Secret Key Region in Multiple Antenna Wiretap Interference Channels with Public Discussion

Physical layer security recently gained increased attention because it can provide different levels of security without the need for complicated infrastructure or complex cryptographic algorithms. In this paper, we consider a multiple antenna interference channel with confidential messages in which a public discussion channel is available. The receivers can reliably but publicly communicate with their transmitters. First, we derive an achievable secret key region. This region can improve the achievable secrecy rate region. Then the optimal transmit beamforming vectors achieving efficient operating points are characterized. Finally, the non-cooperative transmit strategy problem is studied for a specifically designed utility function for which there exists a unique Nash equilibrium in dominating strategies. Interestingly, the secret key rate region is not necessarily larger than the secrecy rate region (in contrast to single-user systems).