MAXIMUM-LIKELIHOOD DECODING OF THE LEECH LATTICE

A new algorithm for maximum likelihood decoding of the Leech lattice is presented. The algorithm involves projecting the points of the Leech lattice directly onto the codewords of the (6,3,4) quaternary code-the hexacode. Projection on the hexacode induces a partition of the Leech lattice into four cosets of a certain sublattice Q24. Such a partition into cosets enables maximum likelihood decoding of the Leech lattice with 3595 real operations in the worst case and only 2955 operations on the average. This is about half the worst case and the average complexity of the best previously known algorithm [3]. Moreover the proposed decoder is far simpler, both conceptually and structurally, than the state of the art decoder of [3].