Ha Q. Nguyen

  1. Frame Permutation Quantization.

    Authors: Vivek K Goyal, Ha Q. Nguyen, Lav R. Varshney
    Subjects: Information Theory
    Abstract

    Frame permutation quantization (FPQ) is a new vector quantization technique
    using finite frames. In FPQ, a vector is encoded using a permutation source
    code to quantize its frame expansion. This means that the encoding is a partial
    ordering of the frame expansion coefficients. Compared to ordinary permutation
    source coding, FPQ produces a greater number of possible quantization rates and
    a higher maximum rate. Various representations for the partitions induced by
    FPQ are presented and reconstruction algorithms based on linear programming and
    quadratic programming are derived.

  2. Concentric Permutation Source Codes.

    Authors: Vivek K Goyal, Ha Q. Nguyen, Lav R. Varshney
    Subjects: Information Theory
    Abstract

    Permutation codes are a class of structured vector quantizers with a
    computationally-simple encoding procedure. Here we provide an extension that
    preserves the computational simplicity but yields improved operational
    rate--distortion performance. The new class of vector quantizers has a codebook
    comprising several permutation codes as subcodes. Methods for designing good
    code parameters are given. One method depends on optimizing the rate allocation
    in a shape--gain vector quantizer with gain-dependent wrapped spherical shape
    codebook.

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