Patent ID: 7529327

Claim:
A method of compensating for a frequency offset between a transmission signal and a reception signal for a u th user (1≦u≦U, where U denotes the number of users) in an interleaved frequency division multiple access (IFDMA) system, the method comprising the steps of: (a) estimating the frequency offset from a selection signal in the IFDMA system that is determined as the reception signal for the u th user in an initial mode and as a feedback signal in a normal mode; (b) estimating multiple access interferences representing an extent to which reception signals for i th other users (1≦i≦U−1) at the same time interfere with the reception signal for the u th user; (c) subtracting the estimated multiple access interferences from the reception signal for the u th user and determining the subtraction result as the feedback signal; (d) determining whether steps (a), (b), and (c) have been repeated a predetermined number of times, and if it is determined that steps (a), (b), and (c) have not been repeated the predetermined number of times, going back to step (a); and (e) if it is determined that steps (a), (b), and (c) have been repeated the predetermined number of times, estimating the transmission signal for the u th user using the feedback signal finally determined in step (c) and the estimated frequency offset, wherein in step (a), the frequency offset is estimated from the selection signal using the following equation: ɛ u ^ = ∠ ⁢ ⁢ C u 2 ⁢ π where {circumflex over (ε)} u denotes the frequency offset,  ɛ u ^  < 1 2 , ∠ ⁢ ⁢ C u , denotes the angle of a correlation value ∑ k = 1 N u - 1 ⁢ * , N u denotes the number of carriers used by the u th user, k (k=0, 1, . . . , and N u −1) denotes the order of the reception signal for the u th user among a plurality of signals contained in a frame, z k ( u ) ⁡ [ u ] denotes the selection signal, N denotes the number of chips constituting a block, z k + N ( u ) ⁡ [ u ] denotes the result obtained by delaying the selection signal z k ( u ) ⁡ [ u ] by N, and ( z k ( u ) ⁡ [ u ] ) * denotes a conjugate of the selection signal z k ( u ) ⁡ [ u ] .