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arXiv · 2504.11131

A Fully Asynchronous Unsourced Random Access Scheme

Mert Ozates·Mohammad Kazemi·Gianluigi Liva·Deniz Gündüz
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Abstract

We investigate fully asynchronous unsourced random access (URA), and propose a high-performing scheme that employs on-off division multiple access (ODMA). In this scheme, active users distribute their data over the transmit block based on a sparse transmission pattern without any limitations on the starting time. At the receiver side, we adopt a double sliding-window decoding approach, utilizing a smaller inner decoding window of two block lengths within a larger outer window to enhance the interference cancellation process. Within the inner window, the receiver iteratively applies preamble-free joint starting time and pattern detection, single-user decoding, and successive interference cancellation operations. A notable feature of the proposed scheme is its elimination of the need for a preamble for starting time detection; this is achieved using ODMA transmission patterns. Numerical results demonstrate that the proposed asynchronous URA scheme outperforms existing alternatives.

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Mert Ozates, Mohammad Kazemi, Gianluigi Liva, Deniz Gündüz. 2025-04-15. A Fully Asynchronous Unsourced Random Access Scheme. https://arxiv.org/abs/2504.11131

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