• Title/Summary/Keyword: 적응 등화기

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Improved Multiplication Free Adaptive Digital Filter with the Fractionally-Spaced Equalizer (분할등화기를 이용한 개선된 비적적응필터)

  • Yoon, Dal-Hwan
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.39 no.2
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    • pp.137-146
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    • 2002
  • In order to remove the intersymbol interference(ISI) phenomenon in data transmission channel, the structure and convergence analysis of the improved multiplication free adaptive digital filter(IMADF) is presented. Under conditions of zero-mean, wide-sense stationary and white Gaussian noise, it is shown that this paper analyze the convergence characteristics of the IMADF with a fractionally-spaced equalizer(FSE). In the experimental results, the convergence characteristics of the IMADF algorithm is almost same as the sign algorithm, but is better than the MADF algorithm. Here, this algorithm has useful characteristics when the correlation of the input signal is highly.

자력복구 적응 채널등화기를 위한 Run and Go 알고리즘 (Run and Go Algorithm for Blind Equalization)

  • Chung, Won-Zoo
    • Journal of IKEEE
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    • v.10 no.1 s.18
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    • pp.62-68
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    • 2006
  • In this paper, we propose an adaptation strategy for blind equalizers, which combines a blind algorithm based on high order statistics and the decision directed LMS algorithm. In contrast to 'Stop-and-Go' algorithm, where adaptation is stopped for unreliable signals, the proposed algorithm applies high order statistics (HOS) blind algorithm to the unreliable signals and applies DD-LMS for the reliable signals. The proposed algorithm, named 'Run-and-Go' algorithm, inherits minimum MSE performance of DD-LMS and acquisition ability of blind algorithms. Furthermore, by updating the reliable signal region according to signal quality in each iteration, the convergence speed and acquisition ability is further improved.

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The Performance Comparison of the CMA and MMA Algorithm for Blind Adaptive Equalization (블라인드 적응 등화를 위한 CMA와 MMA 알고리즘의 성능 비교)

  • Lim, Seung-Gag
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.12 no.2
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    • pp.153-158
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    • 2012
  • This paper deals with the performance comparison of adaptive equalization algorithm, CMA and MMA, that is used for the minimization of the distortion and noise effect in the communication channel at receiver.. We confirmed the application possibilities of the point to point or point to multipoint digital transmission technologies by analyzing the performance of MMA which is changing the error function of CMA that is the possible algorithm of fast equalization by relatively simple arithmatic computation compared to the other method. In CMA algorithm, we need the PLL for the amplitude compensation only and not possible to phase compensation inherently. But in MMA algorithm, we confired that the amplitude and phase of received signal can be compensated by computer simulation. For the comparison of algorithm, we used the essential performance index, convergence characteristics and residual isi. The result of performance comparison of algorithms, the MMA has good in convergence characteristic and the CMA has good in residual isi that is used for the amplitude compensation.

A Performance Comparison of VSCA and VSDA Adaptive Equalization Algorithm using Distance Adjusted Approach in QAM Signal (QAM 신호에서 Distance Adjusted Approach를 이용한 VSCA와 VSDA 적응 등화 알고리즘의 성능 비교)

  • Lim, Seung Gag
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.15 no.1
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    • pp.139-145
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    • 2015
  • This paper compare the VSCA (Variable stepsize Square Contour Algorithm) and VSDA (Variable stepsize Square contour Decision directed Algorithm) adaptive equalization algorithm that is used for the minimization of the intersymbol interference which occurs in the time dispersive channel for the transmission of 16-QAM signal.. In the SCA, it is possible to compensates the amplitude and phase in the received signal that are mixed with the intersymbol interference by the constellatin dependent constant by using the 2nd order statistics of the transmitted signal. But in the VSCA and VSDA, it is possible to the improving the equalization performance by varing the stepsize using the concept of distance adjusted approach for constellation matching. We compare the performance of the VSCA and VSDA algorithm by the computer simulation. For this, the equalizer output signal constellation, residual isi, maximum distortion and MSE were used in the performace index. As a result of computer simulation, the VSCA algorithm has better than the VSDA in every performance index.

Performance of VSCA Adaptive Equalization Algorithm for 16-QAM Signal (16-QAM 신호에 대한 VSCA 적응 등화 알고리즘의 성능)

  • Lim, Seung-Gag
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.13 no.4
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    • pp.67-73
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    • 2013
  • This paper relates with the performance of VSCA adaptive equalization algorithm that is used for the minimization of the intersymbol interference due to the distortion which occurs in the time dispersive channel for the transmission of 16-QAM signal. In the conventional SCA, it is possible to compensates the amplitude and phase in the received signal that are mixed with the intersymbol interference by the constellatin dependent constant by using the 2nd order statistics of the transmitted signal. But in the VSCA, it is possible to the increase the equalization performance by adding the concept of distance adjusted approach for constellation matching. We compare the performance of VSCA and SCA algorithm by computer simulation. For this, the equalizer output signal constellation, residual isi, maximum distortion and MSE were used for perfomance comparison. It was confirmed that, the VSCA algorithm has better than the SCA in every performance index by computer simulation.

A Performance Comparison of mSE-MMA and mDSE-MMA Adaptive Equalization Algorithm in 16-QAM Signal Transmission (16-QAM 신호 전송에서 mSE-MMA와 mDSE-MMA 적응 등화 알고리즘의 성능 비교)

  • Lim, Seung-Gag
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.21 no.2
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    • pp.61-66
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    • 2021
  • This paper related with the performance comparison of mSE-MMA and mDSE-MMA adaptive equalization algorithm which is possible to reduce the intersymbol interference that occurs in the nonlinear communication channel transmitting 16-QAM signal. This two algorithm is possible to reduce the computational load compared to the current MMA algorithm, it has the degraded equalization performance due to simplified arithmetic in order to applying the mobile communication terminal. In order to improve the performance degradation, they controls the step size according to the existence of arbitrary radius circle of equalizer output compared to transmitted symbol point. The variation of step size according to this principle is applied to the SE-MMA and DSE-MMA, namely mSE-MMA and mDSE-MMA algorithm, the algorithm's performance were compared in the same channel and noise environment by computer simulation. As a result of simulation, the mSE-MMA has more superior to the mDSE-MMA in residual value of every performance index and SER performance, and the vice versa result in convergence speed.

FC-MMA Adaptive Equalization Algorithm to improve the Convergence Speed of MMA in 16-QAM System (16-QAM 시스템에서 MMA의 수렴 속도를 개선시킨 FC-MMA 적응 등화 알고리즘)

  • Lim, Seung-Gag
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.14 no.1
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    • pp.93-99
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    • 2014
  • This paper deals with the FC-MMA (Fast Convergence-Multi Modulus Algorithm) which is improving the convergence characteristics of the MMA (Multiple Modulus Algorithm) adaptive equalization algorithm that is used for the minimization of the intersymbol interference which occurs in the time dispersive communication channel. In the time varying charateristics and the abnormal situation like as outage of the communication channel, the adaptive equalizer needs to adapting the new environment more rapidly. For this problem, the residual isi and the maximum distortion performance index which are meaning the convergence characteristics are widely adapted in the adaptive equalizer. The 16-QAM signal is transmitted and it was confirmed that the proposed algorithm, the FC-MMA has the fast convergence performance such as in the 1.75 times fast in residual isi and 2.5 times fast in the maximum distortion in order to reaching the steady state compare to the MMA algorithm in the same channel environment by the computer simulation.

Self-Adaptive Performance Improvement of Novel SDD Equalization Using Sigmoid Estimate and Threshold Decision-Weighted Error (시그모이드 추정과 임계 판정 가중 오차를 사용한 새로운 SDD 등화의 자기적응 성능 개선)

  • Oh, Kil Nam
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.8
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    • pp.17-22
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    • 2016
  • For the self-adaptive equalization of higher-order QAM systems, this paper proposes a new soft decision-directed (SDD) algorithm that opens the eye patterns quickly as well as significantly reducing the error level in the steady-state when it is applied to the initial equalization stage with completely closed eye patterns. The proposed method for M-QAM application minimized the computational complexity of the existing SDD by the symbol estimated based on the two symbols closest to the observation, and greatly simplified the soft decision independently of the QAM order. Furthermore, in the symbol estimating it increased the reliability of the estimates by applying the superior properties of the sigmoid function and avoiding the erroneous estimation of the threshold function. In addition, the initialization performance was improved when an error is generated to update the equalizer, weighting the symbol decision by the threshold function to the error, resulting in an extension of the range of error fluctuations. As a result, the proposed method improves remarkably the computational complexity and the properties of initialization and convergence of the traditional SDD. Through simulations for 64-QAM and 256-QAM under multipath channel conditions with additive noise, the usefulness of the proposed methods was confirmed by comparing the performance of the proposed 2-SDD and two forms of weighted 2-SDD with CMA.

Algorithm and Experimental Verification of Underwater Acoustic Communication Based on Passive Time-Reversal Mirror (수동형 시역전에 기반한 수중음향통신 알고리즘 및 실험적 검증)

  • Eom, Min-Jeong;Kim, J.S.;Cho, Jung-Hong;Kim, Hoeyong;Sung, Il
    • The Journal of the Acoustical Society of Korea
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    • v.33 no.6
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    • pp.392-399
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    • 2014
  • The underwater acoustic communication is characterized by doubly spread channels, which are the delay spread due to multiple paths and the doppler spread due to environmental fluctuations or a moving platform. An equalizer is used to remove the inter-symbol interferences that the delay spread causes, but an equalizer doesn't use an acoustic environment such as a multipath. However, a passive time-reversal mirror is simpler than an equalizer because a matched filter is implemented numerically at the receiver structure along with one-way propagation. In this paper, a passive time-reversal mirror is applied to remove interferences due to a multipath in sea-going experimental data in East Sea in Oct. 2010 and improved communication performance is confirmed. The performance is verified by comparing the signal-to-interference plus noise ratio before/after passive time-reversal mirror. It is also performed independently of the passive time-reversal mirror and adaptive equalizer and the bit error rate is compared to verify the performance of underwater acoustic communication.

Adaptive Equalization Algorithms of Channel Nonlinearities in Data Transmission Systems. (전송 시스템에서 비선형 채널특성을 이용한 적응 등화기 알고리즘)

  • 안봉만;임규만
    • Proceedings of the Korea Institute of Convergence Signal Processing
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    • 2003.06a
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    • pp.238-241
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    • 2003
  • This paper presents a nonlinear least squares decision feedback equalizer Bilinear systems are attractive because of the ability to approximate a large class of nonlinear systems efficiently. The nonlinearity of channel is modeled using a bilinear system. The algorithms are derived by using the QR decomposition for minimization covariance matrix of prediction error by applying Givens rotation to the bilinear model. Result of computer simulation experiments that compare the performance of the bilinear DFE to two other DFE's in eliminating the intersymbol interference caused by a nonlinear channel are presented In the paper.

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