133 research outputs found
Myths and Realities of Rateless Coding
Fixed-rate and rateless channel codes are generally treated separately in the related research literature and so, a novice in the field inevitably gets the impression that these channel codes are unrelated. By contrast, in this treatise, we endeavor to further develop a link between the traditional fixed-rate codes and the recently developed rateless codes by delving into their underlying attributes. This joint treatment is beneficial for two principal reasons. First, it facilitates the task of researchers and practitioners, who might be familiar with fixed-rate codes and would like to jump-start their understanding of the recently developed concepts in the rateless reality. Second, it provides grounds for extending the use of the well-understood code design tools — originally contrived for fixed-rate codes — to the realm of rateless codes. Indeed, these versatile tools proved to be vital in the design of diverse fixed-rate-coded communications systems, and thus our hope is that they will further elucidate the associated performance ramifications of the rateless coded schemes
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
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