We study the half-duplex Gaussian two-way relay channel with direct user-to-user links. In this setup, two users exchange data via a relay and via direct user-to-user links. Due to the half-duplex constraint, the channel can be in one of eight different states at any time (two of which are useless: no node transmitting and no node listening). Restricting to only four states, we propose a scheme that utilizes lattice codes to improve upon existing four-state schemes. Using all six states, we propose another scheme that utilizes lattice codes and coherent combining, and show that it can outperform existing schemes.
2015 IEEE International Symposium on Information Theory (ISIT). Proceedings of the 2015 IEEE International Symposium on Information Theory (ISIT) (Hong Kong, China 14-19 June, 2015) p. 1891-1895