Browse Prior Art Database

Equalization of Non-Linear Channels

IP.com Disclosure Number: IPCOM000017128D
Publication Date: 2003-Jul-22
Document File: 5 page(s) / 153K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method that introduces a new equalizer structure to digitally post compensate non-linear Inter-Symbol Interference (ISI). Benefits include the ability to equalize channels that suffer from both non-linear distortion and linear dispersion.

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Equalization of Non-Linear Channels

Disclosed is a method that introduces a new equalizer structure to digitally post compensate non-linear Inter-Symbol Interference  (ISI). Benefits include the ability to equalize channels that suffer from both non-linear distortion and linear dispersion.

Background

Non-linear ISI cannot be optimally compensated with conventional Feed Forward Equalizers (FFE’s) or Decision Feedback Equalizers (DFE’s).  These conventional equalizers were intended to compensate for linear ISI only.

Often data, x, transmitted through a non-ideal channel is received as a corrupted signal, y, and is unrecoverable without equalization. Thus receiver designers often use a Linear Feed Forward Equalizer that consists of a linear Finite Impulse Response (FIR) filter for a Feed Forward Filter (FFF). See Figure 1. To initialize this filter, one must find a set of coefficients, wf, which Minimizes the Mean Square Error (MMSE) between the equalized and transmitted waveform. 

To implement this equalizer, the coefficients, wff, are applied to a FIR filter (see Figure 2). Figure 2 assumes a three tap FIR filter functions as the FFF shown in Figure 1.

On other occasions, receiver designers use a DFE that consists of a two linear FIR filters – one for a FFF and one for a Feed Back Filter (FBF). See Figure 3. To initialize this filter, one must find a set of coefficients, w, which minimizes the MSE between the equalized and transmitted waveform. The coefficients wff are applied to a FIR filter in the location of the FFF and the coefficients wfb are applied to a FIR filter in the location of the FBF shown in Figure 3.

General Description

The disclosed method uses Volterra non-linear f...