Joint applications of Tomlinson-Harashima precoding and interference alignment in amplify-and-forward multi-relay cellular networks

This paper proposes a downlink multi-user transmission scheme for the amplify-and-forward (AF)-based multi-relay cellular network, in which Tomlinson-Harashima precoding (TH precoding) and interference alignment (IA) are jointly applied. The whole process of transmission is divided into two phases: TH precoding is first performed at base-station (BS) to support the multiplexing of data streams transmitted to both mobile-stations (MS) and relay-stations (RS), and then IA is performed at both BS and RSs to achieve the interference-free communications. During the whole process, neither data exchange nor strict synchronization is required among BS and RSs, thus reducing the system complexity as well as improving the system performance. Our analysis and simulation results show that the joint applications of TH precoding and IA outperforms other schemes in multi-relay framework.