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The following topics were dealt with: properties of codes; feedback and cooperation in networks; channel coding, communication techniques and estimation methods; construction, analysis and decoding of LDPC codes; sequences and permutations; universal lossless compression; capacity and coding for fading channels; network theory; statistical mechanics; turbo and turbo-like code constructions; communication...
We introduce a new problem of broadcast source coding with a discrimination requirement - there is an eavesdropping user from whom we wish to withhold the true message in an entropic sense. Binning can achieve the Slepian-Wolf rate, but at the cost of full information leakage to the eavesdropper. Our main result is a lower bound that implies that any entropically efficient broadcast scheme must be...
Consider a directed graph, in which vertices represent sensor nodes, and edges represent a discrete memoryless channel of a given capacity over which two neighbors nodes can communicate. The channels are independent. Each node gets to observe one element of a set of discrete sources of information drawn i.i.d., according to some joint probability distribution. Our goal is to solve an incast problem...
This paper addresses near-capacity dirty-paper code designs based on TCQ and IRA codes, where the former is employed as the most efficient means of vector quantization and the latter for their capacity-approaching performance. By bringing together TCQ - the best quantizer from the source coding community and EXIT chart based IRA code designs - the best from the channel coding community, we are able...
In Bell Syst. Tech. J., 1948, Shannon wrote: "The semantic aspects of communication are irrelevant to the engineering problem." Indeed Shannon demonstrated that the information that is generated by a source depends only on the statistics of the source, and not on the meaning of the source output. By contrast with this we investigate here whether in a compaction system the codewords can be...
Vector quantization of the BCJR and Viterbi algorithms' state metrics for detection of finite-state channels is considered. An estimate is given for the gain associated with vector quantization, over conventional implementations. This is expressed using the volume of the recurrent region, and the maximum state metric difference, which are both intrinsic properties of the channel detector. One application...
This paper presents both an information lossless coding scheme and a method to evaluate constrained capacity for channels with memory and unknown state. The fundamental idea is to decompose the original channel into a bank of memoryless sub-channels with partially known states, then successively decode these sub-channels. The receiver of each sub-channel consists of an optimal estimator followed by...
It is known that every solvable multicast network has a scalar linear solution over a sufficiently large finite field alphabet. It is also known that this result does not generalize to arbitrary networks. There are several examples in the literature of solvable networks with no scalar linear solution over any finite field. However, each example has a linear solution for some vector dimension greater...
The concatenation of nearly-MDS expander codes of Roth and Skachek, "On Nearly-MDS Expander Codes," Proc. IEEE ISIT'04, with 'typical' LDPC codes is investigated. It is shown that for the rates R = (1 - epsi)C (C is the capacity of the binary symmetric channel (BSC)), under certain condition on the parameters of LDPC codes, these concatenated codes have decoding time linear in their length...
This paper presents a new method for designing noisy channel scalar quantizers, which is fast, more robust to initial conditions, and more amenable to a variety of distortion criteria
In this paper, we present a novel class of simple soft-input soft-output (SISO) detection algorithms for transmission over phase-uncertain channels. In order to limit the complexity, the set of possible phase values (i.e., the interval [0,2pi)) is properly quantized. We then use a forward-backward (FB) algorithm in correspondence to each quantized phase value. The forward and backward metrics computed...
This paper derives an iterative receiver for noncoherent fading channels that exhibit block fading with correlation between blocks. Pilot symbols and Kalman smoothing are used in conjunction with sum-product decoding of LDPC codes to implement an iterative channel estimation and decoding structure. Density evolution is employed to analyze the performance of such a structure and to optimize the degree...
A multi-access problem is considered where two encoders wish to communicate their messages to two decoders. The encoders can further cooperate via a conference, as introduced by Willems for multi-access channels. The capacity region of this channel is shown to be the intersection of the capacity regions of two multi-access channels with partially cooperating encoders
Diversity-embedded codes for fading channels are high-rate codes that are designed so that they have a high-diversity code embedded within them. This allows a form of communication where the high-rate code opportunistically takes advantage of good channel realizations whereas the embedded high-diversity code ensures that at least part of the information is received reliably. This can also be thought...
This paper presents a new coding scheme with capacity approaching performance for correlated fading channels with unknown state. The transceiver employs a deep interleaver to decompose the original channel into a bank of independent fading sub-channels. Sub-channels are successively decoded and decisions are fed back as new training symbols. The unknown state of each sub-channel can be estimated from...
Binary sequences where successive ones are separated by at most k consecutive zeros, are said to be k-constrained. We introduce a new fixed-rate algorithm for efficiently encoding and decoding k-constrained sequences. Our approach is based on bit stuffing proposed by Bender and Wolf. Bit stuffing is a simple algorithm that can produce near-optimal codes for a wide range of constraints. While bit stuffing...
In this paper, we present an analytical method to compute the performance of product codes on channels with memory. A channel with memory introduces correlated error bursts, and hence, it is described as hidden Markov models. A hard-decision distance-bounded decoder for product code is assumed. Such an analysis is relevant for evaluating the performance of product-code-based error-correcting scheme...
The cutoff rate R0(W) of a discrete memoryless channel (DMC) W is often used as a figure of merit, alongside the channel capacity C(W). Given a channel W consisting of two possibly correlated subchannels W1, W2, the capacity function always satisfies C(W1) + C(W2) les C(W), while there are examples for which R0(W1) + R0(W 2) > R0(W). This fact that the cutoff rate can be "created" by...
In this paper we present a theoretical analysis of serial concatenation schemes for transmission over AWGN channels employing a geometrically uniform constellation having Zopfm as a generating group. Our schemes possess a uniform error property both with respect to the word and to the symbol. This allows to prove exact convergence results on the probability of error. We then show that, as in the binary...
Asymptotic nonexistence bounds for unequal error protecting codes with two protection levels are considered. We show that the improved estimates, reported by Litsyn on the possible distance distributions for codes, may sometimes yield sharper upper bounds than the previously known ones, for both nonlinear and linear codes having two protection levels
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