Patent ID: 7756001

Claim:
A symbol decision apparatus of a M-ary phase shift keying (M-PSK) system, the apparatus comprising: a linear transform unit performing linear transform, to which a phase error is applied, of a received pair of symbols, wherein the linear transform unit transforms the pair of received symbols (Xn,Yn) according to the following equation: [ U i V i ] = [ - sin ⁡ ( π ⁡ ( 2 ⁢ i - 3 ) M + Ψ ) cos ⁡ ( π ⁡ ( 2 ⁢ i - 3 ) M + Ψ ) - sin ⁡ ( π ⁡ ( 2 ⁢ i - 1 ) M + Ψ ) cos ⁡ ( π ⁡ ( 2 ⁢ i - 1 ) M + Ψ ) ] ⁡ [ X n Y n ] where i is a transmitted symbol index having a value among 1, . . . , M, M is the level of modulation of the PSK system, and ψ is the estimated phase error; and a symbol decision unit deciding a transmitted symbol corresponding to the received pair of symbols according to the sign value of the transformed symbol pair, wherein the symbol decision unit decides an i-th transmitted symbol if the transformed symbols (Ui,Vi) of the pair are a positive number and a negative number, respectively.