512 research outputs found
Outer Bounds on the Admissible Source Region for Broadcast Channels with Correlated Sources
Two outer bounds on the admissible source region for broadcast channels with
correlated sources are presented: the first one is strictly tighter than the
existing outer bound by Gohari and Anantharam while the second one provides a
complete characterization of the admissible source region in the case where the
two sources are conditionally independent given the common part. These outer
bounds are deduced from the general necessary conditions established for the
lossy source broadcast problem via suitable comparisons between the virtual
broadcast channel (induced by the source and the reconstructions) and the
physical broadcast channel
Secure Multiterminal Source Coding with Side Information at the Eavesdropper
The problem of secure multiterminal source coding with side information at
the eavesdropper is investigated. This scenario consists of a main encoder
(referred to as Alice) that wishes to compress a single source but
simultaneously satisfying the desired requirements on the distortion level at a
legitimate receiver (referred to as Bob) and the equivocation rate --average
uncertainty-- at an eavesdropper (referred to as Eve). It is further assumed
the presence of a (public) rate-limited link between Alice and Bob. In this
setting, Eve perfectly observes the information bits sent by Alice to Bob and
has also access to a correlated source which can be used as side information. A
second encoder (referred to as Charlie) helps Bob in estimating Alice's source
by sending a compressed version of its own correlated observation via a
(private) rate-limited link, which is only observed by Bob. For instance, the
problem at hands can be seen as the unification between the Berger-Tung and the
secure source coding setups. Inner and outer bounds on the so called
rates-distortion-equivocation region are derived. The inner region turns to be
tight for two cases: (i) uncoded side information at Bob and (ii) lossless
reconstruction of both sources at Bob --secure distributed lossless
compression. Application examples to secure lossy source coding of Gaussian and
binary sources in the presence of Gaussian and binary/ternary (resp.) side
informations are also considered. Optimal coding schemes are characterized for
some cases of interest where the statistical differences between the side
information at the decoders and the presence of a non-zero distortion at Bob
can be fully exploited to guarantee secrecy.Comment: 26 pages, 16 figures, 2 table
Simulation of a Channel with Another Channel
In this paper, we study the problem of simulating a DMC channel from another
DMC channel under an average-case and an exact model. We present several
achievability and infeasibility results, with tight characterizations in
special cases. In particular for the exact model, we fully characterize when a
BSC channel can be simulated from a BEC channel when there is no shared
randomness. We also provide infeasibility and achievability results for
simulation of a binary channel from another binary channel in the case of no
shared randomness. To do this, we use properties of R\'enyi capacity of a given
order. We also introduce a notion of "channel diameter" which is shown to be
additive and satisfy a data processing inequality.Comment: 31 pages, 10 figures, and some parts of this work were published at
ITW 201
On Joint Source-Channel Coding for Correlated Sources Over Multiple-Access Relay Channels
We study the transmission of correlated sources over discrete memoryless (DM)
multiple-access-relay channels (MARCs), in which both the relay and the
destination have access to side information arbitrarily correlated with the
sources. As the optimal transmission scheme is an open problem, in this work we
propose a new joint source-channel coding scheme based on a novel combination
of the correlation preserving mapping (CPM) technique with Slepian-Wolf (SW)
source coding, and obtain the corresponding sufficient conditions. The proposed
coding scheme is based on the decode-and-forward strategy, and utilizes CPM for
encoding information simultaneously to the relay and the destination, whereas
the cooperation information from the relay is encoded via SW source coding. It
is shown that there are cases in which the new scheme strictly outperforms the
schemes available in the literature. This is the first instance of a
source-channel code that uses CPM for encoding information to two different
nodes (relay and destination). In addition to sufficient conditions, we present
three different sets of single-letter necessary conditions for reliable
transmission of correlated sources over DM MARCs. The newly derived conditions
are shown to be at least as tight as the previously known necessary conditions.Comment: Accepted to TI
Broadcast Channels with Cooperating Decoders
We consider the problem of communicating over the general discrete memoryless
broadcast channel (BC) with partially cooperating receivers. In our setup,
receivers are able to exchange messages over noiseless conference links of
finite capacities, prior to decoding the messages sent from the transmitter. In
this paper we formulate the general problem of broadcast with cooperation. We
first find the capacity region for the case where the BC is physically
degraded. Then, we give achievability results for the general broadcast
channel, for both the two independent messages case and the single common
message case.Comment: Final version, to appear in the IEEE Transactions on Information
Theory -- contains (very) minor changes based on the last round of review
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