• Title/Summary/Keyword: Modified Constant Modulus Algorithm

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Performance Improvement of MCMA Equalizer with Parallel Structure (병렬 구조를 갖는 MCMA 등화기의 성능 개선)

  • Yoon, Jae-Sun;Lim, Seung-Gag
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.11 no.5
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    • pp.27-33
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    • 2011
  • In digital communication system that the Modified Constant Modulus Algorithm (MCMA) reduced the use of the adaptive equalization algorithm to combat the Inter-symbol Interference (ISI). MCMA is relatively brief operation. The major point of MCMA that it only achieves moderate convergence rate and steady state mean square error (MSE). In this paper suggest, MCMA equalization improve the performance with parallel structure. It combines Modified Constant Modulus Algorithm(MCMA) and Modified Decision Directed(MDD) algorithm. By exploiting the inherent structural relationship between the 4-QAM signal's coordinates and 16-QAM signal's coordinates, another style of cost function for Modified Constant Modulus Algorithm(MCMA) is defined and If it happen to offset of received signals and MCMA is poor performance in order to overcome this because the paper combines apply for MCMA and MDD(Modified Decision Direct) algorithm. By computer simulation, we confirmed that the proposed PMCMA-MDD algorithm has the fater convergence rate and steady mean square error than the conventional MCMA.

The Performance Improvement of MCMA Adaptive Equalization in 16-QAM Signal using Dual Weight Vector (이중 가중치 벡터를 이용한 16-QAM 신호의 MCMA 적응 등화 성능 개선)

  • Yoon, Jae-Sun;Lim, Seung-Gag
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.11 no.6
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    • pp.41-47
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    • 2011
  • This paper is concerned with the DW-MCMA(Dual Weight vector Modified Constant Modulus Algorithm) adaptive equalization algorithm using the dual weight vector in order to improve the convergence characteristic and residual inter-symbol interference which are used as the performance index for an adaptive equalizer. The equalizer is used to reduce the distortion caused by the inter-symbol interference on the wireless and the wired band-limited channel that connect the transmitting system and receiving system. The CMA is widely known as the representative algorithm for equalization. In order to transmitting the mass information with a high speed through the channels, a fast convergence speed in the equalizer performance that is able to minimize overhead needed for equalization is acquired. In this paper, By the computer simulation, we confirmed that the proposed DW-MCMA has the faster convergence speed and the smaller residual inter-symbol interference than the conventional CMA and MCMA.

Multi-Modulus Blind Equalization Algorithm (다중 Modulus 블라인드 등화 알고리즘)

  • Choi, Ik-Hyun;Kim, Chul-Min;Oh, Kil-Nam;Choi, Soo-Chul
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • v.9 no.2
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    • pp.465-468
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    • 2005
  • MMA(Multi-Modulus Algorithm) is inferior at a initial equalization in high ISI(intersymbol interference), because it is the inaccurate decision. To improve this probel SMMA(Sliced Multi-Modulus Algorithm) is based on using the MCMA(Modified Constant Modulus Algorithm). SMMA is a improved capability than MMA in high SNR but is inaccurate decision in low SNR. In this paper, We propose some multi-modulus blind equalization algorithm scheme. It is a method of operation in some multi-modulus algorithm which does no obstruct a convergence property at the initial equalization in the low SNR. Proposed algorithm improves the steady-state performance. And it uses residual ISI of the equalizer output in order to decide the optimum switching time between the single modulus and the multi-modulus algorithm.

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Dual-mode Blind Equalization Algorithm for QAM Demodulation (QAM 복조용 이중 모드 채널 등화 알고리즘)

  • Ryu, Seok-Kyu;Hwang, Hu-Mor;Song, Jin-Ho
    • Proceedings of the KIEE Conference
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    • 1999.07g
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    • pp.3209-3211
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    • 1999
  • We propose a robust Dual-Mode blind equalization algorithm based on Quadrant-partitioned Constant Modulus Algorithm (QCMA) and Modified Constant Modulus Algorithm(MCMA) for QAM demodulation and its performance evaluated. The proposed algorithm show that the stability in setting 2d range and the faster convergence accomplished to conventional Dual-Mode algorithm.

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Adaptive Blind Equalization Algorithm based on Mixed-Modified Constant Modulus Algorithm (Miced-MCMA 적응 블라인드 등화 알고리즘)

  • 정영화
    • The Journal of Information Technology
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    • v.1 no.2
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    • pp.39-53
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    • 1998
  • The CMA and MCMA adaptive blind equalization algorithm has an inevitable error caused by mismatching between the original constellation at the steady state after the equalization and the unique constellation. This problem is due to considering the new type constellation(constant modulus, reduced constellation) as desired constellation. In this paper, we propose a new adaptive blind equalization algorithm which can reach to the steady state with rapid convergence speed and achive the improvement of error value in the steady state. The Proposed algorithm has a new error function using the decided original constellation instead of the reduced constellation. By computer simulation, it is comfirmed that the proposed algorithm has the performance superiority in terms of residual ISI and convergence speed compared with the adaptive blind equalization algorithm of CMA family, Constant Modulus Algorithm with Carrier Phase Recovery and Modified CMA(MCMA).

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A Stop-and-Go Dual-Mode Modified Constant Modulus Algorithm for Adaptive Blind Equalization of High-Order QAM Signals (고밀도 광 기록 채널을 위한 터보 코드와 터보 등화기를 연접한 데이터 복호 방법)

  • 임창현;김기윤;김동규;최형진
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.25 no.6B
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    • pp.1074-1081
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    • 2000
  • In this paper, in order to speed up the convergence process and improve the steady mean square error simultaneously, we propose the Stop-and-Go Dual Mode Modified Constant Modulus Algorithm(SAG DM MCMA) for adaptive blind channel equalization of high order QAM. The proposed algorithm is a hybrid scheme of the Modified CMA that treat error signals with real and imaginary components of the equalizer output, the concept of dual mode CMA, and Stop-and-Go algorithm. As a result it can prevent blind equalization from converging to incorrect direction and simultaneously operates reliably for tap weight adaptation. We demonstrate via simulation that the proposed algorithm achieves lower steady state mean square error and residual ISI than the conventional algorithms under high order QAM signals and severe channel environment.

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A Performance Comparison of CR-MMA and FC-MMA Adaptive Equalization Algorithm in 2 dimensional QAM Signal (2차원 QAM 신호에서 CR-MMA와 FC-MMA 적응 등화 알고리즘의 성능 비교)

  • Lim, Seung-Gag
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.18 no.1
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    • pp.85-90
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    • 2018
  • This paper compares the equalization algorithm of CR-MMA (Constellation Reduction-Multi Modulus Algorithm) and FC-MMA (Fast Convergence-Multi Modulus Algorithm) for the compensation of channel's distortion in transmitting the 2 dimensional 16-QAM signals. The CR-MMA adaptive equalizer use the error signal by reduce the nonconstant modulus signal to constant modulus signal in order to updates the tap coefficient, and the FC-MMA adptive equalizer use the error signal applying the modified dispersion constant considering the number of symbol level instead of signal point reduction. These two algorithm are known to its superior to the convergence characteristic among the MMA series equalizer. In this paper, the other equalization performance including the convergence characteristic was compared by computer simulation. As a result of computer simulation, FC-MMA has more good performance in the residual isi, maximum distortion and SER performance than CR-MMA, but not in convergence speed.

Performance Evaluation of FC-MMA and RMMA Algorithm for Adaptive Equalization in 2-dimensional QAM Signals (2차원 QAM 신호에서 적응 등화를 위한 FC-MMA와 RMMA 알고리즘의 성능 평가)

  • Lim, Seung-Gag;Kang, Dae-Soo
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.16 no.5
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    • pp.91-97
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    • 2016
  • This paper evaluates the equalization algorithm of FC-MMA (Fast Convergence-Multi Modulus Algorithm) and RMMA (Region based Multi Modulus Algorithm) for the compensation of intersymbol interference which is due to the distortion of communication channel. In order to obtain the error signal for adaptive equalization, the FC-MMA use the modified dispersion constant considering the number of signal symbol, the RMMA separates the 4 region which every symbol points are located, then reduce the symbol point based on this region into constant modulus symbol point. By applying the different principle in order to get the error signal for the updating the tap coefficient of adaptive equalizer, it has the different equalization performance by these error signal. The computer simulation was performed in order to compare the different equalization performance in this paper. The performance index includes the output signal constellation, the residual isi and maximum distortion that is for the convergence characteristics, the SER. As a result of computer simulation, RMMA has more good performance in the residual isi, maximum distortion after in steady state and SER performance than FC-MMA, but not in convergence speed to reach the steady state.

A new dual-mode blind equalization algorithm combining carrier phase recovery (반송파 위상 복원을 결합한 새로운 이중모드 블라인드 등화 알고리즘)

  • 오길남;진용옥
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.32A no.5
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    • pp.14-23
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    • 1995
  • A new dual-mode algorithm for blind equalization of quadrature amplitude modulation (QAM) signals is proposed. To solve the problem that the constant modulus algorithm (CMA) converges to the constellation with the arbitrary phase rotation, with the modification of the CMA, the proposed algorithm accomplishes blind equalization and carrier phase recovery simultaneously. In addition, the dual-mode algorithm combining the modified constant modulus algorithm (MCMA) with decision-directed (DD) algorithm achieves the performance enhancement of blind convergence speed and steady-state residual ISI. So we can refer the proposed algorithm to as a scheme for joint blind equalization and carrier phase recovery. Simulation results for i.i.d. input signals confirm that the dual-mode algorithm results in faster convergence speed, samller residual ISI, and better carrier phase recovery than those of the CMA and DD algorithm without any significant increase in computational complexity.

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Performance Analysis of Blind Equalization Algorithms using Multilevel Modulus (다중레벨 Modulus를 사용한 블라인드 등화 알고리즘의 성능 분석)

  • 오길남
    • Proceedings of the IEEK Conference
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    • 2001.09a
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    • pp.69-72
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    • 2001
  • 본 논문에서는 디지털 통신 시스템의 블라인드 등화에 있어서, 다중레벨 modulus를 기준 신호로 사용하여 등화기의 탭 계수 갱신 식에 사용되는 오차 신호를 형성함으로써 등화기의 블라인드 수렴 특성을 개선한 다중레벨 modulus 알고리즘들의 성능을 분석하였다. 다중경로 채널 하에서 QAM 신호점에 대해 컴퓨터 모의실험을 통하여 단일/다중레벨 modulus 알고리즘(SMMA)과 기존의 modified constant modulus algorithm(MCMA) 및 최근에 제안된 다중레벨 modulus 알고리즘(MMA) 등의 블라인드 수렴 및 정상 상태 성능을 비교하였다.

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