On conjugacy classes of subgroups of the general linear group and cyclic orbit codes

Orbit codes are a family of codes employable for communications on a random linear network coding channel. The paper focuses on the classification of these codes. We start by classifying the conjugacy classes of cyclic subgroups of the general linear group. As a result, we are able to focus the study of cyclic orbit codes to a restricted family of them.Comment: 5 pages; Submitted to IEEE International Symposium on Information Theory (ISIT) 201

A Complete Characterization of Irreducible Cyclic Orbit Codes

We give a complete list of orbit codes that are generated by an irreducible cyclic group, i.e. an irreducible group having one generator. We derive some of the basic properties of these codes such as the cardinality and the minimum distance.Comment: in Proceedings of The Seventh International Workshop on Coding and Cryptography 2011 April 11-15 2011, Paris, Franc

Message Encoding for Spread and Orbit Codes

Spread codes and orbit codes are special families of constant dimension subspace codes. These codes have been well-studied for their error correction capability and transmission rate, but the question of how to encode messages has not been investigated. In this work we show how the message space can be chosen for a given code and how message en- and decoding can be done.Comment: Submitted to IEEE International Symposium on Information Theory 201

A Complete Characterization of Irreducible Cyclic Orbit Codes and their Pl\"ucker Embedding

Constant dimension codes are subsets of the finite Grassmann variety. The study of these codes is a central topic in random linear network coding theory. Orbit codes represent a subclass of constant dimension codes. They are defined as orbits of a subgroup of the general linear group on the Grassmannian. This paper gives a complete characterization of orbit codes that are generated by an irreducible cyclic group, i.e. a group having one generator that has no non-trivial invariant subspace. We show how some of the basic properties of these codes, the cardinality and the minimum distance, can be derived using the isomorphism of the vector space and the extension field. Furthermore, we investigate the Pl\"ucker embedding of these codes and show how the orbit structure is preserved in the embedding.Comment: submitted to Designs, Codes and Cryptograph

Cyclic Orbit Codes

In network coding a constant dimension code consists of a set of k-dimensional subspaces of F_q^n. Orbit codes are constant dimension codes which are defined as orbits of a subgroup of the general linear group, acting on the set of all subspaces of F_q^n. If the acting group is cyclic, the corresponding orbit codes are called cyclic orbit codes. In this paper we give a classification of cyclic orbit codes and propose a decoding procedure for a particular subclass of cyclic orbit codes.Comment: submitted to IEEE Transactions on Information Theor

Problems on q-Analogs in Coding Theory

The interest in $q$-analogs of codes and designs has been increased in the last few years as a consequence of their new application in error-correction for random network coding. There are many interesting theoretical, algebraic, and combinatorial coding problems concerning these q-analogs which remained unsolved. The first goal of this paper is to make a short summary of the large amount of research which was done in the area mainly in the last few years and to provide most of the relevant references. The second goal of this paper is to present one hundred open questions and problems for future research, whose solution will advance the knowledge in this area. The third goal of this paper is to present and start some directions in solving some of these problems.Comment: arXiv admin note: text overlap with arXiv:0805.3528 by other author

Geometrically uniform subspace codes and a proposal to construct quantum networks

Orientador: Reginaldo Palazzo JuniorTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de ComputaçãoResumo: Códigos de subespaço se mostram muito úteis contra a propagação de erros em uma rede linear multicast. Em particular, a família dos códigos de órbita apresenta uma estrutura algébrica bem definida o que, possivelmente, resultará na construção de bons algoritmos de decodificação e uma forma sistemática para o cálculo dos parâmetros do código. Neste trabalho, apresentamos um estudo dos códigos de órbita vistos como códigos geometricamente uniformes. A caracterização destas duas classes segue direto da definição de códigos de órbita e, dado um particionamento geometricamente uniforme destes códigos a partir de subgrupos normais do grupo gerador, propomos uma redução sobre o número de cálculos necessários para a obtenção das distâncias mínimas de um código de órbita abeliano e de um código L-nível, além de um algoritmo de decodificação baseado nas regiões de Voronoi. No último capítulo deste trabalho, propomos uma ideia de como projetar, do ponto de vista teórico, uma possível rede capaz de transmitir e operar informações quânticas. Tais informações são representadas por estados quânticos emaranhados, onde cada ket destes estados está associado a um subespaço vetorialAbstract: Subspace codes have been very useful to solve the error propagation in a multicast linear network. In particular, the orbit codes family presents a well-defined algebraic structure, which it will probably provide constructions of good decoding algorithms and a systematic way to compute the parameters of the code. In this work, we present a study of orbit codes seen as geometrically uniform codes. The characterization of both classes is direct from the definition of orbit codes and, given a uniform geometrically partition of these orbit codes from their normal subgroups of the generator group, we propose a reduction of the computation necessary for obtaining the minimum distances of an abelian orbit code and an L-level code, in addition to a decoding algorithm based on Voronoi regions. In the last chapter, we propose a hypothetical quantum network coding for the transmission of quantum information. This network consists of maximum entangled pure quantum states such that each ket of these states is associated with a vector subspaceDoutoradoTelecomunicações e TelemáticaDoutor em Engenharia Elétrica142094/2013-7CAPESCNP