By employing spectrum sensing and frequency-domain spreading, cognitive-CDMA systems allow users to interact with surrounding environment and transmit signal over clean and non continuous spectrum bands . The idea of cognitive - CDMA is oriented from transform domain communication systems (TDCS), which have been widely used as a CR overlay technology [6]–[10]. The basic idea behind TDCS aims to dynamically synthesis a smart waveform based on the knowledge of surrounding environment [11]–[14].