3,049 research outputs found
Lattice structures for optimal design and robust implementation of two-channel perfect-reconstruction QMF banks
A lattice structure and an algorithm are presented for the design of two-channel QMF (quadrature mirror filter) banks, satisfying a sufficient condition for perfect reconstruction. The structure inherently has the perfect-reconstruction property, while the algorithm ensures a good stopband attenuation for each of the analysis filters. Implementations of such lattice structures are robust in the sense that the perfect-reconstruction property is preserved in spite of coefficient quantization. The lattice structure has the hierarchical property that a higher order perfect-reconstruction QMF bank can be obtained from a lower order perfect-reconstruction QMF bank, simply by adding more lattice sections. Several numerical examples are provided in the form of design tables
A joint time-invariant filtering approach to the linear Gaussian relay problem
In this paper, the linear Gaussian relay problem is considered. Under the
linear time-invariant (LTI) model the problem is formulated in the frequency
domain based on the Toeplitz distribution theorem. Under the further assumption
of realizable input spectra, the LTI Gaussian relay problem is converted to a
joint design problem of source and relay filters under two power constraints,
one at the source and the other at the relay, and a practical solution to this
problem is proposed based on the projected subgradient method. Numerical
results show that the proposed method yields a noticeable gain over the
instantaneous amplify-and-forward (AF) scheme in inter-symbol interference
(ISI) channels. Also, the optimality of the AF scheme within the class of
one-tap relay filters is established in flat-fading channels.Comment: 30 pages, 10 figure
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