Patent ID: 7376173

Claim:
A method for encoding a sequence of blocks of input bits to be transmitted over a wireless channel, comprising: converting each block of input bits to a codeword; mapping each codeword to a plurality of a sub-blocks of complex numbers; multiplying each sub-block of complex numbers by a disambiguating spreading transform to obtain a sub-block of transformed symbols; constructing a normal factor graph for the disambiguating spreading transform, the normal factor graph including a plurality of stacks of butterfly factor nodes and a single stack of normalization factor nodes, the number of butterfly factor nodes in each stack being half the number of complex symbols in the sub-block of the complex symbols; defining each normalization factor node by a normalization factor 1/Z, where Z = ∑ k = 0 2 ⁢ B - 1 ⁢ ⁢ 2 2 ⁢ k , and where B is related to a number N of complex symbols in a sub-block by N=2 B and B is an integer greater then or equal to 1; and modulating each sub-block of transformed symbols.