  Most of the non-linear transceivers, which are based on Tomlinson Harashima
(TH) precoding and have been proposed in the literature for two-way relay
networks, assume perfect channel state information (CSI). In this paper, we
propose a novel and robust TH precoding scheme for two-way relay networks with
multiple antennas at the transceiver and the relay nodes. We assume imperfect
CSI and that the channel uncertainty is bounded by a spherical region.
Furthermore, we consider the sum of the mean square error as the objective
function, under a limited power constraint for transceiver and relay nodes.
Simulations are provided to evaluate the performance and to validate the
efficiency of the proposed scheme.
