Quadrature Mirror Filter Banks Research Articles

Empowering quadrature mirror filter bank architectures: dynamic-grey wolf optimization approach for elevated filter orders

The present study introduces a revised version of the Grey Wolf Optimization (GWO) algorithm called Dynamic-GWO, which integrates a dynamic parameter adaptation mechanism for population diversity enhancement. This mechanism implements the real-time adjustment of control parameters throughout the optimization procedure. The algorithm's effectiveness is demonstrated by its consistent performance across a variety of intricate benchmark functions. Further, the suggested approach is employed to determine the eminent filter tap coefficients of the Quadrature-Mirror-Filter (QMF) bank that enables the configuration with filter orders of 120 and 150, which have yet to be achieved using existing methods. The uniqueness of the proposed approach lies in its capability to overcome the inherent difficulties associated with higher-order filter design, including increased filter length and computational complexity. The primary objective function is to minimize the algebraic sum of three types of distortion: pass-band error, excess power of stop-band, and squared error of the overall transfer function at the quadrature frequency ω q = π / 2 , which generally occur in the procedure of Near-Perfect-Reconstruction (NPR) QMF bank design. In addition, the measured maximum reconstruction errors are 1.303 × 10 − 15 , 2.93 × 10 − 16 and 2.18 × 10 − 06 dB, and aliasing distortions are A L = 85.80 , 128.49 and 153.52 dB for filter orders N = 100, 120 and 150, correspondingly. The proposed algorithm yields significant improvements with an 86.68% reduction in the ripple factor and a 10.45% increase in attenuation compared to the baseline GWO for filter order 120, underscoring its effectiveness in enhancing filter performance. The observed outcomes indicate that the Dynamic-GWO algorithm consistently surpasses the baseline GWO and other Nature-Inspired Algorithms (NIAs) regarding computational ease and convergence speed.

Avocodo: Generative Adversarial Network for Artifact-Free Vocoder

Neural vocoders based on the generative adversarial neural network (GAN) have been widely used due to their fast inference speed and lightweight networks while generating high-quality speech waveforms. Since the perceptually important speech components are primarily concentrated in the low-frequency bands, most GAN-based vocoders perform multi-scale analysis that evaluates downsampled speech waveforms. This multi-scale analysis helps the generator improve speech intelligibility. However, in preliminary experiments, we discovered that the multi-scale analysis which focuses on the low-frequency bands causes unintended artifacts, e.g., aliasing and imaging artifacts, which degrade the synthesized speech waveform quality. Therefore, in this paper, we investigate the relationship between these artifacts and GAN-based vocoders and propose a GAN-based vocoder, called Avocodo, that allows the synthesis of high-fidelity speech with reduced artifacts. We introduce two kinds of discriminators to evaluate speech waveforms in various perspectives: a collaborative multi-band discriminator and a sub-band discriminator. We also utilize a pseudo quadrature mirror filter bank to obtain downsampled multi-band speech waveforms while avoiding aliasing. According to experimental results, Avocodo outperforms baseline GAN-based vocoders, both objectively and subjectively, while reproducing speech with fewer artifacts.

Spider monkey optimization method to design two channel quadrature mirror filter bank with linear phase

Spider monkey optimization method to design two channel quadrature mirror filter bank with linear phase

Quadrature mirror filter bank design based on hybrid bee colony technique

This paper proposed a modified evolutionary technique formed by the hybridization of the bee colony technique and Nelder–Mead Simplex search technique to optimize the coefficients of Quadrature Mirror Filter (QMF). The performance of QMF can be evaluated in terms of error in the pass-band, stop-band and measure of ripple. A modified objective function is designed in this work, expressed as a weighted sum of errors in the pass-band, stop-band and measure of ripple. A modified objective function is minimized by using the proposed technique. The results obtained from the proposed technique are compared with the previously reported evolutionary optimization techniques based on QMF design. A significant improvement in various performance attributes has been attained compared to earlier reported QMF bank design techniques.

Design of a Two-Channel Quadrature Mirror Filter Bank Through a Diversity-Driven Multi-Parent Evolutionary Algorithm

A multi-objective problem-solving technique for designing a two-channel quadrature mirror filter bank is proposed, where the objectives are to minimize the errors of the passband, stopband and transition band. An evolution-based algorithm, “diversity-driven multi-parent evolutionary algorithm with adaptive non-uniform mutation” (DDMPEA), is proposed for this purpose. The proposed algorithm employs the concepts of population space aggregation and fitness variance to guide the solution away from local optima. This algorithm is also validated on benchmark optimization problems. Furthermore, Wilcoxon’s test for statistical analysis at a 5% significance level confirms the effectiveness of the algorithm. From Wilcoxon’s rank-sum test, it is clear that for all considered benchmark functions, the DDMPEA is superior to other state-of-the-art optimization algorithms. The results achieved from the designed filter are compared with other available results from the existing literature. The percentage improvements in peak reconstruction error, attenuation of the stopband, and overall amplitude distortion are calculated for filter lengths of 32 and 48.

A Novel Approach of QMF Bank using Modified PSO Technique for Biomedical Image Applications

Introduction Work on efficient design of two-channel quadrature mirror filter (QMF) banks has gained significant attention over the past two decades, because they are used in wide range of applications like speech signals [1, 2], image processing [3] and communication systems [4, 5]. In the past,

Iterative technique for optimizing two-channel: Quadrature mirror, bi-orthogonal and graph filter bank

An iterative technique is proposed to optimally design the two-channel linear phase (LP) FIR quadrature mirror filter bank (2c-LP-FIR-QMFB). In each iteration, first, the frequency-domain reconstruction error function of the 2c-LP-FIR-QMFB is approximately converted into a convex function, by approximating all its sub-functions using first order Taylor series expansion. Then, the approximated reconstruction error function is minimized as the optimization objective function while the frequency selectivity performance metric function of the sub-filter is taken as the constraint function. Further, the optimal step-size optimization problem for each iteration is solved using a similar iterative strategy. Additionally, the proposed technique can also be utilized to optimize the coefficients of a class of structurally perfect reconstruction two-channel LP FIR bi-orthogonal filter bank, as well as a class of two-channel graph filter bank. Simulation results reveal that the proposed technique outperforms the previously existing techniques in terms of the frequency-domain reconstruction error and/or the frequency selectivity performance metric of the sub-filter. Particularly, for the graph filter bank, the reconstruction error of the proposed technique is only (3.1e-11)% of its previous counterpart. The proposed technique might also be useful to optimize the coefficients of other classes of two-channel traditional signal or graph signal filter banks.

Performance Analysis of QMF Filter Bank For Wireless Voip in Pervasive Environment

Background: Voice over Internet Protocol (VoIP) has emerged as one of the most significant technology in the field of communication and evolved as a substitute to the conventional communication method as the Public Switched Telephone Network (PSTN). Along with the advantages such as scalability and security, VoIP has some threats such as voice quality and interference that must be dealt with. The voice quality in VoIP is degraded when transmitted over a computer network due to delay, jitter and packet loss etc. Packet loss is one of major reasons for the signal quality degradation. Objective: In this research article, Quadrature Mirror Filter Bank (QMF) has been implemented in wireless VoIP system to enhance the quality of the signals transmitted. Results: The performance has been evaluated under varying network conditions of packet loss. Conclusion: Significant improvement has been observed in the quality of VoIP signal.

Neural network‐based design of 2‐channel quadrature mirror filter banks

SummaryTwo‐channel quadrature mirror filter banks can be efficiently established by the combination of real‐valued infinite impulse response all‐pass filters without incurring aliasing and magnitude distortions. The design problem of filter banks is therefore to seek for the phase error minimization of the all‐pass filter coefficients. In this paper, a neural network‐based Lyapunov energy function is used to relate to the objective function of the designed all‐pass filter coefficients. Based on the architecture of neural networks and suitable selection of Hopfield‐related parameters, the all‐pass filter coefficients are obtained when the networks reach convergence. By further using the suitable combination of the designed all‐pass filters, the 2‐channel quadrature mirror filter banks with perfect reconstruction can be efficiently accomplished. Simulation results indicate that the neural network‐based approach has the advantage of satisfactory performance in magnitude and group delay responses in a parallelism manner.

Design and Implementation of Efficient Analysis and Synthesis QMF Bank for Multicarrier Cognitive Radio Communication.

The present section deals with a new type of technique for designing an efficient two channel Quadrature Mirror Filter Bank with constant phase in frequency. For achieving the Perfect Reconstruction Condition in Filter bank, an attempt has been made to design the low pass prototype filter with its impulse response and frequency response in three regions namely pass band, stop band and transition band region. With the error in terms of Reconstruction and the attenuation in the stop band as seen in the prototype filter response, one can evaluate the performance of the introduced filter with the help of filter coefficients generated in the design examples that affects the quality of filter bank design under the constraints of Near Perfect Reconstruction Conditions.

Low‐complexity design framework of all‐pass filters with application in quadrature mirror filter banks design

Digital all-pass filters design problem can be simplified by solving a set of linear equations associated with a Toeplitz-plus-Hankel matrix in the least-squares sense. Consequently, the Cholesky decomposition or split Levinson technique can be appropriately used to obtain the optimal solution. In this study, the determination of the set of linear equations to calculate the all-pass-based quadrature mirror filter banks is achieved by exploiting some trigonometric identities and the frequency sampling method. The proposed simplification allows for expressing a sum of sinusoids by a single expression. The simulation results indicate that the presented new and simpler closed-form expressions of the Toeplitz-plus-Hankel associated matrices can achieve accurate performance with a considerable reduction in computational complexity.

Quadrature Mirror Filter Bank Design for Mitral Valve Doppler Signal Using Artificial Bee Colony Algorithm

In this paper, a new design method was developed for quadrature mirror filter (QMF) bank. Previous QMF bank design methods focused on frequency response properties such as pass band and stop band parameters with symmetrical filters. With the proposed method, QMF bank was designed using on time domain signals as mitral valve signal with unsymmetrical filter. The design problem was formulated as an objective function of difference between QMF bank’s input and output signals. QMF bank signal disparity was compared with correlation and peak reconstruction error (PRE). QMF bank prototype filter parameters were optimized with Artificial Bee Colony (ABC) and Differential Evaluation (DE) Algorithms. Design outputs were compared with previous works. DOI: http://dx.doi.org/10.5755/j01.eie.23.1.17584

An improved speech enhancement algorithm for dual-channel mobile phones using wavelet and genetic algorithm

In this paper, a speech enhancement algorithm for dual-microphone mobile phones is improved. The proposed method is based on the exploitation of the coherence function and the quadrature mirror filter banks. This latter is designed by the genetic algorithm as criteria for noise reduction. Thus, the quadrature mirror filter banks are used as a mother wavelet in the speech enhancement algorithm. The adopted algorithm benefits of non-interfering signals statistics prediction. Hence, it can be applied with two closely microphones in small cellular mobile phones. Finally, referred to the objective measures and the time domain waveforms, the proposed method proves its effectiveness in term of speech quality and intelligibility compared with other algorithms when the speech is corrupted by different noise types.

Primary user Emulation Attack Defense in Filter Bank based Cognitive Radio

Background/Objectives: The spectrum scarcity problem arising due to reckless development in wireless communication can be addressed using cognitive radio technology. An important step in cognitive radio technology is spectrum sensing and associated with that is an attack called primary user emulation attack. Methods/Statistical Analysis: A two channel Quadrature Mirror Filter (QMF) bank is employed for a single user spectrum sensing. The energy detection method is used as reference for comparing the performance of the filter bank method in the presence of attackers. Existing approaches like Neyman-Pearson Criterion, Improved Detection Scheme with Double threshold and Location Verification Method for detecting PUE attacks were examined. A new method which combines improved detection scheme and location verification method is proposed for detecting PUE attacks. Findings: The simulation result shows that the filter bank method shows better performance than the energy detection method in the presence of attackers. The probability of detection of PUE attacks using improved detection scheme and location verification method for the filter bank method and energy detection method was analyzed and found out that the filter bank based spectrum sensing method outperforms energy detection method. By incorporating AND rule logic, OR rule logic and Alternate logic approach into the filter bank spectrum sensing technique, the probability of detection of PUE attack was investigated and it is seen that the probability of detection has increased to 0.98 in FB method at SNR = 1 dB when employing an alternate approach. Application/Improvements: The feasibility of deploying the filter bank method integrated with the alternate logic is to be tested using Universal Software Radio Peripheral (USRP) module.

Optimisation of two-channel QMF bank using modified cuckoo search technique for biomedical image applications

In this paper, an improved technique for the design of two-channel linear phase Quadrature Mirror Filter (QMF) bank with Modified Cuckoo Search (MCS) technique is represented. The performance of proposed scheme is compared with other reported methods for QMF bank design. Based on the simulation results, it is demonstrated that the proposed MCS method can achieve 17 times reduction in pass band error, 215 times lower stop band error, 41 times decrease in transition band error and 7.7 times reduction in measure of ripple (mor) when compared with recently reported Improved Particle Swarm Optimisation (IPSO) technique. Moreover, the proposed QMF bank applied for sub-band decomposition reconstruction of a biomedical image provides 43% reduction in mean square error and 8.3 dB higher peak signal-to-noise ratio compared to IPSO algorithm.

An efficient gbest-guided Cuckoo Search algorithm for higher order two channel filter bank design

Abstract This paper proposes a new algorithm based on Gbest-guided Cuckoo Search (GCS) algorithm for the design of higher order Quadrature Mirror Filter (QMF) bank. Although the optimization of lower order filters can be performed easily by applying existing meta-heuristic optimization techniques like Particle Swarm Optimization (PSO), Artificial Bee Colony (ABC) etc., these methods are unsuccessful in searching higher order filter coefficients due to multimodality and nonlinear problem space; leads to some undesirable behaviors in filter responses like ripples in transition band, lower stop-band attenuation etc.. Comparison with other available results in the literature indicate that the proposed method exhibits an 69.02% increase in stop-band attenuation and 99.71% reduction in Perfect Reconstruction Error (PRE) of higher order filter bank. Besides, the percentage improvements in Fitness Function Evaluations (FFEs) of GCS based 55th order QMF bank design with respect to PSO, ABC and CSA are 81%, 82% and 59% respectively, and execution time is improved by 73%, 72% and 42% respectively. The simulation results also reveal that the proposed approach exhibits lowest mean and variance in different assessment parameters of filter bank and it does not require tuning of algorithmic parameters whereas in standard CSA replacement factor need to be adjusted. Further, the proposed algorithm is tested on six standard benchmark problems and complex benchmark functions from the CEC 2013 where it demonstrated significant performance improvements than other existing methods.

A Hardware/Software Co-design of High Efficiency AAC Audio Decoder

This paper presents an implementation of hardware/software co-design for high efficiency advanced-audio-coding (HE-AAC) audio decoder. The decoder system is partitioned into software and hardware part throughout the computation analysis. In our design strategy, the bitstream parser and lower complexity part are performed by software solution, and the higher complexity part is computed by hardware solution. As in the dedicated hardware, four units are developed to cope with IMDCT, analysis quadrature mirror filterbank (AQMF), HF generator and envelope adjuster and synthesis quadrature mirror filterbank (SQMF). To support the various types of transformation-based functions in HE-AAC decoding, we manipulate it based on the decomposition of common radix-2 FFT method. The hardware part is designed as an intellectual property (IP) by TSMC 90 nm library. As a cost-effective design, it consumes about 150 K gates and executes at a very low operation frequency with 1.75 MHz. The power consumption is only 7.69 mW with some low power design considerations. Moreover we construct the overall system including the wrapper design and embedded platform as a system on a programmable chip (SOPC) platform. With this design approach, over 91.26 % processor-based loading can be saved and substituted by this hardware IP.

Two-channel perfect reconstruction (PR) quadrature mirror filter (QMF) bank design using logarithmic window function and spline function

In this work, two-channel perfect reconstruction quadrature mirror filter (QMF) bank has been proposed based on the prototype filter using windowing method. A novel window function based on logarithmic function along with the spline function is utilized for the design of prototype filter. The proposed window has a variable parameter ‘ $$\alpha $$ ’, which varies the peak side lobe level and rate of fall-off side lobe level which in turn affects the peak reconstruction error (PRE) and amplitude distortion ( $$e_{am}$$ ) of the QMF bank . The transition width of the prototype is controlled by the spline function using the parameter ‘ $$\mu $$ ’. The perfect reconstruction condition is satisfied by setting the cutoff frequency ( $$\omega _{c}$$ ) of the prototype low-pass filter at ‘ $$\pi /2$$ ’. The performance of the proposed design method has been evaluated in terms of mean square error in the pass band, mean square error in the stop band, first side lobe attenuation ( $$A_{1}$$ ), peak reconstruction error (PRE) and amplitude error ( $$e_{am}$$ ) for different values of ‘ $$\alpha $$ ’ and ‘ $$\mu $$ ’. The results are provided and compared with the existing methods.

Passive congregation-based particle swarm optimisation for designing quadrature mirror filter bank

In this paper, we propose two different approaches based on Particle Swarm Optimisation (PSO) for the design of Near Perfect Reconstruction (NPR) Quadrature Mirror Filter (QMF) bank. The proposed method employs Constriction Factor-based PSO (CPSO) and PSO with Passive Congregation (PSOPC) approach for the design of prototype filter. Both the PSO methods are presented to optimise FIR filter coefficients that lead to NPR filter bank. Passband ripple, stopband energy, transition-band error and amplitude distortion of the overall bank are combined to obtain a closed form objective function. Two illustrative examples are given to demonstrate the feasibility of our proposed scheme and performances are compared with other existing methods. The experimental results show that PSOPC algorithm provides better performance parameters with great accuracy and convergence.

Passive congregation-based particle swarm optimisation for designing quadrature mirror filter bank

In this paper, we propose two different approaches based on Particle Swarm Optimisation (PSO) for the design of Near Perfect Reconstruction (NPR) Quadrature Mirror Filter (QMF) bank. The proposed method employs Constriction Factor-based PSO (CPSO) and PSO with Passive Congregation (PSOPC) approach for the design of prototype filter. Both the PSO methods are presented to optimise FIR filter coefficients that lead to NPR filter bank. Passband ripple, stopband energy, transition-band error and amplitude distortion of the overall bank are combined to obtain a closed form objective function. Two illustrative examples are given to demonstrate the feasibility of our proposed scheme and performances are compared with other existing methods. The experimental results show that PSOPC algorithm provides better performance parameters with great accuracy and convergence.