Enhanced Codebook Assisted Tomlinson-Harashima Precoding with Low Feed-Forward Overhead

Tomlinson-Harashima precoding (THP) with tilted constellation (THP-TC) is being noted for an efficient method to reduce the transmission power and enhance the performance of THP. However, THP-TC requires heavy feed-forward overhead to inform the receivers the rotation angles for each symbol. In this paper, for enhancing the performance and alleviating the heavy feed-forward of THPTC, we propose a class of Tomlinson-Harashima precoding schemes assisted with codebook (THP-CB) to help the processing of angle selection and signal rotation jointly for the transmit signals. The simulation results show that the proposed THP-CB schemes achieve significant performance improvement than the conventional counterparts. Furthermore, we show that the proposed THP-CB reduces more than 90% of the feed-forward overhead, while remaining identical transmission performance to conventional THPTC.