Polar Coding and Sparse Spreading for Massive Unsourced Random Access

TL;DR

This paper introduces a novel polar coding scheme with sparse spreading for massive unsourced random access, achieving better performance and lower complexity than previous methods, especially for large active user counts.

Contribution

The paper presents a new polar coding scheme combined with sparse spreading and SIC for unsourced random access, improving performance and reducing complexity.

Findings

Outperforms previous schemes for active users $K_a extgreater= 250$

Provides competitive performance for $K_a extless= 225$

Has significantly lower complexity due to single-user polar coding

Abstract

In this paper, we propose a new polar coding scheme for the unsourced, uncoordinated Gaussian random access channel. Our scheme is based on sparse spreading, treat interference as noise and successive interference cancellation (SIC). On the transmitters side, each user randomly picks a code-length and a transmit power from multiple choices according to some probability distribution to encode its message, and an interleaver to spread its encoded codeword bits across the entire transmission block. The encoding configuration of each user is transmitted by compressive sensing, similar to some previous works. On the receiver side, after recovering the encoding configurations of all users, it applies single-user polar decoding and SIC to recover the message list. Numerical results show that our scheme outperforms all previous schemes for active user number $K_a\geq 250$, and provides competitive performance for $K_a\leq 225$. Moreover, our scheme has much lower complexity compared to other schemes as we only use single-user polar coding.