6 research outputs found
Lossy Source Coding with Reconstruction Privacy
We consider the problem of lossy source coding with side information under a
privacy constraint that the reconstruction sequence at a decoder should be kept
secret to a certain extent from another terminal such as an eavesdropper, a
sender, or a helper. We are interested in how the reconstruction privacy
constraint at a particular terminal affects the rate-distortion tradeoff. In
this work, we allow the decoder to use a random mapping, and give inner and
outer bounds to the rate-distortion-equivocation region for different cases
where the side information is available non-causally and causally at the
decoder. In the special case where each reconstruction symbol depends only on
the source description and current side information symbol, the complete
rate-distortion-equivocation region is provided. A binary example illustrating
a new tradeoff due to the new privacy constraint, and a gain from the use of a
stochastic decoder is given.Comment: 22 pages, added proofs, to be presented at ISIT 201
Heegard-Berger and Cascade Source Coding Problems with Common Reconstruction Constraints
For the HB problem with the CR constraint, the rate-distortion function is
derived under the assumption that the side information sequences are
(stochastically) degraded. The rate-distortion function is also calculated
explicitly for three examples, namely Gaussian source and side information with
quadratic distortion metric, and binary source and side information with
erasure and Hamming distortion metrics. The rate-distortion function is then
characterized for the HB problem with cooperating decoders and (physically)
degraded side information. For the cascade problem with the CR constraint, the
rate-distortion region is obtained under the assumption that side information
at the final node is physically degraded with respect to that at the
intermediate node. For the latter two cases, it is worth emphasizing that the
corresponding problem without the CR constraint is still open. Outer and inner
bounds on the rate-distortion region are also obtained for the cascade problem
under the assumption that the side information at the intermediate node is
physically degraded with respect to that at the final node. For the three
examples mentioned above, the bounds are shown to coincide. Finally, for the HB
problem, the rate-distortion function is obtained under the more general
requirement of constrained reconstruction, whereby the decoder's estimate must
be recovered at the encoder only within some distortion.Comment: to appear in IEEE Trans. Inform. Theor
Adaptive data acquisition for communication networks
In an increasing number of communication systems, such as sensor networks or local area networks within medical, financial or military institutions, nodes communicate information sources (e.g., video, audio) over multiple hops. Moreover, nodes have, or can acquire, correlated information sources from the environment, e.g., from data bases or from measurements. Among the new design problems raised by the outlined scenarios, two key issues are addressed in this dissertation: 1) How to preserve the consistency of sensitive information across multiple hops; 2) How to incorporate the design of actuation in the form of data acquisition and network probing in the optimization of the communication network. These aspects are investigated by using information-theoretic (source and channel coding) models, obtaining fundamental insights that have been corroborated by various illustrative examples. To address point 1), the problem of cascade source coding with side information is investigated. The motivating observation is that, in this class of problems, the estimate of the source obtained at the decoder cannot be generally reproduced at the encoder if it depends directly on the side information. In some applications, such as the one mentioned above, this lack of consistency may be undesirable, and a so called Common Reconstruction (CR) requirement, whereby one imposes that the encoder be able to agree on the decoder’s estimate, may be instead in order. The rate-distortion region is here derived for some special cases of the cascade source coding problem and of the related Heegard-Berger (HB) problem under the CR constraint. As for point 2), the work is motivated by the fact that, in order to enable, or to facilitate, the exchange of information, nodes of a communication network routinely take various types of actions, such as data acquisition or network probing. For instance, sensor nodes schedule the operation of their sensing devices to measure given physical quantities of interest, and wireless nodes probe the state of the channel via training. The problem of optimal data acquisition is studied for a cascade source coding problem, a distributed source coding problem and a two-way source coding problem assuming that the side information sequences can be controlled via the selection of cost-constrained actions. It is shown that a joint design of the description of the source and of the control signals used to guide the selection of the actions at downstream nodes is generally necessary for an efficient use of the available communication links. Instead, the problem of optimal channel probing is studied for a broadcast channel and a point-to-point link in which the decoder is interested in estimating not only the message, but also the state sequence. Finally, the problem of embedding information on the actions is studied for both the source and the channel coding set-ups described above
2011 IEEE International Symposium on Information Theory Proceedings Constrained Wyner-Ziv Coding
Abstract—We consider a variation on the Wyner-Ziv source coding problem with side-information at the decoder where the encoder is required to be able to compute the decoder’s reconstruction sequence with some fidelity. This requirement limits the extent to which the reconstruction sequence can depend on the side-information, which is not available to the encoder. For finite-alphabet memoryless sources and single-letter distortion measures we compute the minimal description rate as a function of the joint law of the source and side-information and of the allowed distortions at the encoder and decoder. We also treat memoryless Gaussian sources with mean squared-error distortion measures. I. PROBLEM STATEMENT Inspired by Steinberg [1], we study a variation on the Wyner-Ziv source coding problem [2]. What makes our proble