Title

A Unified Formulation of Gaussian Versus Sparse Stochastic Processes-Part I: Continuous-Domain Theory

Authors

Authors

M. Unser; P. D. Tafti;Q. Y. Sun

Comments

Authors: contact us about adding a copy of your work at STARS@ucf.edu

Abbreviated Journal Title

IEEE Trans. Inf. Theory

Keywords

Sparsity; non-Gaussian stochastic processes; innovation modeling; continuous-time signals; stochastic differential equations; wavelet; expansion; Levy process; infinite divisibility; LINEAR INVERSE PROBLEMS; THRESHOLDING ALGORITHM; SIGNALS; TRANSFORM; ANALOG; Computer Science, Information Systems; Engineering, Electrical &; Electronic

Abstract

We introduce a general distributional framework that results in a unifying description and characterization of a rich variety of continuous-time stochastic processes. The cornerstone of our approach is an innovation model that is driven by some generalized white noise process, which may be Gaussian or not (e.g., Laplace, impulsive Poisson, or alpha stable). This allows for a conceptual decoupling between the correlation properties of the process, which are imposed by the whitening operator L, and its sparsity pattern, which is determined by the type of noise excitation. The latter is fully specified by a Levy measure. We show that the range of admissible innovation behavior varies between the purely Gaussian and super-sparse extremes. We prove that the corresponding generalized stochastic processes are well-defined mathematically provided that the (adjoint) inverse of the whitening operator satisfies some L p bound for p >= 1. We present a novel operator-based method that yields an explicit characterization of all Levy-driven processes that are solutions of constant-coefficient stochastic differential equations. When the underlying system is stable, we recover the family of stationary continuous-time autoregressive moving average processes (CARMA), including the Gaussian ones. The approach remains valid when the system is unstable and leads to the identification of potentially useful generalizations of the Levy processes, which are sparse and non-stationary. Finally, we show that these processes admit a sparse representation in some matched wavelet domain and provide a full characterization of their transform-domain statistics.

Journal Title

Ieee Transactions on Information Theory

Volume

60

Issue/Number

3

Publication Date

1-1-2014

Document Type

Article

Language

English

First Page

1945

Last Page

1962

WOS Identifier

WOS:000331902400042

ISSN

0018-9448

Share

COinS