• 대한음성학회지:말소리
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• 제66호
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• pp.73-86
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• 2008

Beamforming is one of the spatial filtering techniques which extract only desired signals from noisy environments using microphone arrays. Fixed beamforming is a simple concept and easy to implement. However, it does not show good performance in real noisy conditions. As an adaptive beamforming, Frost algorithm can be a good candidate. It uses the concept of the linearly constrained minimum variance (LCMV) algorithm. The difference between the Frost and the LCMV algorithm is the error correction scheme which is very effective feature in the aspect of performance. In this paper, as quadrature mirror filtering (QMF)-based filterbank is utilized as the pre-processing of the Frost beamformning, the filter length and the learning rate of each band is optimized to improve the performance. The performance is measured by the signal-to-noise ratio (SNR) and the Bark's scale spectral distortion (BSD).

• Journal of Positioning, Navigation, and Timing
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• 제3권2호
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• pp.37-44
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• 2014

The most effective method to overcome GPS jamming problem is to use an adaptive array antenna which has the capability of beamforming or nulling to a certain direction. In this paper, Space Time Adaptive Processing (STAP) beamforming algorithm of four elements array antenna will be designed and the anti-jamming performance will be analyzed. According to the analysis, the signal to noise ratio (SNR) and anti-jamming performance can be enhanced by beamforming algorithm. Also, the time tap effect of STAP algorithm will be analyzed theoretically and verified with array antenna modeling and simulation. Specially, the cautious selection of reference time tap in STAP can prevent the degradation of position accuracy performance.

• 한국통신학회논문지
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• 제31권12A호
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• pp.1214-1222
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• 2006

본 논문에서는 orthogonal frequency-division multiple-access 스마트 안테나 시스템을 위한 효율적인 도래각 추정 기반의 적응 빔 형성 알고리즘을 제안한다. 제안된 알고리즘은 추정된 도래각 정보를 이용하여 원하는 신호의 방향으로 주 빔 (main beam)을 형성하는 반면, 간섭 신호의 방향에는 null을 형성함으로써 간섭 신호를 효율적으로 제거한다. 또한, 다중 경로 신호에 대한 빔 형성 출력들을 효율적으로 결합함으로써 공간 다이버시티 이득을 얻을 수 있다. 제안된 알고리즘의 효율성을 입증하기 위해 셀룰러 이동통신 환경에서 WiBro 시스템을 목표 시스템 (target system)으로 설정하여 알고리즘의 성능을 분석하고 least-sqaures 빔 형성 알고리즘과 성능을 비교한다.

• International journal of advanced smart convergence
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• 제9권1호
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• pp.177-184
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• 2020

In this paper, we studied to direction of arrival (DoA) estimation to use DoA and optimum weight algorithms in coherent interference channels. The DoA algorithm have been considerable attention in signal processing with coherent signals and a limited number of snapshots in a noise and an interference environment. This paper is a proposed method for the desired signal estimation using MUSIC algorithm and adaptive beamforming to compare classical subspace techniques. Also, the proposed method is combined the updated weight value with LCMV beamforming algorithm in adaptive antenna array system for direction of arrival estimation of desired signal. The proposed algorithm can be used with combination to MUSIC algorithm, linearly constrained minimum variance beamforming (LCMV) and the weight value method to accurately desired signal estimation. Through simulation, we compare the proposed method with classical direction of in order to desired signals estimation. We show that the propose method has achieved good resolution performance better that classical direction arrival estimation algorithm. The simulation results show the effectiveness of the proposed method.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권6호
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• pp.1379-1397
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• 2013

We consider a system where a licensed radio spectrum is shared by multiple primary users(PUs) and secondary users(SUs). As the spectrum of interest is licensed to primary network, power and channel allocation must be carried out within the cognitive radio network so that no excessive interference is caused to PUs. For this system, we study the joint beamforming and power allocation problem via game theory in this paper. The problem is formulated as a non-cooperative beamforming and power allocation game, subject to the interference constraints of PUs as well as the peak transmission power constraints of SUs. We design a joint beamforming and power allocation algorithm for maximizing the total throughput of SUs, which is implemented by alternating iteration of minimum mean square error based decision feedback beamforming and a best response based iterative power allocation algorithm. Simulation results show that the algorithm has better performance than an existing algorithm and can converge to a locally optimal sum utility.

• 디지털산업정보학회논문지
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• 제5권3호
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• pp.99-105
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• 2009

This paper suggests novel signal processing methods for optimal beamforming of smart antenna system in CDMA2000 mobile communication environments. This method utilize characteristics of the reverse pilot channel of CDMA2000 mobile communication systems, and applies them to improve the performance of an adaptive algorithm, which is used to a smart antenna system for beamforming. To perform the best beamforming, it is important to get an exact beamforming algorithm. This paper proposed an algorithm based on Laglange multiplier which has such an adaptive process, and also proposed the method to demodulate the received signal through array antenna using pilot channel in CDMA2000 environment. This paper analysed the enhanced performance of proposed algorithm in various signal environment through signal modeling of physical layer in CDMA2000 reverse link.

• 한국음향학회지
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• 제37권1호
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• pp.66-72
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• 2018

본 논문에서 우리는 능동소나 시스템에서 삼중 배열의 적응 빔형성 기법을 제안한다. 제안하는 기법은 정합필터, 카디오이드 빔형성, 선배열 빔형성으로 구성된 3단계의 과정을 통해 빔형성을 수행한다. 먼저, 송신 펄스에 대한 정합필터를 개별 수신 센서 신호에 적용하여 필터링된 신호를 획득한다. 그리고 정합필터 출력에 푸리에 변환을 적용하고, 각 삼각 센서 별 카디오이드 빔을 형성한다. 최종적으로 삼각 센서에 대한 카디오이드 빔들을 선배열 신호의 입력으로 가정하여 선배열 적응 빔형성을 적용한다. 실험 결과를 통해 제안하는 방법의 성능이 기존 기법보더 더 우수함을 확인한다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.730-734
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• 2003

A beamforming method is a kind of spatial filter that focus the amy's signal capturing abilities in a desired direction. In this paper, we detect the location of a source under reflective condition using the multi-dimensional MUSIC algorithm then, we can iud the image source locations from the experimental geometry, and we reconstruct the partial fields for direct wave and reflected wave by using Adaptive nulling algorithm. Numerical simulations are performed to verify its performance under various conditions.

• ETRI Journal
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• 제31권3호
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• pp.321-323
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• 2009

A wideband beamforming algorithm for estimating the azimuth angle, elevation angle, velocity, and range using a planar phased radar array with antenna switching is proposed. It uses the time-variant steering vector model. Simulation results illustrating the performance of the proposed beamformer are presented.

• 한국통신학회논문지
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• 제40권9호
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• pp.1686-1692
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• 2015

본 논문에서는 메쉬 네트워크의 이동노드에 대해 기존의 유전알고리즘을 이용한 빔형성과 같은 성능을 가지면서 빠른 수렴속도를 가지고 지역해에 빠지지 않는 개선된 유전알고리즘을 제안한다. 제안한 빔형성 유전알고리즘은 빠른 수렴속도를 얻기 위해서 교배과정에서 적합도가 높은 염색체의 일정비율을 추출하고 지역해에 빠지는 것을 방지하기 위해 하위 염색체로 교배에 사용하였다. 그리고 적합도 측정용 빔형성의 기준 빔패턴을 가우시안 함수를 이용하여 수렴속도를 더욱 빠르게 하였다. 전산모의 실험을 통하여 제안한 빔형성 유전알고리즘이 기존의 빔형성 유전알고리즘 방식과 비교하여 약 20%의 빠른 수렴속도가 향상되었음을 보였다.