A Multi-user Identification Method based on Power Superposition for Unsourced Random Access

We propose a power superposition-based multi-user identification scheme in unsourced random access (URA) scenarios, which is able to identify users by attaching power coefficients to them. We use a specific set of powers, and the users randomly select one of the powers to transmit their messages. We have proved that, without repeated power selection, the set of superposition symbols corresponds to the power selection, so the receiver can identify the user well. We also propose a low-complexity estimation scheme by power estimation from received message sequence.