1. An encoding method comprising the steps of: quantizing a vector x by: approximating a vector x by a lattice vector y 0 belonging to a lattice Λ 0 ; successively decomposing said lattice vector y 0 into a sequence of quotient vectors y i and a sequence of remainder vectors r i on successive lattices Λ i−1 by lattice division with integers from a corresponding predetermined sequence of integers p i ≧2, where i=1. .. k and k is a positive integer greater than 1 representing the number of elements in each sequence, and where each successive decomposition is obtained in accordance with: { y i = Q Λ i - 1 ⁡ ( y i - 1 - a i p i ) r i = y i - 1 - p i ⁢ y i where Q Λ i - 1 ⁡ ( y i - 1 - a i p i ) denotes quantization of vector y i - 1 - a i p i to lattice Λ i−1 , and where a i is a predetermined displacement vector belonging to the voronoi region V Λ i−1 (0) of lattilce Λ i−1 and selected to break ties in such a way that no lattice point lies on the boundary of p i V Λ i−1 (0)+a i ; coding each remainder vector r i in a corresponding voronoi codebook V Λ i−1 (p i ,a i ); representing said vector x by a set of parameters that include said coded remainder vectors r i , the number k of such remainder vectors r i and said sequence of integers p i and displacement vectors a i defining said voronoi codebooks V Λ i−1 (p i ,a i ).