Trust Degree-Based Cooperative Transmission for Communication Secrecy

For communication secrecy, we develop the cooperative transmission strategies by taking into account the degree of trust between users as well as physical wireless channels. For a given trust degree information, we derive an optimal power allocation for confidential message and jamming signal to maximize an expected secrecy rate with respect to the trust degree information. In order to further increase the expected secrecy rate, by adopting cooperative transmission via user relaying, we derive the optimal transmission strategy and corresponding power allocation based on the trust degree information. Our analytical and numerical results show that the proposed strategies achieve substantially higher secrecy rates than that without exploiting the trust degree information of users.