Robust Tomlinson-Harashima Precoding

Tomlinson-Harashima precoding (THP) for a wireless system with multiple cooperative transmitters and non-cooperative receivers is considered (downlink channel). In the literature THP has been optimized for this channel assuming complete channel state information (CSI). But quality of CSI is generally poor at the transmitter due to the time-varying channel. We present a robust optimization of THP and a combined optimization of THP and channel estimation, which take into account the quality of CSI. They yield a significantly improved robustness towards errors in CSI