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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 433 records · Page 24

Improving turbo-like codes using iterative decoder analysis

The density evolution method is used to analyze the performance and optimize the structure of parallel and serial turbo codes, and generalized serial concatenations of mixtures of different outer and inner codes. Design examples are given for mixture codes.

turbo codes iterative decoding↗

Trellis Decoding Complexity of Linear Block Codes

We consider the problem of finding a trellis for a linear block code that minimizes one or more measures of trellis complexity. The domain of optimization may be different permutations of the same code, or different codes with the same parameters. Constraints on trellises, including relationships between the minimal trellis of a code and that of the dual code, are used to derive bounds on complexity. We define a partial ordering on trellises: if a trellis is optimum with respect to this partial ordering, it has the desirable property that it simultaneously minimizes all of the complexity measures examined. We examine properties of such optimal trellises and give examples of optimal permutations of codes, most notably the (48,24,12) quadratic residue code.

trellis decoding↗

Decoder Synchronization for Deep Space Missions

The Consultative committee for Space Data STandards (CCSDS) recommends that space communication links employ a concatenated error-correcting channel-coding system in which the inner code is a convolutional (7, 2/2) code and the outer code is a (255,223) Reed-Solomon code.

Decoder↗