• 한국컴퓨터정보학회논문지
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• 제24권2호
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• pp.57-66
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• 2019

This paper compared the performance with an overview of channel equalization techniques used in high-speed serial transceivers, including the homogeneous architecture and associated components for the GHz interconnect of backplane and cable channels. It also used the MATLAB tool to present system analysis and simulation results for continuous time equivalent structures. In the case of conventional continuous equalization, high frequency deficits occur due to the use of a comparator that is difficult to implement as well as the low speed limit. In this paper, the channel equalization technique based on the power spectrum analysis of clocks was used to compensate for the frequency loss, and the application of the TX+Channel and TX+Equalizer filters enabled the measurement of attenuation and equivalence without comparators. The application of blender and band-pass filters at high speeds also showed significant effectiveness.

• 한국통신학회논문지
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• 제19권11호
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• pp.2116-2132
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• 1994

본 논문에서는 완전 디지틀 방식의 HDTV 시스템의 채널 등화기법에 관하여 연구하였다. 기존의 등화기법에 대해 고찰하고 이의 컴퓨터 모의실험을 위하여 전송채널을 모델링하였다. 시정수 개념을 이용한 가변스텝크기를 갖는 LMS 알고리즘을 제안하여 성능을 평가하였다. HDTV 시스템을 위한 여러가지 채널 등화기법을 모델링된 채널조건하에서 실험하고 등화기 특성을 분석하였다. 고정소수점 연산으로 등화기법을 모의실험하고 고전송율에 적합한 필터구조를 보였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.75-78
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• 1999

The iterative usage of soft outputs increases the performance of digital radio receiver. The feedback of reliability information reduces the channel estimation errors and increases the performance of equalization. This paper investigates the turbo equalization techniques for wireless cellular systems over continuous time varying channel. Simulation results over a GSM channel were presented.

• International Journal of Contents
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• 제2권4호
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• pp.19-24
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• 2006

In this paper, the performance of pre-equalization technique which can be applicable for the B-WLL uplink is evaluated and compared to post-equalization technique under three kinds of rain attenuation channels such as rain, intermittent light rain and thundershower. The BER performance comparisons of two algorithms (LMS and RLS) are investigated in the context of channel models and the length of training sequence. From the simulation results, it is shown that the post-equalization outperforms only at quite good channel conditions such as AWGN, while the pre-equalization can guarantee better BER performance at every channel conditions, especially performance gain increases as the severity of channel increases. It is concluded that the pre-equalizer using LMS algorithm is preferable at delay-tolerant situation where the complexity of algorithm is not a strict factor, while one using RLS is suitable for fast burst transmission with a relatively short training sequence.

• 전자공학회논문지C
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• 제35C권1호
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• pp.42-54
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• 1998

For decreasing intersymbol interference (ISI) due to band-limited channels in digitalcommunication, the uses of equalization techniques are necessary. Among the useful adaptive equalization techniques, because of their ease of implementation and nonlinear capabilites, the neural networks have been used as an alternative for effectively dealing with the channel distortion. In this paepr, a complex-valued multilayer percepron is proposed as a nonlinear adaptive equalizer. After the important properties that a suitable complex-valued activation function must possess are discussed, a new complex-valued activation function is developed for the proposed schemes to deal with M-ary QAM signals of any constellation sizes. It has been further proven that by the nonlinear transformation of the proposed function, the correlation coefficient between the real and imaginary parts of input data decreases when they are jointly Gaussian random variables. Lastly, the effectiveness of the proposed scheme is demonstrated by simulations. The proposed scheme provides, compared with the linear equalizer using the least mean squares (LMS) algorith, an interesting improvement concerning Bit Error Rate (BER) when channel distortions are nonlinear.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제4권3호
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• pp.283-287
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• 2004

In this paper, a method of designing the efficient batch blind equalization with low complexity using a micro genetic algorithm (GA), is presented. In general, the blind equalization techniques that are focused on the complexity reduction might be carried out with minor effect on the performance. Among the advanced various subjects in the field of GAs, a micro genetic algorithm is employed to identity the unknown channel impulse response in order to reduce the search space effectively. A new cost function with respect to the constant modulus criterion is suggested considering its relation to the Wiener criterion. We provide simulation results to show the superiority of the proposed techniques compared to other existing techniques.

• ETRI Journal
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• 제37권5호
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• pp.906-916
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• 2015

High-speed I/O channels require adaptive techniques to optimize the settings for filter tap weights at decision feedback equalization (DFE) read channels to compensate for channel inter-symbol interference (ISI) and crosstalk from multiple adjacent channels. Both ISI and crosstalk tend to vary with channel length, process, and temperature variations. Individually optimizing parameters such as those just mentioned leads to suboptimal solutions. We propose a joint optimization technique for crosstalk cancellation (XTC) at DFE to compensate for both ISI and XTC in high-speed I/O channels. The technique is used to compensate for between 15.7 dB and 19.7 dB of channel loss combined with a variety of crosstalk strengths from $60mV_{p-p}$ to $180mV_{p-p}$ adaptively, where the transmit non-return-to-zero signal amplitude is a constant $500mV_{p-p}$.

• Journal of information and communication convergence engineering
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• 제8권3호
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• pp.267-272
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• 2010

For the last decade, recurrent neural networks (RNNs) have been commonly applied to communications channel equalization. The major problems of gradient-based learning techniques, employed to train recurrent neural networks are slow convergence rates and long training sequences. In high-speed communications system, short training symbols and fast convergence speed are essentially required. In this paper, the derivative-free Kalman filter, so called the unscented Kalman filter (UKF), for training a fully connected RNN is presented in a state-space formulation of the system. The main features of the proposed recurrent neural equalizer are fast convergence speed and good performance using relatively short training symbols without the derivative computation. Through experiments of nonlinear channel equalization, the performance of the RNN with a derivative-free Kalman filter is evaluated.

• 방송과미디어
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• 제7권1호
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• pp.81-93
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• 2002

• 방송공학회논문지
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• 제9권4호
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• pp.357-370
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• 2004

본 논문에서는 ATSC 디지털 TV (DTV) 시스템의 등화형 동일 채널 중계기(Equalization Digital On-Channel Repeater)를 위한 복조, 등화, 그리고 재변조로 구성된 디지털 신호 처리(Digital Signal Processing: DSP) 기술들을 제안한다. EDOCR에서의 신호처리 과정에 의해 발생기는 시스템 지연은 기존 수신기의 수신 성능 저하를 야기할 수 있기 때문에 가능한 그 지연을 최소화 하여야 한다. 본 논문에서 제안한 DSP 기술들은 EDOCR의 성능 저하를 최소화 하면서 시간 지연을 줄일 수 있도록 하였다. 또한, 본 논문에서는 전산 실험을 통해 하드웨어 구현에 적합한 필터의 탭 수를 다양하게 제시한다.