Rate-aware three phase analog network coding with low-complexity multi-antenna relay processing

A low-complexity design of multi-antenna relay processing is proposed for two-way relay networks with asymmetric data flows. The proposed scheme adopts three-phase (3P) analog network coding (ANC) which allows orthogonal transmission of two communicating nodes to overcome some disadvantages of two-phase (2P) ANC protocols. For the 3P ANC, we propose antenna selection at the relay to exploit the diversity without channel estimation and rate-aware relay power allocation (RPA) to improve the outage performance under the asymmetric rate requirements. The results show that the proposed scheme without or with RPA outperforms the conventional two-phase ANC significantly in various relay locations. It is also shown that the suboptimal RPA proposed for practical implementation provides a performance close to that of the optimal RPA.