An opportunistic cooperative transmission scheme and its BER performance in Cognitive Networks

Cognitive radio (CR), promote the efficient utilization of the licensed spectrum, and solve the problem of increasing demands for the wireless radio spectrum with the emergency of many new wireless communication networks. In this paper, we against a backdrop of cognitive radio technology, proposed a new opportunistic cooperative transmission scheme based on AF combining spectrum sensing and data transmission in Cognitive Networks (CNs). Besides, closed-form expressions of BER (bit error ratio) of secondary user for the proposed opportunistic cooperative transmission scheme and tradition non-cooperative scheme are presented over Rayleigh fading channels. Then, numerical simulations are conducted to compare our scheme with the non-cooperative transmission, showing the merits of the proposed opportunistic cooperative transmission in terms of BER, and transmission performance of secondary user in CNs can be improved without interfering the regular transmissions of the primary users (PU).