• Title/Summary/Keyword: Subband adaptive filtering

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Polyphase Representation of the Relationships Among Fullband, Subband, and Block Adaptive Filters

  • Tsai, Chimin
    • 제어로봇시스템학회:학술대회논문집
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    • 2005.06a
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    • pp.1435-1438
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    • 2005
  • In hands-free telephone systems, the received speech signal is fed back to the microphone and constitutes the so-called echo. To cancel the effect of this time-varying echo path, it is necessary to device an adaptive filter between the receiving and the transmitting ends. For a typical FIR realization, the length of the fullband adaptive filter results in high computational complexity and low convergence rate. Consequently, subband adaptive filtering schemes have been proposed to improve the performance. In this work, we use deterministic approach to analyze the relationship between fullband and subband adaptive filtering structures. With block adaptive filtering structure as an intermediate stage, the analysis is divided into two parts. First, to avoid aliasing, it is found that the matrix of block adaptive filters is in the form of pseudocirculant, and the elements of this matrix are the polyphase components of the fullband adaptive filter. Second, to transmit the near-end voice signal faithfully, the analysis and the synthesis filter banks in the subband adaptive filtering structure must form a perfect reconstruction pair. Using polyphase representation, the relationship between the block and the subband adaptive filters is derived.

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VLSI Implementation for the MPDSAP Adaptive Filter

  • Choi, Hun;Kim, Young-Min;Ha, Hong-Gon
    • Journal of the Institute of Convergence Signal Processing
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    • v.11 no.3
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    • pp.238-243
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    • 2010
  • A new implementation method for MPDSAP(Maximally Polyphase Decomposed Subband Affine Projection) adaptive filter is proposed. The affine projection(AP) adaptive filter achieves fast convergence speed, however, its implementation is so expensive because of the matrix inversion for a weight-updating of adaptive filter. The maximally polyphase decomposed subband filtering allows the AP adaptive filter to avoid the matrix inversion, moreover, by using a pipelining technique, the simple subband structured AP is suitable for VLSI implementations concerning throughput, power dissipation and area. Computer simulations are presented to verify the performance of the proposed algorithm.

Detection and Tracking of Time Varying Power System Frequencies and Harmonics using Subband Adaptive Filtering (적응 부밴드 필터링을 이용한 전력계통 시변 주파수와 고조파 검출 및 추적)

  • Sohn, Sang-Wook;Choi, Hun;Bae, Hyeon-Deok
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.4
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    • pp.679-687
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    • 2009
  • In this paper, a subband filtering and adaptive prediction technique for analyzing harmonics in power systems is presented. In this method, the filter banks are designed to decompose odd and even order harmonics separately. The adaptive prediction has been employed reduce the transient and white noise effect in time varying harmonics detecting and tracking. The frequencies and amplitudes of the decomposed harmonics are estimated by recursive algorithm. To demonstrate the performances of the developed technique, computer simulations to the signal with the time-varying frequency and THD are carried out.

Subband IPNLMS Adaptive Filter for Sparse Impulse Response Systems (성긴임펄스 응답 시스템을 위한 부밴드 IPNLMS 적응필터)

  • Sohn, Sang-Wook;Choi, Hun;Bae, Hyeon-Deok
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.60 no.2
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    • pp.423-430
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    • 2011
  • In adaptive filtering, the sparseness of impulse response and input signal characteristics are very important factors of it's performance. This paper presents a subband improved proportionate normalized least square (SIPNLMS) algorithm which combines IPNLMS for impulse response sparseness and subband filtering for prewhitening the input signal. As drawing and combining the advantage of conventional approaches, the proposed algorithm, for impulse responses exhibiting high sparseness, achieve improved convergence speed and tracking ability. Simulation results, using colored signal(AR(4)) and speech input signals, show improved performance compared to fullband structure of existing methods.

A Subband Adaptive Blind Equalization Algorithm for FIR MIMO Systems (FIR MIMO 시스템을 위한 부밴드 적응 블라인드 등화 알고리즘)

  • Sohn, Sang-Wook;Lim, Young-Bin;Choi, Hun;Bae, Hyeon-Deok
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.59 no.2
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    • pp.476-483
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    • 2010
  • If the data are pre-whitened, then gradient adaptive algorithms which are simpler than higher order statistics algorithms can be used in adaptive blind signal estimation. In this paper, we propose a blind subband affine projection algorithm for multiple-input multiple-output adaptive equalization in the blind environments. All of the adaptive filters in subband affine projection equalization are decomposed to polyphase components, and the coefficients of the decomposed adaptive sub-filters are updated by defining the multiple cost functions. An infinite impulse response filter bank is designed for the data pre-whitening. Pre-whitening procedure through subband filtering can speed up the convergence rate of the algorithm without additional computation. Simulation results are presented showing the proposed algorithm's convergence rate, blind equalization and blind signal separation performances.

Subband Affine Projection Algorithm (부밴드 인접투사 알고리즘)

  • Choi, Hun;Bae, Hyeon Deok
    • The Journal of the Acoustical Society of Korea
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    • v.23 no.3
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    • pp.221-227
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    • 2004
  • This paper presents the subband affine projection algorithm(SAPA). The improved performance of SAPA is achieved by applying the affine projection algorithm to the subband adaptive structure. In this algorithm, the weight updating formula of adaptive filter is simply derived by using the orthogonal quadrature filter(OQF) as an analysis filter bank for subband filtering. The derived SAPA has the fast convergence speed and small computational complexity. The efficiency of the proposed algorithm for colored input signal is evaluated through some experiments.

Individual Variable Step-Size Subband Affine Projection Algorithm (독립 가변 스텝사이즈 부밴드 인접투사 알고리즘)

  • Choi, Hun
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.26 no.3
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    • pp.443-448
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    • 2022
  • This paper presents a subband affine projection algorithm with variable step size to improve convergence performance in adaptive filtering applications with long adaptive filters and highly correlated input signals. The proposed algorithm can obtain fast convergence speed and small steady-state error by using different step sizes for each adaptive sub-filter in the subband structure to which polyphase decomposition and noble identity are applied. The step size derived to minimize the mean square error of the adaptive filter at each update time shows better convergence performance than the existing algorithm using a variable step size. In order to confirm the convergence performance of the proposed algorithm, which is superior to the existing algorithm, computer simulations are performed for mean square deviation(MSD) for AR(1) and AR(2) colored input signals considering the system identification model.

Time Delay Estimation using Third-order Statistics and Subband Adaptive Filtering (3차 통계기법과 서브밴드 적응 필터링을 이용한 시간 지연 추정)

  • 박현석;남상원
    • Proceedings of the IEEK Conference
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    • 2001.09a
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    • pp.907-910
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    • 2001
  • In this paper, we address a new time delay estimation method using third-order statistics and subband adaptive filtering to improve the accuracy of target detection for acoustic backscattered signals in a noise interference environment. Each reference and primary signals are decorrelated using the multiresolution analysis framework through a M-band discrete wavelet transform(M-DWT). Then noise effect can be reduced. Here, time delays are estimated iteratively in each subband using two different adaptation mechanisms that minimize the mean squared error (MSE) between the references and primary signal. More specifically, third-order cumulants and projection cross-correlation(PCC) criterion are utilized to achieve an effective SNR improvement for the time delay estimation.

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Study on Improvement of Convergence Rate of Acoustic Echo Canceller (음향 반향 제거기의 수렴속도 개선에 대한 연구)

  • Kang, Hee Hoon
    • The Journal of the Korea institute of electronic communication sciences
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    • v.4 no.1
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    • pp.66-69
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    • 2009
  • An adaptive echo canceller is necessary for an application such as a speakerphone, 3G image telephony and VoIP service system. These echo cancellers need to have many taps for filtering echo signals. Many taps cause computation data to increase and convergence speed to be low. To overcome these problems, An adaptive echo canceller with the advanced convergence speed is proposed in this paper. To improve the speed, we divide an echo band into subbands and place a subband filter to be adaptive for each subband. Each subband filter recognizes the echo signal as subband echo signals. So, dynamic range of subband is small, the convergence speed is fast. Moreover, as the number of Tap and weight update are estimated in each subband, the implementation complex of a adaptive filter is low.

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Convergence Analysis of Multiple Constrained Subband Affine Projection Algorithm (다중제한조건을 갖는 부밴드 AP 알고리즘의 수렴해석)

  • Kim, Young-Min;Sohn, Sang-Wook;Choi, Hun;Bae, Hyeon-Deok
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2009.10a
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    • pp.474-476
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    • 2009
  • In the radio communication, such as echo cancellation and channel equalization, adaptive filtering is very practical. Its convergence behavior that is used for updating the weights depends on the correlation of the input signal and length of adaptive filter. Highly correlated input and long length of adaptive filter deteriorate the convergence behavior. To solve this problem, recently, subband affine projection algorithm which pre-whiten the correlation of the input and update the weights in subband structure has been presented. This paper presents convergence analysis method of multiple constrained subband affine projection algorithm.

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