• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.3
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• pp.407-416
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• 2021

An active phased array antennas can not only electrically steer the beam by controlling the weighting of the excitation signal, but can also form a pattern null in the direction of the interference source. The weight of the excitation signal to steer the main beam can be easily calculated based on the position of the radiating element. In addition, the weight of the excited signal for pattern null formation can also be calculated by setting the required radiation pattern and using WLSM(Weighted Least Squares Method). However, in a general wireless communication network environment, the location of the interference source is unknown. Therefore, an adaptive pattern null synthesis is needed. In this paper, it was confirmed that pattern null synthesis according to the required radiation characteristic was possible. And based on this, adaptive pattern null synthesis into the direction of an interference source was studied using a binary search algorithm based on observation area. As a result of conducting a simulation based on the presented technique, it was confirmed that adaptive pattern null forming into the direction of an interference is possible in efficient way.

• The Journal of the Acoustical Society of Korea
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• v.11 no.3
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• pp.53-60
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• 1992

Many adaptive beamforming methods have been studied for interference cancellation and speech signal enhancement in telephone conference and auditorium. Main aspect of adaptive beamforming methods for speech signal processing is different from radar, sonar and seismic signal processing because desire output signal should be apt to the human ear. Considering that phase of speech is quite insensible to the human ear, Sondhi proposed a nonlinear constrained optimization technique whose constraint was on the magnitude transfer function from the source to the output. In real environment the phase response of the speech signal affects the human auditorium system. So it is desirable to design linear phase system. In this paper, linear phase beamformer is proposed and sample processing algorithm is also proposed for real time consideration Simulation results show that the proposed algorithm yields more consistent beam patterns and deep nulls to the noise direction than Sondhi's.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.1
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• pp.9-18
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• 2021

The 5G communication system employs the millimeter wave with the extremely high frequency. Since the high frequency signal has the strong straightness, the beamforming technology based on the multiple base stations is required for services covering wide range. The beamformer needs the angle-of-arrival(AOA) information of the signal incident to the antenna, and it is generally estimated through the high resolution AOA estimation algorithm such as Multiple Signal Classification (MUSIC) or Estimation of Signal Parameters via Rotational Invariacne Technique (ESPRIT). Although various antenna array shapes can be employed for the beamformer, a single shape (square, circle, or hexagonal) is typically utilized. In this paper, we introduce a transmitting/receiving beamforming system based on the combined array antenna with square and circular shapes, which is proper to various frequency signals, and evaluate its performance. For evaluating the performance of the proposed beamforming system based on the combined array antenna, we implement the computer simulation employing various scenarios.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.145-148
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• 2004

수중음향 시스템에서는 빔형성(Beamforming) 기법을 이용하여 목표물로부터 신호를 수신하고 이에 대한 정보를 얻어낼 수 있는데, 이러한 빔형성에 있어서 주엽(Mainlobe)의 빔폭(Beamwidth)과 부엽(Sidelobe)의 크기(Level)를 설계자가 목표하는 값에 최적화 시킬 수 있는 방법을 찾는 것이 무엇보다도 중요하다 최근 연구된 빔형성 기법의 대표적인 결과 중 하나로는 Phi1ip의 Weighting Function Method를 들 수 있다. 이러한 Phi1ip의 방법은 목표 주엽폭과 부엽 준위를 정하고 이를 적응필터 설계방식과 유사하게 적응시켜 나가는 과정을 이용한다. 그러나 이 방법은 주엽폭과 부엽 준위간의 상관관계로 인해서 원하는 부엽준위에 다다르지 못하거나 결과값을 얻는데 상당한 시간이 소요되는 경우가 자주 발생하는데, 이러한 단점을 보완하기 위하여 본 논문에서는 부엽 준위에 미치지 못하는 일부에 대하여 부분 최적화를 시켜 비교적 쉽게 설계를 만족시키는 새로운 알고리듬을 제안하고자 한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.1A
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• pp.84-92
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• 2004

Eigenstructure-based adaptive beamfoming has advantages of fast convergence and the insentivity to errors in the arrival angle of the desired signal. Eigen-decomposing the sample matrix to extract a basis for the Sl (signal plus interference) subspace, however, is very computationally expensive. In this paper, we present a simple subspace based beamforming which utilizes off-diagonal elements of the sample matrix to estimate the Sl subspace. The outputs of overlapped subarrays are combined to produce the final adaptive output, which improves SINR (signal-to-interference-plus-noise ratio) comapred to exploiting a single subarray. The proposed adaptive beamformer, which employs an efficient angle estimation is very roubust to errors in both the arrival angles and the number of the incident signals, while the eigenstructure-based beamforer suffers from severe performance degradation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.10A
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• pp.1006-1012
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• 2008

This paper presents a Duvall-structure-based adaptive beamforming method which efficiently cancels coherent and incoherent interferences. The proposed method exploits several correlation vectors to increase the dimension of the weight vector, compared to the existing method which uses a single correlation vector only. The increased dimension of the weight vector leads to an improvement in the signal-to-interference plus noise ratio (SINR) performance. Moreover, the proposed method can suppress more interferences than the existing one. Simulation shows that the former is superior to the latter in terms of the steady-state and transient responses.

• The Journal of the Korea Contents Association
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• v.9 no.6
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• pp.37-44
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• 2009

In this paper, we present a switched beamforming RFID reader and propose a convenient shopping system using it. The smart gate with the switched beamforming RFID reader(s) improves tag detection probability, tag false alarm probability, automatic detection functionality of shopping system compared to existing RFID based systems. The proposed system consists of a smart gate to read and verify the tags within cart, a check-out counter to approve customer purchase, and a central server to manage inventory & delivery and to analyze customer purchase trend. The proposed shopping system is more practical, convenient, and cost-effective to A/S than existing RFID shopping systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.1C
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• pp.72-80
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• 2003

This paper proposed the method of finding optimal weight vectors for enhancing the performance of an adaptive array antenna system by adopting a novel beam-forming algorithm in CDMA (code division multiple access) channel. This algorithm is a liberalized power method, based on power method, with the total computational load, O(4N). Where, N denotes the number of antenna elements. The performance of the proposed algorithm is shown in terms of SER (symbol error rates), allowable capacity, and the convergence characteristic in IS2000 1X CDMA channel. As a result of simulations, the adaptive way antenna system allows 6-10 times more users than the conventional one in a cell of a base station. Furthermore, the proposed algorithm shows superior performance to the conventional one regarding symbol error rates, converging characteristics, and computational load.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.3
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• pp.491-498
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• 2017

GPS (global positioning system) is a popular system that provides location information by measuring arrival time difference at the receiver between several GPS satellite signals. GPS is widely used in commercial area as well as military systems. Reliable GPS signal reception is more important in the military applications such as guided missiles. However, since the carrier frequencies of the GPS signals are well known and the received power is extremely low, the GPS systems are vulnerable to intentional jamming attacks. To remove jammers while maintaining GPS signals at the received signals, a popular technique is an adaptive beam steering method based on array antenna. Among adaptive beam steering techniques, this paper considers MVDR (minimum variance distortionless response) algorithm, and proposes a new adaptive technique that preserves the received signals at desired directions, but removes the unknown jamming signals adaptively. The performance of the proposed method is verified through computer simulation.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2003.11a
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• pp.167-170
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• 2003

본 논문은 ATSC방식의 지상파 DTV의 이동수신 성능 개선을 위해 적응 어레이 안테나를 사용하여 입사되는 신호의 위상 정보를 통해 원하는 신호원의 방향을 찾고 주신호와 다중경로 신호 사이에 capon알고리즘을 통해 최대의 이득을 얻는 최적의 빔을 형성하며 이동수신채널인 도플러효과가 포함된 다중경로신호득의 영향을 약화시킨다. 빔형성 알고리즘을 통한 채널의 개선이 LMS 알고리즘을 사용한 통화기의 성능을 얼마나 향상시키는지 전산 모의 실험을 통해 확인하였다.