Patent Document ID: 8036289
Application ID: 12094282
Patent Flag: 1

Claim One:
1. An iterative frequency and phase compensation apparatus for an OFDM communication system including a OFDM demodulator and an iterative decoder, comprising: a first classifying means for classifying OFDM demodulated symbol sequences by each subcarrier wave according to a location in a frame of a corresponding data symbol; a soft-decision calculating means for calculating a soft-decision value of a data symbol using a soft-decision reliability obtained from iterative decoding performed by the iterative decoder; a second classifying means for receiving the soft-decision values from the soft-decision calculating means and classifying the received soft-decision values by a carrier wave; a frequency estimating means for estimating a residual frequency error of each carrier wave for symbols of each carrier wave inputted from the first classifying unit using the soft-decision value of each carrier wave inputted from the second classifying unit; a phase estimating means for estimating an average residual phase error of carrier waves for symbols of each carrier wave inputted from the first classifying unit using the soft-decision value of each carrier wave inputted from the second classifying unit; a frequency and phase compensating means for compensating frequencies and phases for input symbols of each carrier wave using the estimated frequency error and the estimated phase error; and a buffering means for temporally storing frequency and phase compensated symbols from the frequency and phase compensating means to provide the frequency and phase compensated symbols to the first classifying means; wherein the residual frequency error and the average residual phase error are estimated using phases of the compensated symbols according to the soft-decision value; wherein the phase estimating means calculates a sum-average value of the phases of the compensated symbols for the symbols of each carrier wave determined according to a code rate.