521 research outputs found
Symbol synchronization in convolutionally coded systems
Alternate symbol inversion is sometimes applied to the output of convolutional encoders to guarantee sufficient richness of symbol transition for the receiver symbol synchronizer. A bound is given for the length of the transition-free symbol stream in such systems, and those convolutional codes are characterized in which arbitrarily long transition free runs occur
Concatenation of convolutional and block codes Final report
Comparison of concatenated and sequential decoding systems and convolutional code structural propertie
Quasi-Cyclic Codes
Quasi-cyclic codes form an important class of algebraic codes that includes
cyclic codes as a special subclass. This chapter focuses on the algebraic
structure of quasi-cyclic codes, first. Based on these structural properties,
some asymptotic results, a few minimum distance bounds and further applications
such as the trace representation and characterization of certain subfamilies of
quasi-cyclic codes are elaborated. This survey will appear as a chapter in "A
Concise Encyclopedia of Coding Theory" to be published by CRC Press.Comment: arXiv admin note: text overlap with arXiv:1906.0496
On the Minimum Distance of Array-Based Spatially-Coupled Low-Density Parity-Check Codes
An array low-density parity-check (LDPC) code is a quasi-cyclic LDPC code
specified by two integers and , where is an odd prime and . The exact minimum distance, for small and , has been calculated, and
tight upper bounds on it for have been derived. In this work, we
study the minimum distance of the spatially-coupled version of these codes. In
particular, several tight upper bounds on the optimal minimum distance for
coupling length at least two and , that are independent of and
that are valid for all values of where depends on , are
presented. Furthermore, we show by exhaustive search that by carefully
selecting the edge spreading or unwrapping procedure, the minimum distance
(when is not very large) can be significantly increased, especially for
.Comment: 5 pages. To be presented at the 2015 IEEE International Symposium on
Information Theory, June 14-19, 2015, Hong Kon
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