Massive Unsourced Random Access over Rician Fading Channels: Design, Analysis, and Optimization

TL;DR

This paper proposes a novel unsourced random access scheme for 6G mMTC over Rician fading channels, featuring a new detection algorithm and optimized message length allocation, validated through extensive simulations.

Contribution

It introduces a new codeword activity detection algorithm based on ML and Fisher Information, and an optimization scheme for message and parity bit allocation in Rician fading scenarios.

Findings

The proposed detection algorithm outperforms existing methods.

Optimized length allocation improves error probability and complexity balance.

Simulation results confirm the effectiveness of the proposed schemes.

Abstract

In this paper, we investigate an unsourced random access scheme for massive machine-type communications (mMTC) in the sixth-generation (6G) wireless networks with sporadic data traffic. Firstly, we establish a general framework for massive unsourced random access based on a two-layer signal coding, i.e., an outer code and an inner code. In particular, considering Rician fading in the scenario of mMTC, we design a novel codeword activity detection algorithm for the inner code of unsourced random access based on the distribution of received signals by exploiting the maximum likelihood (ML) method. Then, we analyze the performance of the proposed codeword activity detection algorithm exploiting Fisher Information Matrix, which facilitates the derivative of the approximated distribution of the estimation error of the codeword activity vector when the number of base station (BS) antennas is sufficiently large. Furthermore, for the outer code, we propose an optimization algorithm to allocate the lengths of message bits and parity check bits, so as to strike a balance between the error probability and the complexity required for outer decoding. Finally, extensive simulation results validate the effectiveness of the proposed detection algorithm and the optimized length allocation scheme compared with an existing detection algorithm and a fixed length allocation scheme.