2,435 research outputs found
Z2Z4-Additive Perdect Codes in Steganography
Steganography is an information hiding application which aims to
hide secret data imperceptibly into a cover object. In this paper, we describe a
novel coding method based on Z2Z4-additive codes in which data is embedded
by distorting each cover symbol by one unit at most (+-1-steganography). This
method is optimal and solves the problem encountered by the most e cient
methods known today, concerning the treatment of boundary values. The
performance of this new technique is compared with that of the mentioned
methods and with the well-known rate-distortion upper bound to conclude that
a higher payload can be obtained for a given distortion by using the proposed
method
Binary and Ternary Quasi-perfect Codes with Small Dimensions
The aim of this work is a systematic investigation of the possible parameters
of quasi-perfect (QP) binary and ternary linear codes of small dimensions and
preparing a complete classification of all such codes. First we give a list of
infinite families of QP codes which includes all binary, ternary and quaternary
codes known to is. We continue further with a list of sporadic examples of
binary and ternary QP codes. Later we present the results of our investigation
where binary QP codes of dimensions up to 14 and ternary QP codes of dimensions
up to 13 are classified.Comment: 4 page
The q-ary image of some qm-ary cyclic codes: permutation group and soft-decision decoding
Using a particular construction of generator matrices of
the q-ary image of qm-ary cyclic codes, it is proved that some of these codes are invariant under the action of particular permutation groups. The equivalence of such codes with some two-dimensional (2-D) Abelian codes and cyclic codes is deduced from this property. These permutations are also used in the area of the soft-decision decoding of some expanded Reed–Solomon (RS) codes to improve the performance of generalized minimum-distance decoding
The hull of two classical propagation rules and their applications
Propagation rules are of great help in constructing good linear codes. Both
Euclidean and Hermitian hulls of linear codes perform an important part in
coding theory. In this paper, we consider these two aspects together and
determine the dimensions of Euclidean and Hermitian hulls of two classical
propagation rules, namely, the direct sum construction and the
-construction. Some new criteria for resulting codes
derived from these two propagation rules being self-dual, self-orthogonal or
linear complement dual (LCD) codes are given. As applications, we construct
some linear codes with prescribed hull dimensions and many new binary, ternary
Euclidean formally self-dual (FSD) LCD codes, quaternary Hermitian FSD LCD
codes and good quaternary Hermitian LCD codes which are optimal or have best or
almost best known parameters according to Datebase at
. Moreover, our methods contributes positively to
improve the lower bounds on the minimum distance of known LCD codes.Comment: 16 pages, 5 table
Self-Dual Codes
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
High-rate self-synchronizing codes
Self-synchronization under the presence of additive noise can be achieved by
allocating a certain number of bits of each codeword as markers for
synchronization. Difference systems of sets are combinatorial designs which
specify the positions of synchronization markers in codewords in such a way
that the resulting error-tolerant self-synchronizing codes may be realized as
cosets of linear codes. Ideally, difference systems of sets should sacrifice as
few bits as possible for a given code length, alphabet size, and
error-tolerance capability. However, it seems difficult to attain optimality
with respect to known bounds when the noise level is relatively low. In fact,
the majority of known optimal difference systems of sets are for exceptionally
noisy channels, requiring a substantial amount of bits for synchronization. To
address this problem, we present constructions for difference systems of sets
that allow for higher information rates while sacrificing optimality to only a
small extent. Our constructions utilize optimal difference systems of sets as
ingredients and, when applied carefully, generate asymptotically optimal ones
with higher information rates. We also give direct constructions for optimal
difference systems of sets with high information rates and error-tolerance that
generate binary and ternary self-synchronizing codes.Comment: 9 pages, no figure, 2 tables. Final accepted version for publication
in the IEEE Transactions on Information Theory. Material presented in part at
the International Symposium on Information Theory and its Applications,
Honolulu, HI USA, October 201
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