Unsourced Random Access with a Massive MIMO Receiver Using Multiple Stages of Orthogonal Pilots

TL;DR

This paper introduces a novel unsourced random access scheme for massive MIMO systems using multiple stages of orthogonal pilots and polar coding, significantly improving decoding performance over existing methods.

Contribution

The paper proposes a new multi-stage orthogonal pilot scheme combined with polar coding and iterative decoding for URA in MIMO channels, demonstrating superior performance.

Findings

Significant performance gains over existing URA methods.

Effective iterative decoding with successive interference cancellation.

Robustness in Rayleigh block-fading channels.

Abstract

We study the problem of unsourced random access (URA) over Rayleigh block-fading channels with a receiver equipped with multiple antennas. We employ multiple stages of orthogonal pilots, each of which is randomly picked from a codebook. In the proposed scheme, each user encodes its message using a polar code and appends it to the selected pilot sequences to construct its transmitted signal. Accordingly, the received signal consists of superposition of the users' signals each composed of multiple orthogonal pilot parts and a polar coded part. We use an iterative approach for decoding the transmitted messages along with a suitable successive interference cancellation scheme. Performance of the proposed scheme is illustrated via extensive set of simulation results which show that it significantly outperforms the existing approaches for URA over multiple-input multiple-output fading channels.