Patent ID: 7164706

Claim:
A method of processing spread spectrum waveforms transmitted by a plurality of users of a spread spectrum system, comprising: computing a matrix representing cross correlations among the waveforms, said computing step including performing matrix calculation on at least a first one of two matrix components related by a symmetry property defined in accord with the relation: R l,k ( m )=ξ R k,l (− m ) wherein R lk (m) and R kl (m) refer to (l,k) and (k,l) elements of the cross correlation matrix, respectively, and ξ is a proportionality constant, computing a second one of the two matrix components as a function of the first matrix component by applying said symmetry property, and generating estimates of symbols transmitted by the users and encoded in said waveforms as a function of the cross correlation matrix wherein the step of computing the cross-correlation matrix comprises computing a matrix (herein referred to as Γ-matrix) that represents correlations among short code sequences associated with the respective users in accord with the relation: Γ l ⁢ ⁢ k ⁡ [ m ] ≡ 1 2 ⁢ N l ⁢ ∑ n = 0 N - 1 ⁢ c l * ⁡ [ n ] · c k ⁡ [ n - m ] wherein c l * [n] represents complex conjugate of the short code sequence associated with the l th user, c k [n−m] represents the short code sequence associated with k th user, N represents the length of the code, and N l represents the number of non-zero length of the code wherein the step of computing the cross-correlation matrix comprises computing a matrix (herein referred to as C matrix) representing cross-correlations among time lags associated with the transmitted waveforms and correlations among the short code sequences of the respective users as a function of the Γ-matrix in accord with the relation: C l ⁢ ⁢ k ⁢ ⁢ q ⁢ ⁢ q ′ ⁡ [ m ′ ] = ∑ m ⁢ g ⁡ [ m ⁢ ⁢ N c + τ ] · Γ l ⁢ ⁢ k ⁡ [ m ] wherein g is a pulse shape vector, N 0 is the number of samples per chip, τ is a time lag, m is a symbol period, and Γ represents the aforesaid Γ matrix.