139 research outputs found
On feedback in network source coding
We consider source coding over networks with
unlimited feedback from the sinks to the sources. We first show
examples of networks where the rate region with feedback is
a strict superset of that without feedback. Next, we find an
achievable region for multiterminal lossy source coding with
feedback. Finally, we evaluate this region for the case when one
of the sources is fully known at the decoder and use the result
to show that this region is a strict superset of the best known
achievable region for the problem without feedback
Alphabet Sizes of Auxiliary Variables in Canonical Inner Bounds
Alphabet size of auxiliary random variables in our canonical description is
derived. Our analysis improves upon estimates known in special cases, and
generalizes to an arbitrary multiterminal setup. The salient steps include
decomposition of constituent rate polytopes into orthants, translation of a
hyperplane till it becomes tangent to the achievable region at an extreme
point, and derivation of minimum auxiliary alphabet sizes based on
Caratheodory's theorem.Comment: 20 pages, no figures, explanation of a part of impending IEEE IT
submissio
On networks with side information
In this paper, we generalize the lossless coded side
information problem from the three-node network of Ahlswede
and K¨orner to more general network scenarios. We derive
inner and outer bounds on the achievable rate region in the
general network scenario and show that they are tight for some
families of networks. Our approach demonstrates how solutions
to canonical source coding problems can be used to derive bounds
for more complex networks and reveals an interesting connection
between networks with side information, successive refinement,
and network coding
The Three-Terminal Interactive Lossy Source Coding Problem
The three-node multiterminal lossy source coding problem is investigated. We
derive an inner bound to the general rate-distortion region of this problem
which is a natural extension of the seminal work by Kaspi'85 on the interactive
two-terminal source coding problem. It is shown that this (rather involved)
inner bound contains several rate-distortion regions of some relevant source
coding settings. In this way, besides the non-trivial extension of the
interactive two terminal problem, our results can be seen as a generalization
and hence unification of several previous works in the field. Specializing to
particular cases we obtain novel rate-distortion regions for several lossy
source coding problems. We finish by describing some of the open problems and
challenges. However, the general three-node multiterminal lossy source coding
problem seems to offer a formidable mathematical complexity.Comment: New version with changes suggested by reviewers.Revised and
resubmitted to IEEE Transactions on Information Theory. 92 pages, 11 figures,
1 tabl
Multiple Description Quantization via Gram-Schmidt Orthogonalization
The multiple description (MD) problem has received considerable attention as
a model of information transmission over unreliable channels. A general
framework for designing efficient multiple description quantization schemes is
proposed in this paper. We provide a systematic treatment of the El Gamal-Cover
(EGC) achievable MD rate-distortion region, and show that any point in the EGC
region can be achieved via a successive quantization scheme along with
quantization splitting. For the quadratic Gaussian case, the proposed scheme
has an intrinsic connection with the Gram-Schmidt orthogonalization, which
implies that the whole Gaussian MD rate-distortion region is achievable with a
sequential dithered lattice-based quantization scheme as the dimension of the
(optimal) lattice quantizers becomes large. Moreover, this scheme is shown to
be universal for all i.i.d. smooth sources with performance no worse than that
for an i.i.d. Gaussian source with the same variance and asymptotically optimal
at high resolution. A class of low-complexity MD scalar quantizers in the
proposed general framework also is constructed and is illustrated
geometrically; the performance is analyzed in the high resolution regime, which
exhibits a noticeable improvement over the existing MD scalar quantization
schemes.Comment: 48 pages; submitted to IEEE Transactions on Information Theor
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