Multi-cell multi-user relaying exploiting overheard signals

Two-way relay analog network coding improves the communication rate of a network with symmetric traffic between two end nodes by combining different transmission flows and exploiting the fact that the self-interference can be cancelled at each node. However, this scheme does not efficiently work in the case of asymmetric traffic between the nodes. We propose a novel scheme for a multi-cell multi-user shared-relay network with asymmetric traffic. By exploiting the overheard signals from the users with uplink messages to the users with downlink messages, we determine the precoding matrices at the base stations and the relay station, and use interference alignment such that all interference signal is suppressed. Numerical results show that the new scheme's performance is better than a corresponding benchmark scheme in terms of sum-rate and user rates.