• 한국통신학회논문지
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• 제36권12C호
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• pp.753-758
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• 2011

The constant modulus algorithm (CMA) widely used in blind equalization applications minimizes the averaged power of constant modulus error (CME) defined as the difference between an instant output power and a constant modulus. In this paper, a decision feedback version of the linear blind algorithm based on maximization of the zero-error probability for CME is proposed. The Gaussian kernel of the maximum zero-error criterion is analyzed to have the property to cut out excessive CMEs that may be induced from severely distorted channel characteristics. Decision feedback approach to the maximum zero-error criterion for CME is developed based on the characteristic that the Gaussian kernel suppresses the outliers and this prevents error propagation to some extent. Compared to the linear algorithm based on maximum zero-error probability for CME in the simulation of blind equalization environments, the proposed decision feedback version has superior performance enhancement particularly in cases of severe channel distortions.

• Journal of the Optical Society of Korea
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• 제14권1호
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• pp.22-27
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• 2010

Bit error rate (BER) monitoring is the ultimate goal of performance monitoring in all digital transmission systems as well as optical fiber transmission systems. To achieve this goal, optimization of the decision threshold must also be considered because BER is dependent on the level of decision threshold. In this paper, we analyze a pseudo-error counting scheme and propose an algorithm to achieve both BER monitoring and adaptive decision threshold optimization in optical fiber transmission systems. To verify the effectiveness of the proposed algorithm, we conduct computer simulations in both Gaussian and non-Gaussian distribution cases. According to the simulation results, BER and the optimum decision threshold can be estimated with the errors of < 20% and < 10 mV, respectively, within 0.1-s processing time in > 40-Gb/s transmission systems.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권3호
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• pp.1016-1030
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• 2018

In this paper, an error-detection-coding-aided iterative hard decision interference cancellation (EDC-IHIC) scheme for multiple-input multiple-output systems employing hybrid automatic repeat request (HARQ) for multi-packet transmission is developed and investigated. In the EDC-IHIC scheme, only packets identified as error-free by the EDC are submitted to the interference cancellation (IC) stage for cancellation from the received signals. Therefore, the possibility of error propagation, including inter-transmission error propagation, can be eliminated using EDC-IHIC. Because EDC must be implemented in systems that employ HARQ to determine packet retransmission, error propagation can be prevented without the need for additional redundancy. The results of simulations conducted herein verify that the EDC-IHIC scheme outperforms conventional hard decision IC schemes in terms of the packet error rate in various environments.

• 한국소음진동공학회논문집
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• 제22권7호
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• pp.605-618
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• 2012

In this study, the possibility of decision error is investigated to identify and improve the reliability of participants in the process of conducting the sound quality analysis for laser printers. So far, there is not a way to identify and express the possibility of individual participant quantitatively. Thus, the decision error model is proposed which is based on the expectation value between the perceived sounds. Through the experimental verification on the laser printers, it was found that the possibility of decision error is affected according to the normalized difference. The possibility of decision error has inversely proportional to the normalized difference between the perceived sounds. When the normalized difference becomes small value, the uncertainly between decisions is inversely increase, and then it is difficult to obtain the proper result in the process of the jury evaluation for laser printers. For this reason, in this study, the proposed decision error model is added in the previous step of the correlation verification. Comparing to the conventional process only using the correlation based method, after the reliability of each participant is verified, the correlation with the mean response of participants is verified. It was found that the participants who were recognized as having unusual preferences are actually identified as having the reliability problem. Based on the results of this study, the proposed decision error model will be helpful to identify and improve the reliability of participants in the following study for the sound quality analysis.

• 전자공학회논문지A
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• 제33A권2호
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• pp.32-39
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• 1996

Hybrid decision decoding for the extended hamming codes without retransmission, which is a combination of hard and soft decision decoding, is proposed and its performance is analyzed in this paper. As results, hybsrid decision decoding shows a little bit higher residual bit error rate than soft decision decoding. However, as the size of the extended hamming code increases, the difference of th enumber of comparisons increases further. In addition, hybrid decision decoding shows almost same residual bit error rate as hard decision decoding with retrassmission and shows much lower residual bit error rate than hard decision decoding without retransmission.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권4호
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• pp.649-664
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• 2011

Cooperative spectrum sensing (CSS) with decision fusion is considered as a key technology for tackling the challenges caused by fading/shadowing effects and noise uncertainty in spectrum sensing in cognitive radio. However, most existing solutions assume an error-free decision transmission, which is obviously not the case in realistic scenarios. This paper extends the general decision-fusion-based CSS scheme by considering the fading/shadowing effects and noise corruption in the common control channels. With this more practical model, the fusion centre first estimates the local decisions using a binary minimum error probability detector, and then combines them to get the final result. Theoretical analysis and simulation of this CSS scheme are performed over typical channels, which suggest some performance deterioration compared with the pure case that assumes an error-free decision transmission. Furthermore, the fusion strategy optimization in the proposed cooperation model is also investigated using the Bayesian criteria. The numerical results show that the total error rate of noisy CSS is higher than that of the pure case, and the optimal values of fusion parameter in the counting rule under both cases decrease as the local detection threshold increases.

• 한국산학기술학회논문지
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• 제12권5호
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• pp.2390-2395
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• 2011

이 논문에서는, 통신 채널의 다중경로에 의한 심볼간 간섭 (ISI)과 와 임펄스 잡음을 극복하도록 하기 위해 오류 확률의 유클리드 거리를 최소화하는 결정 궤환 등화 알고리듬을 제안하였다. 오류 확률의 유클리드 거리는 오류 확률과 델타 함수의 차이로 정의하였다. 등화기 가중치에 대해 유클리드 거리를 최소화함으로써 제안한 알고리듬은 임펄스 잡음에 대한 강건성 뿐 아니라 심각한 다중경로 채널의 잔여 ISI를 제거하는 효과를 보였다.

• 한국항행학회논문지
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• 제16권6호
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• pp.982-987
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• 2012

본 논문에서는 AWGN 채널에서 특정 판정영역 내에 수신된 샘플들을 이용해 DD(Decision Directed) 방식으로 SNR을 추정하는 경우에 발생하는 SNR 추정 오차에 대해서 분석하였다. 수신기에서 특정 성좌점에 해당하는 기준 판정영역에 수신된 샘플들로 이상적인 수신점과의 에러벡터를 이용하여 SNR을 추정하는 경우, 다른 판정영역에 대응되는 송신심볼이 잡음의 영향으로 기준 판정영역으로 넘어온 샘플들까지 포함되므로, 추정된 신호 성좌점의 평균치가 이동함으로써 DD방식의 SNR 추정이 부정확하게 이루어진다. 이러한 현상을 변형된 확률밀도 함수를 기반으로 설명하고 실제 SNR과 추정 SNR과의 오차를 유도하여 정량적으로 분석하였다. 또한 컴퓨터 시뮬레이션을 통한 SNR 추정오차가 이론적으로 유도된 SNR 추정오차와 일치하고, 제안한 보정기법을 통해 SNR 추정 성능을 크게 개선할 수 있음을 확인하였다.

• 한국컴퓨터정보학회논문지
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• 제22권4호
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• pp.33-39
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• 2017

In this paper, we expand the process of classification to an ensemble of fuzzy decision tree. For indoor space recognition, many research use Boosted Tree, consists of Adaboost and decision tree. The Boosted Tree extracts an optimal decision tree in stages. On each stage, Boosted Tree extracts the good decision tree by minimizing the weighted error of classification. This decision tree performs a hard decision. In most case, hard decision offer some error when they classify nearby a dividing point. Therefore, We suggest an ensemble of fuzzy decision tree, which offer some flexibility to the Boosted Tree algorithm as well as a high performance. In experimental results, we evaluate that the accuracy of suggested methods improved about 13% than the traditional one.

• 한국통신학회논문지
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• 제40권3호
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• pp.419-424
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• 2015

판정의거(decision-directed: DD) 등화는 수신 신호의 눈모형이 완전히 닫힌 채널 조건에서는 눈모형을 충분히 열지 못하여 블라인드 등화기를 초기화하는 데는 효과적이지 않은 것으로 알려져 있다. 본 논문에서는 기존 DD 알고리즘의 오차를 대체하는 새로운 오차를 제안한다. 새로운 DD 오차는 신호점 판정의 모듈러스를 기존 DD 오차에 스케일링한 것으로, 이를 적용한 새로운 DD 알고리즘은 기존 DD와는 달리 등화 초기의 닫힌 눈모형을 여는데 효과적이다. 새로운 오차를 적용한 DD 알고리즘은 블라인드 초기화에 널리 쓰이는 CMA에 비해 우수한 수렴 특성을 보이며, 특히 다중 모듈러스를 가지는 신호 등화에 유용하다. 고차 QAM 신호에 대한 모의실험을 통해 새로운 DD 알고리즘의 성능을 검증하였다.