6,866 research outputs found
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
Quasi-Cyclic Complementary Dual Code
LCD codes are linear codes that intersect with their dual trivially. Quasi
cyclic codes that are LCD are characterized and studied by using their
concatenated structure. Some asymptotic results are derived. Hermitian LCD
codes are introduced to that end and their cyclic subclass is characterized.
Constructions of QCCD codes from codes over larger alphabets are given
Skew Cyclic codes over \F_q+u\F_q+v\F_q+uv\F_q
In this paper, we study skew cyclic codes over the ring
R=\F_q+u\F_q+v\F_q+uv\F_q, where , and
is an odd prime. We investigate the structural properties of skew cyclic codes
over through a decomposition theorem. Furthermore, we give a formula for
the number of skew cyclic codes of length over $R.
Cyclic LRC Codes and their Subfield Subcodes
We consider linear cyclic codes with the locality property, or locally
recoverable codes (LRC codes). A family of LRC codes that generalizes the
classical construction of Reed-Solomon codes was constructed in a recent paper
by I. Tamo and A. Barg (IEEE Transactions on Information Theory, no. 8, 2014;
arXiv:1311.3284). In this paper we focus on the optimal cyclic codes that arise
from the general construction. We give a characterization of these codes in
terms of their zeros, and observe that there are many equivalent ways of
constructing optimal cyclic LRC codes over a given field. We also study
subfield subcodes of cyclic LRC codes (BCH-like LRC codes) and establish
several results about their locality and minimum distance.Comment: Submitted for publicatio
Distance Properties of Short LDPC Codes and their Impact on the BP, ML and Near-ML Decoding Performance
Parameters of LDPC codes, such as minimum distance, stopping distance,
stopping redundancy, girth of the Tanner graph, and their influence on the
frame error rate performance of the BP, ML and near-ML decoding over a BEC and
an AWGN channel are studied. Both random and structured LDPC codes are
considered. In particular, the BP decoding is applied to the code parity-check
matrices with an increasing number of redundant rows, and the convergence of
the performance to that of the ML decoding is analyzed. A comparison of the
simulated BP, ML, and near-ML performance with the improved theoretical bounds
on the error probability based on the exact weight spectrum coefficients and
the exact stopping size spectrum coefficients is presented. It is observed that
decoding performance very close to the ML decoding performance can be achieved
with a relatively small number of redundant rows for some codes, for both the
BEC and the AWGN channels
Cyclic LRC Codes, binary LRC codes, and upper bounds on the distance of cyclic codes
We consider linear cyclic codes with the locality property, or locally
recoverable codes (LRC codes). A family of LRC codes that generalize the
classical construction of Reed-Solomon codes was constructed in a recent paper
by I. Tamo and A. Barg (IEEE Trans. Inform. Theory, no. 8, 2014). In this paper
we focus on optimal cyclic codes that arise from this construction. We give a
characterization of these codes in terms of their zeros, and observe that there
are many equivalent ways of constructing optimal cyclic LRC codes over a given
field. We also study subfield subcodes of cyclic LRC codes (BCH-like LRC codes)
and establish several results about their locality and minimum distance. The
locality parameter of a cyclic code is related to the dual distance of this
code, and we phrase our results in terms of upper bounds on the dual distance.Comment: 12pp., submitted for publication. An extended abstract of this
submission was posted earlier as arXiv:1502.01414 and was published in
Proceedings of the 2015 IEEE International Symposium on Information Theory,
Hong Kong, China, June 14-19, 2015, pp. 1262--126
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