Robust physical layer service integration in bidirectional relay networks: Common messages

The efficient integration of multiple services at the physical layer is a key technique to improve the overall performance of next generation wireless networks. Further, a robust system design is inevitable, since channel uncertainty is a ubiquitous phenomenon, which becomes even worse if resources are shared with other coexisting systems inducing unknown interference. Here we consider robust physical layer service integration in bidirectional relay networks, where a relay node establishes a bidirectional communication between two other nodes using a decode-and-forward protocol. In the broadcast phase the relay efficiently integrates additional multicast services at the physical layer, which requires the study of the bidirectional broadcast channel with common messages. We establish the corresponding capacity regions for compound and arbitrarily varying channels.