이블에서의 신호에 대한 감쇠를 구하였다. 또한 단독주택과 아파트의 구내전송망의 채널 모델링을 통해 구내전송망에서의 반송파대 잡음비를 구하였고, 구내전송망에서 주파수대역에 따른 64-QAM, 256-QAM 변조방식의 BER성능을 분석하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.9
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• pp.3481-3485
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• 2010

In this paper, we propose a concept and model of an additional service system as a kind of convergence system of broadcast and telecommunication. The proposed system use existing back-bone network such as broadcasting or communication networks. For this, we derive channel capacity formula as an approximated closed-form expression in order to show how many reliable additional data can be transmitted through wireless fading channel. From the derived formula, we confirm that the channel capacity is varied according to channel and system parameters.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.328-331
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• 2007

In this paper, the capacity of the clustered response model for correlated MIMO-OFDM fading channel is investigated. We compare the capacities achieved by correlation at receiver and achieved by correlation at both the transmitter and the receiver for the case where the channel is known and unknown at the transmitter are considered. It is found that the capacity achieved by correlation at receiver is better than the other. It is also shown that the capacity using the water-filling methed is larger than that using the uniform power allocation due to the water-filling gain. But it is negligible when the number of clusters is over the maximum rank of the sum correlation matrix and SNR is high.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.11
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• pp.2188-2195
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• 2015

In tactical wireless local area networks, jamming attack can easily occur by sending out continuous radio signals. The damage will be serious when the channel frequency is identical. Since wireless channel environment is open to everyone, the perfect solution for jamming attack does not exist. However, a channel-hopping scheme is well known for mitigating those jamming attacks. In this paper, I consider various channel-hopping schemes in order to analyze the throughput and fairness performance under smart jammer attack. Also an analytical model is introduced to evaluate the throughput performances of channel-hopping schemes. After analyzing well known channel-hopping schemes, I propose a simple channel-hopping scheme that can enhance fairness significantly at minimal throughput degradation expense.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.7
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• pp.23-28
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• 2010

We propose a reference vector diversity method in multi-cell multi-user uplink system with the subspace interference alignment to obtain higher sum rate capacity. The proposed method transmits several reference vectors before the data transmission, and selects the best reference vector to maximize the cell sum rate. The proposed method provides higher sum-rate capacity compared with the previous interferenc alignment. Simulation result exhibits the proposed method improves the sum-rate capacity by 60%.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.12A
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• pp.1868-1875
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• 1999

The design of LAI(Local Area Identifier), the first paging area for searching the mobile terminal has a close relation with the performance of paging channel in CDMA cellular network. This paper discussed the performance of the forward channel of IS-95 CDMA standard, known as the paging through the related messages such as call control message, channel assignment message, etc. Modeling and simulation work were conducted to quantify the performance of paging channel in terms of traffic handling capacity and blocking levels. The results shown are based on a specific system call model based on the operating system of cell cite. This serves as illustrative guidelines for the proper engineering of common control channel, which has a major impact on the overall performance of cellular network.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.609-610
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• 2017

Cognitive radio communication techniques have been attracting attention to efficiently use the scarce spectrum as the wireless communication service increases. In cognitive radio communication, efforts to minimize interference to the primary user are important technical factors. In a multi-hop wireless ad hoc network, multi-hop transmission requires path and channel selection considering channel interference as well as collision with primary users. In the multi-channel environment, cognitive radio network has different capacities depending on the inter-channel interference and collision with the main users. In this paper, we propose a multi-hop transmission scheme that minimizes inter-channel interference and reduce collision with primary users.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.3
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• pp.40-47
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• 1997

안테나의 특성은 셀룰러 시스템의 서비스 품질에 직접적으로 영향을 미치는 요소가 되며, 특히 섹터화로 인한 용량의 증가를 기할 수 있는 CDMA 시스템의 경우에는 매우 중요한 의미를 갖는다. 본 논문의 지향성 안테나를 이용하여 전력 제어된 CDMA 셀을 섹터화할 경우 얻을 수 있는 용량의 이득을 논의한다. 용량의 측면에서 이상적인 안테나 패턴과 비교할 때 실제 안테나 패턴의 역방향 링크 용량 효율을 해석적으로 구한다. 셀룰러 CDMA 시스템의 용량은 동일한 주파수 대역을 사용할 수 있는 최대 통신 채널의 수이므로 용량 효율은 결국 주파수 스펙트럼 이용 효율을 의미한다. 측정된 반사판 섹터 안테나 패턴을 대상으로 분석한 결과를 제시하고 패턴 특성과 섹터 셀의 배치 구조에 따라 용량 효율이 86~97%로 변화함을 보인다.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1994.06a
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• pp.463-467
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• 1994

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1995.06a
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• pp.61-64
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• 1995