7,565 research outputs found
Euclidean Quantum Mechanics and Universal Nonlinear Filtering
An important problem in applied science is the continuous nonlinear filtering
problem, i.e., the estimation of a Langevin state that is observed indirectly.
In this paper, it is shown that Euclidean quantum mechanics is closely related
to the continuous nonlinear filtering problem. The key is the configuration
space Feynman path integral representation of the fundamental solution of a
Fokker-Planck type of equation termed the Yau Equation of continuous-continuous
filtering. A corollary is the equivalence between nonlinear filtering problem
and a time-varying Schr\"odinger equation.Comment: 19 pages, LaTeX, interdisciplinar
Observability and nonlinear filtering
This paper develops a connection between the asymptotic stability of
nonlinear filters and a notion of observability. We consider a general class of
hidden Markov models in continuous time with compact signal state space, and
call such a model observable if no two initial measures of the signal process
give rise to the same law of the observation process. We demonstrate that
observability implies stability of the filter, i.e., the filtered estimates
become insensitive to the initial measure at large times. For the special case
where the signal is a finite-state Markov process and the observations are of
the white noise type, a complete (necessary and sufficient) characterization of
filter stability is obtained in terms of a slightly weaker detectability
condition. In addition to observability, the role of controllability in filter
stability is explored. Finally, the results are partially extended to
non-compact signal state spaces
Development of Nonlinear Filtering Algorithms of Digital Half-Tone Images
This chapter is devoted to solving the problem of algorithms and structures investigations for Radio
Receiver Devices (RRD) with the aim of the nonlinear filtering of Digital Half-Tone Images (DHTI)
representing the discrete-time and discrete-value random Markovian process with a number of states
greater than two. At that, it is assumed that each value of the DHTI element is represented by the binary
g-bit number, whose bits are transmitted via digital communication links in the presence of Additive
White Gaussian Noise (AWGN). The authors present the qualitative analysis of the optimal DHTI filtering
algorithm. The noise immunity of the optimal radio receiver device for the DHTI filtering with varying
quantization and dimension levels is investigated
Dynamic Models and Nonlinear Filtering of Wave Propagation in Random Fields
In this paper, a general model of wireless channels is established based on
the physics of wave propagation. Then the problems of inverse scattering and
channel prediction are formulated as nonlinear filtering problems. The
solutions to the nonlinear filtering problems are given in the form of dynamic
evolution equations of the estimated quantities. Finally, examples are provided
to illustrate the practical applications of the proposed theory.Comment: 12 pages, 1 figur
Phase Transitions in Nonlinear Filtering
It has been established under very general conditions that the ergodic
properties of Markov processes are inherited by their conditional distributions
given partial information. While the existing theory provides a rather complete
picture of classical filtering models, many infinite-dimensional problems are
outside its scope. Far from being a technical issue, the infinite-dimensional
setting gives rise to surprising phenomena and new questions in filtering
theory. The aim of this paper is to discuss some elementary examples,
conjectures, and general theory that arise in this setting, and to highlight
connections with problems in statistical mechanics and ergodic theory. In
particular, we exhibit a simple example of a uniformly ergodic model in which
ergodicity of the filter undergoes a phase transition, and we develop some
qualitative understanding as to when such phenomena can and cannot occur. We
also discuss closely related problems in the setting of conditional Markov
random fields.Comment: 51 page
The Hitchhiker's Guide to Nonlinear Filtering
Nonlinear filtering is the problem of online estimation of a dynamic hidden
variable from incoming data and has vast applications in different fields,
ranging from engineering, machine learning, economic science and natural
sciences. We start our review of the theory on nonlinear filtering from the
simplest `filtering' task we can think of, namely static Bayesian inference.
From there we continue our journey through discrete-time models, which is
usually encountered in machine learning, and generalize to and further
emphasize continuous-time filtering theory. The idea of changing the
probability measure connects and elucidates several aspects of the theory, such
as the parallels between the discrete- and continuous-time problems and between
different observation models. Furthermore, it gives insight into the
construction of particle filtering algorithms. This tutorial is targeted at
scientists and engineers and should serve as an introduction to the main ideas
of nonlinear filtering, and as a segway to more advanced and specialized
literature.Comment: 64 page
White noise theory of robust nonlinear filtering with correlated state and observation noises
In the direct white noise theory of nonlinear filtering, the state process is still modeled as a Markov process satisfying an Ito stochastic differential equation, while a finitely additive white noise is used to model the observation noise. In the present work, this asymmetry is removed by modeling the state process as the solution of a (stochastic) differential equation with a finitely additive white noise as the input. This makes it possible to introduce correlation between the state and observation noise, and to obtain robust nonlinear filtering equations in the correlated noise cas
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