Fully Asynchronous Unsourced Random Access over Fading Channels
Abstract
We examine unsourced random access in a fully asynchronous setup, where active users transmit their data without restriction on the start time over a fading channel. In the proposed scheme, the transmitted signal consists of a pilot sequence and a polar codeword, with the polar codeword distributed across the data part of the packet in an on-off pattern. The receiver uses a double sliding-window decoder, where the inner window employs iterative decoding with joint timing and pilot detection, channel estimation, single-user decoding, and successive interference cancellation to recover the message bits, while the outer window enhances interference cancellation. The numerical results indicate that the proposed scheme exhibits only a slight performance loss compared to the synchronous benchmark while being more applicable in practice.
Cite
@article{arxiv.2512.19468,
title = {Fully Asynchronous Unsourced Random Access over Fading Channels},
author = {Mert Ozates and Mohammad Kazemi and Gianluigi Liva and Deniz Gündüz},
journal= {arXiv preprint arXiv:2512.19468},
year = {2025}
}