Patent ID: 7844011

Claim:
An apparatus for improving a symbol error rate of an M-ary phase shift keying (M-PSK) system having a quadrature error, the apparatus comprising: a conversion parameter detector that detects a conversion parameter for converting a symbol decision region using the quadrature error and at least one pair of first received symbols; and a converter & determiner converting a pair of second received symbols using the detected conversion parameter, and determining a transmission symbol according to a symbol of the converted pair of second received symbols, wherein the conversion parameter detector comprises: a first transmission symbol estimator estimating the pair of received symbols of a transmission symbol having an in-phase component only among the at least one pair of first received symbols; and a conversion parameter determiner determining an angle between an in-phase symbol average value of the estimated pair of symbols and a quadrature symbol average value as the conversion parameter, wherein the first transmission symbol estimator comprises: a first symbol converter converting the pair of first received symbols (X n ,Y n ) using equation, [ Y ⁢ ⁢ 1 Y ⁢ ⁢ 2 ] = [ - sin ⁡ ( - π M + y ) cos ⁡ ( - π M + y ) - sin ⁡ ( π M + y ) cos ⁡ ( π M + y ) ] ⁡ [ X n Y n ] , wherein y denotes the quadrature error, and M denotes a modulation level of the PSK system; and a transmission symbol determiner determining the pair of received symbols that make Y1 and Y2 positive and negative values, respectively, as a pair of received symbols of the transmission symbol having an in-phase component only.