A 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 +aSUB1/SUB.zSUP-1/SUP+aSUB2/SUB.zSUP-2/SUP+aSUB3/SUB.zSUP31 3/SUP+ . . . +aSUBn/SUB.zSUP-n/SUP)/( 1 +bSUB1/SUB.zSUP-/SUP+bSUB2/SUB.zSUP-2/SUP+bSUB-3/SUB.zSUP-3/SUP+ . . . +bSUBp/SUB.zSUP-p/SUP). 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.