Modified Tomlinson-Harashima precoding method circuit for infinite impulse response (IIR) channels

摘要

A precoding circuit for minimizing distortion of an input signal in a communication channel having a compound transfer function in the Z-Domain: H(z)=( 1 +a₁.z^-1+a₂.z^-2+a₃.z^{31 3}+ . . . +a_n.z^-n)/( 1 +b₁.z^-+b₂.z^-2+b_-3.z^-3+ . . . +b_p.z^-p). A feedback circuit comprises a first FIR filter and a transfer function corresponding to the inverse of a feedforward part of a transfer function of the communication channel. A feedforward circuit comprises a second FIR filter and a transfer function corresponding to the inverse of a feedback part of a transfer function of the communication channel. A first subtracting circuit subtracts a feedback signal of the feedback circuit from a feedforward signal of the feedforward circuit and outputs a difference signal which is added to a transmit end signal by a first adding circuit. The difference signal is also added to the input signal by a second adding circuit, the output from the second adding circuit is fed to a quantizing circuit which outputs a value kM which is subtracted from the input signal by a second subtracting circuit.