8,799 research outputs found

    Some results on type IV codes over Z4

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    Code Design for Non-Coherent Detection of Frame Headers in Precoded Satellite Systems

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    In this paper we propose a simple method for generating short-length rate-compatible codes over ZM\mathbb{Z}_M that are robust to non-coherent detection for MM-PSK constellations. First, a greedy algorithm is used to construct a family of rotationally invariant codes for a given constellation. Then, by properly modifying such codes we obtain codes that are robust to non-coherent detection. We briefly discuss the optimality of the constructed codes for special cases of BPSK and QPSK constellations. Our method provides an upper bound for the length of optimal codes with a given desired non-coherent distance. We also derive a simple asymptotic upper bound on the frame error rate (FER) of such codes and provide the simulation results for a selected set of proposed codes. Finally, we briefly discuss the problem of designing binary codes that are robust to non-coherent detection for QPSK constellation.Comment: 11 pages, 5 figure

    Self-Dual Codes

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    Self-dual codes are important because many of the best codes known are of this type and they have a rich mathematical theory. Topics covered in this survey include codes over F_2, F_3, F_4, F_q, Z_4, Z_m, shadow codes, weight enumerators, Gleason-Pierce theorem, invariant theory, Gleason theorems, bounds, mass formulae, enumeration, extremal codes, open problems. There is a comprehensive bibliography.Comment: 136 page
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