9:30, SPTM-P4.1
OPTIMIZED FILTERBANK DESIGN FOR SUBBAND IDENTIFICATION WITH OVERSAMPLING
D. MARELLI, M. FU
In this paper, we study the problem of filterbank design for the subband identification method in the oversampled case. We aim to design the filterbanks such that the coupling between adjacent subbands is minimized. This will allow the subband model of the system to be diagonal, thus simplifying the complexity of identification. Solutions are given to two minimization criteria: the worst-input case and white-input case.

9:30, SPTM-P4.2
PERFECT RECONSTRUCTION INTEGER-MODULATED FILTER BANKS
A. MERTINS, T. KARP
In this paper, we present design methods for perfect reconstruction (PR) integer-modulated filter banks, including biorthogonal (low-delay) filter banks. Both the prototype filter and the modulation sequences are composed of integers, thus allowing efficient hardware implementations. To derive such filter banks, we first extend the PR conditions known for cosine modulation to other, more general, modulation schemes. We present solutions where the PR conditions on the prototype and the modulation are entirely decoupled and where some simple coupling is introduced. The conditions are derived for both even and odd numbers of channels. Design examples are presented for both cases.

9:30, SPTM-P4.3
MINIMUM MEAN SQUARE ERROR NONUNIFROM FIR FILTER BANKS
A. HJØRUNGNES, T. SARAMÄKI
Theory for jointly optimizing FIR nonuniform analysis and synthesis filter banks with arbitrary filter lengths and an arbitrary delay through the filter bank is developed. The FIR subband coder is optimized with respect to the minimum mean square error between the output and the input signals under a bit constraint. The subband quantizers are modeled as additive noise sources. Theoretical comparisons are made against a well-known 5_3 wavelets used in a tree-structure. The proposed filter banks, which are both rate and source dependent, have a better distortion rate performance. Equations for finding jointly optimized analysis and synthesis filter banks under a power constraint are also presented.

9:30, SPTM-P4.4
OPTIMAL PREFILTERS FOR THE MULTIWAVELET FILTER BANKS
K. ATTAKITMONGCOL, D. HARDIN, D. WILKES
This paper proposes a method to obtain optimal 2nd-order approximation preserving prefilters for a given orthogonal unbalanced multiwavelet basis. This procedure uses the prefilter construction introduced by Hardin and Roach. The prefilter optimization scheme exploits the Taylor series expansion of the prefilter combined with the multiwavelet. Using the DGHM multiwavelet with the obtained optimal prefilter, we find that quadratic input signals are annihilated by the high-pass portion of filter bank at the first level of decomposition.

9:30, SPTM-P4.5
AN EFFICIENT APPROACH FOR DESIGNING NEARLY PERFECT-RECONSTRUCTION COSINE-MODULATED AND MODIFIED DFT FILTER BANKS
T. SARAMÄKI, R. BREGOVIC
Efficient two-step algorithms are described for optimizing the stopband response of the prototype filter for cosine-modulated and modified DFT filter banks either in the minimax or in the least-mean-square sense subject to the maximum allowable aliasing and amplitude errors. The first step involves finding a good start-up solution using a simple technique. This solution is improved in the second step by using nonlinear optimization. Several examples are included illustrating the flexibility of the proposed approach for making compromises between the re-quired filter lengths and the aliasing and amplitude errors. These examples show that by allowing very small amplitude and aliasing errors, the stopband performance of the resulting filter bank is significantly improved compared to the corresponding perfect-reconstruction filter bank. Alternatively, the filter orders and, consequently, the overall delay can be significantly reduced to achieve practically the same performance.

9:30, SPTM-P4.6
DESIGN OF COSINE-MODULATED FILTER BANK PROTOTYPE FILTERS USING THE FREQUENCY-RESPONSE MASKING APPROACH
P. DINIZ, L. BARCELLOS, S. NETTO
In this paper, we use the frequency-response masking (FRM) approach to design prototype filters for cosine-modulated filter banks in the nearly-perfect reconstruction case. With such approach, it is possible to design a FRM filter with overall order almost equal to the direct-form FIR design, with only slight changes in the values of the inter-carrier and inter-symbol interferences and the attenuation of the bank filters. The result is an efficient design with reduced number of multipliers for the prototype filter.

9:30, SPTM-P4.7
IMPLEMENTATION OF PARALLEL COSINE AND SINE MODULATED FILTER BANKS FOR EQUALIZED TRANSMULTIPLEXER SYSTEMS
A. VIHOLAINEN, J. ALHAVA, M. RENFORS
Filter bank based transmultiplexer systems have certain advantages compared with existing DFT-based multicarrier systems and they are promising candidates for data transmission in frequency selective channels. We have recently proposed a novel and efficient channel equalization idea to be used with critically decimated perfect reconstruction cosine modulated transmultiplexer systems. The equalizer utilizes parallel cosine and sine modulated filter banks in the receiver end. This paper explores efficient realization structures for the needed parallel filter bank system, which finds applications also in other areas.

9:30, SPTM-P4.8
AN EFFICIENT ALGORITHM FOR FILTER BANK COMPLETION
C. POPEEA, B. DUMITRESCU, B. JORA
This paper presents an algorithm for designing an FIR paraunitary filter bank when one or several filters are given. The algorithm is based on the properties of the balanced state-space representation of the polyphase matrix. We show that this representation may be computed via a single RQ decomposition, thus gaining significant efficience with respect to previous work. Application of the algorithm to signal adapted filter banks is also discussed.

9:30, SPTM-P4.9
DESIGN OF OVERSAMPLED UNIFORM DFT FILTER BANKS WITH DELAY SPECIFICATION USING QUADRATIC OPTIMIZATION
J. DE HAAN, N. GRBIC, I. CLAESSON, S. NORDHOLM
Subband adaptive filters have been proposed to avoid the drawbacks of slow convergence and high computational complexity associated with time domain adaptive filters. Subband processing introduces transmission delays caused by the filter bank and signal degradations due to aliasing effects. One efficient way to reduce the aliasing effects is to allow a higher sample rate than critically needed in the subbands and thus reduce subband signal degradation. We suggest a design method, for uniform DFT filter banks with any oversampling factor, where the total filter bank group delay may be specified, and where the aliasing and magnitude/phase distortions are minimized.