4,696 research outputs found
Simultaneous generation for zeta values by the Markov-WZ method
By application of the Markov-WZ method, we prove a more general form of a
bivariate generating function identity containing, as particular cases,
Koecher's and Almkvist-Granville's Ap\'ery-like formulae for odd zeta values.
As a consequence, we get a new identity producing Ap\'ery-like series for all
convergent at the geometric rate with ratio
Comment: 7 page
A Universal Scheme for WynerâZiv Coding of Discrete Sources
We consider the WynerâZiv (WZ) problem of lossy compression where the decompressor observes a noisy version of the source, whose statistics are unknown. A new family of WZ coding algorithms is proposed and their universal optimality is proven. Compression consists of sliding-window processing followed by LempelâZiv (LZ) compression, while the decompressor is based on a modification of the discrete universal denoiser (DUDE) algorithm to take advantage of side information. The new algorithms not only universally attain the fundamental limits, but also suggest a paradigm for practical WZ coding. The effectiveness of our approach is illustrated with experiments on binary images, and English text using a low complexity algorithm motivated by our class of universally optimal WZ codes
Stability of Noisy Metropolis-Hastings
Pseudo-marginal Markov chain Monte Carlo methods for sampling from
intractable distributions have gained recent interest and have been
theoretically studied in considerable depth. Their main appeal is that they are
exact, in the sense that they target marginally the correct invariant
distribution. However, the pseudo-marginal Markov chain can exhibit poor mixing
and slow convergence towards its target. As an alternative, a subtly different
Markov chain can be simulated, where better mixing is possible but the
exactness property is sacrificed. This is the noisy algorithm, initially
conceptualised as Monte Carlo within Metropolis (MCWM), which has also been
studied but to a lesser extent. The present article provides a further
characterisation of the noisy algorithm, with a focus on fundamental stability
properties like positive recurrence and geometric ergodicity. Sufficient
conditions for inheriting geometric ergodicity from a standard
Metropolis-Hastings chain are given, as well as convergence of the invariant
distribution towards the true target distribution
Secure Multiplex Coding with Dependent and Non-Uniform Multiple Messages
The secure multiplex coding (SMC) is a technique to remove rate loss in the
coding for wire-tap channels and broadcast channels with confidential messages
caused by the inclusion of random bits into transmitted signals. SMC replaces
the random bits by other meaningful secret messages, and a collection of secret
messages serves as the random bits to hide the rest of messages. In the
previous researches, multiple secret messages were assumed to have independent
and uniform distributions, which is difficult to be ensured in practice. We
remove this restrictive assumption by a generalization of the channel
resolvability technique.
We also give practical construction techniques for SMC by using an arbitrary
given error-correcting code as an ingredient, and channel-universal coding of
SMC. By using the same principle as the channel-universal SMC, we give coding
for the broadcast channel with confidential messages universal to both channel
and source distributions.Comment: We made several changes to improve the presentatio
Side-information Scalable Source Coding
The problem of side-information scalable (SI-scalable) source coding is
considered in this work, where the encoder constructs a progressive
description, such that the receiver with high quality side information will be
able to truncate the bitstream and reconstruct in the rate distortion sense,
while the receiver with low quality side information will have to receive
further data in order to decode. We provide inner and outer bounds for general
discrete memoryless sources. The achievable region is shown to be tight for the
case that either of the decoders requires a lossless reconstruction, as well as
the case with degraded deterministic distortion measures. Furthermore we show
that the gap between the achievable region and the outer bounds can be bounded
by a constant when square error distortion measure is used. The notion of
perfectly scalable coding is introduced as both the stages operate on the
Wyner-Ziv bound, and necessary and sufficient conditions are given for sources
satisfying a mild support condition. Using SI-scalable coding and successive
refinement Wyner-Ziv coding as basic building blocks, a complete
characterization is provided for the important quadratic Gaussian source with
multiple jointly Gaussian side-informations, where the side information quality
does not have to be monotonic along the scalable coding order. Partial result
is provided for the doubly symmetric binary source with Hamming distortion when
the worse side information is a constant, for which one of the outer bound is
strictly tighter than the other one.Comment: 35 pages, submitted to IEEE Transaction on Information Theor
Extended master equation models for molecular communication networks
We consider molecular communication networks consisting of transmitters and
receivers distributed in a fluidic medium. In such networks, a transmitter
sends one or more signalling molecules, which are diffused over the medium, to
the receiver to realise the communication. In order to be able to engineer
synthetic molecular communication networks, mathematical models for these
networks are required. This paper proposes a new stochastic model for molecular
communication networks called reaction-diffusion master equation with exogenous
input (RDMEX). The key idea behind RDMEX is to model the transmitters as time
series of signalling molecule counts, while diffusion in the medium and
chemical reactions at the receivers are modelled as Markov processes using
master equation. An advantage of RDMEX is that it can readily be used to model
molecular communication networks with multiple transmitters and receivers. For
the case where the reaction kinetics at the receivers is linear, we show how
RDMEX can be used to determine the mean and covariance of the receiver output
signals, and derive closed-form expressions for the mean receiver output signal
of the RDMEX model. These closed-form expressions reveal that the output signal
of a receiver can be affected by the presence of other receivers. Numerical
examples are provided to demonstrate the properties of the model.Comment: IEEE Transactions on Nanobioscience, 201
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