Non-linear lattice precoding for multiuser cellular two-way relay channels

This paper considers transceiver design for the cellular two-way relay channel (cTWRC), where a multi-antenna base station (BS) exchanges information with multiple single-antenna mobile stations via a multi-antenna relay station. We propose a novel network coding scheme to approach the sum capacity of the cTWRC. Specifically, a new non-linear lattice-based precoding technique is proposed at the BS to pre-compensate the inter-stream interference, in order to allow efficient interference-free lattice decoding at the relay. We derive sufficient conditions for the proposed scheme to asymptotically achieve the sum capacity of the cTWRC in the high signal-to-noise ratio (SNR) regime. Numerical results show that the proposed scheme outperforms the existing schemes and is able to asymptotically achieve the cut-set bound of the cellular relay networks.