Patent ID: 8059710

Claim:
A space-time coding method for a UWB transmission system comprising at least two radiative elements, said method comprising: coding a block of information symbols (S=(a 1 , a 2 , . . . , a p ,)) belonging to an M-PPM modulation or M-PPM-Mâ€²-PAM composite modulation alphabet with M being even, into a sequence of vectors (s i,j , Î©s i,j ), the components of a vector being intended to modulate a UWB pulse signal for a radiative element of said system and for a given transmission interval (T f ), wherein said vectors are defined as the elements of the matrix: C = ( s 1 , 1 s 2 , 1 s 3 , 1 â€¦ s P , 1 Î© â¢ â¢ s P , 2 s 1 , 2 s 2 , 2 â€¦ s P - 1 , 2 â‹® Î© â¢ â¢ s P , 3 s 1 , 3 â‹± â‹® Î© â¢ â¢ s 3 , P - 1 â‹± â‹± â‹± s 2 , P - 1 Î© â¢ â¢ s 2 , P Î© â¢ â¢ s 3 , P â€¦ Î© â¢ â¢ s P , P s 1 , P ) defined to within one permutation of its lines and/or its columns, a line corresponding to a transmission interval and a column to a radiative element, wherein P is the number of radiative elements and Î© is a matrix of size MÃ—M defined by Î© = ( Ï‰ O 2 Ã— 2 â€¦ O 2 Ã— 2 O 2 Ã— 2 Ï‰ â€¦ O 2 Ã— 2 â‹® â‹® â‹± â‹® O 2 Ã— 2 â€¦ O 2 Ã— 2 Ï‰ ) wherein Ï‰ = ( cos â¢ â¢ Î¸ sin â¢ â¢ Î¸ - sin â¢ â¢ Î¸ cos â¢ â¢ Î¸ ) and O 2Ã—2 is the zero matrix of size 2Ã—2, s i , j = ( R j âŠ— I M ) â¢ ( a ( i - 1 ) â¢ P + 1 a ( i - 1 ) â¢ P + P â‹® a iP ) to within a margin of Â±10%, wherein I M is the identity matrix of size MÃ—M, is the tensor product, a l , =1, . . . , P 2 are the information symbols, R j is a line vector of dimension P corresponding to the j th line of an orthogonal matrix R generating the lattice points A={uÎ¸|uÎµZ p } with Î˜ = ( 1 Î¸ 0 â€¦ Î¸ 0 P - 1 1 Î¸ 1 â€¦ Î¸ 1 P - 1 â‹® â‹® â€¦ â‹® 1 Î¸ P - 1 â€¦ Î¸ P - 1 P - 1 ) where Î¸ p = 2 â¢ â¢ cos â¡ ( 2 â¢ ( p + 1 ) â¢ Ï€ N ) wherein N is a positive integer such that Ï†(N)=2P wherein Ï†(.) is the Euler indicator and Î¸ = 2 â¢ â¢ Ï€ N â€² wherein Nâ€² is a positive integer such that Ï†(Nâ€²)â‰§P and N, Nâ€² are prime together.