arXiv subjects

Xianmang He

Publications and source records attributed to Xianmang He.

6 recordsLinked to original sources

arXiv2021

New Construction for Constant Dimension Subspace Codes via a Composite Structure

One of the most fundamental topics in subspace coding is to explore the maximal possible value ${\bf A}_q(n,d,k)$ of a set of $k$-dimensional subspaces in $\mathbb{F}_q^n$ such that the subspace distance satisfies $\operatorname{d_S}(U,V) = \dim(U+V)-\dim(U\cap V) \geq d$ for any two different $k$-dimensional subspaces $U$ and $V$ in this set. In this paper, we propose a construction for constant dimension subspace codes by inserting a composite structure composing of an MRD code and its sub-codes. Its vast advantage over the previous constructions has been confirmed through extensive examples. At least $49$ new constant dimension subspace codes which exceeds the currently best codes are constructed.

cs.IT↗

arXiv2020

Improving the Linkage Construction with Echelon-Ferrers for Constant-Dimension Codes

Echelon-Ferrers is an important method to improve lower bounds for constant-dimension codes, which can be applied on various parameters. Fagang Li [12] combined the linkage construction and echelon-Ferrers to obtain some new lower bounds of constant-dimension codes. In this letter, we generalize this linkage construction to obtain new lower bounds.

cs.IT↗

arXiv2020

Construction of Const Dimension Code from Two Parallel Versions of Linkage Construction

The linkage construction and its generalization is one of the most powerful constructions for constant dimension code, accounting for approximately 50\% of all the listed parameters. We show how to improve the linkage construction of subspace codes by two parallel versions of the linkage construction. This proof allows us to attain codes of larger size for a given minimum distance, which exceeds the latest improvements on the linkage construction \cite{combining2019Antonio} in the cases $A_q(13,4,4),A_q(17,4,4), A_q(19,6,6)$.

cs.IT↗

arXiv2020

New Constructions of Subspace Codes Using Subsets of MRD codes in Several Blocks

A basic problem for the constant dimension subspace coding is to determine the maximal possible size A_q (n, d, k) of a set of k-dimensional subspaces in Fnq such that the subspace distance satisfies d(U, V )> or =d for any two different subspaces U andV in this set. We present two new constructions of constant dimension subspace codes using subsets of maximal 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 of 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.

cs.IT↗

arXiv2019

Construction of Const Dimension Codes from Serval Parallel Lift MRD Code

In this paper, we generalize the method of using two parallel versions of the lifted MRD code from the existing work [1]. The Delsarte theorem of the rank distribution of MRD codes is an important part to count codewords in our construction. We give a new generalize construction to the following bounds: if n>=k>=d, then $Aq(n + k,k,d)>=q^{n(k-\frac{d}{2}+1)}+\sum_{r=\frac{d}{2}}^{k-\frac{d}{2}} A_r(Q_q(n,k,\frac{d}{2})).$ On this basis, we also give a construction of constant-dimension subspace codes from several parallel versions of lifted MRD codes. This construction contributes to a new lower bounds for Aq((s+1)k+n,d,k).

cs.IT↗

arXiv2015

New $q$-ary Quantum MDS Codes with Distances Bigger than $\frac{q}{2}$

Constructions of quantum MDS codes have been studied by many authors. We refer to the table in page 1482 of [3] for known constructions. However there are only few $q$-ary quantum MDS $[[n,n-2d+2,d]]_q$ codes with minimum distances $d>\frac{q}{2}$ for sparse lengths $n>q+1$. In the case $n=\frac{q^2-1}{m}$ where $m|q+1$ or $m|q-1$ there are complete results. In the case $n=\frac{q^2-1}{m}$ where $m|q^2-1$ is not a factor of $q-1$ or $q+1$, there is no $q$-ary quantum MDS code with $d> \frac{q}{2}$ has been constructed. In this paper we propose a direct approch to construct Hermitian self-orthogonal codes over ${\bf F}_{q^2}$. Thus we give some new $q$-ary quantum codes in this case. Moreover we present many new $q$-ary quantum MDS codes with lengths of the form $\frac{w(q^2-1)}{u}$ and minimum distances $d > \frac{q}{2}$.

cs.IT↗