• Title/Summary/Keyword: Adaptive Blind Equalizer

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Training Adaptive Equalization With Blind Algorithms

  • Namiki, Masanobu;Shimamura, Tetsuya
    • Proceedings of the IEEK Conference
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    • 2002.07c
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    • pp.1901-1904
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    • 2002
  • A good performance on communication systems is obtained by decreasing the length of training sequence In the initial stage of adaptive equalization. This paper presents a new approach to accomplish this, with the use of a training adaptive equalizer. The approach is based on combining the training and tracking modes, in which the training equalizer is updated by the LMS algorithm with the training sequence and then updated by a blind algorithm. By computer simulations, it is shown that a class of the proposed equalizers provides better performance than the conventional training equalizer.

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The Performance improvement of CMA Blind Adaptive equalizer using the Constellation Matching Method (Constellation Matching 기법을 이용한 CMA 블라인드 적응 등화기의 성능 개선)

  • Lim, Seung-Gag;Kang, Dae-Soo
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.10 no.1
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    • pp.121-127
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    • 2010
  • This paper relates with the improved CMA blind adaptive equalization algorithm which uses the constellation matching method that improve the inverse modelling efficiency of a communication channel compared to the present CMA blind adaptive equalizer. The amplitude distortion can be compensated in the present CMA blind adaptive equalizer which is used for the reduction of intersymbol interference by distortion that generate such as a band limited wireless mobile channel, but in the improved adaptive alogorithm operates with the minimize the amplitude phase distortion in the output of equalizer by applying the cost function that is composition of additional signal constellation matching error terms. In order to evaluation of the inverse modeling efficiency of improved algorithm, the residual intersymbol interference and recovered signal constellation were compared by computer simulation. As a result of comparion of computer simulation, the improved algorithm has a good stability in the residual intersymbol interference in the steady state, but it has a slow convergence rate in the adaptation state in initial state.

A Study on Performance Comparison of Bussgang-type Adaptive Blind Algorithms (Bussgang계열의 적응 Blind 알고리듬들의 성능비교에 관한 연구)

  • Kim, Hyoung-Seok;Kang, Hyun-Cheol;Byun, Youn-Shik
    • The Journal of the Acoustical Society of Korea
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    • v.14 no.5
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    • pp.20-28
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    • 1995
  • This paper studied adaptive blind equalizer which belong to Bussgang type. It is well known that blind equalizer performs equalization without using a training sequence. Especially, this paper concentrated on real time processing of them. The channel characteristic was obtained from measurements taken in a real urban multipath environment. A T/2 fractionally-spaced equalizer was used at the receiving end. Our computer simulations demonstrated that Stop and Go, Benveniste-Goursat, and optimal Bussgang algorithms have relatively low MSE property. CMA shows faster convergence property than any other of Bussgang type algorithm.

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Multichannel Blind Equalization using Multistep Prediction and Adaptive Implementation

  • Ahn, Kyung-Seung;Hwang, Ho-Sun;Hwang, Tae-Jin;Baik, Heung-Ki
    • Proceedings of the IEEK Conference
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    • 2001.06a
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    • pp.69-72
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    • 2001
  • Blind equalization of transmission channel is important in communication areas and signal processing applications because it does not need training sequence, nor does it require a priori channel information. Recently, Tong et al. proposed solutions for this problem exploit the diversity induced by antenna array or time oversampling, leading to the second order statistics techniques, fur example, subspace method, prediction error method, and so on. The linear prediction error method is perhaps the most attractive in practice due to the insensitive to blind equalizer length mismatch as well as for its simple adaptive filter implementation. Unfortunately, the previous one-step prediction error method is known to be limited in arbitrary delay. In this paper, we induce the optimal delay, and propose the adaptive blind equalizer with multi-step linear prediction using RLS-type algorithm. Simulation results are presented to demonstrate the proposed algorithm and to compare it with existing algorithms.

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Design of a Blind DFE Equalizer for high-speed data communication (고속 데이터 통신을 위한 Blind DFE Equalizer의 설계)

  • 박원흠;선우명훈
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.27 no.7C
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    • pp.704-711
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    • 2002
  • This paper proposes a DFE (Decision Feedback Equalizer) equalizer ASIC using the Multi-Modulus Algorithm (MMA) for cable modem applications. We believe that it is the first effort to combine the DFE structure and the MMA algorithm. The proposed equalizer has been designed for 64/256 QAM modems. The existing MMA equalizer uses two transversal filters and updates two tap weights while the proposed equalizer uses two DFE filter banks to improve the channel adaptive performance and to reduce the number of taps and updates only one tap weights. We have used the 0.35 $\mu\textrm{m}$ standard cell library. The implemented equalizer ASIC operates at 8 MHz and provides 64 Mbps which is higher than existing equalizers. The total number of gates are about 160,000.

Design of a high-speed DFE Equaliser of blind algorithm using Error Feedback (Error Feedback을 이용한 blind 알고리즘의 고속 DFE Equalizer의 설계)

  • Hong Ju H.;Park Weon H.;Sunwoo Myung H.;Oh Seong K.
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.42 no.8 s.338
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    • pp.17-24
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    • 2005
  • This paper proposes a Decision Feedback Equalizer (DFT) with an error feedback filter for blind channel equalization. The proposed equalizer uses Least Mean Square(LMS) Algorithm and Multi-Modulus Algorithm (MMA), and has been designed for 64/256 QAM constellations. The existing MMA equalizer uses either two transversal filters or feedforward and feedback filers, while the proposed equalizer uses feedforward, feedback and error feedback filters to improve the channel adaptive performance and to reduce the number of taps. The proposed equalizer has been simulated using the $SPW^{TM}$ tool and it shows performance improvement. It has been modeled by VHDL and logic synthesis has been performed using the $0.25\;\mu m$ Faraday CMOS standard cell library. The total number of gates is about 190,000 gates. The proposed equalizer operates at 15 MHz. In addition, FPGA vertification has been performed using FPGA emulation board.

Joint Blind Data/Channel Estimation Based on Linear Prediction

  • Ahn, Kyung-Seung;Byun, Eul-Chool;Baik, Heung-Ki
    • Proceedings of the IEEK Conference
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    • 2001.09a
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    • pp.869-872
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    • 2001
  • Blind identification and equalization of communication channel is important because it does not need training sequence, nor does it require a priori channel information. So, we can increase the bandwidth efficiency. The linear prediction error method is perhaps the most attractive in practice due to the insensitive to blind channel estimator and equalizer length mismatch as well as for its simple adaptive algorithms. In this paper, we propose method for fractionally spaced blind equalizer with arbitrary delay using one-step forward prediction error filter from second-order statistics of the received signals for SIMO channel. Our algorithm utilizes the forward prediction error as training sequences for data estimation and desired signal for channel estimation.

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Blind adaptive equalization using the multi-stage decision-directed algorithm in QAM data communications (QAM 시스템에서 다단계 결정-지향 알고리듬을 이용한 블라인드 적응 등화)

  • 이영조;조형래;강창언
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.22 no.11
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    • pp.2451-2458
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    • 1997
  • Adaptive channel equalization complished without resorting to a training sequence is known as blind equalization. In this paper, in order to increase the speed of the convergence and to reduce the steady-state mean squared error simulatneously, we propose the multi-stage DD(decision-direct) algorithm derived from the combination of the Sato algorithm and the decision-directed algorithm. In the starting stage, the multi-stage DD algorithm is identical to the Sato algorithm which guarantees the convergence of the equalizer. As the blind equalizer converges, the number of the level of the quantizers is increased gradally, so that the proposed algorithm operates identical to the decision-directed algorithm which leads to the low error power after the convergence. Therefore, the multi-stage DD algorithm obtains fast convergence rate and low steady state mean squared error.

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Blind adaptive equalizations using the multi-stage radius-directed algorithm in QAM data communications (QAM 시스템에서 다단계 반경-지향 알고리듬을 이용한 블라인드 적응 등화)

  • 이영조;임승주;이재용;강창언
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.22 no.9
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    • pp.1957-1967
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    • 1997
  • Adaptive channel equlization accomplished without resorting to a training sequence is known as blind equalization. In this paper, in order to reduce the speed of the convergence and the steady-state mean squared error simultaneously, we propose the multi-stage RD(radius-directed) algorithm derived from the combination of the constant modulus algorithm and the radius-directed algorithm. In the starting stage, multi-stage RD algorithm are identical to the constant modulus algorithm which guarantees the convergence of the equalizer. As the blind identical to the constant modulus algorithm which guarantees the convergence of the equalizer. As the blind equalizer converges, the number of the level of the quantizers is increased gradually, so that the proposed algorithm operate identical to the radius-directed algorithm which leads to the low error power after the covnergence. Therefore, the multi-stage RD algorithm obtains fast convergence rage and low steady stage mean square error.

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An Adaptive Blind Equalizer Based on Dynamic Error Signal Generation Using Equalized Output State (등화기 출력 상태에 따른 동적 오차 신호 발생 기반의 적응 블라인드 등화기)

  • Oh, Kil Nam
    • Journal of the Institute of Electronics and Information Engineers
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    • v.50 no.7
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    • pp.52-58
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    • 2013
  • This paper proposes an adaptive algorithm based on a method of dynamic error signal generation suitable for signal state by examining the equalizer output signal in blind equalization. In the proposed method, it estimates the error signals using single modulus and multiple modulus each effective to the early stage of equalization or steady-state, and it generates a new error signal from the two error estimates. Two equalizer structures are implemented and their performances are compared: 1-equalizer structure that generates a new error signal by combining the two error estimates weightedly and updates the equalizer using this, and 2-equalizer structure that updates two equalizers respectively depending on the weights of the two error signals. In the proposed method, as the error signals were generated optimally before and after the initial convergence respectively, it was confirmed by computer simulations that the equalizer was updated effectively.