• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 하계종합학술대회 논문집(1)
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• pp.265-268
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• 2004

In this paper. we propose an adaptive step-size algorithm for the adaptive interference canceller (AIC) in the space-time trellis coded DS-CDMA system. In the AIC, the performance of the blind LMS algorithms that updates the tap-weight vector of the AIC is heavily dependent on the choice of step-size. To improve the performance of the fixed step-size AIC (FS-AIC), the regular adaptive step-size algorithm is extended in complex domain and applied to the joint AIC and ML decoder scheme. Simulation results show that the joint adaptive step-size AIC (AS-AIC) and ML decoder scheme using the proposed algorithm has boner performance than not only the conventional ML decoder but also the joint FS-AIC and ML decoder scheme without much increase of the decoding delay and complexity.

• 한국음향학회지
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• 제25권2호
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• pp.56-60
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• 2006

시간영역에서 오디오 신호는 일반화된 가우시안 분포를 갖는다는 사실에 기초하여 BER (Bit Error Rate)이 최소가 되는 ML (Maximum Likelihood) 시험 기반 오디오 워터마크 디코더의 최적 변수추정방법을 제안하였다. 제안한 방법이 기존의 변수추정방법이나 상관관계에 기초한 디코더 보다 성능이 우수함을 실험적으로 증명하였다.

• Journal of information and communication convergence engineering
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• 제4권2호
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• pp.75-78
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• 2006

This work presents a low complexity maximum-likelihood decoder for signal detection in VBLAST-STBC system, which employs non-square O-STBC code rate 3/4. Stacking received symbols from different symbol duration and applying QR decomposition result in the special format of upper triangular matrix R so that the proposed decoder is able to provide not only ML-like BER performance but also very low computational load. The low computational load and ML-like BER performance properties of the proposed decoder are verified by computer simulations.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2005년도 춘계종합학술대회
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• pp.126-130
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• 2005

In this paper, a low-complexity maximum-likelihood (ML) decoder based on QR decomposition, called real-valued LCMLDec decoder or RVLCMLDec for short, is proposed for the Vertical Bell Labs Layered Space-Time (V-BLAST) architecture, a promising candidate for providing high data rates in future fixed wireless communication systems [1]. Computer simulations, in comparison with other detection techniques, show that the proposed decoder is capable of providingthe V-BLAST schemes with ML performance at low detection complexity.

• Journal of information and communication convergence engineering
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• 제3권2호
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• pp.76-79
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• 2005

In this paper, a low-complexity maximum-likelihood (ML) decoder based on QR decomposition, called real-valued LCMLDec decoder or RVLCMLDec for short, is proposed for the Vertical Bell Labs Layered Space-Time (V-BLAST) architecture, a promising candidate for providing high data rates in future fixed wireless communication systems [1]. Computer simulations, in comparison with other detection techniques, show that the proposed decoder is capable of providing the V­BLAST schemes with ML performance at low detection complexity

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2006년도 춘계종합학술대회
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• pp.107-110
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• 2006

This work presents a low complexity maximum-likelihood decoder for signal detection in VBLAST-STBC system, which employs non-square O-STBC code rate 3/4. By stacking received symbols from different received symbolduration and applying QR decomposition resulting the special format of upper triangular matrix R, the proposed decoder is able to provide not only ML-like BER performance but also very low computational load. The low computational load and ML-like BER performance properties of the proposed decoder are verified by computer simulations.

• 한국항행학회논문지
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• 제15권3호
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• pp.392-404
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• 2011

본 논문에서는 최근 4세대 이동통신에서 논의 되고 있는 기술인 셀 간 협력 통신이 가능한 다중 셀 환경에서 상향링크에서의 다중 사용자 신호 검출기술에 대해서 다루었다. 먼저 기존 검출 기술로 ML, ZF, MMSE 그리고 SIC 등을 다루었고, 보통 ML은 최적의 성능을 보이지만, 복잡도가 지수적으로 증가하며, ZF나 MMSE는 간단하지만 성능이 떨어지며, SIC는 복잡하고 오류전파 현상이 발행 할 수 있는 문제점을 가지고 있다. 이에 기존의 ZF/MMSE 에 비해서는 성능 개선이 이루어지면서, 복잡도를 유지 또는 감소시킬 수 있는 구조 제안을 위해서 ZF/MMSE 방식과 ML 의 적용구조를 단순화 시킨 부분 ML 복호 방식을 결합한 검출 방식을 제안하였다. 모의실험 결과, 제안방식은 ZF/MMSE 기반의 SIC 방식에 비해 BER 성능이 개선 또는 유지 되었으며, 복잡도 측면에서 감소하는 효과를 보였으며, 또한 복잡도 감소는 협력 기지국 및 안테나 수가 증가할수록 더 감소 효과가 커질 수 있음을 알 수 있었다.

• Journal of Communications and Networks
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• 제16권1호
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• pp.26-35
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• 2014

We consider multiple-input multiple-output decode-and-forward relay systems in Rayleigh fading channels under the partial channel state information (CSI) that the channel statistics of the source-relay (SR) link and the instantaneous CSI of the source-destination and relay-destination links are known at the destination. In this paper, we propose a new near maximum likelihood (near-ML) decoder with two-level pairwise error probability (near-ML-2PEP) which uses the average PEP instead of the exact PEP. Then, we theoretically prove that the near-ML and near-ML-2PEP decoders achieve the maximum diversity, which is confirmed by Monte Carlo simulations. Moreover, we show that the near-ML-2PEP decoder can also achieve the maximum diversity by substituting the average PEP with the values that represent the error performance of the SR link.

• 한국정보통신학회논문지
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• 제13권12호
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• pp.2525-2532
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• 2009

본 논문에서는 uncoded V-BLAST(Vertical Bell Laboratories Layered Space Time) 시스템에서 PSK 신호들을 joint-detection하기 위한 fast sphere decoder를 제안한다. 이른바 PSD라 불리는 제안된 디코더는 예비처리단계와 검색단계로 구성된다. PSD의 검색단계에서는 depth-first branch and bound 알고리즘을 통해 검출 후보가 되는 신호원들의 최상우선순위(best-first order)를 정하고 이 순위에 따라 신호를 검출하게 된다. 이 때 제안된 디코더는 최상우선순위(best-first order)를 정하는데 있어 계산복잡성을 줄이는 새로운 방법을 제안한다. 시뮬레이션 결과는 PSD에 의해 시스템의 복잡성은 줄이면서 시스템 성능은 ML과 동일하게 유지할 수 있음을 보여준다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2008년도 추계종합학술대회 B
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• pp.890-893
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• 2008

In this paper, we present a low complexity modified multi-level sphere decoder (SD) for multiple-input multiple-output (MIMO) systems employing quadrature amplitude modulation (QAM) signals. The proposed decoder, exploiting the multi-level structure of the QAM signal scheme, first decomposes the high-level constellation into low-level 4-QAM constellations, so-called sub-constellations. Then, it deploys SD in the sub-constellations in parallel. In addition, in the searching stage, it uses the optimal low-complexity sort method. Computer simulation results show that the proposed decoder can provide near optimal maximum-likelihood (ML) performance while it significantly reduces the computational load.