67 research outputs found
Polycyclic codes over Galois rings with applications to repeated-root constacyclic codes
Cyclic, negacyclic and constacyclic codes are part of a larger class of codes
called polycyclic codes; namely, those codes which can be viewed as ideals of a
factor ring of a polynomial ring. The structure of the ambient ring of
polycyclic codes over GR(p^a,m) and generating sets for its ideals are
considered. Along with some structure details of the ambient ring, the
existance of a certain type of generating set for an ideal is proven.Comment: arXiv admin note: text overlap with arXiv:0906.400
A NOTE ON NEGACYCLIC AND CYCLIC CODES OF LENGTH p(s) OVER A FINITE FIELD OF CHARACTERISTIC p
Recently, the minimum Hamming weights of negacyclic and cyclic codes of length p(s) over a finite field of characteristic p are determined in [4]. We show that the minimum Hamming weights of such codes can also be obtained immediately using the results of [1]
Constacyclic Codes over Finite Fields
An equivalence relation called isometry is introduced to classify
constacyclic codes over a finite field; the polynomial generators of
constacyclic codes of length are characterized, where is the
characteristic of the finite field and is a prime different from
Covering -Symbol Metric Codes and the Generalized Singleton Bound
Symbol-pair codes were proposed for the application in high density storage
systems, where it is not possible to read individual symbols. Yaakobi, Bruck
and Siegel proved that the minimum pair-distance of binary linear cyclic codes
satisfies and introduced -symbol metric
codes in 2016. In this paper covering codes in -symbol metrics are
considered. Some examples are given to show that the Delsarte bound and the
Norse bound for covering codes in the Hamming metric are not true for covering
codes in the pair metric. We give the redundancy bound on covering radius of
linear codes in the -symbol metric and give some optimal codes attaining
this bound. Then we prove that there is no perfect linear symbol-pair code with
the minimum pair distance and there is no perfect -symbol metric code if
. Moreover a lot of cyclic and algebraic-geometric codes
are proved non-perfect in the -symbol metric. The covering radius of the
Reed-Solomon code in the -symbol metric is determined. As an application the
generalized Singleton bound on the sizes of list-decodable -symbol metric
codes is also presented. Then an upper bound on lengths of general MDS
symbol-pair codes is proved.Comment: 21 page
Decoding of Repeated-Root Cyclic Codes up to New Bounds on Their Minimum Distance
The well-known approach of Bose, Ray-Chaudhuri and Hocquenghem and its
generalization by Hartmann and Tzeng are lower bounds on the minimum distance
of simple-root cyclic codes. We generalize these two bounds to the case of
repeated-root cyclic codes and present a syndrome-based burst error decoding
algorithm with guaranteed decoding radius based on an associated folded cyclic
code. Furthermore, we present a third technique for bounding the minimum
Hamming distance based on the embedding of a given repeated-root cyclic code
into a repeated-root cyclic product code. A second quadratic-time probabilistic
burst error decoding procedure based on the third bound is outlined. Index
Terms Bound on the minimum distance, burst error, efficient decoding, folded
code, repeated-root cyclic code, repeated-root cyclic product cod
Tree-Based Construction of LDPC Codes Having Good Pseudocodeword Weights
We present a tree-based construction of LDPC codes that have minimum
pseudocodeword weight equal to or almost equal to the minimum distance, and
perform well with iterative decoding. The construction involves enumerating a
-regular tree for a fixed number of layers and employing a connection
algorithm based on permutations or mutually orthogonal Latin squares to close
the tree. Methods are presented for degrees and , for a
prime. One class corresponds to the well-known finite-geometry and finite
generalized quadrangle LDPC codes; the other codes presented are new. We also
present some bounds on pseudocodeword weight for -ary LDPC codes. Treating
these codes as -ary LDPC codes rather than binary LDPC codes improves their
rates, minimum distances, and pseudocodeword weights, thereby giving a new
importance to the finite geometry LDPC codes where .Comment: Submitted to Transactions on Information Theory. Submitted: Oct. 1,
2005; Revised: May 1, 2006, Nov. 25, 200
New bounds for -Symbol Distances of Matrix Product Codes
Matrix product codes are generalizations of some well-known constructions of
codes, such as Reed-Muller codes, -construction, etc. Recently, a
bound for the symbol-pair distance of a matrix product code was given in
\cite{LEL}, and new families of MDS symbol-pair codes were constructed by using
this bound. In this paper, we generalize this bound to the -symbol distance
of a matrix product code and determine all minimum -symbol distances of
Reed-Muller codes. We also give a bound for the minimum -symbol distance of
codes obtained from the -construction, and use this bound to
construct some -linear -symbol almost MDS codes with arbitrary
length. All the minimum -symbol distances of -linear codes and
-linear codes for are determined. Some examples are
presented to illustrate these results
- …