Adaptive full duplex communications in cognitive radio networks

In this paper we propose a novel adaptive scheme for full duplex communication of secondary users (SUs) in a cognitive radio network. The secondary network operates in three modes; Cooperative Sensing (CS), Full Duplex Transmit and Sensing (FDTS), and Full Duplex Transmit and Receive (FDTR). In the CS mode, SUs detect the activity of primary users (PUs) through a novel cooperative MAC protocol and will decide the system's mode of operation in the subsequent spectrum hole. In the FDTS mode one of the SUs senses the PUs' activity continuously whilst transmitting to another node. In the FDTR mode, SUs communicate bidirectionally in an asynchronous full duplex manner, with decreased collision durations. It is shown that the performance of the proposed protocol in terms of average and maximum collision duration and network throughput outperforms the traditional methods.