The Error-Pattern-Correcting Turbo Equalizer

TL;DR

This paper introduces a turbo equalizer with an integrated error-pattern correcting code (EPCC) that significantly reduces the BER floor by targeting low Hamming-weight errors, outperforming conventional methods especially at high rates.

Contribution

The paper proposes a novel TE-EPCC design that corrects dominant error events, providing a theoretical BER floor bound and demonstrating improved SNR gains over existing techniques.

Findings

TE-EPCC achieves lower BER floors than conventional turbo equalizers.

Theoretical bounds confirm SNR gains for various channel conditions.

Superior performance demonstrated for short interleavers and high coding rates.

Abstract

The error-pattern correcting code (EPCC) is incorporated in the design of a turbo equalizer (TE) with aim to correct dominant error events of the inter-symbol interference (ISI) channel at the output of its matching Viterbi detector. By targeting the low Hamming-weight interleaved errors of the outer convolutional code, which are responsible for low Euclidean-weight errors in the Viterbi trellis, the turbo equalizer with an error-pattern correcting code (TE-EPCC) exhibits a much lower bit-error rate (BER) floor compared to the conventional non-precoded TE, especially for high rate applications. A maximum-likelihood upper bound is developed on the BER floor of the TE-EPCC for a generalized two-tap ISI channel, in order to study TE-EPCC's signal-to-noise ratio (SNR) gain for various channel conditions and design parameters. In addition, the SNR gain of the TE-EPCC relative to an existing precoded TE is compared to demonstrate the present TE's superiority for short interleaver lengths and high coding rates.