• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.10
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• pp.904-910
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• 2016

The choice of nulling antenna type to be used for a given specification of user locations usually centers on whether to use a phased array antenna(PAA) or a multiple-beam antenna(MBA) for a satellite payload. This paper considers a MBA to analysis the nulling effect in the Korean peninsula jamming circumstance. First, the nulling performance and characteristics on the region of the earth coverage are confirmed with respect to the case of 7 beams. Then, optimum results are derived and compared to what can be accomplished with a fixed set of beams(the case of 10 and 19 beams are considered) for null steering to reject interference is investigated for a MBA.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.2A
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• pp.147-154
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• 2009

Antenna grouping algorithm is hybrid of beamforming and spatial multiplexing. In antenna grouping system, we partition $N_t$ transmit antennas into $N_r$ groups and use beamforming in a group, spatial multiplexing between groups. We can transmit $N_r$ data streams in the $N_t{\times}N_r$ antenna grouping system. With antenna grouping, we can achieve diversity gain through beamforming, and high spectral efficiency through spatial multiplexing. But if channel is ill-conditioned or there are some correlations between antennas, the performance of antenna grouping is seriously degraded and in that case, beamforming is the best transmit strategy. By selecting the antenna grouping mode when channel is well-conditioned and by selecting the beamforming mode when channel is ill-conditioned, we can prevent serious fluctuation of BER performance caused by varying channel condition and achieve the best BER performance. In this paper, we investigate mode selection algorithm which can select antenna grouping mode or beamforming mode. we also propose a simple mode selection criterion.

• Journal of Convergence for Information Technology
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• v.11 no.4
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• pp.26-34
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• 2021

In the era of the Fourth Industrial Revolution, the future battlefield will carry out multi-area operations with hyper-connected, high-speed and mobile systems. In order to prepare for changes in the future, the Korean military intends to develop various weapons systems and form a multi-layer tactical network to support On The Move communication. However, current tactical networks are limited in support of On The Move communications. In other words, the operation of multi-beam antennas is necessary to efficiently construct a multi-layer tactical network in future warfare. Therefore, in this paper, we look at the need for multi-beam antennas through the operational scenario of a multi-layer tactical network. In addition, based on development consideration factors, features of rotary-wing and fixed-wing aircraft, we present the location and operation of airborne relay drone installations of multi-beam antennas.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.2
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• pp.219-224
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• 2020

In this paper, we studied the compact MIMO(: Multi-Input Multi-Output) antenna for multi-beam pattern generation and control in narrow space. The characteristics and performance of the basic Dipole SPA and Monopole SPA structures are shown. We implemented a monopole SPA antenna and measured its performance in an 802.11g system. When the average transmission rate was measured using the SPA antenna, the SPA antenna improved the best performance by 8.7 times compared to commercial antenna.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.1
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• pp.16-22
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• 2015

This paper proposes a power allocation method for multiple node beamforming with uniform circular array antennas to increase SIR of nodes in wireless mesh network. The proposed method calculates beamforming power allocation vectors that maximizes SIR satisfied with power constraint of HPA. The simulation results demonstrate the proposed method achieves the enhanced SIR of nodes than that of beamforming method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.6
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• pp.1286-1291
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• 2013

Intensive researches on multiuser-based Massive MIMO are performed to increase the spectral efficiency. Although the Massive MIMO scheme based on huge number of antennas inevitably causes hardware and computational complexity in baseband and radio frequency (RF) elements, the problem can be mitigated without serious performance degradation by limiting the number of baseband and RF elements below the number of transmit antennas of base station and opportunistically selecting transmit antennas according to channel states. Accordingly, this paper proposes a simple antenna selection scheme for multiuser-based Massive MIMO systems.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2003.06a
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• pp.193-196
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• 2003

시공간 빔포밍 기술은 기존의 배열 안테나가 공간만의 처리를 해온 것에 대하여 이를 시간 영역으로까지 확장하여 특정한 방향에서 특정한 시간에 도착하는 다중경로는 증폭하고 다른 다중경로는 제거하는 것을 의미한다. 본 논문은 배열 안테나를 가진 DS-CDMA에서 시스템 파라미터 부정합이 존재할 때, 시공간 빔 형성기의 성능에 대하여 연구하였다. 시뮬레이션 결과, 부정합이 존재할 때 전통적인 빔포머가 상대적으로 강인함을 보였지만 원근 문제는 해결할 수 없었으며, 실제의 추정 결과를 적용했을 때는 MUSIC 시공간 빔포머가 가장 우수한 성능을 보였다.

• 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.

• Journal of Satellite, Information and Communications
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• v.5 no.2
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• pp.45-49
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• 2010

This paper presents the study on multi-beam large aperture antenna systems for a satellite payload. Multi-beam large antenna provides the universal communication and broadcasting services to personal portable terminals. The hybrid antenna composed of a large reflector and a feed array forms multi-beams. The feed cluster consists of a group of feed elements and each element should be optimized for the appropriate amplitude and phase. The optimization progress for amplitude and phase was performed by GO (Geometrical Optics) and PO (Physical Optics) method. The number of feed elements as well as the power level per element were also optimized to meet the required EIRP (Effective Isotropically Radiated Power). In conclusion, 30m-class reflector and twenty five elements for fifteen beams over Korean Peninsula were designed through the optimization process.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.5
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• pp.220-228
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• 2014

ESPAR(Electronically Steerable Parasitic Array Radiator) antenna is the technique for overcoming the problems of space limitation and energy efficiency due to the multiple RF-chain. Conventional MIMO system with multiple antenna requires a large number of RF-chain for transmitting the multiple data because it transmits the data in proportion to the number of antenna. Beamspace MIMO system using the ESPAR antenna which has single RF-chain was proposed for solving the problems caused by using the multiple antenna and RF-chain. In this paper, therefore we propose 2x2 beamspace MIMO system using the 16, 64-QAM modulation and evaluate the performance of this system to reveal that it is possible that beamspace MIMO system can use not only PSK modulation but also QAM modulation. We confirm that QAM symbol can be generated by adjusting reactance of parasitic elements and making reactance set and also we confirm that performance of beamspace MIMO system is similar to the conventional MIMO system by transmitting the QAM symbol made by reactance set through the simulation.