Improved Markov models for terrestrial free‐space optical links

Improved Markov Models for Terrestrial Free-Space Optical Links

Finite-state Markov chains are a useful tool for modelling communication channels with correlated fading and have recently also been applied with success to terrestrial free-space optical (FSO) communication channels. However, the issue of how such Markov models should be optimized in order to accurately approximate the original continuous fading channel has not been addressed in a systematic m...

Improved Hidden Markov Models for Speech Recognition

The basic hidden Markov model used in most statistical approaches to speech recognition needs to be considerably expanded and modified in order to become fully efficient. The purpose of this paper is to describe some of these improvements brought to the original scheme. First, good starting values are needed for the training procedure by which the model parameters are adjusted to their optimal ...

Improved estimators for constrained Markov chain models

Links Between Markov Models and Multilayer Perceptrons

Hidden Markov models are widely used for automatic speech recognition. They inherently incorporate the sequential character of the speech signal and are statistically trained. However, the a-priori choice of the model topology limits their flexibility. Another drawback of these models is their weak discriminating power. Multilayer perceptrons are now promising tools in the connectionist approac...

Atmospheric Channel Effects on Terrestrial Free Space Optical Communication Links

This paper illustrates the challenges imposed by the atmospheric channel on the design of a terrestrial laser communication link. The power loss due to scattering effect is described using the Kim/Kruse scattering model while the effect and the penalty imposed by atmospheric turbulence is highlighted by considering the bit error rate (BER) of an OnOff Keying modulated link in an optical Poisson...