2,736 research outputs found
An Efficient Joint Source-Channel Decoder with Dynamical Block Priors
An efficient joint source-channel (s/c) decoder based on the side information
of the source and on the MN-Gallager algorithm over Galois fields is presented.
The dynamical block priors (DBP) are derived either from a statistical
mechanical approach via calculation of the entropy for the correlated
sequences, or from the Markovian transition matrix. The Markovian joint s/c
decoder has many advantages over the statistical mechanical approach. In
particular, there is no need for the construction and the diagonalization of a
qXq matrix and for a solution to saddle point equations in q dimensions. Using
parametric estimation, an efficient joint s/c decoder with the lack of side
information is discussed. Besides the variant joint s/c decoders presented, we
also show that the available sets of autocorrelations consist of a convex
volume, and its structure can be found using the Simplex algorithm.Comment: 13 pages, to appear in "Progress in Theoretical Physics Supplement",
May 200
Finite-Block-Length Analysis in Classical and Quantum Information Theory
Coding technology is used in several information processing tasks. In
particular, when noise during transmission disturbs communications, coding
technology is employed to protect the information. However, there are two types
of coding technology: coding in classical information theory and coding in
quantum information theory. Although the physical media used to transmit
information ultimately obey quantum mechanics, we need to choose the type of
coding depending on the kind of information device, classical or quantum, that
is being used. In both branches of information theory, there are many elegant
theoretical results under the ideal assumption that an infinitely large system
is available. In a realistic situation, we need to account for finite size
effects. The present paper reviews finite size effects in classical and quantum
information theory with respect to various topics, including applied aspects
Tight Upper and Lower Bounds to the Information Rate of the Phase Noise Channel
Numerical upper and lower bounds to the information rate transferred through
the additive white Gaussian noise channel affected by discrete-time
multiplicative autoregressive moving-average (ARMA) phase noise are proposed in
the paper. The state space of the ARMA model being multidimensional, the
problem cannot be approached by the conventional trellis-based methods that
assume a first-order model for phase noise and quantization of the phase space,
because the number of state of the trellis would be enormous. The proposed
lower and upper bounds are based on particle filtering and Kalman filtering.
Simulation results show that the upper and lower bounds are so close to each
other that we can claim of having numerically computed the actual information
rate of the multiplicative ARMA phase noise channel, at least in the cases
studied in the paper. Moreover, the lower bound, which is virtually
capacity-achieving, is obtained by demodulation of the incoming signal based on
a Kalman filter aided by past data. Thus we can claim of having found the
virtually optimal demodulator for the multiplicative phase noise channel, at
least for the cases considered in the paper.Comment: 5 pages, 2 figures. Accepted for presentation at ISIT 201
The age of information in gossip networks
We introduce models of gossip based communication networks in which each node
is simultaneously a sensor, a relay and a user of information. We model the
status of ages of information between nodes as a discrete time Markov chain. In
this setting a gossip transmission policy is a decision made at each node
regarding what type of information to relay at any given time (if any). When
transmission policies are based on random decisions, we are able to analyze the
age of information in certain illustrative structured examples either by means
of an explicit analysis, an algorithm or asymptotic approximations. Our key
contribution is presenting this class of models.Comment: 15 pages, 8 figure
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