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We introduce and investigate the class of bounded-delay-encodable block-decodable (BDB) codes. Several characterizations for this class of codes are given, and some construction methods, especially for one-symbol look-ahead BDB codes, are described. In another direction, we use our results to show the existence of a decision procedure for some basic coding problems. Index Terms - RLL code, BDB code, block-decodable code, principal state-set, look-ahead coding.

This paper presents different results related to the ordering of a sequence of N received symbols with respect to their reliability measure, for BPSK transmission over the AWGN channel model. First, a tight approximation of Pe (i; N), the probability that the hard decision associated with the ith symbol of the ordered sequence is in error, is derived. Then, it is shown that despite the fact that the random variables representing the noise at positions [n.sub.1], [n.sub.2], ..., [n.sub.j] of the ordering are no longer independent, the events of having a hard decision decoding error at these positions remain almost independent. Pe([n.sub.1], [n.sub.2], ..., [n.sub.j]; N). the probability that the hard decisions associated with the symbols at positions [n.sub.1], [n.sub.2], ..., [n.sub.j] in the ordered sequence are in error, is thus well approximated from each of the Pe ([n.sub.i]; N), for i [element of] [1, j]. Finally, based on the independence of these events, the fully connected [2.sup.N]-state BSC representing the channel after ordering is simplified by N independent time-shared 2-state BSC's. This new model allows one to easily and tightly approximate the capacity of the channel after ordering. Index Terms - Soft-decison decoding, block codes, ordered statistics, reliability information.

The application of set theory methods to problems in estimation, system identification, and classification is emerging as a viable approach to a number of different problems. This correspondence studies the use of set-membership methods in symbol-by-symbol decoding of binary data in data-transmission systems. Theorems for necessary and sufficient conditions for error-free decoding are presented. Following these theorems, an algorithm is presented for selection of decode threshold levels based on set-membership properties of the system. A second algorithm is presented for automatic generation of logic truth tables for the decoder. Index Terms - Set-membership, set-distinguishability, threshold detector, decode logic, decision rules, set-distinguishing receivers.

A K-out-of-M multiple-access channel is a mathematical model for transmission of information between a large number of potential transmitters and one receiver, where at any transmission interval only a (usually small) number of transmitters are active transmitting their messages. In this work we study the problem of matching between correlated information sources and a K-out-of-M multiple-access channel. We show that by employing the correlation between the information sources and using a two-step coding scheme better results can be achieved compared to separate source and channel coding. A coding and decoding scheme is described and sufficient conditions for reliable transmission of the correlated information sources via the K-out-of-M multiple-access channel, based on this scheme are obtained. Index Terms - Multi-user information theory, multiple-access channels, joint source-channel coding, correlated information sources, source-channel matching

Transmission algorithms are introduced for use in a single-hop packet switching system with nonuniform traffic and with propagation delay that is large relative to the packet transmission time. The traffic model allows arbitrary traffic streams subject only to a constraint on the number of data packets which can arrive at any individual source in the system or for any individual destination in the system over time periods of specified length. The algorithms are based primarily on sending transmission schedules to the receivers immediately before transmitting each data packet multiple times so that the receiver can maximize the number of packets it captures. An algorithm based on matchings in a random graph is shown to provide mean total delay divided by mean propagation delay arbitrarily close to one, as the propagation delay tends to infinity. Index Terms - Switching, scheduling, large propagation delay, nonuniform traffic.