I. Introduction
THE brain computer interface (BCI) provides a new communication channel for subjects to interact the external world without using their muscles. Electroencephalogram (EEG) based BCI systems analyzed electrical brain activity recorded from electrodes placed the subject's scalp and extract features to determine the intents of the user. Then, translate them into the control signals that are used to control external devices (e.g., an electromechanical arm, a wheelchair) [1], [2].