一种设计近似完全重构非均匀余弦调制滤波器组的新算法

该文提出了一种设计近似完全重构非均匀余弦调制滤波器组的新算法。针对现有合并算法中非均匀滤波器组性能无法直接控制优化的缺点,新算法把非均匀滤波器组的设计问题归纳为一个关于原型滤波器的无约束优化问题,其中目标函数是非均匀滤波器组传递失真与原型滤波器阻带能量的加权和,最后利用线性迭代算法求解该优化问题。理论分析和数值实验表明,新算法获得的非均匀余弦调制滤波器组比现有算法设计的滤波器组整体性能更佳。     

双原型离散傅里叶变换调制滤波器组的快速设计方法

针对大规模的离散傅里叶变换(DFT)调制滤波器组设计算法复杂度高的问题,该文提出一种基于无约束优化的快速设计算法。该算法将两个原型滤波器的设计问题归结为一个无约束优化问题,将滤波器组的传递失真,混叠失真以及原型滤波器阻带能量的加权和作为目标函数。进而,采用双迭代机制来求解该优化问题。在单步迭代中,运用矩阵求逆的等效条件和Toeplitz矩阵求逆的快速算法,显著地降低了迭代的计算代价。仿真对比表明,与已有的设计算法相比,新算法计算代价低 ,可以得到整体性能更好的滤波器组,并且可以快速设计大规模的滤波器组。     

一类冗余比为2的二维DFT调制滤波器组的设计

本文构建了一类冗余比为2的二维线性相位的双原型离散傅立叶变换（DFT）调制滤波器组。利用原型滤波器的多相位分解,推导出了该滤波器组的完全重构(PR)条件。基于该PR条件,我们将滤波器组的设计归结为一个关于原型滤波器的多相位分量的无约束优化问题。由于原型滤波器是线性相位的,多相位分量之间具有一定的关系,因此我们可以简化该优化问题。仿真结果验证了滤波器组PR条件的正确性。同时,仿真表明了优化算法的有效性,设计所得的滤波器组重构误差很小、频率特性较好,基本满足实际应用的需要。      

M带余弦调制滤波器组的迭代设计算法

余弦调制滤波器组的设计问题通常是关于原型滤波器系数的非凸优化问题,设计的优劣很大程度上取决于设计问题的归结和所采用的求解算法.本文提出了一种基于迭代的设计方法,用于设计近似完全重构的余弦调制滤波器组.该方法通过松弛完全重构条件和运用迭代的思想,将余弦调制滤波器组的设计归结为一个易于求解的优化问题.在该优化问题中,原型滤...     

基于拉格朗日乘子法的二维修正DFT调制滤波器组设计算法

基于拉格朗日乘子法,该文提出一种2维修正离散傅里叶变换调制滤波器组的迭代设计方法。在每次迭代中,原型滤波器的设计描述成一个约束为2次函数的2次规划问题。引入拉格朗日乘子法将问题转化为无约束的优化问题,通过求解线性矩阵方程得到优化问题的解。针对矩阵方程中的系数矩阵的特点,运用块LU分解,显著降低了运算复杂度。仿真实验表明,与现有的设计方法相比,该文方法设计得到的2维修正离散傅里叶变换调制滤波器组的重构误差和阻带衰减均有较大的改善。     

基于DFT滤波器组的多载波调制系统设计

采用DFT滤波器组来代替OFDM系统中的IDFT/DFT模块,形成基于滤波器组的收发器。设计适于多经衰落信道的DFT滤波器组收发器。其均衡与OFDM系统一样,是在接收端采用单抽头的均衡器。实验采用随机多径信道,仿真结果表明所提出的滤波器组收发器可以获得较好的频谱特性,以及较满意的SIR（信号与干扰比值）。     

基于相位调制的非均匀DFT调制滤波器组的构造算法

由于具有灵活的频率划分能力,非均匀滤波器组在语音、图像等信号的处理中有着广泛的应用。该文针对非均匀DFT调制滤波器组无法直接合并构造的缺点,提出一种基于相位调制的构造方法。在该方法中,非均匀DFT调制滤波器组的子带滤波器由均匀DFT调制滤波器组经子带合并和相位调制获得。构造所得的非均匀滤波器组与原均匀滤波器组的重构特性近似相等。同时推导出非均匀子带滤波器具备良好频率特性的条件。理论分析和仿真结果均表明了所提的构造方法的有效性。     

基于DFT滤波器组的宽带信号谱分析方法

本文利用DFT滤波器组、ZFFT,提出了一种宽带信号的实时谱分析方法。有效地解决了宽带信号高分辨率 谱分析要求的大运算量与实时性之间的矛盾。理论分析与计算机仿真表明该算法切实可行、有效并且易于实现。     

DFT调制方向滤波器组在图像去噪中的应用

通过对DFT调制滤波器组进行二维扩展,给出了具有方向选择性的新型滤波器组的原理结构。分析了利用DFT调制滤波器组构造的方向滤波器组在图像去噪中的应用方案。仿真分析结果表明：新方案可消除对角子带的方向交叉,并可提供更多的方向信息。同时还可将不同频率、不同方向的信息划分到不同的子带。从而为多尺度的方向划分提供可能。     

过采样DFT滤波器组的一种简单设计方法

提出了一种几乎完全重构的过采样DFT调制滤波器组的设计方法.分析和综合滤波器组采用了不同的原型滤波器,使得设计自由度大为增加.考虑滤波器组的子带混叠、输出混叠、系统失真要求,推导并给出了相应的设计算法.实验结果证明提出的方法在相同滤波器长度情况下可以得到更好的阻带衰减.     

Design of 2D oversampled linear phase DFT modulated filter banks via modified Newton's method

In this paper, the structure of the 2D oversampled DFT modulated filter banks is analyzed and a spatial-domain condition of a filter bank without transfer function distortion is derived. Based upon the spatial-domain condition, a modified Newton's method is presented for fast design of 2D oversampled linear phase (LP) DFT modulated filter banks with nearly perfect reconstruction (NPR). We formulate the design problem into an unconstrained optimization with a fourth-order objective function, which is the weighted sum of the transfer function distortion of the filter bank and the stopband energy of the prototype filter (PF). The optimization is solved by the modified Newton's method, where each of iterations updates the PF by a set of linear equations. It is proved that the iteration process fast converges to a stationary point of the objective function. Compared with the existing methods, the new method is fast in computation and can design 2D filter banks with a large number of subbands.     

Time-domain modified DFT modulated filter banks for multi-carrier transceiver systems

A time domain designing method is proposed for discrete Fourier transform （DFT） modulated filter banks （DFT-FBs） for application in multi-carrier transceiver systems. Instead of using the time-reversed pair limitation between the transmitting /receiving filter pair, the receiving filters in the proposed filter banks are derived from transmitting filters in accordance with the Moore-Penrose generalized inverse matrix. It can be freely obtained to design the transmitting prototype filter, which mainly affects the level of spectral containment. Furthermore, the symbol error rate （SER） performance of the proposed filter bank based trans-multiplexer with one tap equalizer is investigated in ideal channel and multi-path channel environments respectively. Simulation shows that the proposed approach can achieve significant SER reductions when square root raised cosine （RRC） prototype filter is used for comparing with the orthogonal frequency division multiplexing （OFDM） and the general DFT-FBs based applications.     

Joint use of time-domain and windowed method for design of modulated DFT filter banks

A novel and efficient technique to design modulated discrete Fourier transform （DFT） filter banks is introduced in this paper. The proposed method first relaxes the limits that the synthesis filters are the time-reversed version of the analysis filters and then adopts the time domain formula of the perfect reconstruction property as the solution to design the synthesis filters. The prototype filter in analysis filter banks is designed based on Fourier-Kaiser window approach. Simulation results show that the designed filter banks approximately satisfy the perfect reconstruction with controllable reconstruction errors.     

Joint use of DFT filter banks and modulated transmultiplexers for multicarrier communications

In this paper, new procedures for performing multicarrier modulation (MCM) are presented, based on using IFFT/FFT embedded in a filter bank-based transmultiplexer system. The IFFT/FFT blocks, along with the use of cyclic prefix or zero-padding strategies, enable easy equalization of the transmission channel. Additionally, the transmultiplexer system provides improved spectral discrimination, which can increases the transceiver robustness against mainly narrow-band interferences. Moreover, one of the proposed procedures presents an IDFT as the final stage of the MCM transmitter, and a DFT as the first stage of the receiver. This front-end is similar to standardized systems, enabling its compatibility. As it is illustrated by means of several examples, given a signal to noise ratio and comparing the new procedures to DFT-based MCM adopted in several digital communications standards, the following attractive features can be found: (a) greater spectral separation in the information transmitted over each subcarrier and (b) the robustness of the systems in noisy environments, mainly when narrow-band interferences appear, can be increased, allowing a reduction in the bit error probability.     

线性相位余弦调制滤波器组研究

图像子带编码要求滤波器组具有线性相位特性，非线性相位特性可对图像编译码带来影响。现研究了一种具有线性相位的最大抽取FIR余弦调制滤波器组，该滤波器组中每一个滤波器都具有线性相位，且由原型滤波器经余弦序列调制得到。经推导这种滤波器组可以设计成具有近似准确重构（NPR）特性或准确重构（PR）特性，文中分别给出了两种情况下滤波器组应满足的条件。通过对一幅图像的二维可分离滤波实验说明了当原型滤波器满足一定条件时滤波器组是准确重构的。     

一种新的调制型混合滤波器组设计算法

针对经典的准确重构混合滤波器组设计问题,提出一种调制型混合滤波器组(MHFB)的设计算法,推导了分析滤波器组系数矩阵的行列式与原型滤波器系数的解析关系,给出了具有普适性的综合滤波器组解的一般形式,并讨论了因果、稳定系统的设计方法。针对多通道HFB设计复杂的问题,提出一种FIR形式综合滤波器组的优化设计算法,适用于多通道HFB的设计。仿真结果验证了算法的有效性。