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RISS 인기검색어
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- 주제어 : Maximum likelihood (ML) estimation (검색결과 4 건)
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Biased SNR Estimation using Pilot and Data Symbols in BPSK and QPSK Systems
박치현,홍광석,남상원,장준혁 한국통신학회 2014 Journal of communications and networks Vol.16 No.6
In wireless communications, knowledge of the signal-tonoiseratio is required in diverse communication applications. Inthis paper, we derive the variance of the maximum likelihood estimatorin the data-aided and non-data-aided schemes for determiningthe optimal shrinkage factor. The shrinkage factor is usuallythe constant that is multiplied by the unbiased estimate and it increasesthe bias slightly while considerably decreasing the varianceso that the overall mean squared error decreases. The closed-formbiased estimators for binary-phase-shift-keying and quadraturephase-shift-keying systems are then obtained. Simulation resultsshow that the mean squared error of the proposed method is lowerthan that of the maximum likelihoodmethod for low and moderatesignal-to-noise ratio conditions.
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An Aircraft's Parameter Identification Algorithm Based on Cloud Model Optimization
Zhang Wei,Liu Yi-lei,Guo Da-Peng,Khayyam Masood,Tian Jing 제어로봇시스템학회 2014 제어로봇시스템학회 국제학술대회 논문집 Vol.2014 No.10
The maximum likelihood (ML) estimation method has been extensively applied to identifying the parameters of an aircraft. But it has to derive sensitivity equations in advance and solve sensitivity matrices, thus being complicated for its application and easily reaching locally optimal solutions. The paper proposes an aircraft"s parameter identification algorithm, which optimizes the ML function with the cloud model optimization theory in accordance with the ML estimation principle, thus obtaining the values of the parameters to be identified. The algorithm does not have to derive sensitivity matrices, has no high requirements for initial values and is little affected by noise. Thus it is easy to apply, can be optimized by the cloud model and have rather fast convergence and nice global search capability and thus not easily reaching locally optimal solutions. The Twin Otter airplane is used as a numerical example to verify the algorithm. The numerical results show that the parameter identification algorithm is easy to implement, has good identification precision and fast convergence and does not reach locally optimal solutions.
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가우시안 재밍 환경에서 채널 추정 에러를 고려한 인덱스 변조 비직교 다중 접속 기법
배유경,염정선,정방철 한국통신학회 2022 韓國通信學會論文誌 Vol.47 No.9
In this paper, we propose an uplink IM-NOMA technique in which IM is applied to the existing NOMA, in order to support a military communication service that is robust to the jamming signal of the enemy in the military communication environment. We consider the channel estimation error for realistic military communication environment. We compare IM-NOMA with the conventional NOMA when there are PBJ and BJ. Through computer simulations, it can be confirmed that the IM-NOMA performs better than the NOMA system in both PBJ and BJ environments. 본 논문에서는 군통신 환경에서 적군의 재밍 신호에도 강인한 통신 서비스를 지원하기 위해 기존 비직교 다중접속 (non-orthogonal multiple access: NOMA)와 인덱스 변조 기법(index modulation: IM) 을 적용한 상향링크 IM-NOMA 기법을 제안한다. 또한, 채널 추정 오류가 있는 현실적인 환경을 고려한다. 부분대역 재밍(partial band jamming: PBJ)과 전대역 재밍 (barrage jamming: BJ)이 있을 때 기존NOMA와 비교 분석하였다. 시뮬레이션 결과로부터IM-NOMA기법이 NOMA 시스템보다 PBJ와 BJ 환경에서 모두 우수한 성능을 확인할 수 있다.
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수중음향 MIMO 채널에서 VBLAST 검파방식의 성능분석
강희훈(Heehoon Kang) 대한전자공학회 2016 전자공학회논문지 Vol.53 No.8
수중음파통신은 지상과는 다른 환경적 문제에 의해 고속 데이터 전송률을 얻기 위해서는 여러 가지 어려움이 있다. 고속 데이터 전송을 위해서 다중안테나 전송방식에 대해서 많은 연구가 진행되고 있다. V-BLAST 알고리즘은 무선통신에서 다중안테나 전송방식에 적용되고 검파방식이다. 본 논문에서는 수중음파채널에 대해서 여 MIMO 시스템의 VBLAST 검파 방식에 대해서 성능을 분석한다. For obtaining high speed data rate, underwater acoustic communication has several problems by the different environmental problem. To achieve high speed data rate, a method of multiple antennas have been researched. V-BLAST Algorithm is a detection method applied to terrestrial wireless communications. In this paper, BER performance of VBLAST detection for MIMO system is analyzed in the paper.
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