constant dimension codes (CDCs) have drawn extensive attention due to their applications in random network coding. This paper introduces a new class of codes, namely generalized bilateral Ferrers diagram rank-metric c...
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constant dimension codes (CDCs) have drawn extensive attention due to their applications in random network coding. This paper introduces a new class of codes, namely generalized bilateral Ferrers diagram rank-metric codes, to generalize the bilateral multilevel construction in Etzion and Vardy (Adv Math Commun 16:1165-1183, 2022). Combining our generalized bilateral multilevel construction and the double multilevel construction in Liu and Ji (IEEE Trans Inf Theory 69:157-168, 2023), we present an effective technique to construct CDCs. By means of bilateral identifying vectors, this approach helps us to select fewer identifying and inverse identifying vectors to construct CDCs with larger size. The new constructed CDCs have the largest size regarding known codes for many sets of parameters. Our method gives rise to at least 138 new lower bounds for CDCs.
The fundamental problem of subspace coding is to explore the maximum possible cardinality A(q)(n, d, k) of a set of k-dimensional subspaces of an n-dimensional vector space over F(q )such that the subspace distance sa...
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The fundamental problem of subspace coding is to explore the maximum possible cardinality A(q)(n, d, k) of a set of k-dimensional subspaces of an n-dimensional vector space over F(q )such that the subspace distance satisfies d(S)(W-1, W-2) >= d for any two distinct subspaces W-1,W(2 )in this set. In this paper, we construct a new class of constant dimension codes (CDCs) by generalizing the coset construction and combining it with CDCs derived from parallel linkage construction and coset construction with an aim to improve the new lower bounds of A(q)(n, d, k). We found a remarkable improvement in some of the lower bounds of A(q)(n, d, k).
constant dimension codes (CDCs) have drawn extensive attention due to their applications in random network coding. A fundamental problem for CDCs is to explore the maximum possible cardinality A(q)(n,d,k) of a set of ...
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constant dimension codes (CDCs) have drawn extensive attention due to their applications in random network coding. A fundamental problem for CDCs is to explore the maximum possible cardinality A(q)(n,d,k) of a set of k-dimensional subspaces in F-q(n) such that the sub-space distance statisfies dis(U,V) = 2k - 2 dim(U boolean AND V) >= d for all pairs of distinct sub-spaces U and V in this set. In this paper, by means of an appropriate combination of the matrix blocks from rank metric codes and small CDCs, we present three constructions of CDCs based on the generalized block inserting construction by Niu et al. in 2021. According to our constructions, we obtain 28 new lower bounds for CDCs which are better than the previously known lower bounds.
constant dimension codes (CDCs), as special subspace codes, have received a lot of attention due to their application in random network coding. This paper introduces a family of new codes, called Ferrers diagram rank-...
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constant dimension codes (CDCs), as special subspace codes, have received a lot of attention due to their application in random network coding. This paper introduces a family of new codes, called Ferrers diagram rank-metric codes with given ranks (GFRMCs), to generalize the parallel construction and the parallel multilevel construction in [IEEE Trans. Inf. Theory, 66 (2020), 6884-6897]. The lower bounds for GFRMCs are derived from Ferrers diagram rank-metric codes (FDRMCs). Via GFRMCs, the inverse multilevel construction for CDCs is showed. Furthermore, the double multilevel construction, as an effective construction for CDCs, is presented by combining the inverse multilevel construction and the multilevel construction. Many CDCs with larger size than the previously best known codes are given.
constant dimension codes (CDCs), as special sub-space codes, have received a lot of attention due to their application in random network coding. This paper introduces a family of new codes, called rank metric codes wi...
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constant dimension codes (CDCs), as special sub-space codes, have received a lot of attention due to their application in random network coding. This paper introduces a family of new codes, called rank metric codes with given ranks (GRMCs), to generalize the parallel construction in [Xu and Chen, IEEE Trans. Inf. Theory, 64 (2018), 6315-6319] and the classic multilevel construction. A Singleton-like upper bound and a lower bound for GRMCs derived from Gabidulin codes are given. Via GRMCs, two effective constructions for CDCs are presented by combining the parallel construction and the multilevel construction. Many CDCs with larger size than the previously best known codes are given. The ratio between the new lower bound and the known upper bound for (4 delta, 2 delta, 2 delta)q(-) CDCs is calculated. It is greater than 0.99926 for any prime power q and any delta >= 3.
In this paper, we study bounds for optimal constant dimension codes furl By the construction for constant dimension codes in [4], we improve some bounds on q-ary constant dimension codes in some cases. By combinatoria...
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In this paper, we study bounds for optimal constant dimension codes furl By the construction for constant dimension codes in [4], we improve some bounds on q-ary constant dimension codes in some cases. By combinatorial method, we show that there exists no optimal constant dimension code A(q)[n, 2 delta, k] meeting both Wang-Xing-Safavi-Naini-Bound and the maximal distance separate bound simultaneously.
Given a finite field F q and a positive integer n, a flag is a sequence of nested F q -subspaces of a vector space F q n and a flag code is a nonempty collection of flags. The projected codes of a flag code are the co...
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Given a finite field F q and a positive integer n, a flag is a sequence of nested F q -subspaces of a vector space F q n and a flag code is a nonempty collection of flags. The projected codes of a flag code are the constant dimension codes containing all the subspaces of prescribed dimensions that form the flags in the flag code. In this paper we address the notion of equivalence for flag codes and explore in which situations such an equivalence can be reduced to the equivalence of the corresponding projected codes. In addition, this study leads to new results concerning the automorphism group of certain families of flag codes, some of them also introduced in this paper. (c) 2024 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY -NC license (http:// creativecommons .org /licenses /by -nc /4 .0/).
Subspace codes and constant dimension codes have become a widely investigated research topic due to their significance to error control in random linear network coding. Rank metric codes in Ferrers diagrams can be use...
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Subspace codes and constant dimension codes have become a widely investigated research topic due to their significance to error control in random linear network coding. Rank metric codes in Ferrers diagrams can be used to construct good subspace codes and constant dimension codes. In this paper, three constructions of Ferrers diagram rank metric codes are presented. The first two constructions are based on subcodes of maximum rank distance codes, and the last one generates new codes from known Ferrers diagram rank metric codes. Each of these constructions produces optimal codes with different diagrams and parameters for which no optimal construction was known before.
Subspace codes, motivated by their extensive application in random network coding, have become one of central topics in algebraic coding theory during the last 10 years. Due to the significant application in subspace ...
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Subspace codes, motivated by their extensive application in random network coding, have become one of central topics in algebraic coding theory during the last 10 years. Due to the significant application in subspace codes, Ferrers diagram rank-metric (FDRM) codes also have drawn a lot of attention. In this paper, we introduce two new constructions based on subcodes ofMRD codes. The first one makes use of a characterization on generator matrices of a class of systematic maximum rank distance codes. Apply the first construction to solve the optimality of [F, 4]q-FDRM codes, where F = [2, 2, 4, 4,..., 2l, 2l], which was raised in Etzion et al. (IEEE Trans Inf Theory 62:1616-1630, 2016). By the restricted Gabidulin codes and improving the way to select the subcodes, the second construction is presented, which unifies and generalizes all known constructions based on subcodes of Gabidulin codes. By the second construction, we can give new families of optimal FDRM codes, whose numbers of codewords are unequal to qv0. This paper also shows new families of FDRM codes whose optimality cannot be obtained by the constructions based on subcodes of Fqm -linear MRD codes.
Four constructions for Ferrers diagram rank-metric (FDRM) codes are presented. The first one makes use of a characterization on generator matrices of a class of systematic maximum rank distance codes. By introducing r...
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Four constructions for Ferrers diagram rank-metric (FDRM) codes are presented. The first one makes use of a characterization on generator matrices of a class of systematic maximum rank distance codes. By introducing restricted Gabidulin codes, the second construction is presented, which unifies many known constructions for FDRM codes. The third and fourth constructions are based on two different ways to represent elements of a finite field Fe, (vector representation and matrix representation). Each of these constructions produces optimal codes with different diagrams and parameters. (C) 2019 Elsevier Inc. All rights reserved.
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