Interpolated signal processing for echo cancellation, precoding and turbo equalization

Echo cancellation, precoding, and equalization are common signal processing operations performed in wireline communications. For high-speed systems such as digital subscriber line (DSL), the channel response is usually very long and the computational complexity requirement for those operations is very high. In this paper, efficient algorithms based on interpolated filtering are developed to solve the problem. The idea of interpolated filtering is realized with a cascade of an FIR and an interpolated FIR (IFIR) filter, and with a tap-weight overlapping method. The interpolated filtering scheme can effectively reduce the computational complexity while inherits all the numerical stability advantages of the conventional FIR filter. The interpolated filtering framework is then applied to echo cancellation, decision feedback equalization (DFE), and Tomlinson-Harashima precoding (THP). Performance indicates that the complexity of the proposed methods is lower enough such that real-world implementation becomes feasible.