# Design and Decoding of Polar Codes for the Gaussian Multiple Access Channel

## TL;DR

This paper explores polar code-based NOMA schemes for 5G mMTC, proposing an efficient code design algorithm and demonstrating performance improvements over LDPC solutions in Gaussian MAC scenarios.

## Contribution

It introduces a novel polar code design algorithm for NOMA in GMAC and compares decoding techniques, showing improved performance over existing LDPC-based methods.

## Key findings

- Polar codes outperform LDPC by ~1 dB in GMAC.
- The proposed design approaches the theoretical capacity bounds.
- Joint decoding techniques enhance scheme performance.

## Abstract

Massive machine-type communications (mMTC) is one of the key application scenarios for future 5G networks. Non-orthogonal multiple access (NOMA) is a promising technique for the use in mMTC scenario. In this paper, we investigate NOMA schemes based on polar codes. We compare two possible decoding techniques: joint successive cancellation algorithm and joint iterative algorithm. In order to optimize the codes (choose frozen bits) we propose a special and efficient design algorithm. We investigate the performance of the resulting scheme in the Gaussian multiple access channel (GMAC) by means of simulations. The scheme is shown to outperform LDPC based solution by approximately 1 dB and to be close to the achievability bound for GMAC.