Patent ID: 7751472

Claim:
A wireless communication device comprising: means for receiving a transmission signal through a propagation channel; means for performing a demodulation process of the transmission signal, the transmission signal having been subjected to a multi-level modulation process that, corresponding to a combination of bit values, performs mapping of an n-bit binary signal into 2 n signal points created in an I,Q signal constellation by using a combination of phase and amplitude, wherein in the multi-level modulation process, signal-point arrangement of reference symbols is made so that information of a respective one of transmission bits is set on one of an I axis and a Q axis in the I,Q signal constellation; a phase rotation compensating means that: (a) acquires a phase rotation angle in the propagation channel which phase rotation angle is contained in a received symbol; and (b) performs rotation compensation of the acquired phase rotation angle for the received symbol, wherein the phase rotation compensating means includes: (i) first symbol rotating means that rotates a received pilot symbol to a first quadrant by a rotating angle; (ii) a first Coordinate Rotation Digital Computer that obtains the phase rotation angle for a pilot symbol present within the first quadrant; (iii) second symbol rotating means that rotates a received data symbol by said rotation angle; and (iv) a second Coordinate Rotation Digital Computer that performs rotation compensation of the data symbol by using the rotation angle obtained by the first Coordinate Rotation Digital Computer; a reference signal generating means that generates, as a respective reference signal level, a coordinate value of the respective I, Q axis in the signal constellation on which the information of the respective reference signal point is set; a probability calculating means that, for the respective transmission bit, obtains respective probabilities that the transmission bit is 0 and 1 by making a distance determination of the distance between the received symbol after the rotation compensation and the respective reference signal level on only one of the I and Q axes; and a determining means that makes a likelihood determination of the bit value of the respective transmission bit in accordance with at least one of said probability values obtained by the probability calculating means.