34 research outputs found
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
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