ITERATIVE RESIDUAL FREQUENCY AND PHASE COMPENSATION FOR TURBO CODED OFDM SYSTEM

摘要

An apparatus and a method for iterative residual frequency and phase compensation for a turbo coded OFDM(Orthogonal Frequency Division Multiplex) system are provided to obtain synchronization in a low power environment, by estimating and compensating phases per sub carrier by using a soft decision reliability value of a channel decoder iteratively. In an apparatus for iterative residual frequency and phase compensation for an OFDM communication system including an OFDM demodulator(301) and an iterative decoder(308), a first classification per carrier unit aligns an OFDM-demodulated symbol stream per each sub carrier according to the position in the frame of a corresponding data symbol. A soft decision calculation unit(309) calculates a soft decision value of the data symbol by using a soft decision reliability value obtained in an iterative decoding process by the iterative decoder. A second classification per carrier unit classifies the soft decision value calculated by the soft decision calculation unit per sub carrier. A frequency estimation unit(311) estimates a residual frequency error of each carrier for the symbol per carrier inputted from the first classification per carrier unit using the soft decision value per carrier inputted from the second classification per carrier unit. A phase estimation unit(312) estimates an average residual phase error of a carrier for the symbol per carrier inputted from the first classification per carrier unit using the soft decision value per carrier inputted from the second classification per carrier unit. A frequency and phase compensation unit(305) compensates frequency and phase for the inputted symbol per carrier using the estimated frequency error and the estimated phase error. A buffering unit stores the frequency and phase-compensated symbol temporarily before the symbol is transmitted to the first classification per carrier unit.