Mutual Information of Buffer-Aided Full-Duplex Relay Channels

We derive the mutual information (MI) of the wireless links in a buffer-aided full-duplex (FD) multiple-input multiple-output (MIMO) relaying network. The FD relay still suffers from residual selfinterference (RSI), after the application of self-interference mitigation techniques. We investigate both cases of the slow-RSI channel, where the RSI is fixed over the entire codeword, and the fast-RSI channel, where the RSI changes from one symbol duration to another within the codeword. We show that the RSI can be completely eliminated when the FD relay is equipped with a buffer in the case of slow RSI. In the case of fast RSI, the RSI cannot be eliminated. Closed-form expressions for the links’ MI are derived under both RSI scenarios. For the fixed-rate data transmission scenario, we derive the optimal transmission strategy that should be adopted by the source and relay nodes to maximize the system throughput. We verify our analytical findings through simulations.