An improved algorithm for classification of MDPSK signals based on cumulants is presented in this paper

which is robust to the error of the carrier synchronization.The new algorithm uses the corresponding relationship between signal difference phase constellation and higher order cumulants.From the relationship a new feature is derived.The feature is invariant with respect to constellation scale

rotation

the shift and the carrier frequency offset between transmitter and receiver.The invariant property of the feature is proved in theory.The simulation results show that the new classification algorithm is high in performance.