• 제어로봇시스템학회논문지
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• 제8권1호
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• pp.74-79
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• 2002

A fast and practical method is proposed to resolve the half cycle ambiguity by comparing data sequences from multiple antennas. The method uses the fact that demodulated data sequences from multiple antennas are identical for the same SV (Satellite Vehicle). The performance of the proposed method is evaluated using an attitude determination system. the test results show that the half cycle ambiguity can be resolved within a few bit periods after carrier lock and a seamless attitude is obtained.

• Journal of Communications and Networks
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• 제13권3호
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• pp.257-265
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• 2011

In this paper, a cooperative relaying protocol called soft-decision-and-forward (SDF) with multiple antennas in each node is introduced. SDF protocol exploits the soft decision source symbol values from the received signal at the relay node. For orthogonal transmission (OT), orthogonal codes including Alamouti code are used and for non-orthogonal transmission (NT), distributed space-time codes are designed by using a quasi-orthogonal space-time block code. The optimal maximum likelihood (ML) decoders for the proposed protocol with low decoding complexity are proposed. For OT, the ML decoders are derived as symbolwise decoders while for NT, the ML decoders are derived as pairwise decoders. It can be seen through simulations that SDF protocol outperforms AF protocol for both OT and NT.

• 한국통신학회논문지
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• 제38A권11호
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• pp.976-978
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• 2013

본 논문은 LoS(line-of-sight) 환경에서 두 개의 선형편파 안테나를 사용하는 데이터 통신 기법을 다룬다. 편파안테나의 물리적인 각도가 채널용량과 오류성능에 미치는 영향을 분석한다. 두 가지 관점에서의 최적 안테나 각도가 상이함을 보이며, 두 각도에 대해 채널용량 및 오류성능을 비교한다.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2011년도 추계학술대회
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• pp.78-81
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• 2011

본 논문에서는 ATSC (Advanced Television Systems Committee) 지상파 DTV (digital television) 방송 시스템에서 부가 데이터 전송률을 향상시키면서 비트 오율 (bit error rate) 성능을 개선하기 위한 다중 안테나 부가데이터 전송 방식을 제안한다. 제안된 다중 안테나 전송방식은 Alamouti 기법을 사용하여 단일 안테나 전송 방식에 비해 신호대 잡음비 이득을 얻는다. 또한, 제안하는 전송 방식은 기존의 ATSC 지상파 DTV 수신기와 역호환성을 가진다는 장점이 있다.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2011년도 추계학술대회
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• pp.247-250
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• 2011

본 논문에서는 ATSC (Advanced Television Systems Committee) 지상파 DTV (digital television) 방송 시스템에서 부가 데이터 전송률을 향상시키면서 비트 오율 (bit error rate) 성능을 개선하기 위한 다중 안테나 부가데이터 전송 방식을 제안한다. 제안된 다중 안테나 전송방식은 Alamouti 기법을 사용하여 단일 안테나 전송 방식에 비해 신호대 잡음비 이득을 얻는다. 또한, 제안하는 전송 방식은 기존의 ATSC 지상파 DTV 수신기와 역호환성을 가진다는 장점이 있다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(1)
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• pp.149-152
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• 2002

In this paper, an adaptive interference canceller (AIC) Is applied to the space-time coded DS-CDMA system in fading channels with arrival time difference from multiple transmit antennas In a CDMA system, arrival time difference causes not only inter-antenna and Inter-symbol interference but also multiple-access Interference even in a downlink. To mitigate the effect of the Interferences an AIC and ML decoding joint scheme Is proposed fur a space-time coded DS-CDMA system in which an adaptation process of tile AIC is merged in the Viterbi decoding algorithm. The performance of the proposed receiver is evaluated for the system with two transmit antennas. It is shown that the proposed receiver achieves significant performance improvement over the ML decoding receiver without the AIC

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2007년도 하계종합학술대회 논문집
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• pp.83-84
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• 2007

Multiple-input multiple-output (MIMO) systems can achieve the increasing of performances by using an adaptive power allocation. The related previous work limited the transmit antenna number because orthogonal space-time block codes (OSTBCs) yield full transmit rate only for two transmit antennas. We extend a robust system under imperfect channel estimation for four transmission antennas with maintaining a full transmission rate.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2008년도 정보통신설비 학술대회
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• pp.379-383
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• 2008

Cognitive Radio (CR) technology is proposed for using the unused spectrum band efficiently because of the spectrum scarcity problems. Spectrum sensing is one of the most challenging issues in cognitive radio system. In this paper, we focus on the signal detection of WiBro system band. As most of the modulated signals can be treated as cyclostationary random process, we can detect the signal of the OFDM signals in WiBro system. OFDM symbols using WiBro system have several pilot subcarriers and periodic pilots have cyclostationary characteristic. To improve of the detection performance, we get diversity gain using multiple antennas.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2008년도 정보통신설비 학술대회
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• pp.409-413
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• 2008

In this paper, we introduce a platform of advanced multiple antenna system based on orthogonal frequency-division multiplexing (OFDM). The advanced multiple antennas have beamforming gain using array antenna. In array antenna systems, received signal has phase delay caused distance of each antennas, therefore it should compensate with optimum weight vector which calculated by Lagrange algorithm. To implement the presented above procedures using Digital Signal Processor (DSP), we should fixed-point design. The performance of implemented platform is verified through MATLAB$^{(R)}$ simulations with various signal environments.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2004년도 SMICS 2004 International Symposium on Maritime and Communication Sciences
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• pp.32-35
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• 2004

In this paper, we propose two novel high-rate high-performance space-time codes for multiple-input multiple-output (MIMO) systems. When $n_{T}$ transmit antennas and $n_{R}$ = $n_{T}$ receive antennas are deployed, the two proposed codes respectively offer transmission rates of ( $n_{T}$ -I) and ( $n_{T}$ - 2) symbols per channel use and diversity orders of 3 and 5. As a consequence, our proposed codes allow the MIMO systems to employ a simple detection technique based on QR decomposition. Moreover, for equal or even higher spectral efficiencies, our proposed codes always provide much better bit error rate (BER) performances than V-BLAST architecture does when $n_{R}$ = $n_{T}$. Computer simulation is given to verify performances of our proposed codes.sed codes.des.