Reticulados e codigos / Lattices and codes
AUTOR(ES)
Carina Alves
DATA DE PUBLICAÇÃO
2008
RESUMO
We approach here some problems related to minimizing the error probability in signals transmission over Gaussian and Rayleigh channels. Algebraic ideal lattice theory is used to construct rotations of the n-dimensional integer lattice via cyclotomic fields. This construction allows to evaluate the minimum product distance of the lattice, parameter which controls the signal transmission probability through Rayleigh fading channels. We present here such constructions in the cases n = 3 and n a power of 2. Spherical codes generated by commutative group codes of orthogonal matrices in even dimensions, 2m; can be determined by a quotient of n-dimensional lattices, where the sublattice has an orthogonal basis. We characterize families of such sublattices in the lattices with best packing densities in dimensions 2; 3; 4; 6 e 8 and construct the associated spherical codes which approach the commutative group code upper bound for the minimum distance
ASSUNTO(S)
geometria discreta teoria dos reticulados sphere packings empacotamento de esferas minimin distance distancia minima teoria dos numeros algebricos lattice theory dsicrete geometry
