Rate Balancing Based Tomlinson–Harashima Precoding for G.Fast Systems

Abstract

Due to the much higher crosstalk impairing in G.fast high-frequency channels compared with digital subscriber line low-frequency channels, the nonlinear Tomlinson–Harashima precoding (THP) has a good potential to enhance the G.fast system performance. However, ordering plays an important role for the data rate performance in THP. The users precoded earlier experience enhanced data rate performance, while the users precoded later are punished with lower data rates. This would be undesirable from the service providers’ point of view. In this letter, a systemic rate balancing method named projected sorting is developed by sorting the G.fast lines with respect to the projected channel vectors. Simulation results show that the proposed projected sorting can achieve performance among users in a more controlled way.