Capacity Bounds for Two-Way Relay Channels

The authors provide achievable rate regions for Two-way Relay Channels (TRC). At first, for a binary TRC, they show that the subspace-sharing of linear codes can achieve the capacity region. And, for a Gaussian TRC, they propose the subset-sharing of lattice codes. In some cases, the proposed lattice coding scheme can achieve within 1/2-bit the capacity and is asymptotically optimal at high Signal-to-Noise Ratio (SNR) regimes. They consider Two-way Relay Channels (TRC) as Nodes 1 and 2 want to exchange messages with each other only through a relay node. There is no direct communication link between them, and all nodes operate in full-duplex mode.