Patent ID: 7515644

Claim:
A transmitter with three transmit antennas in a communication system using a space-time-frequency block coding scheme, comprising: a pre-coder for pre-coding a symbol vector of an input symbol sequence by multiplying the symbol vector by e jθ , θ being a phase rotation angle; and a space-time-frequency block code (STFBC) mapper for selecting an STFBC based on feedback channel quality indicators (CQIs) received from a receiver, mapping the pre-coded symbols to the transmit antennas according to the selected STFBC, and transmitting the mapped symbols through the transmit antennas; wherein the STFBC mapper selects the STFBC based on the feedback CQIs according to, if CQI — ant 1=select max( CQI — ant 1 ,CQI — ant 2 ,CQI — ant 3) use Matrix B if CQI — ant 2=select max( CQI — ant 1 ,CQI — ant 2,CQI — ant 3) use Matrix A if CQI — ant 3=select max( CQI — ant 1 ,CQI — ant 2 ,CQI _ant3) use Matrix C where CQI_ant 1 , CQI_ant 2 , and CQI_ant 3 represent CQIs for first, second and third transmit antennas, respectively, select max is a function for selecting a maximum value, and the matrices A, B and C are given as A = [ s 1 - s 2 * 0 0 s 2 s 1 * s 3 - s 4 * 0 0 s 4 s 3 * ] B = [ s 1 - s 2 * s 3 - s 4 * s 2 s 1 * 0 0 0 0 s 4 s 3 * ] C = [ s 1 - s 2 * 0 0 0 0 s 3 - s 4 * s 2 s 1 * s 4 s 3 * ] where a row represents symbols for a corresponding antenna and a column represents symbols mapped with a subcarrier.