Turning interference weakness into PHY security enhancement for cognitive radio networks

Traditionally, the transmitting power of secondary users (SUs) in the cognitive radio (CR) network is limited under a certain threshold, since it is harmful for primary user´s (PU) channel capacity. However, when it comes to PU´s secrecy capacity, the transmitting power may be either harmful or beneficial. On one hand, the attendance of SUs in the CR network can be threatened to PU´s main channel and decreases PU´s secrecy capacity. On the other hand, the signals transmitted by SUs can also decrease the wire-tap channel capacity, and therefore improves PU´s secrecy capacity. In order to find the tradeoff, by modeling this scenario as a coalition formation game, we apply the “merge” and “split” algorithm to select the appropriate SUs which are beneficial to PU´s secrecy capacity. The simulation results verify the efficiency of the proposed algorithm in various scenarios.