Confidential Cooperative Communication With Trust Degree of Potential Eavesdroppers

Abstract

For a confidential communication, we develop the transmission strategies by taking into account trust degree among users, which shows how much a user can be trusted in terms of an eavesdropping attack. For a single potential eavesdropper (PE) case, we derive an optimal power allocation for confidential message and jamming signal to maximize an expected secrecy rate with respect to the trust degree. In order to further increase the expected secrecy rate, by exploiting relaying transmission via PE, we derive the optimal transmission strategy and corresponding power allocation based on the threshold of trust degree. Furthermore, to investigate the effect of the accuracy of trust degree, we analyze the expected secrecy rate loss caused by an estimation error of the trust degree and provide the robust power allocation based on imperfect trust degree. Finally, we extend the results to the case of confidential communication in the presence of multiple PEs. Our analytical and numerical results show that the proposed strategies achieve substantially higher secrecy rates than that without exploiting the trust degree of users.