# TDMR Detection System with Local Area Influence Probabilistic a Priori Detector

## TL;DR

This paper introduces a three-track detection system for TDMR that combines a local area influence probabilistic detector with a trellis-based BCJR detector, significantly improving data density and reducing error rates.

## Contribution

It presents a novel combined detection approach that effectively mitigates intersymbol and intertrack interference in TDMR media, outperforming existing methods.

## Key findings

- Achieves 6.8% density gain for center-track detection.
- Attains 1.2% density gain for three-track detection.
- Lower bit error rates compared to recent two-track BCJR systems.

## Abstract

We propose a three-track detection system for two dimensional magnetic recording (TDMR) in which a local area influence probabilistic (LAIP) detector works with a trellis-based Bahl-Cocke-Jelinek-Raviv (BCJR) detector to remove intersymbol interference (ISI) and intertrack interference (ITI) among coded data bits as well as media noise due to magnetic grain-bit interactions. Two minimum mean-squared error (MMSE) linear equalizers with different response targets are employed before the LAIP and BCJR detectors. The LAIP detector considers local grain-bit interactions and passes coded bit log-likelihood ratios (LLRs) to the channel decoder, whose output LLRs serve as a priori information to the BCJR detector, which is followed by a second channel decoding pass. Simulation results under 1-shot decoding on a grain-flipping-probability (GFP) media model show that the proposed LAIP/BCJR detection system achieves density gains of 6.8% for center-track detection and 1.2% for three-track detection compared to a standard BCJR/1D-PDNP. The proposed system's BCJR detector bit error rates (BERs) are lower than those of a recently proposed two-track BCJR/2D-PDNP system by factors of (0.55, 0.08) for tracks 1 and 2 respectively.