• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권3호
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• pp.494-507
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• 2011

In this paper, we propose two schemes to reduce the complexity of fixed-complexity sphere decoder (FSD) algorithm in the ordering and tree-search stages, respectively, while achieving quasi-ML performance. In the ordering stage, we propose a QR-decomposition-based FSD signal ordering based on the zero-forcing criterion (FSD-ZF-SQRD) that requires only a few number of additional complex flops compared to the unsorted QRD. Also, the proposed ordering algorithm is extended using the minimum mean square error (MMSE) criterion to achieve better performance. In the tree-search stage, we introduce a threshold-based complexity reduction approach for the FSD depending on the reliability of the signal with the largest noise amplification. Numerical results show that in 8 ${\times}$ 8 MIMO system, the proposed FSD-ZF-SQRD and FSD-MMSE-SQRD only require 19.5% and 26.3% of the computational efforts required by Hassibi's scheme, respectively. Moreover, a third threshold vector is outlined which can be used for high order modulation schemes. In 4 ${\times}$ 4 MIMO system using 16-QAM and 64-QAM, simulation results show that when the proposed threshold-based approach is employed, FSD requires only 62.86% and 53.67% of its full complexity, respectively.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권2호
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• pp.330-343
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• 2011

In this paper, we propose two schemes to reduce the complexity of fixed-complexity sphere decoder (FSD) algorithm in the ordering and tree-search stages, respectively, while achieving quasi-ML performance. In the ordering stage, we propose a QR-decomposition-based FSD signal ordering based on the zero-forcing criterion (FSD-ZF-SQRD) that requires only a few number of additional complex flops compared to the unsorted QRD. Also, the proposed ordering algorithm is extended using the minimum mean square error (MMSE) criterion to achieve better performance. In the tree-search stage, we introduce a threshold-based complexity reduction approach for the FSD depending on the reliability of the signal with the largest noise amplification. Numerical results show that in $8{\times}8$ MIMO system, the proposed FSD-ZF-SQRD and FSD-MMSE-SQRD only require 19.5% and 26.3% of the computational efforts required by Hassibi’s scheme, respectively. Moreover, a third threshold vector is outlined which can be used for high order modulation schemes. In $4{\times}4$ MIMO system using 16-QAM and 64-QAM, simulation results show that when the proposed threshold-based approach is employed, FSD requires only 62.86% and 53.67% of its full complexity, respectively.

• 한국통신학회논문지
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• 제34권10C호
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• pp.1010-1015
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• 2009

본 논문에서는 QR분해 및 순차적 간섭제거 기반의 MIMO 신호검출기법을 위한 새로운 검출 순서화 방법을 제안한다. 최근 공간다중화 MIMO 시스템을 위한 신호검출기법으로서 한 개의 공간 레이어에는 모든 가능한 성 상점을 추정 신호로 시도하고 나머지 레이어의 추정치는 순차적 간섭제거를 수행하여 후보 벡터들을 생성한 후 각 후보 벡터의 ML 메트릭을 계산하여 송신 벡터를 추정하는 기법들이 제안되었다. 이러한 신호검출기법에는 기존 V-BLAST의 순서화와는 다른 순서화를 적용해야 된다는 점이 지적되었다. 본 논문은 이러한 신호검출기법을 위한 새로운 순서화방법을 제안하고, 이에 따라 성능의 이득을 달성할 수 있음을 모의실험을 통해 보인다.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1990년도 추계학술대회
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• pp.15-18
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• 1990

In abdominal NMR imaging the respiratory ordering techniques have been successfully used to remove the ghosting artifacts arising from the respiratory motion. In the existing respiratory ordering schemes, however, it is generally accepted that blurring of the moving parts still remains as in the signal averaging technique. A new optimal respiratory ordering scheme which can correct the blurring as well as the ghosting artifacts is theoretically derived through the analysis of the phase encoding directional motion effects in Fourier imaging. The performance of the optimal respiratory ordering scheme is experimentally confirmed together with a suboptimal ordering scheme which is suggested as a compromise for the practicality.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2005년도 추계종합학술대회
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• pp.93-96
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• 2005

We propose a computationally efficient sphere decoding (SD) algorithm with smart radius control (SRC). As a baseline algorithm for SD, we consider the modified Schnorr-Euchner (SE) algorithm [1] (hereafter, called as the MSE algorithm). In principle, the radius after zero-forcing decision feedback equalization (ZF-DFE) estimation can be reduced further if we select a new lattice vector closer to the received signal vector than the lattice vector corresponding to the ZF-DFE estimate does. In our case, we obtain such a better lattice vector by performing a sequence of alternating one-dimensional searches, starting from the ZF-DFE estimate. We then develop a novel SRC algorithm that adopts adaptively the additional radius reduction process according to the estimated signal-to-noise-power ratio (SNR) after ZF-DFE estimation. In addition, we analyze the effect of detection ordering on the complexity for SD. Column-norm ordering of the channel matrix and optimal ordering [1] are considered here. From our analyses, we see that SRC can reduce greatly the complexity for SD and the degree of complexity reduction gets significant as the SNR decreases, irrespective of detection ordering schemes used.

• Journal of Magnetics
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• 제11권2호
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• pp.95-97
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• 2006

The electron spin resonance signals of $Bi_xCa_{1-x}MnO_3$ have been acquired for two samples of x=0.15 and 0.22. ESR signal of the sample of x=0.15 clearly shows signal shape change into Dysonian with g-value shift at around 165 K so that the charge ordering temperature can be identified. The general features of ESR signal of the two samples well correlate with magnetic susceptibility measurement and also confirm the validity of former investigations.

• 한국멀티미디어학회논문지
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• 제21권8호
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• pp.925-933
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• 2018

In this paper, we propose a new smart ordering application system for granting the customer numbers. The proposed system assigns sequence number of customers who visit at offline store as using speaker and microphone of smart device. This system has more advantage than the existing ordering system. Because the proposed system does not need any customer information like as phone number or SNS ID, it can protect customer privacy information. In this system, we use high frequency which is inaudible to the human ear as communication signal between speaker and microphone. To confirm performance evaluation, we perform a test with ten smart devices like as iPhone 6, 7, 8, Galaxy s8 and the result shown a success rate of 98.7 percent. Therefore, the proposed system can be useful service technology at the various offline store which need to assign a sequence number for customers, because many customers visit at the store.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.415.1-415.1
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• 2014

Carrying out first-principles calculations, we study N-doped capped carbon nanotube (CNT) electrodes applied to DNA sequencing. While we obtain for the face-on nucleobase junction configurations a conventional conductance ordering where the largest signal results from guanine according to its high highest occupied molecular orbital (HOMO) level, we extract for the edge-on counterparts a distinct conductance ordering where the low-HOMO thymine provides the largest signal. The edge-on mode is shown to operate based on a novel molecular sensing mechanism that reflects the chemical connectivity between N-doped CNT caps that can act both as electron donors and electron acceptors and DNA functional groups that include the hyperconjugated thymine methyl group[1].

• 한국통신학회논문지
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• 제30권6C호
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• pp.560-569
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• 2005

본 논문은 순차적인 간섭제거와 전송 안테나 별 전송률을 제어하는 공간 다중화 전송 MIMO 시스템에서 채널환경에 따라 전송에 사용되는 안테나를 선택하고 데이터 율을 조절하는 알고리즘을 제안한다. 수신기에서 전송에 사용될 송신 안테나 및 전송률을 결정하고, 이는 각 송신 안테나 별 전송률에 대한 피드백 채널을 통해 송신기로 전송된다. 본 연구에서는 각 단계에서 최소의 SINR을 가지는 안테나를 제거해가는 연속적인 단계들로 이루어진 직렬 결정 방식을 제안한다. 또한, 각 연속적인 심볼 추정 단계에서 가장 낮은 신호 대 간섭 비를 갖는 심볼을 먼저 추정하는 "reverse detection ordering"이 각 안테나에 할당되는 용량 차이를 증가시킴으로서 안테나 선택에 의한 이득을 증가시킴을 보인다. 시뮬레이션 결과는 제안된 "reverse detection ordering"을 기반으로 하는 직렬 결정 방식이 낮은 복잡도을 가지면서 heuristic 방식과 비슷한 용량을 제공함을 보여준다.

• ETRI Journal
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• 제29권2호
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• pp.240-242
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• 2007

This letter proposes a simplified maximum likelihood detection (SMLD) scheme to improve the detection performance of multiple-input multiple-output receivers. The SMLD detects V streams according to the first detected V sub-streams. Through an ML test, the most probable stream is selected. Moreover, to detect the layer with the worst post-detection SNR accurately, reverse ordering is applied to the SMLD. Simulation results show that the performance of the Vertical Bell Laboratories layered space-time (V-BLAST) system can be improved by adopting the SMLD technique. In the case of reverse ordering, the SMLD can achieve a similar ML performance with significant reduction in computational complexity.