• Title/Summary/Keyword: MMSE filter

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Research on an Equivalent Wiener-Hopf Equation (등가의 Wiener-Hopf 방정식에 관한 연구)

  • Ahn, Bong-Man;Cho, Ju-Phil
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.33 no.9C
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    • pp.743-748
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    • 2008
  • This paper makes a research on the equivalent Wiener-Hopf equation which can obtain the coefficient of TDL filter on orthogonal input signal in terms of mean square error. Using this result, we can present the coefficient and error of TDL filter directly without inverse orthogonalization process on orthogonal input signal. We make a theoretical analysis on MMSE and show an Wiener-Hopf solution and the proposed equivalent one in mathematical example simultaneously.

Noise Reduction Using MMSE Estimator-based Adaptive Comb Filtering (MMSE Estimator 기반의 적응 콤 필터링을 이용한 잡음 제거)

  • Park, Jeong-Sik;Oh, Yung-Hwan
    • MALSORI
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    • no.60
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    • pp.181-190
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    • 2006
  • This paper describes a speech enhancement scheme that leads to significant improvements in recognition performance when used in the ASR front-end. The proposed approach is based on adaptive comb filtering and an MMSE-related parameter estimator. While adaptive comb filtering reduces noise components remarkably, it is rarely effective in reducing non-stationary noises. Furthermore, due to the uniformly distributed frequency response of the comb-filter, it can cause serious distortion to clean speech signals. This paper proposes an improved comb-filter that adjusts its spectral magnitude to the original speech, based on the speech absence probability and the gain modification function. In addition, we introduce the modified comb filtering-based speech enhancement scheme for ASR in mobile environments. Evaluation experiments carried out using the Aurora 2 database demonstrate that the proposed method outperforms conventional adaptive comb filtering techniques in both clean and noisy environments.

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MMSE Receiver Filter for CDMA1xEV-DV (CDMA 1xEV-DV를 위한 MMSE 수신 필터 설계)

  • 안성우;허서원;김용석;정상운
    • Proceedings of the IEEK Conference
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    • 2003.07a
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    • pp.31-34
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    • 2003
  • 본 논문에서는 3GPP2 에 명시된 전송파형 필터의 특성을 살펴보고, 기존 시스템에서 고려되지 않았던 전송파형 정합필터의 간섭특성에 의한 성능손실을 분석하고 실험을 통해 검증한다. 또한, FCC 의 요구사항을 만족하며 수신필터의 간섭을 크게 줄인 MMSE 수신필터를 제안하며, 실험과 분석을 통해 제안된 필터에 의해 SNR 손실이 크게 줄어드는 결과를 보인다.

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Performance Analysis of Adaptive MMSE Receiver for CDMA Downlink

  • Nam, Ock-woo;Kim, Jae-hyung
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.5 no.3
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    • pp.435-441
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    • 2001
  • In this paper, we proposed adaptive MMSE receiver, which use channel equalizer to eliminate the interference due to multi-path fading and adaptive filter to eliminate the multiple access interference. The unique features of proposed receiver schemes are as following. We use pilot channel to estimate the channel coefficients exactly and guard symbols which are inserted periodically to estimate channel coefficients exactly without interference from user signals. The length of channel equalizer also can be reduced with the help of guard symbols. Especially utilizing adaptive code-matched filter(AMMSE) when the user population is high and SNR is not low we accepts excellent performance improvement.

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Background Noise Reduction Algorithm Based on Frequency Domain Adaptive Filter and MMSE-LSA in Dual-microphone situation (Dual-microphone 환경에서 주파수 영역 적응 필터와 MMSE-LSA기반 배경 잡음 알고리즘)

  • Lee, Keunsang;Park, Youngchul
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.6 no.1
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    • pp.23-28
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    • 2013
  • In this paper, background noise reduction method using dual microphone is proposed in mobile environment. Each Signal, reference and primary, would be replaced by microphone input signals, which were measured by reference and primary microphones, and then, noise reduction was performed using FDAF. After then, residual and background noise would be estimated and reduced by MMSE-LSA. For consistent noise reduction performance, result of VAD that could be caculated by PLD between two microphones was used.

Adaptive MMSE multiuser detector combined with decision-feedback detector for DS-CDMA system (DS-CDMA 시스템을 위한 결정 귀환 검출기와 결합된 적응 최소평균제곱오류 다중사용자 검출기법)

  • 이혜정;이재흥
    • Proceedings of the IEEK Conference
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    • 2002.06a
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    • pp.69-72
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    • 2002
  • In this paper, adaptive minimum mean-squared error (MMSE) multiuser detector combined with decision-feedback detector (DFD) is considered fur near-far resistant DS-CDMA system. To provide a reliable input to the adaptive MMSE detector, multiple-access interference (MAI) is regenerated using bit estimates from DFD and subtracted from the received signal. In the adaptive MMSE detector, the effect of the imperfect cancellation is compensated by a least mean square (LMS) algorithm. Through the numerical results, it is shown that, in a near-far situation, the proposed scheme provides superior performance to the matched filter (MF) receiver, adaptive MMSE detector, and DFD in terms of the bit error rate (BER).

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Structure and Performance Analysis of a New Long Code MMSE Detectors in a W-CDMA Communication System (W-CDMA 통신 시스템에서 새로운 롱 코드 MMSE 검파기 구성 및 성능 분석)

  • Kang, Myoung-Ku
    • The Journal of the Korea institute of electronic communication sciences
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    • v.6 no.2
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    • pp.163-170
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    • 2011
  • This study proposed the composition of a new long-code MMSE detector using the pilot channel that demonstrated the most excellent performance under Rayleigh fading in the previous studies. It analyzed and explained how to maintain the stability of the weight vector(introduction to the course of radio waves) in the receiver. In the operation of the receiver system to remove radio interference, the signal vector distortion received in the channel where fading was present achieved good results by compensating for signal errors. When there was distortion, the response characteristics of the received signals were superior to the common matching filter according to the computer simulation. The long-code MMSE receiver proposed in the study was able to prolong the cycle by $16{\times}T_b$ in the fading environment to fulfill the satisfaction.

A Visual Quality Enhancement of Medical Image Using Optimized High-Frequency Emphasis Filter (고주파 강조필터를 이용한 의료영상의 화질향상을 위한 최적화 방법)

  • Shin, Choong-Ho;Jung, Chai-Yeoung
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.18 no.7
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    • pp.1681-1685
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    • 2014
  • The visual quality of medical image is an important factor for diagnosis accuracy. Therefore, the methods to improve the quality of medical image have studied. Among them, frequency domain filter is very powerful method to impove the visual quality of image. In this paper, the X-ray medical image using optimized high-pass filter was improved edges. The result image was improved edge and contrast of flat area using optimized high frequency emphasis filter. At last, the result image is to minimize the noise using the minimum mean square error(MMSE) filter. As a result, the proposed method has enhanced contrast and edge of the image in the contrast of existing filters, with the noise canceling effect.

Performance of the Long Code MMSE Detector With Pilot Channel in the Presence of Rayleigh Fading

  • Lee, Yun-Soo;Chinn, Yong-Oak
    • Journal of information and communication convergence engineering
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    • v.5 no.4
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    • pp.333-338
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    • 2007
  • In this paper we propose a new structure of the long code MMSE receiver with pilot channel, which maintians excellent symbol detection capability even in the presence of Rayleigh fading. We explain analytically how the stability of the receiver weight vector, which is critical to the system performance, can be achieved by compensating the error signal as well as received signal vector distorted by fading channel. Computer simulation shows while maintaining better performance than the conventional matched filter receiver, the proposed long code MMSE receiver can extend its period up to $16{\times}T_b$ in a fading environment.

Design of a Frequency Domain Equalizer Algorithm for MBOK DS-UWB System (MBOK DS-UWB 시스템을 위한 주파수 영역 등화기 알고리즘의 설계)

  • Kang, Shin-Woo;Im, Se-Bin;Choi, Hyung-Jin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.32 no.10A
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    • pp.1034-1041
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    • 2007
  • In this paper, we propose a FD USE (frequency domain minimum mean square error) equalizer algorithm for MBOK DS-UWB (M-ary bi-orthogonal keying direct sequence UWB) systems considered as a PHY proposal for high-speed wireless communication in IEEE 802.15.TG3a. The conventional FD MMSE equalization scheme has a structural limit due to insertion of the cyclic prefix (CP) in all transmit packets, but the proposed scheme is able to equalize the channel effect without CP. In order to overcome channel estimation error by multipath delay, we introduce a moving FFT and a moving average scheme. Compared with conventional FD MMSE equalizer and the traditional TD (time domain) MMSE-RAKE receiver, the proposed FD MMSE equalizer has better BER performance and we demonstrate this result by computer simulation.