1,793 research outputs found
Source coding with in-block memory and controllable causal side information
Abstract-The recently proposed set-up of source coding with a side information "vending machine" allows the decoder to select actions in order to control the quality of the side information. The actions can depend on the message received from the encoder and on the previously measured samples of the side information, and are cost constrained. Moreover, the final estimate of the source by the decoder is a function of the encoder's message and depends causally on the side information sequence. Previous work by Permuter and Weissman has characterized the rate-distortioncost function in the special case in which the source and the "vending machine" are memoryless. In this work, motivated by the related channel coding model introduced by Kramer, the ratedistortion-cost function characterization is extended to a model with in-block memory. Various special cases are studied including block-feedforward and side information repeat request models
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
Blahut-Arimoto Algorithm and Code Design for Action-Dependent Source Coding Problems
The source coding problem with action-dependent side information at the
decoder has recently been introduced to model data acquisition in
resource-constrained systems. In this paper, an efficient algorithm for
numerical computation of the rate-distortion-cost function for this problem is
proposed, and a convergence proof is provided. Moreover, a two-stage code
design based on multiplexing is put forth, whereby the first stage encodes the
actions and the second stage is composed of an array of classical Wyner-Ziv
codes, one for each action. Specific coding/decoding strategies are designed
based on LDGM codes and message passing. Through numerical examples, the
proposed code design is shown to achieve performance close to the lower bound
dictated by the rate-distortion-cost function.Comment: Extended version of a paper submitted to ISI
MAC with Action-Dependent State Information at One Encoder
Problems dealing with the ability to take an action that affects the states
of state-dependent communication channels are of timely interest and
importance. Therefore, we extend the study of action-dependent channels, which
until now focused on point-to-point models, to multiple-access channels (MAC).
In this paper, we consider a two-user, state-dependent MAC, in which one of the
encoders, called the informed encoder, is allowed to take an action that
affects the formation of the channel states. Two independent messages are to be
sent through the channel: a common message known to both encoders and a private
message known only to the informed encoder. In addition, the informed encoder
has access to the sequence of channel states in a non-causal manner. Our
framework generalizes previously evaluated settings of state dependent
point-to-point channels with actions and MACs with common messages. We derive a
single letter characterization of the capacity region for this setting. Using
this general result, we obtain and compute the capacity region for the Gaussian
action-dependent MAC. The unique methods used in solving the Gaussian case are
then applied to obtain the capacity of the Gaussian action-dependent
point-to-point channel; a problem was left open until this work. Finally, we
establish some dualities between action-dependent channel coding and source
coding problems. Specifically, we obtain a duality between the considered MAC
setting and the rate distortion model known as "Successive Refinement with
Actions". This is done by developing a set of simple duality principles that
enable us to successfully evaluate the outcome of one problem given the other.Comment: 1. Parts of this paper appeared in the IEEE International Symposium
on Information Theory (ISIT 2012),Cambridge, MA, US, July 2012 and at the
IEEE 27th Convention of Electrical and Electronics Engineers in Israel (IEEEI
2012), Nov. 2012. 2. This work has been supported by the CORNET Consortium
Israel Ministry for Industry and Commerc
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