Cooperative Interference and Power Allocation in a Bidirectional Untrusted Relay Network With Channel Estimation Errors

The secure communication of a two-way untrusted amplify-and-forward relay network under the imperfect channel state information is investigated. To improve the secrecy of the relay wiretap system, artificial noise is introduced into each source signal. The total and the individual power constraint conditions are considered. To maximize the attainable secrecy rate, an iterative power allocation algorithm is designed under the total power constraint. As a more practical system design, a suboptimal power allocation scheme is proposed. For the sake of comparison, the security performances of the noncooperative interference strategy and the one-way cooperative interference strategy are also investigated. Simulation results demonstrate that the proposed bidirectional cooperative interference schemes perform better in the secrecy rate of communication system.