Patent ID: 7573934

Claim:
A rake receiver for use in a spread spectrum communication system comprising: a timing detecting unit to detect a reception timing t i (i=1 to N, which is an integer number of three or more than three) of each of N paths when direct spread spectrum signals of the N paths are received; an inverse spreading timing setting unit to set, as a timing for inverse spreading, a timing t i,j,k (k=1 to N, k≠j) at which an inverse spread value is obtained that has interference and correlation from the jth (j=1 to N, j≠i) path included in the inverse spread value of the ith path counted from the reception timing t i (i=1 to N) detected by the timing detecting, wherein the timing t i,j,k is a timing of regenerating an interference and correlation given from the jth path to the ith path by the kth path; a plurality of correlators each of which to obtain an inverse spread signal of the received signal corresponding to each timing set by the inverse spreading timing setting; a signal composing unit to compose outputs of the plurality of correlators; and a circuit provided between the correlators and the signal composing unit, to compose a multi-path interference signal (mics(i,j,k)) of a path k (k≠j) from the following MICS ⁡ ( i , j ) = r i , j ⁢ ∑ k = j ⁢ r k ′ ⁢ mics ⁡ ( i , j , k ) , Eq . ⁢ ( 1 ) to reproduce interference α j I i,j and to subtract the interference MICS(i,j) from the ith path, wherein r i,j and r′ k are coefficients, wherein when the multi-path interference signal (mics(i,j,k)) is composed, the coefficients r i,j and r′ k of Eq. (1) are obtained from the following Eq. (2) and Eq. (3), respectively r i,j =α j I 2 /{( I/N ) j +1} Eq. (2), r k ′ = α k * / { ∑ l ≠ k ⁢ ⁢  α 1  2 ⁢ ⁢ I 2 + n 2 } , Eq . ⁢ ( 3 ) wherein α j , α k , and α i are channel estimation values respectively for jth, kth, and ith path and the multi-path interference signal (mics(i,j,k)) is composed using the maximal ratio composition.