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Author

Chao Wu

Bio: Chao Wu is an academic researcher. The author has contributed to research in topics: Adaptive filter & m-derived filter. The author has an hindex of 1, co-authored 1 publications receiving 2 citations.

Papers
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Dissertation
01 Jan 2007
TL;DR: In this article, a generalized polyphase (GP) structure is proposed for the design of M th-band filters and filter banks, which is based on the polyphase matrix representation of the analysis and synthesis filters and a key idea of devising basic building blocks that are capable of propagating the desirable symmetry properties while being cascaded to generate the required lattice structures.
Abstract: Multirate systems, including M th-band filters and filter banks, have greatly facilitated the analysis, understanding and compression of signals. Polyphase structure plays an important role in the study of multirate systems due to the fact that it provides a parallel and very efficient implementation architecture. In this dissertation, some polyphase structure-based approaches for the design and implementation of M th-band filters as well as filter banks are presented. The emphasis is placed on the development of new structures that satisfy certain constraints and having low computational complexity. A design algorithm for M th-band filters is first presented based on the generalized polyphase (GP) structure. Both the interpolation and linear-phase conditions are incorporated in the proposed GP realization of M th-band filters. By deriving a closed-form frequency response specification for each of the constituent filters in the GP structure, the design of the original large-tap FIR filter is simplified to the design of short-length constituent filters to reduce the overall design complexity. The GP-based approach is then extended for the design of M th-band filters meeting certain regularity requirements. To show the wide applicability of the proposed method, the design of 2-D M th-band filters via the GP structure is also considered. It is shown that by applying the singular-value decomposition (SVD) to each 2-D subfilter in the GP structure, the implementation complexity of the overall 2-D filter can be significantly reduced without introducing a large error. The second part of the dissertation is concerned with the development of new lattice structures for perfect reconstruction filter banks (PRFBs) with certain constraints, such as the linear-phase (LP) and the minor-image symmetry (MIS). The innovative work is based on the polyphase matrix representation of the analysis and synthesis filters, and a key idea of devising basic building blocks that are capable of propagating the desirable symmetry properties while being cascaded to generate the required lattice structures. Due to the added constraints, the resulting lattice structures have fewer parameters, leading to a speedy optimization design and a reduction in the heavy implementation burden. It is proved that there exists a complete and minimal lattice structure for MIS-PRFBs. It is shown that a class of well-known filter banks, namely, the cosine-modulated filter banks (CMFBs), is a subclass of MIS-PRFBs, whose non-singular matrices are of sparse coefficients. By introducing more prototype filters, in conjunction with a proper modulation, new CMFBs with more parameters are generated. Combining the linear-phase and mirror-image symmetries, a lattice structure with further reduced number of parameters is also developed for MIS-LPPRFB. The designed MIS-LPPRFB is then utilized as a block transform for image compression coding. Simulation results show that the MIS-LPPRFB, despite its reduced number of parameters, offers a competitive performance in terms of both the visual quality and the peak signal-to-noise ratio for various images under a wide range of compression ratios

2 citations


Cited by
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Patent
10 Jan 2017
TL;DR: In this article, a polyphase finite impulse response (FIR) digital filter with symmetric coefficients is presented, where each sub-filter has at least one pair of sub-filters, each having a symmetric coefficient, and a lattice consisting of two adders and feedlines corresponding to each of the subfilters.
Abstract: Apparatuses (and methods of manufacturing same), systems, and methods concerning polyphase digital filters are described. In one aspect, an apparatus is provided, including at least one pair of subfilters, each having symmetric coefficients, and a lattice comprising two adders and feedlines corresponding to each of the at least one pair of subfilters, each having symmetric coefficients. In one aspect, the apparatus is a polyphase finite impulse response (FIR) digital filter, including an interpolator and a decimator, where each of the interpolator and the decimator have at least one pair of subfilters, each having symmetric coefficients, and a lattice comprising two adders and feedlines corresponding to each of the at least one pair of subfilters, each having symmetric coefficients.

2 citations

Dissertation
01 Jan 2010
TL;DR: In this paper, a second-order cone programming (SOCP) optimization approach is proposed for the design of M th-band filters, which is more appropriate for the 2-D M thband filter design than the SOCP approach because of its efficient and simple optimization structure.
Abstract: Cone programming (CP) is a class of convex optimization technique, in which a linear objective function is minimized over the intersection of a set of affine constraints. Such constraints could be linear or convex, equalities or inequalities. Owing to its powerful optimization capability as well as flexibility in accommodating various constraints, the cone programming finds wide applications in digital filter design. In this thesis, fundamentals of linear-phase M th-band FIR filters are first introduced, which include the time-domain interpolation condition and the desired frequency specifications. The restriction of the interpolation matrix M for linear-phase two-dimensional (2-D) M th-band filters is also discussed by considering both the interpolation condition and the symmetry of the impulse response of the 2-D filter. Based on the analysis of the M th-band properties, a semidefinite programming (SOP) optimization approach is developed to design linear-phase 1-0 and 2-D M th-band filters. The 2-D SOP optimization design problem is modeled based on both the mini-max and the least-square error criteria. In contrast to the 1-D based design, the 2-D direct SDP design can offer an optimal equiripple result. A second-order cone programming (SOCP) optimization approach is then presented as an alternative for the design of M th-band filters. The performances as well as the design complexity of these two design approaches are justified through numerical design examples. Simulation results show that the performance of the SOCP approach is better than that of the SDP approach for 1-D M th-band filter design due to its reduced computational complexity for the worst-case, whereas the SDP approach is more appropriate for the 2-D M th-band filter design than the SOCP approach because of its efficient and simple optimization structure. Moreover, the designed M th-band filters are proved useful in image interpolation according to both the visual quality and the peak signal-to-noise ratio (PSNR) for the images with different levels of details.

1 citations