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The quantization of the output of a binary-input discrete memoryless channel to a smaller number of levels is considered. An algorithm, which finds an optimal quantizer, in the sense of maximizing mutual information between the channel input and quantizer output is given. This result holds for arbitrary channels, in contrast to previous results for(More)
— The reliability-based heuristic search methods for maximum likelihood decoding (MLD) generate test error patterns (or, equivalently, candidate codewords) according to their heuristic values. Test error patterns are stored in lists and its space complexity is crucially large for MLD of long block codes. One of the well-known heuristic search methods for(More)
For the class of mixed channels decomposed into stationary memoryless channels, single-letter characterizations of the ε-capacity have not been known except for restricted classes of channels such as the regular decomposable channel introduced by Winkelbauer. This paper gives single-letter characterizations of ε-capacity for mixed channels(More)
—The problem of finding the optimum output quan-tizer for a given discrete memoryless channel is investigated, where the quantizer output has fewer values than the channel output. While mutual information has received attention as an objective function for optimization, the focus of this paper is use of the random coding exponent, which was originally(More)
SUMMARY We study a modification method for constructing low-density parity-check (LDPC) codes for solid burst erasures. Our proposed modification method is based on a column permutation technique for a parity-check matrix of the original LDPC codes. It can change the burst erasure correction capabilities without degradation in the performance over random(More)
The concatenation of an arbitrary discrete memoryless channel with binary input followed by a quantizer is considered. For a restricted quantizer alphabet size, it is shown that the maximum of the mutual information between the channel input and the quantizer output can be found by dynamic programming. Numerical examples are given to illustrate the results.(More)
A simple four node network in which cooperation improves the information-theoretic secrecy is studied. The channel consists of two senders, a receiver, and an eavesdropper. One or both senders transmit confidential messages to the receiver, while the eavesdropper tries to decode the transmitted message. The main result is the derivation of a newly(More)
In this paper, we discuss collusion-secure traceability codes for digital fingerprinting which is a technique for copyright protection of digital contents. We first state a generalization of conventional collusion attacks where illicit users of a digital content collude to create an illegal digital content. Then we propose a collusion-secure traceability(More)
Efficient laser-diode pumped picosecond self-Q-switched all-ceramic composite Yb:YAG/Cr(4+):YAG microchip lasers with 0.72 MW peak power has been developed. Lasers with nearly diffraction-limited beam quality (M(2) < 1.09), oscillate at stable single- and multi- longitudinal-modes due to the combined etalon effects in the Yb:YAG and Cr(4+):YAG parts of its(More)