• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.3
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• pp.3-8
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• 2013

Conventional MMSE beamforming scheme shows better performance than ZF or MF beamforming, but it does not aim increase of sum rate. This paper proposes sum rate maximizing scheme by representing sum rate as a function of weighted MSE. Proposed scheme increases sum rate iteratively by updating weights and beam whose initial form is conventional MMSE beam. Simulation result shows sum rate of proposed scheme is higher than those of conventional schemes and increases as the number of users increases.

• Journal of Satellite, Information and Communications
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• v.7 no.1
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• pp.86-91
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• 2012

This paper described validation results of COMS Ka band antennas beam coverages which were developed by ETRI. After satellite launch, In Orbit Test(IOT) activities are stat to check spacecraft and payloads are still in healthy condition after launch. During IOT phase, ETRI measured radiation patterns of COMS Ka band antennas and compare with ground test(CATR) results. The antenna patterns similarity between IOT results and CATR results show that COMS Ka band antenna withstand launch vibration and in the good healthy condition. After IOT, ETRI performed field test for beam coverage measurements with vehicle to check if Ka band beam coverage are formed well as designed. For the beam coverage measurement, 17 points were selected over the Korean peninsula. The field measurement data were very similar with CATR data and this confirms that beam coverage are formed well over the Korean peninsula as expected.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.4
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• pp.667-672
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• 2003

Smart antennas will be used mon widely for the higher data rate and the larger number of users as the demand of wireless multimedia service is increased. Therefore, the BER performance is analyzed in this paper for DS-CDMA and MC-CDMA systems using smart antennas. A reverse link channel is simulated assuming the frequency selective Rayleigh fading. The simulation results are presented based on the characteristics of DS-CDMA and MC-CDMA systems according to the signal spectrum bandwidth and the method of adaptive beamforming. The BER performances of both systems are improved as the beam width of smart antennas is decreased. Also, it is shown that the performance of MC-CDMA system is much better than that of DS-CDMA system as the number of users is increased.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.249-252
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• 2001

We, for the first time, propose a novel adaptive beamforming algorithm for smart antenna. The algorithm requires neither spatial knowledge nor reference signal. The algorithm is based on gradient method and its merit is in the simplicity of calculation load while maintaining good performance. Computer simulations are presented to verify the performance.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.2
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• pp.247-250
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• 2001

We, for the first time, propose a novel adaptive beamforming algorithm for smart antenna. The algorithm requires neither spatial knowledge nor reference signal. The algorithm is based on gradient method and its merit is in the simplicity of calculation load while maintaining good performance. Computer simulations are presented to verify the performance.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.11
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• pp.1279-1290
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• 2007

In this paper, a cylindrical hybrid antenna which is spatially fed by an off-set linear feed array is described to form complex beam patterns. The linear feed array consists of twelve micro-strip patch elements and forms a flat-topped beam pattern with a beam-width of $90^{\circ}$ in the horizontal plane. The vertical curve on the cylindrical reflector with the linear feed array is shaped in order to form a cosecant beam pattern within the range of $-5^{\circ}$ to $-25^{\circ}$ in the vertical plane. To form complex beam patterns, the hybrid antenna with cylindrical reflector aperture of $140{\times}50\;cm$ was designed and fabricated to be operated within the IMT 2000 service band, and also electrical performances of the antenna were measured and analyzed.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.6
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• pp.1207-1212
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• 2018

The signal intelligence (SIGINT) technology is actively used for collecting various data, in a number of fields, including a military industry. In order to collect the signal information and data and to transmit/receive the collected data efficiently, the accurate angle-of-arrival (AOA) information is required and communication disturbance from the interference or jamming signal should be minimized. In this paper, we present the structure of an adaptive beam-forming satellite system based on the planar array antenna, for collecting and transmitting/receiving the signal information and data efficiently. The presented adaptive beam-forming system consists of an antenna in the form of a planar array, an AOA estimator based on the Multiple Signal Classification (MUSIC) algorithm, an adaptive Minimum Variance Distortionless Response (MVDR) interference canceler, a signal processing and D/B unit, and a transmission beamformer based on Minimum mean Square Error (MMSE). In addition, through the computer simulation, we evaluate and analyze the performance of the proposed system.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.83-86
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• 2000

DS/CDMA 이동통신 환경에서 채널의 용량을 제한하는 가장 큰 요인은 다중 사용자 간섭 신호의 영향이다. 본 논문에서는 어레이 안테나와 적응 혼합 다중 사용자 검파기 구조 (MUD: Multi-User Detection)를 이용하여 이러한 문제를 제거한다. 어레이 안테나의 각각의 빔 형성기는 MUD에서 궤환되는 기준 신호를 이용하여 원하는 사용자의 방향으로 빔을 형성하고 간섭 신호 방향으로는 널을 형성하여 제거하게 된다. 수신 신호의 전력이 제어되지 못하여 원근 문제(near-far problem)가 발생할 경우, 제안한 MUD는 적응적으로 지배적인 상관 값에 대해서는 직렬형, 비슷한 크기의 신호들은 병렬형 간섭 제거기를 통하여 제거함으로써 기존의 고정형 간섭 제거기보다 우수한 성능을 나타내었다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.9A
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• pp.1058-1066
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• 2004

This paper proposes the acquisition system using the multiple antennas in DS-CDMA system. The conventional acquisition schemes using multiple antennas are the methods to utilize the multi-antenna combining and the fixed multi-beam forming of a serial acquisition. Then, this paper proposes the hybrid acquisition scheme using the fixed multi-beam forming. The numerical results show the performance comparison of two acquisition schemes in terms of the acquisition time ill the multipath Rayleigh fading channel.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.6
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• pp.1081-1088
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• 2021

The modern wireless communication system employes the beamforming technique based on a massive array antenna with a number of elements, for supporting the smooth communication services. A reliable beamforming technology requires the Angle-of-Arrival(: AOA) information for the signal incident to the receiving antenna, which is generally estimated by the high-resolution AOA estimation algorithm such as Multiple Signal Classification(: MUSIC). Although the MUSIC algorithm has the excellent estimation performance, it is difficult to estimate AOA in real time for the massive array antenna due to the extremely high computational complexity. In order to enhance this problem, in this paper, we propose the cascade AOA estimation algorithm based on a Flexible Massive Concentric Circular Array(: FMCCA) antenna with the On/Off function for antenna elements. The proposed cascade algorithm consists of the CAPON algorithm using some elements among entire antenna elements and the Beamspace MUSIC algorithm using entire elements. We provide computer simulation results for various scenarios to demonstrate the AOA estimation performance of the proposed approach.