A Retransmission based Collision Solution for Cognitive Radio Networks

In cognitive radio (CR) networks, the secondary users are allowed to use the licensed frequency bands of the primary users (PUs) when these bands are vacant. However, once the PUs come back, they may collide with the transmitting secondary users. Therefore, the secondary users are generally required to sense the channel periodically to ensure that the primary users are absent during their data transmission in order to avoid the collisions with primary users. In this paper, we first analyze the performance of the periodic sensing scheme. Then retransmission scheme based on the cooperation of the primary base station(PBS) and secondary access point (AP) associated with Independent Component Analysis (ICA) algorithm is proposed, which relieves the impact of packet loss for primary users, while improving the transmission efficiency for secondary users. The computer simulation shows that under the limited spectrum access chances, the proposed scheme outperforms periodical sensing schemes.