• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.323-326
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• 2001

We propose a new MUD adaptive beamforming algorithm. It requires no reference signal and consists of two Processing stages. The first stage performs a scan function, and the second stage performs an adaptive beamforming algorithm. Computer simulations, considering multi-path Rayleigh Fading Channel in CUMA, are presented to verify the performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.9C
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• pp.895-904
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• 2007

This paper proposes a robust sub-optimal smart antenna in Code Division Multiple Access (CDMA) basestation. It makes use of the property of the Least Mean Square (LMS) algorithm and the Conjugate Gradient Method (CGM) algorithm for beamforming processes. The weight update takes place at symbol level which follows the PN correlators of receiver module under the assumption that the post correlation desired signal power is far larger than the power of each of the interfering signals. The proposed algorithm is simple and has as low computational load as five times of the number of antenna elements(O(5N)) as a whole per each snapshot. The output Signal to Interference plus Noise Ratio (SINR) of the proposed smart antenna system when the weight vector reaches the steady state has been examined. It has been observed in computer simulations that proposed beamforming algorithm improves the SINR significantly compared to the single antenna case. The convergence property of the weight vector has also been investigated to show that the proposed hybrid algorithm performs better than CGM and LMS during the initial stage of the weight update iteration. The Bit Error Rate (BER) characteristics of the proposed array has also been shown as the processor input Signal to Noise Ratio (SNR) varies.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.12
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• pp.3-11
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• 2014

Multiple antennas can provide huge capacity gains when the transmitter knows the channel state information (CSI). Precoding is a technique that exploits CSI at the transmitter side. In this paper, an adaptive precoding scheme is proposed, called a hybrid multiple-input multiple-output (MIMO) precoding (HMP). HMP is a combination of linear and nonlinear precoding. The number of transmit antennas less than or equal to four is as same as the conventional antenna selection scheme. Therefore, the HMP scheme uses more than four transmit antennas. The good channel means that the channels must be selected to maximize the channel capacity among the given channels, and the rest channels are called bad channel. In HMP scheme, we use the nonlinear precoding in the good channels and the linear precoding in the bad channels. The well-known Tomlinson-Harashima precoding (THP) is considered as nonlinear precoding. The system throughput and MSE (minimum square error) are shown for the performance of HMP scheme compared to the conventional schemes which are BD (block diagonalization), antenna selection and THP.

• 정보화사회
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• s.23
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• pp.50-55
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• 1989

정보의 가치가 개인과 집단의 사회생활이나 경제활동에 중심이 될 것이라는 사회적 공감대가 형성되고 있는 가운데 최근 한국전기통신공사가 "정보통신사업 종합추진 계획(안)"을 발표, 관심을 모으고 있다. 이번에 전기통신공사가 발표한 이계획은 급변하는 국제환경에 적응하고, PC 1천만대 보급의 기반을 조성하여 정보화사회 실현을 촉진하기 위한 것이다. 이 계획에 따르면 오는 96년까지 총1조4천억원을 투입, 정보통신망.정보원.단말기 등을 구성.개발.보완하여 정 보화사회 구축에 공사가 주도적 역할을 수행할 방침이다. "정보통신사업 종합추진 계획(안)"의 구체적인 내용을 요약.정리한다.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.545-545
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• 2006

• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.41-44
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• 2001

In this paper, we have investigated the adaptive sector antenna which can control the size and direction angle of sectors, and proposed the three sectorization algorithms which are based on distribution of users, distribution of codes and distribution of signal power, respectively. The BERs of each sectorization algorithms are compared through computer simulation. As results of the simulation, the sectorization algorithm based on signal power are better than the other in terms nf BER. We have simulated error performance the DS-CDMA/BPSK system with the antenna in AWGN, frequency non-selective Rayleigh fading and MAI channels.

• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1896-1899
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• 1997

In this paper, New radiation system is presented to improve efficiency and distribution of MWO. And it has one input for two excitatied lines with located on them radiation elements(slots). Radiation elements are distributed along the lines the way that the same electrical distances from the magnetron. New radiation system recompences change of impedance at wide b and frequency.

• Journal of the Korean Institute of Telematics and Electronics
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• v.23 no.2
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• pp.170-177
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• 1986

The adaptive array antenna with the LMS algorithm has the advantage in that it can perform train't because of its slower convergencerate. In this paper, the \ulcornerLMS algorithm is applied to the adaptive array so that the convergence rate can be improved, and the performance of he adaptive array by the \ulcornerLMS algorithm is compared to, that of the LMS adaptive array. It is shown that the adaptive array by the \ulcornerLMS algorithm is superior to the LMS adaptive array in the narrow frequency band.

• Information and Communications Magazine
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• v.18 no.6
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• pp.25-33
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• 2001

현재 IMT-2000 시스템에 대한 일련의 국제 표준 스펙이 발표되고 있으며, 이를 개발하는데 각국의 정보통신업체들이 총력을 기울이고 있다. 또한, 기존의 IMT-2000 시스템의 성능을 향상시킬 수 있는 무선전송 기술로 적응 변조 및 부호화 방법, Hybrid Automatic Repeat request, 빠른 셀 선택 기법, 다중 입력 다중 출력 안테나 처리 등에 대한 연구 및 표준화 작업이 진행 중이다. 또한 사설 또는 공설의 유선 네트워크와 연동하여 사용할 수 있는 Broad-band Wireless Access를 제공하는 표준안 작성 작업이 완성단계에 있으며, 이는 IMT-2000 시스템의 보완물로써 새로운 모빌 플렛폼 또는 새로운 서비스를 제공할 수 있는 기회를 준다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.5
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• pp.592-600
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• 2014

This paper proposes an enhanced adaptive genetic algorithm(EAGA) dedicated to pattern synthesis of array antenna which conforms to a curved surface of rotation with quadratic function. EAGA combines adaptive genetic algorithm(AGA) with invasive weed optimization(IWO) for the faster convergence and the lower cost value of the cost function. The amplitude and phase of each excited weighting factor are optimized to meet the required goals using EAGA. The EAGA results indicate that the proposed algorithm is superior to AGA when applied to the problem of conformal array antenna pattern synthesis.