• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.47-50
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• 1999

Adaptive channel equalization accomplished without resorting to a training sequence is known as blind equalization. The Constant Modulus Algorithm(CMA) and Modified CMA(MCMA) are widely referenced algorithms for blind equalization of a QAM system. This paper proposes a hybrid scheme of CMA and MCMA with Carrier Recovery that is robust for high level QAM with low steady state tracking error.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.3 no.3
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• pp.73-80
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• 2010

Complex-valued blind algorithms which are based on constant modulus error and Euclidian distance (ED) between two probability density functions show relatively poor performance in spite of the advantages of information theoretic learning since the inherent characteristics of the constant modulus error prevent the algorithm from coping with the symbol phase rotation caused by the complex channels. In this paper, we show that the symbol phase rotation problem can be avoided and the advantages of information theoretic learning can be preserved by introducing decision-directed mode to the blind algorithm whenever the equalizer output power lies in the neighborhood of multi-modulus levels. Simulation results through MSE convergence and constellation comparison for severely distorted complex channels show significantly enhanced performance of symbol-point concentration and no phase rotation problems caused by the complex channel models.

• Journal of Communications and Networks
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• v.6 no.1
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• pp.19-25
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• 2004

In this paper, we present a trellis-based blind channel estimation and equalization technique coupling two kinds of adaptive Viterbi algorithms. First, the initial blind channel estimation is accomplished by incorporating the list parallel Viterbi algorithm with the least mean square (LMS) updating approach. In this operation, multiple trellis mappings are preserved simultaneously and ranked in terms of path metrics. Equivalently, multiple channel estimates are maintained and updated once a single symbol is received. Second, the best channel estimate from the above operation will be adopted to set up the whole trellis. The conventional adaptive Viterbi algorithm is then applied to detect the signal and further update the channel estimate alternately. A small delay is introduced for the symbol detection and the decision feedback to smooth the noise impact. An automatic switch between the above two operations is also proposed by exploiting the evolution of path metrics and the linear constraint inherent in the trellis mapping. Simulation has shown an overall excellent performance of the proposed scheme in terms of mean square error (MSE) for channel estimation, robustness to the initial channel guess, computational complexity, and channel equalization.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.8
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• pp.1037-1045
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• 1999

We propose two new classes of robust blind equalization algorithms against abrupt changes of channel conditions, which we call a triple-mode algorithm(TMA) and an automatic switch-over algorithm(ASA). The conventional DMGSA exhibits slow convergence rates due to the incorrect equalizer tap-updating process under the severe channel conditions. In order to speed up the convergence process, the TMA operates in triple-mode that is based on the dual-mode of the DMGSA incorporated with the tap-updating control modes of the SGA as well as the MSGA. Without resorting to the decision region for selecting the operation mode in the TMA, the ASA automatically switches the blind mode to the smoother conventional decision-directed mode. The ASA uses the error functional that is the weighted sum of the Generalized Sato error and the decision-directed error, where the weights correspond to the channel conditions. Test results on 16-QAM and 8-VSB datas confirm that the TMA and the ASA perform well under the sudden changes of channel conditions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.939-943
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• 2004

The side and rear-side collision warning system using fuzzy control algorithms is discussed in this paper. Common rearside warning system has many problems. For example if target vehicle comes into the warning area, it must unconditionally warn. Drivers could be interrupted by it. To solve the problem, I divided measuring area into two sections. One section is blind area of vehicle and the other rear-side area. For blind area, obtained data was filtered inefficient warning signal by using relative velocity method. For rear-side area, a fuzzy logic algorithm is used to recognition of obstacles. According to our experiment relative velocity method and fuzzy logic algorithms were very efficient.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.2 s.191
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• pp.73-85
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• 2007

The rear lateral collision warning system using fuzzy control algorithms is discussed in this paper. Common rear lateral warning system has many problems. For example if target vehicle comes into the warning area, it must unconditionally warn. Drivers could be interrupted by it. To solve the problem, I divided measuring area into two sections. One section is blind area of vehicle and the other rear lateral area. For blind area, obtained data was filtered inefficient warning signal by using relative velocity method. For rear lateral area, a fuzzy logic algorithm is used to recognition of obstacles. According to our experiment relative velocity method and fuzzy logic algorithms were very efficient.

• Journal of the Korean Solar Energy Society
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• v.31 no.6
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• pp.111-124
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• 2011

The objective of this study is to develop the blind control strategy and method which reduce negative effect of incoming daylight on visual comfort of occupants, minimize psychological anxieties caused by frequent motions of a blind, and maximize positive effect of incoming daylight by opening/closing of a blind. In previous researches on blind controls, major problem is that the time interval and amount of blind movement do not meet the control objective at the inflected zone of solar profile curve. To overcome these limitations revealed in theprevious researches, following tasks were performed in this study. i)To establish the control objective to accomplish the goal of this study. ii)To develop the control methods and algorithms which prevent glare on the work-plane at any time and which control the time interval and amount of blind movement to follow the control objective at various solar profile angle curves. This study proposed the control strategy and method that define the base control section implying the inflection point within the control objective zone and subsequently, divide the control sections for the residual time zones. The proposed strategy and method are found to increase the incoming daylight and solar irradiation by 0 to 15 %.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.12C
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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 Institute of Electronics Engineers of Korea CI
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• v.39 no.2
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• pp.10-20
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• 2002

Various blind source separation (BSS) and independent component analysis (ICA) algorithms have been developed. However, comparison study for BSS/ICA algorithms has not been extensively carried out yet. The main objective of this paper is to compare various promising BSS/ICA algorithms in terms of several factors such as robustness to sensor noise, computational complexity, the conditioning of the mixing matrix, the number of sensors, and the number of training patterns. We propose several benchmarks which are useful for the evaluation of the algorithm. This comparison study will be useful for real-world applications, especially EEG/MEG analysis and separation of miked speech signals.

• Journal of Industrial Technology
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• v.21 no.B
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• pp.99-105
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• 2001

In this paper, the selective normalized constant modulus algorithm(SNCMA) is applied to a fractionally spaced equalizer. The fractionally spaced equalizer is insensitive to the sampling timing because it processes received signals with the sampling rate larger than the symbol rate. The SNCMA improves the convergence rate by using the large step size for the most outer covering symbol belonging to the trust-level. This blind equalizer exhibits a fast start-up convergence rate as well as a reduced steady-state residual error compared to the fractionally spaced blind equalizer and the T-spaced blind equalizer using conventional blind algorithms.