• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.6
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• pp.757-763
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• 2018

It is very difficult to achieve sufficient data rate and required quality of service due to the time-varying nature of the radio channel and various jammers such as path loss, delay, Doppler, shadowing and interference. Especially, the propagation path between the transmitting antenna and the tracking antenna mounted on the fuselage during the test and evaluation of the projectile system considered in this paper is based on the rapid movement of the projectile, the interference due to multipath fading due to the terrain, The propagation path may be blocked. In order to effectively improve the multipath fading occurring in the wireless communication system, a diversity combiner technique is required. In this paper, to derive the design and improvement schemes for the space diversity combiner technique among the diversity combiner schemes, the BER performance of maximum ratio combining (MRC) and selection combining (SC) In an adaptive SC / MRC diversity combiner that operates with MRC when it is lower than the specified threshold criterion when comparing the SNR between two signals received from the channel and operates with SC at high and combines the two received signals The BER performance of the system was compared and analyzed.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.07a
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• pp.33-33
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• 2004

• Information and Communications Magazine
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• v.22 no.9
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• pp.100-111
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• 2005

다중안테나 (multiple-input multiple-output: MIMO) 시스템의 장점은 단일안테나에 비해서추가적인 주파수나 송신 전력을 증가시키지 않고 채널 용량을 안테나 수에 비례하여 증가시킬 수 있는 것이다. 본 논문에서는 다중 안테나 시스템의 이론적 용량을 살펴보고, 이를 달성하기 위한 기법들을 소개한다. 다중안테나 기법은 다이버시티 이득을 얻어 전송 신뢰도를 높이는 방식들과, 전송률을 높이는 공간 다중화 방식, 그리고 이 두 가지를 결합한 방식 등으로 크게 나눌 수 있다. 끝으로 휴대 인터넷에 사용되는 다중안테나 기술을 다룬다.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.191-192
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• 2006

An orthogonal antenna is presented for reader applications of radio frequency identification (RFID) at 433 MHz. The antenna is composed of two $1{\times}2$ sub-arrays orthogonally placed on a ground plane. Two different feeding networks are introduced to control horizontal and vertical radiation current flows for each sub-array, respectively. An inverted-F structure is used as a radiation element with vertical and horizontal currents flowing on the radiator, thereby obtaining two linear polarizations. Antenna gains are 3.71 and 3.43 dBi and isolation between the two input ports is less than 25dB.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.11a
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• pp.375-375
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• 2004

• Proceedings of the Korea Multimedia Society Conference
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• 2003.05b
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• pp.32-35
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• 2003

공간-시간 블록 부호(STBC)는 다중안테나 시스템에서 기존 기술에 비해서 부가적인 대역폭 필요 없이 부호화 이득을 얻을 수 있다. STBC의 우수한 디자인 조건은 다이버시티 이득 관점에서는 신호 행렬들의 차가 완전 계수(Full-Rank)를 가져야 하고 코딩 이득의 관점에서는 신호 행렬들의 차의 determinant 값이 최소값을 가져야 한다. 본 논문에서는 STBC가 Full Rank 와 non-Full Rank 때 성능에 관하여 실험하였다. 시스템모델에 관하여 간략한 설명과 이 실험결과에 관하여 논의하였다. 본 논문의 실험 결과는 전송안테나와 수신안테나가 각각 4개씩, BPSK, QPSK, 8PSK 변조(modulation)을 사용하여 실험결과를 얻었다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.1037-1040
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• 2005

In this paper, we analyze the performance of high data rate wireless personal area network (HDR-WPAN) system using multiple antenna scheme, space-time block code in fading channel. Multiple antenna technique is used to improve the error performance by combining the receive signal through multiple receive antenna. Space-time block code is a space-time diversity scheme which can obtain the maximum space diversity gain and easily implements a ML receiver via a simple process. HDR-WPAN system using space-time block code obtain about 14dB diversity gaint at BER 10$^{-5}$ in multipath fading channel. From the simulation result, We confirm that HDR-WPAN system adopting space-time block code has reliable communication even low power.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.4
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• pp.17-22
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• 2015

In this paper, we propose a cooperative vehicle communication scheme for high transmission efficiency and coverage extension under multipath fading environment of moving vehicle networks. The proposed scheme uses a Network coding scheme for improvement of receiving performance by using virtual Multiple-Input Multiple-Output(MIMO) transmit diversity. Simulation results have shown that the proposed scheme also provides alleviated Inter Symbol Interference(ISI) and Inter Channel Interference(ICI) as well as Signal-to-Noise Ratio(SNR) improvement and improve 3dB compared to the conventional scheme, since it can utilize the good properties of spatial diversity and coding gain by using virtual MIMO configuration. In this paper, we propose simulations of Ultra-Wideband(UWB) communication system to show validity by using the MATLAB.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.4
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• pp.31-36
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• 2012

In this paper, we proposed spectrum sensing using cooperative relay to solve problem of sensing performance degradation due to CPE (Customer-Premises equipments) which causes low SNR (signal-to-noise ratio) problem. In cooperative communication system, AF (amplify-and-forward) and DF (decoded-and-forward) is widely used for relay mechanism. Also, it is expected that cooperative relay scheme guarantees the high sensing performance by its diversity gain. Based on these backgrounds, in this paper, we apply to cooperative relay scheme to the CR (Cognitive Radio) system, and simulation results show comparison of the sensing performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.10A
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• pp.968-975
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• 2006

Research about the mode of MIMO that can get a coding benefit at the same time with a diversity benefit using a multiple antenna at the fading channel for a high-speed data transmission have been processed actively But the analysis about the interference of UWB system comes not to consist yet. So this paper analyzed the performance of the interference of UWB system to SFBC-OFDM and SFTC-OFDM system that applied a space block code which has a space diversity characteristic to OFDM system at MIMO channel. We shelved the performance that SFTC-OFDM system is robuster than SFBC-OFDM system under MB-OFDM UWB Interference.