It has been considered impossible to demodulate a fast frequency-hopping (FFH) spread-spectrum signal coherently in a frequency selective fading channel as a result of difficulties with making the receiver local oscillator track the phase of a received signal that lacks phase continuity. This paper
A Fast Algorithm for Adapted Time–Frequency Tilings
✍ Scribed by Christoph M. Thiele; Lars F. Villemoes
- Publisher
- Elsevier Science
- Year
- 1996
- Tongue
- English
- Weight
- 221 KB
- Volume
- 3
- Category
- Article
- ISSN
- 1063-5203
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✦ Synopsis
We first consider orthonormal bases of R N consisting of discretized rescaled Walsh functions, where N is a power of two. Given a vector, the best basis with respect to an additive cost function is found with an algorithm of order O(N log N). The algorithm operates in the time-frequency plane by constructing a tiling of minimal cost among all possible tilings with dyadic rectangles of area one. Then we discuss generalizations replacing the Walsh group, which controls the structure of the time-frequency plane, by other finite abelian groups. The main example here involves the Fast Fourier Transform.
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