# Non-Stationary Polar Codes for Resistive Memories

## TL;DR

This paper introduces non-stationary polar codes tailored for resistive memories, addressing reliability issues caused by wire resistance and sneak paths, and demonstrates their effectiveness through simulations.

## Contribution

It proposes a novel non-stationary polar coding framework for resistive memories and techniques to improve BER performance considering different channel models.

## Key findings

- Significant BER reduction achieved in simulations
- Effective biasing of high-resistance states improves reliability
- Framework applicable to BSC and BSC channel models

## Abstract

Resistive memories are considered a promising memory technology enabling high storage densities with in-memory computing capabilities. However, the readout reliability of resistive memories is impaired due to the inevitable existence of wire resistance, resulting in the sneak path problem. Motivated by this problem, we study polar coding over channels with different reliability levels, termed non-stationary polar codes, and we propose a technique improving its bit error rate (BER) performance. We then apply the framework of non-stationary polar codes to the crossbar array and evaluate its BER performance under two modeling approaches, namely binary symmetric channels (BSCs) and binary asymmetric channels (BSCs). Finally, we propose a technique for biasing the proportion of high-resistance states in the crossbar array and show its advantage in reducing further the BER. Several simulations are carried out using a SPICE-like simulator, exhibiting significant reduction in BER.