Cross-Layer Design for Two-Way Relaying Networks with Multiple Antennas

In this paper, we developed a cross-layer design for two-way relaying (TWR) networks with multiple antennas, where two single antenna source nodes exchange information with the aid of one multiple antenna relay node. The proposed cross-layer design considers adaptive modulation (AM) and space-time block coding (STBC) at the physical layer with an automatic repeat request (ARQ) protocol at the data link layer, in order to maximize the spectral efficiency under specific delay and packet error ratio (PER) constraints. An MMSE-interference cancellation (IC) receiver is employed at the relay node, to remove the interference in the fist phase of the TWR transmission. The transmission mode is updated for each phase of the TWR transmission on a frame-by-frame basis, to match the time-varying channel conditions and exploit the system performance and throughput gain. Simulation results show that retransmission at the data link layer could alleviate rigorous error-control requirements at the physical layer, and thereby allows higher data transmission. As a result, cross-layer design helps to achieve considerable system spectral efficiency gain for TWR networks, compared to those without cross-layer design.