Secrecy in MIMO Gaussian bidirectional broadcast channels

Recent research developments show that the concept of bidirectional relaying significantly improves the performance in wireless networks. This applies to three-node networks, where a half-duplex relay node establishes a bidirectional communication between two other nodes using a decode-and-forward protocol. In this work we assume multiple transmit and receive antennas and consider the scenario when in the broadcast phase the relay transmits additional confidential information to one node, which should be kept completely secret from the other, non-intended node. This is the MIMO Gaussian bidirectional broadcast channel with confidential messages for which we establish the secrecy capacity region.