  We consider the broadcast phase of a three-node network, where a relay node
establishes a bidirectional communication between two nodes using a spectrally
efficient two-phase decode-and-forward protocol. In the first phase the two
nodes transmit their messages to the relay node. Then the relay node decodes
the messages and broadcasts a re-encoded composition of them in the second
phase. We consider Gaussian MIMO channels and determine the capacity region for
the second phase which we call the Gaussian MIMO bidirectional broadcast
channel.
