One of the main problems of subspace coding is to determine the maximal size of a constant dimension subspace code with given parameters. In this paper, we show that mixed dimensionsubspacecodes can be used to const...
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One of the main problems of subspace coding is to determine the maximal size of a constant dimension subspace code with given parameters. In this paper, we show that mixed dimensionsubspacecodes can be used to construct large constant dimension subspace codes. We introduce a new class of subspacecodes called mixed dimension/distance subspacecodes. Using such codes, we present two constructions for large constant dimension subspace codes. The problem about the sizes of our constant dimension subspace codes is transformed into finding mixed dimension/distance subspacecodes with large dimension distributions. The new constructed codes are the largest known for many sets of parameters. Our method gives at least 136 new lower bounds on the sizes of constant dimension subspace codes.
We improve on the lower bound of the maximum number of planes of PG(8, q) mutually intersecting in at most one point leading to the following lower bound: A(q) (9, 4;3) >= q(12) + 2q(8) + 2q(7) + q(6) + q(5) + q(4)...
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We improve on the lower bound of the maximum number of planes of PG(8, q) mutually intersecting in at most one point leading to the following lower bound: A(q) (9, 4;3) >= q(12) + 2q(8) + 2q(7) + q(6) + q(5) + q(4) + 1. We also construct two new nonequivalent (6, (q(3) - 1)(q(2) + q + 1), 4;3) q-constantdimensionsubspace orbit-codes.
A basic problem for the constantdimensionsubspace coding is to determine the maximal possible size A(q)(n, d, k) of a set of k-dimensional subspaces in F-q(n) such that the subspace distance satisfies d(U, V) = 2k -...
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A basic problem for the constantdimensionsubspace coding is to determine the maximal possible size A(q)(n, d, k) of a set of k-dimensional subspaces in F-q(n) such that the subspace distance satisfies d(U, V) = 2k - 2dim (U boolean AND V) >= d for any two different subspaces U and V in this set. We present two new constructions of constant dimension subspace codes using subsets of maximum rank-distance (MRD) codes in several blocks. This method is firstly applied to the linkage construction and secondly to arbitrary number of blocks of lifting MRD codes. In these two constructions, subsets of MRD codes with bounded ranks play an essential role. The Delsarte theorem about the rank distribution of MRD codes is an important ingredient to count codewords in our constructed constant dimension subspace codes. We give many new lower bounds for A(q)(n, d, k). More than 110 new constant dimension subspace codes better than previously best known codes are constructed
The main problem of constant-dimensionsubspace coding is to determine the maximal possible size A(q) (n, d, k) of a set of k-dimensional subspaces in F-q(n) such that the subspace distance satisfies d(U, V) >= d f...
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The main problem of constant-dimensionsubspace coding is to determine the maximal possible size A(q) (n, d, k) of a set of k-dimensional subspaces in F-q(n) such that the subspace distance satisfies d(U, V) >= d for any two different subspaces U and V in this set. In this paper, we give a direct construction of constant-dimensionsubspacecodes from two parallel versions of maximum rank-distance codes. The problem about the sizes of our constructed constant-dimensionsubspacecodes is transformed into finding a suitable sufficient condition to restrict number of the roots of L-1(L-2(x)) -x where L-1 and L-2 are q-polynomials over the extension field F-q(n). New lower bounds for A(q) (4k, 2k, 2k), A(q) (4k + 2, 2k, 2k + 1), and A(q) (4k + 2, 2(k -1), 2k + 1) are presented. Many new constant-dimensionsubspacecodes better than previously best known codes with small parameters are constructed.
Using the geometry of quadrics of a projective plane PG(2, q) a family of (6, q(3)(q(2) - 1)(q - 1)/3 + (q(2) + 1) (q(2) + q + 1), 4;3)(q) constant dimension subspace codes is constructed.
Using the geometry of quadrics of a projective plane PG(2, q) a family of (6, q(3)(q(2) - 1)(q - 1)/3 + (q(2) + 1) (q(2) + q + 1), 4;3)(q) constant dimension subspace codes is constructed.
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