NNMDS CODES

C is an [n, k, d]q linear code over Fq. And s（C） = n ＋ 1 - k - d is the Singleton defect of C. An MDS code C with s（C） = 0 has been studied extensively. Recently, a near-MDS code C with s（C） = s（C⊥） = 1 is studied by many scholars, where C⊥ denotes the dual code of C. This paper concentrates on the linear code C with s（C） = s（C⊥） = 2, and the author calls it an NNMDS code. A series of iff conditions of NNMDS codes are presented. And the author gives an upper bound on length of NNMDS codes. In the last, some examples of NNMDS are given.

New Quantum MDS Code from Constacyclic Codes

In recent years, there have been intensive activities in the area of constructing quantum maximum distance separable(MDS for short) codes from constacyclic MDS codes through the Hermitian construction. In this paper, a new class of quantum MDS code is constructed, which extends the result of [Theorems 3.14–3.15, Kai, X., Zhu, S., and Li,P., IEEE Trans. on Inf. Theory, 60(4), 2014, 2080–2086], in the sense that our quantum MDS code has bigger minimum distance.

Constructing Non-binary Asymmetric Quantum Codes via Graphs

The theory of quantum error correcting codes is a primary tool for fighting decoherence and other quantum noise in quantum communication and quantum computation. Recently, the theory of quantum error correcting codes has developed rapidly and been extended to protect quantum information over asymmetric quantum channels, in which phase-shift and qubit-flip errors occur with different probabilities. In this paper, we generalize the construction of symmetric quantum codes via graphs (or matrices) to the asymmetric case, converting the construction of asymmetric quantum codes to finding matrices with some special properties. We also propose some asymmetric quantum Maximal Distance Separable (MDS) codes as examples constructed in this way.

Note on maximal distance separable codes

In this paper, the maximal length of maximal distance separable (MDS) codes is studied, and a new upper bound formula of the maximal length of MDS codes is obtained. Especially, the exact values of the maximal length of MDS codes in some parameters are given.

RDDP:An Efficient MDS Array Code on Toleration Triple Node Failures in Storage System

It is well known that erasure coding can be used in storage systems to efficiently store data while protecting against failures. Conventionally, the design of erasure codes has focused on the tradeoff between redundancy and reliability. Under this criterion, an maximum distance separable（MDS） code has optimal redundancy. In this paper, we address a new class of MDS array codes for tolerating triple node failures by extending the row di- agonal parity（RDP） code, named the RDDP（row double diagonal parity） code. The RDDP code takes advantages of good perform- ances of the RDP code with balanced I/0. A specific triple-erasure decoding algorithm to reduce decoding complexity is depicted by geometric graph, and it is easily implemented by software and hardware. The theoretical analysis shows that the comprehensive properties of the RDDP code are optimal, such as encoding and decoding efficiency, update efficiency and I/0 balance performance.

On LCD Negacyclic Codes over Finite Fields

This paper deduces the structure of LCD negacyclic codes over the finite field Fq, where q is an odd prime power. Based on the study of q-cyclotomic cosets modulo 2n, the authors obtain the parameters of LCD negacyclic codes of lengths n=qt＋1/2,qm-1/2（q-1） and qt·2τ-1/2（q2＋1）respectively. And many optimal codes are given. Moreover, the authors research two special classes of MDS LCD negacyclic codes of length n｜q-1/2 and n｜q＋1/2,respectively.

Symbol-Pair Distances of Repeated-Root Negacyclic Codes of Length 2^(s) over Galois Rings

Negacyclic codes of length 2^(s) over the Galois ring GR(2a,m)are linearly ordered under set-theoretic inclusion,i.e.,they are the ideals<(x+1)^(i)>,0≤i≤2^(s)a,of the chain ring GR(2^(a),m)[x]/<x^(2s)+1>.This structure is used to obtain the symbol-pair distances of all such negacyclic codes.Among others,for the special case when the alphabet is the finite field F2m(i.e.,a=1),the symbol-pair distance distribution of constacyclic codes over F2m verifies the Singleton bound for such symbol-pair codes,and provides all maximum distance separable symbol-pair constacyclic codes of length 2^(s) over F_(2m).

TSHOVER:A Novel Coding Scheme for Tolerating Triple Disk Failures in RAID/DRAID

This paper presents a novel method, called TSHOVER, for tolerating up to triple disk failures in RAID/DRAID architectures or others reliable storage systems. TSHOVER is two-dimensional code, which employs horizontal code and vertical code at the same time with simple exclusive-OR (XOR) computations. This paper shows the new step ascending concepts used in encoding, and it has the capability of realizing fault tolerance. TSHOVER has better data recovery ability to those disk network storage systems with relatively more dynamic changes in the number of disks. Compared with RS and STAR code, TSHOVER has better encoding performance. When updating a data strip, only 6 XOR operations are needed. Both experimental results and theoretical analyses show that TSHOVER has better performance and higher efficiency than other algorithms.